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DIY Stompboxes => Building your own stompbox => Topic started by: nickbungus on March 09, 2015, 05:25:25 PM

Title: What Does the Foxx Phase?
Post by: nickbungus on March 09, 2015, 05:25:25 PM
Hi Guys

This is my first attempt at anything like this so please go easy on me, but after a few months making a few distortions, treble boosters and the Causality phaser, I decided to try my hand at creating a layout.  Being a super massive Queen / Brian May fan, I've always loved his 70s tone and especially the Foxx Phaser.  Given the number of BM tone sims, Deacy Amps etc available I was shocked that I couldn't find a layout for the Foxx.  The schematic is available on DIYStompboxes but no PCB, Vero or perf layout.




So after many hours of grafting and so many failed attempts, I believe I have something.  Please note, I haven't made it myself as I do have a host of questions I hope some-one can help me with.

The Schematic...
(http://dirtmonkey.org/foxx/FoxxPhaser.jpg)

IT IS UNVERIFIED!!
(http://dirtmonkey.org/foxx/FoxyLayout.png)

(http://dirtmonkey.org/foxx/FoxyPcbMask.png)

And heres the BOM
http://dirtmonkey.org/foxx/FoxBom.csv (http://dirtmonkey.org/foxx/FoxBom.csv)
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on March 09, 2015, 05:40:44 PM
So my questions are...

1.  I can't get the original transistors so I ordered 100x J112 for Fet matching, will they work.  I have based this guess on the following:
(http://dirtmonkey.org/foxx/Fets.png)

2.  I'm not sure on what diodes to use.  I've seen a few phasers (Mr Multi and MXR100 I think), have a zener in them.  I can't see one on the Foxx schematic so I was going to socket these and try 1n4148s for all except D1 which I was going to place a 1N4001. 

3.  Not being an electronics engineer with 0 training, I got a bit confused in the schematics with the 9v, 6v and 1.8v nets.  Can anyone confirm if I got these right in my layout.

4. Lastly, the Opamps I went for were the ones recommended by Digi2it, he recommended LM324's as used in a layout for the Korg Mr Multi you can find on this forum.  I've gone for this for all three opamps, is this right?

I will be etching this week so I'll keep this post posted.
Title: Re: What Does the Foxx Phase?
Post by: Mark Hammer on March 09, 2015, 07:25:09 PM
Took me a bit, but I finally got the pun.  Nicely played!  :icon_lol:
Title: Re: What Does the Foxx Phase?
Post by: Digital Larry on March 09, 2015, 09:30:02 PM
The 1.8V bias at the op-amp at the upper left is going to make the signal distort on one side pretty abruptly.  I'm not familiar with this device - is that part of the sound?
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on March 10, 2015, 05:17:01 AM
Thanks Larry

There is a 1.8v bias going into pin 12 on Opamp 2 and Opamp 3, as well as 3, and 10 on Opamp3.  Oh and 10 on Opamp 2!

Heres a Youtube clip of a guy playing one with a clean tone:

.

The Schematic was posted by Greg Covington of Covington Effects http://www.covingtonguitareffects.net/Products.html (http://www.covingtonguitareffects.net/Products.html).  I know he was making and selling a variation of these without the treadle pedal a few years back, so I'm hoping the schematic is correct.
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on March 10, 2015, 05:47:22 AM
LM324 can work all the way to ground, so 1.8V bias gives 3.6v p-p signal before clipping. Should be enough?
Title: Re: What Does the Foxx Phase?
Post by: antonis on March 10, 2015, 06:11:26 AM
Propably "m" for capacitors refer to "μ" (or "u" for those who haven't Greek keyboard)... :icon_eek:

Title: Re: What Does the Foxx Phase?
Post by: nickbungus on March 10, 2015, 06:16:53 AM
Thanks Antonis, I got the mfd for microfarads in my BOM.

AnotherJim, are you saying the LM324's should be fine here?
Title: Re: What Does the Foxx Phase?
Post by: digi2t on March 10, 2015, 06:35:07 AM
Propably "m" for capacitors refer to "μ" (or "u" for those who haven't Greek keyboard)... :icon_eek:



My Dad's got one. He get's his mu on.  :icon_mrgreen:

What?
Title: Re: What Does the Foxx Phase?
Post by: Mark Hammer on March 10, 2015, 08:26:04 AM
Propably "m" for capacitors refer to "μ" (or "u" for those who haven't Greek keyboard)... :icon_eek:



My Dad's got one. He get's his mu on.  :icon_mrgreen:

What?

Given your own age, I'm assuming that you either have one VERY hip dad (should he own a Foxx Phaser), or you mean he has a Greek keyboard.  :icon_mrgreen:
Title: Re: What Does the Foxx Phase?
Post by: GGBB on March 10, 2015, 11:21:38 AM
µ = Alt-0181 for Windows users (although it doesn't work in all software - Inkscape being one program I know of).
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on March 10, 2015, 12:55:51 PM
It would make a lot of sense for the amps to be LM324's given that low bias voltage.

It's an odd looking Schmitt/Integrator that LFO - the diodes and the centre tap on the bank of switch-able timing caps. Looks more complex than needs to be - unless there's something special about the waveform? Would love to see a 'scope trace.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on March 10, 2015, 04:45:43 PM
Anotherjim, I don't know what you just said but you are my hero.  Do you think the J112's will be ok if I match them, instead of the original PN4302's?  If I get one working I would happily send it down to Wales so you can do a scope trace!
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on March 10, 2015, 04:57:09 PM
I've modified the layout - fewer jumpers and also smaller.  I've binned the jumpers I had on the signal path and now I'm just using them for the power lines.
Title: Re: What Does the Foxx Phase?
Post by: Tony Forestiere on March 10, 2015, 06:22:03 PM
I've binned the jumpers I had on the signal path...

Even the nice ones?  :o
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on March 10, 2015, 06:30:56 PM
It looks like the J122 should do it. You have a trimmer R39 that should help. Matching them would give the best chance of a good phase effect.

Socket the IC's!
Thing with the LM324 is, it was designed to work all the way to ground, which is good for many non-audio path jobs. Most op-amp outputs swing within about a volt of either supply, but the 324 can swing almost exactly to ground, however, it pays for this by not being able to swing very close to the + supply. Expect within about 1.5v of the + supply voltage. This doesn't mean that it can't be used in the audio path - it can and often is, but the asymmetric output swing has to be considered. The phase shift amps have 6volts bias, so this is close to clipping at the positive swing.

The first amp the signal gets to actually reduces the guitar signal by almost a 1/3rd (100k/270k), so this design doesn't want a big signal at all (9volt JFET phasers are notorious for distortion with strong signals), so I'd expect the LM324 would still be ok for headroom except with a run down battery, and you'll probably use an external 9volt feed anyway.

"If I get one working I would happily send it down to Wales so you can do a scope trace!"
Sure, if it has a passport  :icon_lol:

Title: Re: What Does the Foxx Phase?
Post by: anotherjim on March 11, 2015, 01:00:21 PM
Another reason to conclude the intended amps for it are LM324. This chip is subject to crossover distortion. Biasing the signal off-centre is a cure  - hence the 1.8v or 6v biasing level with a 9v supply instead of the usual 4.5v.

Title: Re: What Does the Foxx Phase?
Post by: vigilante397 on March 11, 2015, 01:10:25 PM
I've binned the jumpers I had on the signal path...

Even the nice ones?  :o

And you've made me laugh in the middle of my math class. I just had to explain to those around me that triple integrals aren't actually that funny :P
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on March 12, 2015, 03:45:53 AM
AnotherJim, thank you again!  I've made my FET testing circuit and I'm ploughing through 100 J112s! 

One last question if possible?  The Fet biasing trimmer is not rated, any ideas as to what I should try?  Also, the diodes aren't rated in the schematic either, do you think I can get away with 1n4148s?
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on March 12, 2015, 05:17:30 AM
Sorry Jim, that's 2 questions.
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on March 12, 2015, 07:19:00 AM
FET trimmer, I guess somewhere between 3 to 4 volts. Depends on Vgs of FET's. I think if you know Vgs then bias would be about half of that below the 6v supply. So, Vgs=-4v, then bias = +4v.
Diodes as 1N4148's should be fine.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on March 12, 2015, 11:10:12 AM
Superstar Jim.  With the trimmer I meant in terms of resistance but that's also super helpful.  I bought some Bourns 10k, 100ks and some 1Ms.  Actually, I'll socket it and see which gives me the most control for achieving the 3-4 volts.
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on March 12, 2015, 12:52:47 PM
It's a potentiometer, so the value won't affect the range of voltage out, only the amount of current it's using from the 6volt supply. It's only supplying an amp pin which is almost negligible current, so 100k is probably a good choice. 1M might be noisy and 10k is just wasting a little current, but they're all workable choices.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on March 20, 2015, 06:41:10 PM
(http://www.dirtmonkey.org/foxx/Ow.jpg)

Just a quick note to AnotherJim.  Thanks for all your help, its been really appreciated.  The reason for the lack of progress, if you see the image above is, some idiot broke my thumb, breaking off a bit of bone attached to the tendon (an unnecessary accident but another story).

This has hampered progress a little.  Not sure if its shit skills or a broken bone but I've etched the PCB 3 times but drilling is a bit of an obstacle.   

Anyway, the Foxx will Phase Again!!
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on March 20, 2015, 06:51:30 PM
Also I bought a 100 J112's for this build and matched them so if anyone wants to try a phaser build with some, then send me your details and I'll post 4, 6 or 8 matched ones to you.   
Title: Re: What Does the Foxx Phase?
Post by: 1878 on March 22, 2015, 12:14:54 PM
I was just about to start a thread on this !!

I'm going through a 'conflict of phase' at the moment, I just can't seem to get my phase right. I've had a Nano Stone for a few years & I built a Phaseur Fleur a couple of years ago. I've recently borrowed a few different phasers but none of them cut it. My favourite phase sound is Brian May/Foxx Phaser, but I couldn't give all that space up on my board.

I will be watching this with great interest.

Best of luck !!

p.s. !! CHEEKY MONKEY ALERT !! I'd gladly purchase an undrilled PCB from you if you fancy knocking one up. P.M me if you're interested.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on March 23, 2015, 06:46:56 AM
Hi 1878, I'd gladly sort out a PCB for you.  My PCB etching is probably my best skill as my soldering is woeful and I've also got a hell of a lot of matched transistors that I can send too.  I'd wait a bit though as I haven't verified this. 

I've drilled it now so I'll be getting on with it this week.

I also love the sound of the Foxx, I narrowly missed out on one in eBay at the weekend.  I've never played through one though but everyone says it has its own unique sound.  I hope I get it working.
Title: Re: What Does the Foxx Phase?
Post by: 1878 on March 23, 2015, 02:25:55 PM
Cheers !!

I used to do a bit of session work & one of the blokes I regularly played for had a massive collection of vintage gear including an original foot phaser. It could get a bit noisy at times but it was worth it. Maybe it's just the fact that it's the phase sound from my youth spent listening to Queen & trying to figure out guitar parts, but they don't quite sound like anything else. I also seem to remember a volume drop though. I've tagged a LPB1 on to the back of effects before today as a recovery stage & it's worked out fine though.

Best of luck with the build !!
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on March 23, 2015, 07:12:47 PM
Nice.

If there's a volume drop then I could incorporate the lpb1 into the output. It's such a simple circuit.  Maybe the noise could be fixed with a little help too as long as it doesn't affect the overall tone.
Title: Re: What Does the Foxx Phase?
Post by: Tony Forestiere on March 25, 2015, 09:54:35 PM
Is this the sound?


B side of Bohemian Rhapsody on $% Vinyl.  :)

*edit* ummm?
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on March 26, 2015, 03:59:14 AM
Yeah.  I think its most prominent on White Man (see my first post on this Subject), and White Queen (Live)



Its also used on the solos for Bohemain Rhapsody and We Will Rock You.  He normally uses it really subtly rather than an in your face phase sound
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 01, 2015, 10:11:10 AM
Hi All

I have phasing!!  Ok, I'm not sure if it all works as I had about 10 seconds of testing time.  I'll be back on it when I get in from work.

AnotherJim, just going back to biasing the Fets.  I chose 6 j201s with a Vgs of 3.03 to 3.05, so I'll be biasing to +4.5v  (6v - (3/2)).  I take it I measure at the drain of any of the 6 trannies?

Thanks
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on April 01, 2015, 03:12:37 PM
Good progress.
You know what? I think if you have phasing, you only need your ears for the setting. I'd want to hear it sweeping at maximum depth. The FET's have got to be operating somewhere between fully on and fully off. If the sweep sounds smooth and continuous, with no audible pausing at top or bottom - you've got it.
Then you need some extravagant white satin with feckin' great flares.
 
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 01, 2015, 04:15:29 PM
What do you think I'm wearing now?  That's my soldering outfit.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 01, 2015, 05:51:18 PM
Can anyone help me with this?

(http://dirtmonkey.org/foxx/SpeedControl.jpg)

Going off the schematic for the speed control, I originally had Y as the common either connected to X or Z.  After playing with it, I think I may have got it wrong and Y should be either connected to both or neither.

Can anyone please advise on the correct wiring?

Thanks
Title: Re: What Does the Foxx Phase?
Post by: bluebunny on April 02, 2015, 02:50:13 AM
I would have interpreted that diagram as both or nothing, because of the dotted box around the switches - which are pointing in the same direction.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 02, 2015, 04:36:28 AM
Thanks Marc (BlueBunny).  That certainly gives me the most noticeable effect of slow and fast.

So with my extremely limited knowledge I take it I could use a DPDT with Y going to both commons and X and Z going to the same throw on different poles?

Like this?

(http://www.dirtmonkey.org/foxx/speedwire.png)
Title: Re: What Does the Foxx Phase?
Post by: bluebunny on April 02, 2015, 06:29:06 AM
Yep.  It might look something like this with a real switch:

(http://i.imgur.com/RyhXyAg.jpg)
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on April 02, 2015, 06:33:32 AM
Exactly that, although you can use DPST too, since you don't need contacts for the "both off" position.

Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 02, 2015, 06:45:20 AM
That's great guys!

It sounds just like the Foxx, the only thing not working is the depth control (Q on the schematic - top left).  It doesn't affect the overall sound.  I've played with the trimmer to no avail and I don't understand the schematic enough to begin to debug.  When I matched the 100 Fets, the Vgs seemed to range from -2.4 to -4.5.  I went for 6 around the -3 mark.  Would trying different fets in different ranges be a worth while experiment or does it not really matter as long as they are matched?

Here's the controls as stated at the Effects Database http://www.effectsdatabase.com/model/foxx/footphaser#:
•(treadle in mode 1)controls the depth/amplitude of the LFO that controls the phaser
•(treadle in mode 2)sweeps the phaser like a wah pedal
•Modeswitches between the 2 treadle modes
•Range (Slow-Fast)controls the speed of the LFO wave that controls the phaser in mode 1
•Depthcontrols the depth of the LFO wave that controls the phaser in mode 1

Title: Re: What Does the Foxx Phase?
Post by: anotherjim on April 02, 2015, 02:03:50 PM
Some rough calculation tells me the range of control at the output of Z3 is a total swing of about 1.5v centred on whatever the bias trimmer is set to. I get this from the range of the pedal pot which is 0 to a little less that half 6v - which is halved again by the resistors around Z3. This  should be about the same for pedal sweep or LFO. There isn't a "range" setting, so you have what you have. It's some work to change all of the FETs for a different Vgs, so I'd try the following...

Measure volts to ground on Z3 pin 5. This is the bias you have now, note it so you can go back to it if necessary.
Adjust bias to give 1.5v on Z3 pin 5. This is the centre of the working range (0-3v). The optimum could be anywhere between 0.75v and 2.25v, depends on linearity of the FETs.

A range control could be added, R34 could be a 1M in series with a 1M trimmer, but I guess the designer wanted to keep production setup as simple as possible. If you don't feel the range of sweep is enough, no matter how much you tweak the bias, you could try a lower value for R34. 1M would be the maximum swing The FETs could handle with bias centred at 1.5v - but you would find the extremes of travel have no effect, which would be more noticeable under LFO sweep.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 06, 2015, 05:28:59 PM
Thanks as always Jim.  I did try what you said but I seemed to get the best phasing at the 2.7v mark.  

I also had a dirty experiment with the range mod (simply by  putting another 2M2 in parallel with R34) and you could hear a marked different.  So it would be well worth me implementing this mod fully.

To me it sounds like the Foxx.  Shame I don't have one to compare it to but I do have the Digitech Brian May thing and they are pretty similar.  Actually, mine sounds more like what the recordings sound like to me.

.

I suppose I can call this verified.  I'm sure this can be further tweaked to get it closer to the original or to make it into its own thing.

I've uploaded the pcb etch I used (on page 1).   If anyone makes one please let me know about your results and if you changed anything.
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on April 07, 2015, 11:35:52 AM
Sound the real deal to me -  though I'm not an aficionado, I'm of an age that couldn't help but hear Queen regularly.
How do you plan to box it -  wha pedal shell?. The way the pot is used, it looks like it might be an easy job to have a socket in a normal enclosure to use an separate expression pedal.
Hmmm... that's another thing to watch out for - you can have full pot travel with a manual pot, but it won't be the same in a pedal rack&pinion drive.
Title: Re: What Does the Foxx Phase?
Post by: 1878 on April 07, 2015, 12:48:13 PM
That sounds bang on !!

The Foxx treadle pedals (old DeArmond stock I think) have a slightly longer throw than Crybaby shells. I have a Foxx Loud Machine & I reckon there's one or two teeth extra. I would second anotherjim regarding boxing it up with the option of an expression pedal. I only really found a use for the treadle when using it as a wah type thing.

Congratulations on cracking it. You've got something to be proud of there.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 07, 2015, 01:26:28 PM
I bought one of these:  http://www.ebay.co.uk/itm/Musical-Electric-Guitar-FX-Tones-Effect-Wah-Wah-Pedal-/180692952764?pt=LH_DefaultDomain_3&hash=item2a1223a6bc for Ł18.

Its actually not a bad wah - but its a plastic enclosure, but the plan was to try it in that.  But I just don't think I can fit the beast in (which my wife says is usually not a problem).

So, I had been thinking about the expression pedal route.  Unlike you Jim though, I didn't think far enough ahead and hadn't considered the travel in an expression pedal.

When Greg Convington was selling his version, he discarded the manual mode and just had them wired for auto.  That's the way Brian May used his, but to me, it seems a bit wasteful and taking something away.

So, I think I'm going to explore the expression pedal route.  Its the best of both worlds.  Would it be possible to switch between manual and auto by simply detecting whether a jack has been inserted?  If not, keeping the switch wouldn't hurt.  I'm not sure as how to wire it, but that's why god invented Google.

Just another note, my thumb is broken and I can barely hold my pick so please don't judge my playing.  I wanted to re-record this as a comparison, which I recorded with the Digitech Brian May thing, but that's a few weeks away when I can take off this splint.  https://soundcloud.com/nickbungus/queen-medley-with-vocals

Title: Re: What Does the Foxx Phase?
Post by: 1878 on April 07, 2015, 01:39:46 PM
You would need a switched jack, but yes it's possible to automatically switch to a pedal when it's inserted. Personally, I would have the expression pedal switchable with a footswitch. That way, you could have two different speeds set up & switch between the two, or two different depths, sweep ranges etc...
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on April 08, 2015, 10:15:00 AM
A short travel pedal mechanism might not be so terrible. A log pot can be set up on the gear so that most of the change in resistance is within the travel - since a log pot has one end where there's very little change in resistance per degree of rotation. That would make it tricky to set filter notches versus pedal angle like people do with a Wah - but you can have the manual pot mode for that.
If the pedal travel was really short (about half pot rotation), the pot could be 220k linear and set so the mechanism sweeps it from 0 to about 100k, which is the same as original.

Nick - you shall have a PM shortly...
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 09, 2015, 04:40:42 AM
Usually, I can find this stuff on Google however limited my knowledge, but I just cannot fathom how to wire an expression pedal jack so that when its inserted, it switches between the expression pedal and R26 (the treadle pot)?

(http://dirtmonkey.org/foxx/treadle.jpg)

Any suggestions would be welcome, thanks.
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on April 09, 2015, 11:01:10 AM
Here's a drawing that should help out.

The Foxx treadle pot is connected as a rheostat with lugs 2 & 3 tied together.

The drawing I provided ties the tip and ring together at the jack.

This will enable you to use a standard expression/volume type pedal with a TRS jack/cable.

As anotherjim stated, you'll have to modify the expression pedal with a different pot to get the 100K you need.

EDIT: R28 should be R26. Dim morning light, rough Foxx drawing, and first cup of coffee!  :icon_lol:

(https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/Expression%20pedal.jpg)
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 09, 2015, 11:52:33 AM
Thanks Armdnrdy, amazing!

That's super clear to me now

Shame that the pinout image is unreadable but I take it this will do the job:  http://www.maplin.co.uk/p/635mm-solder-tag-mounting-stereo-socket-hf92a (http://www.maplin.co.uk/p/635mm-solder-tag-mounting-stereo-socket-hf92a)
Title: Re: What Does the Foxx Phase?
Post by: bluebunny on April 09, 2015, 11:54:32 AM
I take it this will do the job

Yep!
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on April 09, 2015, 12:05:16 PM
To clarify things even more...

R26 is now an on board control, When a male stereo 1/4" plug is inserted into the expression jack, the contact/switches marked RN, TN, and SN lift off of the ring, tip, and sleeve connections. The external expression treadle pot now makes those connections to the ring, tip, and sleeve.
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on April 09, 2015, 12:27:15 PM
Looking at the Foxx pedal...the treadle pot is connected lug 3 to ground, lug 1 & 2 connected together to the switch.

(https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/Foxx%20pot.jpg)
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 09, 2015, 01:23:03 PM
Looking at the Foxx pedal...the treadle pot is connected lug 3 to ground, lug 1 & 2 connected together to the switch.


Does that still mean that your original wiring diagram is valid or does it change anything Armdnrdy?
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on April 09, 2015, 02:38:49 PM
No...I have to revise the drawing.

The more I look at the circuit...the more I believe that you should house this in a pedal like the original.

As it stands..if you just put an expression jack to switch in between the onboard control and the pedal...you are going to be left with an onboard sweep control when you switch the toe switch from speed to sweep. (If the expression pedal is not connected)

The way that I see it....you have to purchase a wah type enclosure for the expression pedal. Why not just build this like the original?
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on April 09, 2015, 04:02:06 PM
I don't believe the sweep pedal necessarily has to have a switch. The "Toe" switch can be a toggle switch or latching stomp on the Phaser box. It selects between LFO or Manual pot (the manual works like a "filter matrix" such as on the EM flanger). When you plug an expression pedal in, it switches the manual pot out and you have pedal sweep again like the original. At least that's the way I though this was going?

Armdnrdy's scheme is going to be useful, but you have to know what connections the expression pedal uses.
Need to know the details of the sweep pedal wiring to get into specifics for this. Not all ready made expression pedals  connect pot wiper to jack tip - some it's the ring. You can make that issue irrelevant by simply connecting the phaser "toe" switch to tip AND ring on the jack, and then you've also done the job of connecting one end of the pot to the wiper.

If you're gutting a pedal shell for your own pot and wiring, you can use a mono TS jack, because you only need it to switch between the 2 pot wipers - both pots can remain grounded at one end.


Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 09, 2015, 04:19:29 PM
Thanks Lads!  I'll go back to the original design then as I seem to be making it more complicated by introducing the expression jack.  The knowledge you guys have conveyed hasn't been wasted though, I've definitely learnt a lot and I'm sure others will benefit too.

I've just gutted that cheap plastic wah shell.  After sizing everything up I think I can squeeze it all in.  Hopefully I'll get another YouTube video posted soon showing the manual mode.

I'm trying to source a proper aluminium wah/expression chassis for long-term use though.
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on April 09, 2015, 09:50:04 PM
I don't believe the sweep pedal necessarily has to have a switch. It selects between LFO or Manual pot (the manual works like a "filter matrix" such as on the EM flanger).

Not quite correct.

The "toe" switch chooses between manual pedal sweep and LFO speed. Look at the upper part of the toe switch. It connects the treadle pot to the LFO.

This is where the problem is. One would have to redesign the circuit to switch from auto LFO, to manual speed and manual sweep.
There would have to be another switch.

That's why it makes more sense to build this into a pedal enclosure. Nick is a Brian May fan....what would Brain do?  :icon_rolleyes:
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 10, 2015, 01:58:13 AM
Nick is a Brian May fan....what would Brain do?  :icon_rolleyes:

Hmm, I better get my hair permmed, buy some clogs and start ranting on about saving badgers. 

Actually I read somewhere during my research that his Foxx pedal broke at some point and he got it rehoused in a cry baby shell.
Title: Re: What Does the Foxx Phase?
Post by: 1878 on April 10, 2015, 08:49:53 AM
I can see that happening !! I have a Foxx Loud Machine (volume pedal) & they are as flimsy a pedal as I've seen.

More info on the Foxx.

http://www.brianmayworld.com/PeteCornish.htm
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on April 10, 2015, 09:31:12 AM
I don't believe the sweep pedal necessarily has to have a switch. It selects between LFO or Manual pot (the manual works like a "filter matrix" such as on the EM flanger).

Not quite correct.

The "toe" switch chooses between manual pedal sweep and LFO speed. Look at the upper part of the toe switch. It connects the treadle pot to the LFO.

This is where the problem is. One would have to redesign the circuit to switch from auto LFO, to manual speed and manual sweep.
There would have to be another switch.

That's why it makes more sense to build this into a pedal enclosure. Nick is a Brian May fan....what would Brain do?  :icon_rolleyes:
I see your point -  but my point is that with the "toe" switch mounted on the phaser enclosure NOT in the expression pedal, then all is well. The toe switch functions as original whether or not an expression pedal is plugged in. I didn't think we were aiming for independent controls so you can go back to a preset LFO speed after waggling the sweep manually.

Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on April 10, 2015, 09:42:18 AM
I think that you're missing my point.

The pot in the schematic is shared via the toe switch between the speed control and the sweep control.

If this circuit was built "as is" with the controls mounted on the enclosure...there would be a useless sweep control on the enclosure.

The circuit would have to be redesigned to delete the sweep control.

With that being said...since Nick is a fan of how Brian May uses this Foot Phaser, and he would have to build/modify an expression pedal to work with this circuit....why not just built it as original inside of a wah shell?

Edit:
One could build this circuit into a regular enclosure and delete the speed/sweep pot. It can be "diverted" to the expression jack but...the effect would be useless without the pedal.
The board that Nick worked up is small enough to fit inside of a wah shell so....my thought to build it as the original remains.
Title: Re: What Does the Foxx Phase?
Post by: bluebunny on April 10, 2015, 10:01:08 AM
...since Nick is a fan of how Brian May uses this Foot Phaser . . . why not just built it as original inside of a wah shell?

Why not build it inside a large clog?  ;D
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on April 10, 2015, 10:09:43 AM
...since Nick is a fan of how Brian May uses this Foot Phaser . . . why not just built it as original inside of a wah shell?

Why not build it inside a large clog?  ;D

Or a clog for the treadle! Insert your foot into the shoe and go to town!
I like your way of thinking outside the box! or should I say...inside the clog!  :icon_wink:
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on April 10, 2015, 11:33:10 AM
Oh now I'm baffled Armdnrdy...

"The pot in the schematic is shared via the toe switch between the speed control and the sweep control."
Yes, I never thought otherwise. Just one pot.  Why would it care if that pot is an integral panel mount or external pedal mounted one?

I'm looking at the scheme and imagining an external expression pedal connection via a switched jack next to the existing control  which has become a panel mounted  pot. When a pedal is plugged in, the panel pot is disconnected by the jack switch.

When the expression pedal isn't plugged in, why would this manual sweep control pot on the enclosure be useless?  - it would have exactly the same function according to the toe switch - do exactly what the pedal control pot would do - surely? It's only there to provide a control when an expression pedal isn't used. Yes, while an expression pedal is plugged in, the panel control will not function  - but so what?

I'm pretty sure the aim was to provide the pedal control functions without using a pedal.  I'm at a total loss as to why what I'm suggesting to achieve this shouldn't work.




Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 10, 2015, 11:52:22 AM
As Jim says above, that's the way I thought it would work.  By having an expression pedal plugged in, R26 would be taken out of the circuit and this functionality would be handled by the expression pedal which would house a pot that would give me 0-100k resistance.
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on April 10, 2015, 12:07:12 PM
Well...if you go back and read reply #42, Jim inquired how you were planning to box it. You provided a link (reply #44) to a wah enclosure that you purchased. It was Jim that mentioned the expression pedal jack.

It is my impression that your original goal was to build a work alike of the original Foxx Foot Phaser.

Jim,
The enclosure mounted sweep control could be used to get "%^&*ed" pedal filter sounds as you mentioned but...you can do the same with the pedal with the addition of varying the filter while playing. So...to me...having an enclosure mounted control isn't as useful, and to be honest...sort of redundant.

The word c-o-c-k-e-d was blocked above.  ::)
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 10, 2015, 02:50:32 PM
I'm just grateful for all the help and I'm glad to explore all options.  The expression pedal bit just made it more flexible in terms of enclosures and as a total novice, it was also interesting as to how this could be achieved.

The build I've got is definitely a MkI.  I've made a few mistakes here and there that I've had to 'repair' (bodge), so design/build improvements and recommendations are so helpful.
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on April 10, 2015, 04:17:26 PM
All cool - carry on  ;)
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 13, 2015, 04:49:36 PM
Ok... Its not pretty but its now in an enclosure!  My overall skill level is around the p*ss poor mark, but I can take the boxing of effects to a whole level below that.



But it works, and as far as Mark I goes, its done.  I'm going to make another one and hopefully learn from my mistakes.

(http://dirtmonkey.org/foxx/Img1.jpg)

(http://dirtmonkey.org/foxx/Img2.jpg)

(http://dirtmonkey.org/foxx/Img4.jpg)

Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on April 13, 2015, 06:13:08 PM
There you go!

Take a resistance measurement of the treadle pot: Toe up, and toe down.

See how far away from 100K you are. There are ways to remedy that.

Have you ever come across any measurements of an actual Foxx Phaser?
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 14, 2015, 04:46:21 PM
Hmmm.  Very interesting.  I could definitely tell I wasn't getting the full range but I did think I was closer.  The discarded cheap wah also used a 100k pot, so there was no need to change it.

Anyway, here are the readings:

Toe up 61.5k

Toe Down 1.6k

Its a great sounding Phaser but I'm starting to think the manual mode and fast mode are pretty useless.  I doubt Mk2 will live in an expression shell.  I can get a great tone from it without.

Have you ever come across any measurements of an actual Foxx Phaser?

No, I've never even seen one, let alone played one, let alone measured one!!  There was a re-issue a few years ago but that looked like it was a slightly different design with three speeds (or rather speed ranges) available.  I just missed out on buying one of these on eBay the other week.  The schematic I used I believe is for the original 70s version.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 15, 2015, 02:51:01 AM
See how far away from 100K you are. There are ways to remedy that.

I'm still interested as to how this can be achieved though.
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on April 15, 2015, 04:42:26 AM
Is the pot gear movable or pinned in some way? It should be possible to get it closer to zero at toe down.
Is it a log or linear pot? At half rotation, it would read about 50k if it was linear.
The pot can be a larger value (220k), and the range tweaked to 0-100k by putting a fixed resistance (find the value with another pot first) in parallel with it.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 15, 2015, 06:44:17 AM
Great stuff Jim as always.

Thanks
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 25, 2015, 02:17:54 AM
I've just bought the materials for V2 and I intend to try a few mods such as the range control suggested by AnotherJim.

A mod that I think would be really beneficial would be a level pot.  One of the main criticisms of the fOXX is the volume drop when the pedal is engaged.

Is there an easy way this can be achieved or would it be better to add a boost circuit to the end of the signal chain such as a EHX LPB-1 as previously discussed?
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on April 25, 2015, 06:02:29 AM
There is an easy way to boost the output. R49 could be increased. 220k would be a bit more than 6dB boost. There is a tone change with that though. R49 & C20 form a low pass filter and increasing R49 may well make it sound darker. As designed, the filter is cutting over 7khz, which doesn't really affect guitar tone, to keep it similar, C20 would need to be halved for every doubling of R49.

A booster will give you what you want without necessarily affecting the tone - unless it's designed to.
LPB-1
(http://beavisaudio.com/techpages/HIW/hiw1.gif)
You may well need to increase the value of C1 to avoid bass cut.
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on April 25, 2015, 08:45:23 AM
You can also increase the gain in the last phase stage. (R46)

You might try putting a 20K in there to start.

Also...have you looked at gut shots of the original Foxx Phaser? Much can be learned.  :icon_wink:

The rotary switch has a couple of caps tacked to it. A 22µf and a .47µf. (I've seen tants or electros)

The reissue has these two caps placed on the board instead of the switch.

Even though the rotary switch is labeled "slow" and "fast"...from what I can tell, the rotary switch is a 2P4T (10 lugs) and there are four speeds. That's where the other two caps come into play.

I don't believe that the drawing you are working with is of the final production product.

There are no good sound sample available that go though the speed settings but, here is a review that mentions the differences between the reissue and the original.
http://freeforumzone.leonardo.it/lofi/Foxx-Phaser-Review-by-mark-Reynolds/D6055180.html

The review states that the original has two phase speeds, and two "ring modulator settings".
There is a chance that the two fastest speeds where perceived to be "ring modulator" sounding to the reviewer, or....the original that this individual owned had issues. (bad caps)
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 27, 2015, 05:05:48 AM
I was speaking to a guy called Mike Ryde (http://www.mikeryde.com/switch.html) online over the weekend actually.  He really is an aficionado when it comes to the Brian May sound.

He believes there were 2 70s versions as well as the re-issue with the 4 speed settings.

It would be interesting if I could source another schematic from a different version.

Going off this from the Effects Database (http://www.effectsdatabase.com/model/foxx/footphaser#), the controls describe what I have built.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 27, 2015, 06:13:17 AM
If you look at the schematic it references number #1482 which is probably this version (http://www.effectsdatabase.com/model/sears/phasingpedal).

The gut shots on that closely resemble my build, which is unsurprising as I heavily used it as a reference for placing my components.
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on April 27, 2015, 08:42:23 AM
You have it right Nick.

I figured it out over the weekend. The schematic floating around is for the Sears 1482 Phasing Pedal that Foxx produced.

After researching the Foxx Foot Phaser over that last several weeks, It seems that Foxx produced the Regal Outa Phase, the Foxx Foot Phaser, and the Foxx Foot Phaser Studio Model 7.

The differences that I've seen so far between the Studio Model 7 and the Sears Phasing Pedal are:

Model 7
220µf filter cap and a 12Ω resistor in series with the DC jack
C16 & C21 are .1µf
Rotary switch with .47µ & 22µf tants for two additional speeds

Sears Phasing Pedal 1482
No 220µf filter cap, 12Ω resistor or DC jack (battery powered only)
C16 & C21 as per schematic .01µf
Speed switch as per schematic (toggle switch, two speeds, no additional capacitors)

I've sourced a DeArmond enclosure (same as Foxx) and 50 2N4302s. I'm going to continue to research this circuit to build a good replica of the original Studio Model 7.

I'll update this thread with a schematic when things are a bit further along.



Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 27, 2015, 09:37:54 AM
Great stuff Armdnrdy.  Its all very interesting stuff.

I do believe that mine sounds pretty authentic but I would definitely love to do a build with your Studio Model 7 version. 

Would you be willing to sell me 6 matched 2n4302s?  I socketed my J201s so I could easily swap them out and re-calibrate.

Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on April 27, 2015, 09:48:58 AM
Sure Nick.

I should be receiving them this week...then I'll match em up.

Here is an image of the original Foxx Foot Phaser. (Not the Studio Model 7)

I can't see any difference in the component layout or switching.

(https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/FOXX%20PHASER.jpg)
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 27, 2015, 10:07:58 AM
I had read about the 1482 and the Regal but was guessing they were much the same thing, just rebranded.  Saying that, I had noticed on the gut shots that there were some different off board components, but being a total novice I chose to ignore! :icon_redface:

I don't know if it helps you and might save you a bit of time but here are my DesignSpark files (http://www.dirtmonkey.org/foxx/foxx.zip).

If you use Eagle I think they can converted easily enough.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 27, 2015, 10:17:56 AM
I wonder if this website (http://www.musicparts.com/products.asp?Company=Foxx) is worth a punt?

They have 2 Foxx phaser schematics available, the 1482 and one just branded fOXX phaser.
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on April 27, 2015, 10:20:57 AM
As far as I can tell so far...the Regal is an exact copy of the Studio Model 7....just re-branded.

(https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/Regal.jpg)

I already have your files in my folder. Thanks.

I have already begun to redraw the schematic. I've made it a bit more easy to follow the paths of the different sections.

Once the schematic is finished, I'll work out the board file in Eagle.

I'm still kind of stuck on the speed switching. I don't know the lug numbering of the older style rotary switch, and I'm not sure how the speed switching solder pads in the images correlate with the schematic. I have been trying different configurations to see what gets connected and the results of those connections. Kind of trial and error.  :icon_wink:
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on April 27, 2015, 10:35:34 AM
I wonder if this website (http://www.musicparts.com/products.asp?Company=Foxx) is worth a punt?

They have 2 Foxx phaser schematics available, the 1482 and one just branded fOXX phaser.


I just emailed inquiring if the schematics are truly different. I was just on that site yesterday but...for some reason I could not find the Foxx page. I entered the site from a link on a webpage. I think that link took me into a web black hole!  :icon_eek:
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 27, 2015, 11:03:17 AM
Haha, I emailed them exactly the same thing.  They will be freaked out.

I'd happily take the risk with the schematic and share if you want to do a deal on the 6 fets?  That's if they get back to either of us
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on April 27, 2015, 11:08:51 AM
When did you email them?
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 27, 2015, 11:20:46 AM
A minute before I posted the link.  Today, about 8:15 DiyStompboxes time, 15:15 my time (UK).
Title: Re: What Does the Foxx Phase?
Post by: pinkjimiphoton on April 27, 2015, 11:31:46 AM
Propably "m" for capacitors refer to "μ" (or "u" for those who haven't Greek keyboard)... :icon_eek:



My Dad's got one. He get's his mu on.  :icon_mrgreen:

What?



groaaaaannnnn.......  :icon_mrgreen:
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on April 27, 2015, 11:40:48 AM
A minute before I posted the link.  Today, about 8:15 DiyStompboxes time, 15:15 my time (UK).

Okay..

I was wondering if it was days ago.

I've "ordered" drawings from MusicParts before and.....they don't seem to be the most timely outfit!

I believe the person running the site has a real job. Can't feed the family off of selling other people's schematics alone!  :icon_wink:
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 28, 2015, 05:33:41 AM
The guy at MusicParts has got back to me, 'Thanks for your request, we will check.'
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on April 28, 2015, 06:31:21 AM
Boy...you must have a way with words....he didn't get back to me.  ???

Maybe he's a member of this forum...and read your post: "I'd happily take the risk with the schematic and share if you want to do a deal on the 6 fets?"

Or...maybe he read mine: "I've "ordered" drawings from MusicParts before and.....they don't seem to be the most timely outfit!

I believe the person running the site has a real job. Can't feed the family off of selling other people's schematics alone!
icon_wink"

Some good news...I figured out the rotary switch numbering and connections. It took a while but...I finally got it!
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 28, 2015, 07:38:38 AM
Are you expecting to see many differences between the two schematics or a few very subtle ones?

I've another lead on the schematic, see the comments on the YouTube clip.
https://www.youtube.com/watch?v=6f-8KJ5mK0E

He bought a re-issue and then had the PCB built based on the original by a friend.  I've asked him if he would contact his friend and get a copy of the schematic.  Hopefully I'll hear something back, although he does saying something about 10 fets which is worrying.
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on April 28, 2015, 10:25:55 AM
Here is the rotary switching.

(https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/Foxx%20rotary%20switch.jpg)

The four different positions add/subtract the board mounted 2.2µf & .22µf capacitors in parallel and series with the switch mounted .47µf & 22µf caps.

Position 1 = 1.21µf
Position 2 = 1.11µf
Position 3 = .44µf
Position 4 = .11µf

Slowest speed is in the CCW position, fastest CW
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 28, 2015, 10:39:35 AM
Well done, great stuff.

So would I be able to replace my toggle switch with this without any on-board modifications?
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on April 28, 2015, 10:49:38 AM
Correct.

To answer your earlier question:

I don't anticipate any great differences in the schematics but....maybe just enough to change the sound a bit.

There are cap values/types that I cannot find on the board images.

I have quite a few component side board shots but no trace side shots to follow the circuit and verify the schematic.

If we can get the drawing from MusicParts...that will definitely help out!
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on April 28, 2015, 11:03:03 AM
So what type of rotary switch is that?  (Remember I am an electronics idiot).  2 Pole 4 way and A and B are the poles?
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on April 28, 2015, 11:14:05 AM
The original is a 2 pole, 4 position.

You might have a hard time finding one of those so...you can use the common 3 pole, 4 position and leave the "C" lugs unconnected.

You can use either the open type, or the closed type.

http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR0.TRC0.H0.X3+pole+4+position+rotary+switch.TRS1&_nkw=3+pole+4+position+rotary+switch&_sacat=0
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on April 28, 2015, 11:47:10 AM
Nick,

The switch board pads are a bit different than I originally drew.

The pads are Z, X, Y from the right side of the PCB when looking at the top of the board. Top being toe side.

The above drawing has been revised.

Edit:
I guess it doesn't matter on your board....the XYZ pads are laid out differently then the original.
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on May 01, 2015, 03:29:20 PM
I have a question about the voltage divider coming out of the LFO. (R21, R25, C12)

What exactly is C12 doing? and is the value critical?

The answer to question #1 probably answers question #2.  :icon_wink:

(https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/Foxx%20foot%20phaser%20LFO.jpg)

Title: Re: What Does the Foxx Phase?
Post by: anotherjim on May 03, 2015, 08:20:01 AM
To answer the above, it was dealt with here...
http://www.diystompboxes.com/smfforum/index.php?topic=110857.0
In short, C12 controls a voltage divider R21/25 in a frequency dependant manner, so the LFO signal from Z3 pin8 is progressively cut by up to half amplitude  as it's frequency increases.

I now have Nicks MkI on my bench (Big thanks to Nick). My earlier question about the LFO wave shape is answered -  it's a Sine. Does get a bit bent at extreme settings of the speed pot, but I don't think that's a defect, just a consequence of adjusting speed with a single control.
I'm still struggling to find an ancestor of this circuit (But I'm sure I've seen it's like before). I'm now leaning towards the idea that it's a twin-T oscillator of some sort, even though the "T's" are disguised somewhat.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on May 03, 2015, 09:24:00 AM
I used a polarised cap for c12 as that's all I had.  I take it that shouldn't affect the tone in any way?
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on May 03, 2015, 11:21:08 AM
I've finished the schematic, component value overlay, (of original board) and am working on a designation overlay.

The latter is a bit difficult without trace side images and/or a correct schematic.

Any word from Musicparts?

So far...there are quite a few differences between the Sears and the Foxx models.

The cap that I was inquiring about (C12) along with R25, seem to be missing from the Foxx. I see empty holes where R25 should be.
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on May 03, 2015, 11:47:41 AM
Yes, Nick used an 0.47uF electro. Shouldn't be a difference in itself to the tone.

I've just done some measurement of the LFO, frequency and peak-peak level. The supplied battery was somewhat depleted and my earlier comment about the sine shape distorting is wrong. Powered by a 9v PSU, the wave shape is a pretty good sine at all settings.

Measured from Z3 pin8 (so not influenced by the aforementioned C12).
Slow range. Min=0.24Hz@1.24vpp. Max=0.94Hz@0.8vpp.
Fast range. Min=2.7Hz@1.52vpp. Max=11.36Hz@0.92vpp.

Note that there is a gap between the ranges. Deliberate or timing cap tolerances?

Also, despite what R21,25 & C12 are intended to do, the amplitude drops as speed increases anyway.

On listening, to my ears the sweep sounds as though it's all at one end of the LFO cycle. It does sound like the full phase sweep, but only happening in about 3/4 of the cycle. This gives it a pulsating character with slow to moderate sweep rates, although it isn't so noticeable at fast rates. So the peak to peak of the LFO leaving Z3 pin7 probably needs reducing. That said, it may be something the production pedals did anyway.

R39, the sweep bias pot, is quite sensitive, and it's just as well Nick used a multi-turn type.



Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on May 03, 2015, 11:57:36 AM
Thanks for the info Jim!

You mentioned the LFO output. (Z3 pin 7)

I have the input resistor (R34) verified from images of a few different Foxx boards as a 6.8M, instead of the Sears 2.2M.
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on May 03, 2015, 01:45:32 PM
I have the input resistor (R34) verified from images of a few different Foxx boards as a 6.8M, instead of the Sears 2.2M.
Ah-ha! Larry, do you know if the JFET's used differ between the various productions? Is R38 still 1M whatever?
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on May 03, 2015, 02:30:55 PM
Hey Jim,

Most of the component board shots that I've collected were taken from a 90 degree vantage point so...I don't have a very good view of the JFETs.

I can make out PN4302 from one shot, and the last two numbers (02) from a different board.

The JFETs differ from board to board...standard TO-92 (PN) and glob-top transistors (2N)

Yes, R38 is verified on several boards as 1M.

Title: Re: What Does the Foxx Phase?
Post by: nickbungus on May 03, 2015, 02:48:49 PM

On listening, to my ears the sweep sounds as though it's all at one end of the LFO cycle. It does sound like the full phase sweep, but only happening in about 3/4 of the cycle. This gives it a pulsating character with slow to moderate sweep rates, although it isn't so noticeable at fast rates. So the peak to peak of the LFO leaving Z3 pin7 probably needs reducing.

Could that be because I've made a mistake somewhere along the line?  I've selected the wrong component or I've misread the schematic, some of the decimal points are a bit ropey?

Jim, also the depth control doesn't seem to affect the overall sound to my ears (except in volume really), what do you reckon?

While you have it Jim, if there's anything you want to try, please feel free to take the soldering iron to it.  Like I've said, its mk I so I wouldn't be too bothered.  

Armdnrdy, if the main differences between the 1482 and the Studio are a few components that can directly swapped and some offboard stuff, I'd like to make a PCB layout that can do both.  If thats possible, then I'll get some boards professionally manufactured.  My wife is going mad about all the ferric chloride stains in the garage and around the garden :icon_lol:
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on May 03, 2015, 04:01:07 PM
With the info that I've "uncovered" so far...it seems as if the Sears model either came first...or was introduced as the "castrated" version....not to "out do" the Foxx version.

The Foxx version shows signs of improvement, better power filtering, larger signal path caps,  (C16, C21) among other things.

The Foxx phaser was made "famous" because Brian May played through one. Brian didn't play through the Sears model.

The point I'm trying to make is...I believe that the Foxx is the improved version of the Sears and...people are familiar with the Foxx Phaser because of Brian May's use.

Common sense tells me that since no one has heard of the Sears Phaser....why would anyone build the lesser version?

All three versions including the Regal are made with the same board...it would be easy to do but...I guess I don't understand why  you would want to make the lesser Sears version.  ???


Title: Re: What Does the Foxx Phase?
Post by: anotherjim on May 03, 2015, 04:13:04 PM
Nick, there can always be component errors - even on production boards. An official schematic can fail to reflect any late changes that were found necessary once production got under way. Sometimes, mods were made that can only be seen on the copper side.
I will see what I can do to improve the sweep AND the volume drop when engaged without adding anything.

Sorry Nick, what do you call the depth control? Do you mean the pedal only with LFO switched out? I haven't looked at that aspect yet.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on May 03, 2015, 04:18:26 PM
Armdnrdy:True.  It's just good to keep the options available.  What I don't get is how the 1482 schematic is on the net and the studio isn't.  Especially coming from Greg Covington, as it seems he definitely did his homework.  His site is down now but he make all the Brian May stuff.

I'll be making your version next regardless.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on May 03, 2015, 04:22:43 PM
Hi Jim. R2 and R7 I believe are the depth control.  But remember I'm an idiot.
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on May 03, 2015, 04:44:59 PM
Gotcha.
It's a bit strange really. It's the Q control. Originally, "Q" represents the quality factor or efficiency of a resonant circuit or filter. It's often used to describe the boosting of effected frequencies by providing positive feedback from output back to input. The thing here is that the feedback is from the output wet/dry mixer Z2 pin8. So it includes the un-effected dry signal - which is fed back and mixed with the incoming signal Z2 pin14. The strange part (to me) is that it's more usual to only send the wet signal (as from Z2 pin7) back to the input.

I haven't played with it that much, but it seems to work, changing the density of the effect and makes it more "nasal" sounding.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on May 04, 2015, 03:28:07 AM
According to this (http://www.effectsdatabase.com/model/sears/phasingpedal), its the depth control, but even I could work out that's a wet/dry mixer.  But I also read the following on Wiki (http://en.wikipedia.org/wiki/Phaser_(effect)).

Quote
When signals from the two paths are mixed, the frequencies that are out of phase will cancel each other out, creating the phaser's characteristic notches. Changing the mix ratio changes the depth of the notches; the deepest notches occur when the mix ratio is 50%.
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on May 04, 2015, 06:55:16 AM
I can see where you might come to that conclusion, but in fact what you're thinking is a feed from input to output via the Q control works in the opposite direction. Z2 pin 13 is the (-) inverting amp input. Operational amplifiers with a feedback path (R3) and resistors feeding the (-) input will maintain the voltage at the (-) pin at null. By Null, I mean something we call "virtual ground" or "virtual earth". The amp will drive it's output so that  the feedback resistor path balances the input paths, equal and opposite so the null in between them persists whatever the signal is doing. So pin 13 can only be an input to the amp, it cannot send signal out even though there are other paths connected there.
There are 2 paths into Z2 pin 13 (-) input. The input jack and the Q control. Whenever you see something like this, you have a "virtual earth inverting mixer". However many input paths there are, the amp output will be a mix of the signals from each path and each input does not affect the others because where they meet at the (-) pin is "virtual ground".

The situation isn't quite the same with the (+) input pin, so mixing is done using the inverting input. The cost is the output signal polarity is reversed, so another inverting stage should appear somewhere to correct that. And here is does with the output wet/dry mixer...

The same thing again. The wet/dry mix is set by fixed resistors in each input path, R45 & 48. Z2 (-) pin9 has these 2 paths going in and a feedback path from R49. Another inverting mixer.



Title: Re: What Does the Foxx Phase?
Post by: anotherjim on May 04, 2015, 11:51:50 AM
Tried increasing R34. Largest pot I had was 2.2M so put that in series with the 2.2M R34. Increasing the pot to max I still had plenty of effect without the impression that it was over-driving the phaser sweep.

However, it changes the DC level on the output Z3 pin7 (expected), so a readjustment of the bias pot was required. Also, the variation in amplitude of the LFO signal with frequency means that any change here must be checked at all rates - and no doubt end up having to be a compromise. So, I have R34 effectively totalling 4.4M. I have a feeling it could go higher yet, and of course, Larry found 6.8M in some units.

Other observations...
The pedal sounded very distorted today, but I traced it to RF interference in my workshed (especially from my soldering station). Nick used an unscreened plastic shell, but even then, the circuit has zero RF protection at the input. I think that a 47pF cap across R3 might do some good here, without affecting tone.

Incidentally Nick, if you have to use a plastic shell for MkII, you could screen it with conductive paint inside and make contact to the circuit ground with a tag washer screwed on + one more trapped between the base plate and shell.

Volume drop while engaged... The Q control can boost the volume, so without the pedal having an output volume control, it would be difficult to pick a fixed change to the design. As it stands, it must be a compromise.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on May 04, 2015, 01:51:20 PM
All sounds really interesting.  Don't change it back, I want to hear it.

I'm keeping my eyes open for an aluminium wah shell, but if I don't get one, I'm happy to discard the treadle and just put it into a normal aluminium enclosure.

Feel free to try the 47pf cap across R3 if you want.  I'll definitely give it a shot if not.

I'll try the conductive paint on this version, nothing to lose and all to gain.

I'm thinking Mk II should definitely have an LPB-1 for volume to combat any drop
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on May 04, 2015, 02:27:13 PM
It seems to me putting a pot in replacement for R34 (like you mentioned earlier Jim) for a Range control is a worthy mod too. Especially as it can be up to 6.8M in some units.

Title: Re: What Does the Foxx Phase?
Post by: anotherjim on May 05, 2015, 08:37:30 AM
Trouble is there are limits to pot values. If you take 6.8M as a possible maximum, the variation with a single pot + a fixed resistor is limited. The pot value is too small compared to the fixed resistor to achieve enough variation of the total resistance.
Also, as I said, changing R34 also changes the DC level controlling the FET's, so you have to correct with the bias pot to re-centre the sweep. Not really practical. If R34 included a trim pot, you still have limited range because they don't come higher than 1M. IMO, the practical choice, would be to make R34 "SOT". This means "select on test". The resistor is replaced by header pins and you try different resistors by wrapping them on the pins. When you find the best value, you clip off the excess wire and solder on to the pins. The downside is that you'd need a good range of values between 2.2M and 10M to hand, which most of us don't normally stock. I do have them, so will try it that way.


Title: Re: What Does the Foxx Phase?
Post by: nickbungus on May 05, 2015, 10:31:06 AM
After the post I started looking for high value pots and like you said, the 1M was the highest I could find.

Sorry, I forgot about the biasing.  I am new to this and a bit dumb/forgetful!

The SOT approach does make sense and seems to be inline with what has been previously discussed about different units having different values for R34.
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on May 05, 2015, 11:28:28 AM
What I don't get is how the 1482 schematic is on the net and the studio isn't.  

Many schematics are not on the internet. I would imagine that the 1482 is....and the Studio Model 7 isn't because the 1482 was available for immediate purchase from Musicparts.com. As you've seen....you put in a request for the other Foxx phaser schematic over a week ago....still not available.

Especially coming from Greg Covington, as it seems he definitely did his homework.  His site is down now but he make all the Brian May stuff.

I've looked at an image of Greg Covington's May Z phase board. It appears as if he followed the schematic (Sears) and added a few obvious changes from images he gathered from the net. (C16, C21 .1µf, power supply filtering 12Ω resistor & 220µf capacitor) Greg's build includes the R25/C12 that is on the schematic but deleted from latter production units. (more on that next post)
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on May 05, 2015, 12:11:56 PM
Larry, your powers of research are incredible. Hats off!  It looks like you and Greg followed similar paths then.  You pro's sure know what you are doing!!

No, I never heard back from MusicParts.com, I sent him another email chasing him and no reply.

Really looking forward to your findings and schematic, and then building it!!
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on May 05, 2015, 12:22:51 PM
Here's the schematic that I've drawn using the 1482 drawing and images of actual boards as reference.

(https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/Foxx%20Foot%20Phaser%20Mod.%207.jpg)

PDF for higher resolution:

https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/Foxx%20Foot%20Phaser%20Mod.%207.pdf

Differences that I've found:

R1 input resistor is 100K instead of 270K
C16 & C21 are .1µf instead of .01µf
R13 is 300K instead of 330K
Rotary switch with two additional LFO speeds was added.
R25 and C12 were installed on Sears Phaser and early production Foxx Foot Phaser. These components were deleted in later production Foxx Foot Phasers and the Studio Model 7.
R34 6.8M instead of 2.2M
C18 changed to 10µf polarized capacitor instead of .01µf film
Power filtering added R53 (12Ω) and C25 (220µf)

I have verified R34 as 6.8M on many of the closer images. This is the best shot I've come across. (carbon comp resistor in front of IC3)
(https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/6.8M.jpg)

Here's an image of the empty holes where R25 and C12 would have been placed originally.
(https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/R25%2C%20C12.jpg)

I've went through the images and put together a component overlay for the board values.
As you can see in the images, some of the trace routing can be seen from the component side due to the solder rosin soaking through the fiberglass board.
With this info...I have been working on a designation overlay to match the schematic. I'll post it when completed.

Title: Re: What Does the Foxx Phase?
Post by: Fender3D on May 05, 2015, 12:32:05 PM
Sorry guys,
but...
won't TR1 and P1 feed DC voltage on output jack?
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on May 05, 2015, 12:45:25 PM
Sorry guys,
but...
won't TR1 and P1 feed DC voltage on output jack?

I thought the same thing Federico.

Look at the original schematic on page 1 of this thread.

The only difference I see from that schematic and the actual board is: R51 comes directly off of pin 8 (output) of IC2C, then the output travels to the bottom of the board where it's connected to the positive side of C22. From the negative side of C22, the output signal is routed to the opposite side of the board. (where the Feedback pot is.)
From the feedback pot (P1) the signal works it's way to the switch pads.
The signal almost makes a 360 around the board!  :icon_eek:
Title: Re: What Does the Foxx Phase?
Post by: Fender3D on May 05, 2015, 01:06:12 PM
I saw it,
maybe feedback control was a last time addition...

The signal almost makes a 360 around the board!  :icon_eek:

It's a phaser, after all...  :icon_mrgreen:
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on May 05, 2015, 01:09:59 PM
I was planning to remedy the no feedback cap issue on my build with a couple of .1µf caps on either side of the feedback trimmer/control.

Nick...were you experiencing a loud pop when you engaged/disengaged the pedal?
Title: Re: What Does the Foxx Phase?
Post by: Fender3D on May 05, 2015, 01:16:48 PM
I was planning to remedy the no feedback cap issue on my build with a couple of .1µf caps on either side of the feedback trimmer/control.

one cap should be enough.
You just need to keep DC away from output jack...
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on May 05, 2015, 01:33:50 PM
Here's how I see the output signal/feedback path routing.

(https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/Output%20feedback%20path.jpg)
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on May 05, 2015, 01:44:50 PM
Larry, that all looks amazing.  Well done.

I didn't bother with the pedal switch from the schematic.  Its on my pcb board but I just took the output from Pedal Switch A (on the 1482 Schematic) and wired it as in the Output from the Beavis True bypass wiring diagram (http://www.beavisaudio.com/techpages/StompboxWiring/).  I've used this wiring quite a few times and you always get a pop, but not an unusually loud pop.  Please see the vids on pages 3 and 4 of this thread and can hear it.

(http://www.beavisaudio.com/techpages/StompboxWiring/StompboxWiring.gif)
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on May 05, 2015, 01:58:14 PM
The pop doesn't seem that loud but....if you turn it up to stage volume....it will be!  :icon_wink:

On your build, you can probably take care on that with a 1-10M pull down resistor from the board output to ground.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on May 05, 2015, 02:30:00 PM
Especially as loud as I play.  The rest of them are constantly complaining! ;D
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on May 05, 2015, 02:32:31 PM
Wow! I go off to eat my meatballs and pasta and there's incredible updates when I come back!
Terrific reverse engineering from Larry.

Oh, I failed to notice that DC on output thing... yeh, one cap , maybe between feedback trimmer and pot should do it  + anti-pop pull-down.

Input impedance down to 100k? Single coils only then  :o

I'd be tempted to put it between a TL072 for input buffer and output with some modest gain and vol control.

I've been wondering why all of the LM324 amps in the audio path have 10k pull-downs on the outputs? Something to make the amps more linear? Not something I've noticed in the data sheet.
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on May 05, 2015, 02:49:21 PM
Wow! I go off to eat my meatballs and pasta and there's incredible updates when I come back!
Terrific reverse engineering from Larry.

What I lack in knowledge of electronics theory, (just about everything!) I make up for in electronics forensics and perseverance!  :icon_wink:


I've been wondering why all of the LM324 amps in the audio path have 10k pull-downs on the outputs?

I too thought that this was a bit odd. I looked through a folder of various phaser reference circuits but couldn't find anything that used pull downs at each output of the phase stages.
This phaser design is pretty basic...so....I wonder if the pull downs are to keep the overall phased signal down to keep distortion at bay.
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on May 05, 2015, 04:00:46 PM
I took another look at the 100K input resistor.

R1 is the only resistor that I can't see clearly on the board shots. It is covered by a large .1µf cap!

There is one image where I can make out the last three bands. (Black, Yellow, Gold)

The immediate area contains 100K resistors so...maybe that influenced my choice of the first band.

Since a 100K input resistor will give a gain of 1... and the original 270K a gain of .37 there is quite a difference.

So...I started thinking...what would be an obvious choice for R1?

If you look at R13 on the redrawn schematic, you'll see that the original 330K was changed to a 300K. Not much difference there.

To keep costs down...why source two different value resistors? Why not make the input 300K instead of 270K? Once again...not much difference there. (Gain of .33)

300K color code Orange, Black, Yellow, Gold.

Is orange the missing first band? 
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on May 05, 2015, 04:59:39 PM
Well, I don't know. 100k is possible. A well regarded British solid state amp from the 70's - the H||H IC100 had 100k inputs. Didn't worry Marc Bolan or Wilko Johnson to name 2 users (me too!).

Larry could be right about those amp pull-downs. Some op-amps produce a phase shift as they start to run out of bandwidth and the 324 has low bandwidth. Maybe the 10k load keeps it in check?

Have done some "mods" to Nicks MkI. Nick has fixed the board down, so I've found it easier to work from the top side. I kept the 2.2M R34 and fitted a 4.7M in the toe switch wire, so total = 6.9M. I like that. The bias control is easier to adjust and there is some tonal choice you can make as to where you centre the sweep. I can hear sweeping throughout the LFO cycle now. Of course, this is with R25 & C12 in place. Modulation is more than deep enough at fast rates, but maybe too deep for some.

Thinking a bit more about it, a modulation depth control which does not change the FET bias, could be had by manipulating R25.
C12 AC couples the divider so changing the ratio won't shift the DC level. The filter frequency formed with C12 would change with different resistors, but that might not be too bad.

I put a 100n in the wire to the feedback pot and tacked a 100k pull down between R51 and the ground end of R52. There was bypass popping before - there isn't now  ;D That 100n value doesn't seem to alter the character of the resonance with high feedback - which can be nice and swampy.


Title: Re: What Does the Foxx Phase?
Post by: nickbungus on May 05, 2015, 05:56:51 PM
Jim, please feel free to release the board if you want to do anything.  Its only held in place with a few sticky cable tie holders that I borrowed on a long term basis from work.  

Foxxy Number 1 seems to be enjoying his holiday to the valleys.  These mods have got me excited, I can't wait to hear it!  Although no rush to return it, keep it as long as you like.  You and Larry seem to be bouncing off each other and I believe Larry's is going to be amazing.
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on May 05, 2015, 08:13:10 PM
You and Larry seem to be bouncing off each other......

Yeah...Jim's holding the steering wheel...and I've got my foot on the accelerator!  :icon_lol:

Jim,

You might try lifting the R21 side of R25. I have a feeling that it will open the depth more. If it sounds too "over the top," the feedback control can be dialed back a bit.

On the subject of depth...It seems that a pot to ground at the LFO output would do the trick for a depth control.
Maybe even replace R25 with a pot....not sure what effect changing the resistance between the resistor and capacitor of the RC filter would have. Worth a try?

Edit:
I was looking at the schematic and had another thought.  :icon_idea:

What if a 100K pot to ground were put at the output of IC3B? That should lower the amplitude going to the JFETs.
The pot could probably be connected anywhere after R43 as well if a "lower limit" resistor is connected between the pot and ground. Just a thought!
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on May 06, 2015, 08:02:17 AM
I'll bear all these possibilities in mind Larry. Another is increase C12 - maybe a lot.
The resistors around "IC3b) are probably high value so as not to load the preceding circuits. That said, if 2.2M was originally considered high enough for that - it probably ought to be the 1M feedback that is reduced, and that can be done with a trim pot. You could make holes in the bottom plate over the trimmer screws so it's easy for the user to tweak the sweep to their own taste.

Nick, I'm limiting myself to not pulling it all apart just yet - with the house move (hopefully) imminent, I've only got skeleton facilities available  for now. We've found the steering wheel and accelerator, there had to be a brake somewhere!
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on May 06, 2015, 09:12:04 AM
Sure Jim, I just wanted you to know that you can do whatever you like to it and not worry about breaking it.  'If he dies, he dies', Ivan Drago, 1985. 
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on May 06, 2015, 10:39:59 AM
Here's the component values overlay:

(https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/Foxx%20Phaser%20overlay%20values.jpg)


and here's the component designation overlay:

(https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/Foxx%20Phaser%20overlay%20designations.jpg)

Now that the overlays are finished...I can start work on routing the board.
Due to my not having access to an actual unit or trace side image...the designation overlay may not be 100% accurate. I'm sure that any inaccuracies will be revealed during the routing process.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on May 06, 2015, 11:17:51 AM
Wow!  That really is comprehensive.  

I've tried a little cheeky one for you, theres a pedal reseller in the States selling a 70s one on eBay.  They've given it a bit of a refurb so they arent scared to take it apart, so I've offered to pay them if they take top and bottom shots of the circuit board.

I doubt it will come to anything but you never know.
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on May 06, 2015, 11:40:03 AM
Yeah Nick...don't hold your breath!

That guy replied to a similar request about another pedal. He said he'd take some shots....and then never did.
He's a pedal manufacturer...but he also snipes older pedals off of ebay and then turns around and offers them for outrageous prices!

If you look at his description of the Foxx phaser...he states that it uses "Vactec Opto-Coupled Resistors." (Vactrols)

He is completely wrong! It uses JFETs as variable resistors in the phase stages. There is not one vactrol in this circuit!
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on May 06, 2015, 01:05:12 PM
Yeah I saw that, there also seems to be some discrepancy in the years as well, but trying doesn't hurt. 
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on May 12, 2015, 11:05:00 PM
Here's my take on the Model 7.

I added a 1M pull down resistor at the input, and a .1µf cap between the feedback pot and the output.

I had a bit of a struggle around IC3 without trace side shots and limited view of the trace side from the component side shots.
I was down to three traces for the last three days. I would try different routing...and then end up with three different un-routed traces!
I finally got down to one today and was going to add a jumper but....there was no good place to add one.

Since the input/output is a bit different on my board than the original, I moved things down a little and snaked the last trace in.
There is a chance that the original had a jumper on the trace side. We may never know. ;)

(https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/Foxx%20Foot%20Phaser%20Mod.%207-II.jpg)
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on May 13, 2015, 05:07:28 AM
Outstanding.  Any chance of the PCB mask only and a size guide?  I will be building!!!  

Looks a lot less frantic than mine!
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on May 13, 2015, 12:04:28 PM
I'm waiting on a few parts...as soon as the build is verified, I'll post a whole project including an overlay, component BOM, and a PDF of the trace art.

No word from MusicParts?
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on May 13, 2015, 01:38:18 PM
No, nothing.  Shame we couldn't get an original schematic but I reckon you've nailed it anyway.

Looking forward to building it!
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on May 13, 2015, 02:17:48 PM
I also have to breadboard the LFO with the cap switching.

There are three different combinations that can work.

I can't see the trace side of the X, Y, and Z, pads to be certain where they are connected.

So...I have to breadboard all three combos to "see" which one makes the most sense.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on May 27, 2015, 11:39:42 AM
While I'm really looking forward to Larry's version, its got me thinking of a question that I'm sure has been asked and answered a million times.  But I've had a quick Google and I'm still not sure.

Does the capacitor type really matter for a stompbox (especially the Foxx phaser ;))?  I know Larry is going for a 100% recreation, as will be my second go.  But on my MKI, I used ceramics and electrolytics only (because that's what I had). 
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on May 27, 2015, 12:14:20 PM
It doesn't really matter for the most part. Film capacitors will sound better in the signal path but, I've seen phasers that use all ceramics.

I used to change every resistor to metal film, and ceramics in the audio path to film.
Depending on the circuit, I do not follow that "clean up everything" logic any longer.

I believe that sometimes the original components add a bit of "grit" to the audio path which could be partly responsible for a certain sound inherent in the original. I believe that this is called Mojo.  :icon_lol:

Let take a phaser for example. A little bit of "grit" passing through the phase stages is probably a good thing. The sound will be a bit thicker.

Try the search engine on this site for more info and a lot more opinions!
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on August 18, 2015, 04:22:26 AM
Well MkII is well on its way.  I've made my board, drilled and picked the BOM.  The plan is to socket everything that's different between my original and Larrys parts.

Larry I'll do a quick video of with and without the R25,C12 section.

Jim, regarding the RF interference, did you get to try the following and is it worth it?
Quote
I think that a 47pF cap across R3 might do some good here, without affecting tone.
By across R3, do you mean in parallel?

I'll also add this:
Quote
I put a 100n in the wire to the feedback pot and tacked a 100k pull down between R51 and the ground end of R52. There was bypass popping before - there isn't now  ;D That 100n value doesn't seem to alter the character of the resonance with high feedback - which can be nice and swampy.
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on August 18, 2015, 04:19:25 PM
Oh I think the RF protection is extra "in the case of", because this was designed before cell phones, switch mode power supplies, wifi etc....
No shielding in the plastic mk1 either  - wherever it might be now ;(
Shielded case is recommended!
...but yes, across = parallel.

I'll have to read back the thread, because I can't remember why I put 100n in the feedback or what I did to match the LFO sweep to the FET's control range - if anything.
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on August 18, 2015, 11:25:48 PM
I'll have to read back the thread, because I can't remember why I put 100n in the feedback

The 100n in the feedback was suggested by Fender3D. (Federico)

He thought that DC would be present in the feedback circuit without it.

Title: Re: What Does the Foxx Phase?
Post by: Fender3D on August 19, 2015, 10:25:54 AM
...He thought that DC would be present in the feedback circuit without it.

And I still do...
even better, I wonder what the bleeding resistor in the next pedal might do with stock circuit  ::)
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on August 19, 2015, 06:24:55 PM
Well I'm chuffed to bits.  Just finished V2 and it works a treat.

I'll post a video soon but here's what I've currently got socketed:

R1   Sears = 270K, Studio 7 = 100k.  I'm not even sure what the purpose of this resistor is to be honest.  Because most of the Rs are either 100k or 10k, perhaps the 100k was preferred for keeping costs down.  I went 270k for initial testing.

R13  Sears 330k, Studio 7 = 300k.  I only had a 330k and I doubt there is any real difference here.

Optional R25/C12.  Sorry Larry, I screwed this up and put them in, forgetting to put in sockets.

C18  Sears = .01uf, Studio 7 = 10uf polarised.  I used the .01uf but will try the 10uf.  Again, I'm not sure what this will do but that is a big difference.

C16 and C21  Sears = .01uf, Studio 7 = .1uf.  I'll give this a swap tomorrow night and see what happens.

Larry I've yet to try the rotary switch but I'll do that tomorrow and Jim, I've got a loud pop when engaging the pedal so I'll try your pull-up resistor mod too.

Again the feedback pot still doesn't seem to do much except change the volume.  I need to try the 100n.

R34 is socketed and I put in 6M9 (model 7 value-ish) instead of the 2M2 in the Sears schematic.  Like you said Jim, I'm getting a very even smooth phase and the trimmer and the pot are much easier to control. 

Videos coming soon.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on August 20, 2015, 05:37:17 AM
Jim, when you said you 'tacked a 100k pull down between R51 and the ground end of R52', which end of R51 did you use?

Thanks
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on August 21, 2015, 05:23:11 AM
OK, to be start with I think it needs the 100nF fitted in series with the feedback for the "anti-pop" resistor to work properly. This is to isolate DC on Z2 pin 13 from the extra resistors "pull-down" to ground. The 100nF cap can go anywhere in the feedback path from R51 to Z2 pin13 (these are original "mk1" schematic references) - but the feedback path must have to pass through the 100nF. I cut the wire to the Q pot, soldered the 100nF in between the 2 wires and covered with heat-shrink sleeve to get it in the Mk1.

BTW, if the feedback "Q" circuit is set up correctly, I can't think why you cannot have a resonance effect - you should be able to hear feedback if you adjust the Q controls enough, but it's usual to set the "Q adj" preset just short of uncontrolled feedback with the "Q Cont" at minimum resistance.
Mk1 did resonance ok for me - but, maybe adding the 100nF helped? Hmmmm...

The job of the pull-down resistor is to "pre-charge" the output capacitor. Pop is caused by the output capacitor charging or discharging when the effect is switched out of bypass and the capacitor is connected to whatever you have the pedal feeding via the bypass switch. So adding a resistor to ground on the output is the tried and trusted way of stopping the pop. The capacitor has already fully charged up via the pull-down when you activate the effect - so no pop!

So to answer the "where" question. The pull-down is from the negative end of the output capacitor (Mk1 C22) to ground. It happened to be convenient on the Mk1 to fit the pull down between the wires of R52 ground end and R51 at the C22 end.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on August 21, 2015, 08:22:31 AM
Thanks Jim, you are a legend.

The feedback pot is doing something... just very subtly.  On MKI I'd set the trimmer and pot to be just before the high squealing kicks in, which I haven't yet done on V2.  I'll put the 100n in and then have a play with the trim pot.

Video and/or sound files coming soon!  I've got a gig tonight \m/ but hopefully get something sorted soon! 
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on August 22, 2015, 11:11:30 AM
Mods work a treat.  Pop has gone!

I also put in the rotary switch.  Its a totally different beast.  The feedback Q control really makes a difference now and speed switch gives so much more control.
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on August 22, 2015, 11:50:44 AM
Hey Nick,

Here is the correct rotary switch wiring that I verified on the bread board.
(https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/Foxx%20Foot%20Phaser%20Mod.%207.jpg)
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on August 22, 2015, 12:35:33 PM
Actually Larry, I've wired it that way and I'm only getting phasing in  positions 1 and 4.
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on August 22, 2015, 12:44:42 PM
Actually Larry, I've wired it that way and I'm only getting phasing in  positions 1 and 4.

Did you use the drawing that I just posted, (corrected) or the drawing that I posted a few pages back?
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on August 22, 2015, 01:01:26 PM
I'm comparing the 2 images from page 7 and 9 and I cant see a difference.  (Please remember I'm stupid!)
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on August 22, 2015, 01:20:36 PM
I'm comparing the 2 images from page 7 and 9 and I cant see a difference.  (Please remember I'm stupid!)

When I replaced the drawing in dropbox...it replaced the drawing on page 7.

The new drawing (verified) is different than the one you followed.

The rotary switch lugs go to X, Y, and Z in a different order.

Wire the rotary as per the new drawing.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on August 22, 2015, 01:30:30 PM
Wire the rotary as per the new drawing.

Ok Boss!!

Won't be tonight though, I've cracked open a cold one from the fridge!
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on August 23, 2015, 01:14:18 PM
Great stuff Larry.

I now have 4 speeds!!  Excellent detective work.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on August 23, 2015, 05:44:40 PM
Here's a poor demo of the speed control.   Excuse the poor setup for recording, I need to mic up an amp really. 

Title: Re: What Does the Foxx Phase?
Post by: anotherjim on August 24, 2015, 04:03:10 PM
Sounds about there now Nick. Congratulations. What's the plan for an enclosure?
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on August 25, 2015, 05:11:02 AM
Cheers Jim.  I still need to play with the trimmers a bit, I haven't really paid them too much attention while I was getting the rotary sorted.  Saying that, the wave seems a lot more even with the 6M8 resistor and the cap changes Larry discovered.

Enclosure wise, its such a beast.   The layout for MkII wont fit into a 1590BB but I've made a few changes in my design so that if I make another it will.  The circuit board is small enough, its more to do with height and getting the pots, switch and jack sockets it.

The Dearmond enclosures, as used in the original aren't easy to source.

I was also looking at this (http://www.ebay.co.uk/itm/281169255761?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT).   I'll probably make another one soon, this time without socketing (except for the ICs), this would give me less height restrictions.

I've got an enclosure that the top panel is the same size as a 1590BB but its much deeper.  This will give me loads of space, so I'm also going to fit in a treble booster.  I've also just acquired a Vox AC30cc2 so if I cant get that Brian May tone now, then I might as well give up.  So MkII is going to be expressionless.  The big enclosure would give me the option of adding an expression jack in the future but I'm not too worried about the expression feature.
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on August 25, 2015, 12:34:51 PM
I've sourced two of the Dearmond volume pedals recently.
They come up at a reasonable price (under $40 US) from time to time.

As you know...I plan to build the Model 7 as true to the original as possible.
That's why I followed the board design and size as best I could from the images that were available.

One thing that I noticed about the Dearmond pedal....it has a much larger travel than a standard wah pedal enclosure.

This would be integral to exacting the sweep and the speed range as in the original.

Another thing that needs to be figured out is....where do you set the pedal potentiometer.
The pedal does not accommodate the full travel of the pot so...without having an original Foxx Phaser for reference, one would have to install the pedal pot to where it covers more useful frequencies and speeds.

If you do another sound sample...it would be nice to hear you go through the rotary switch speeds with the rate pot at minimum, and then the rate pot at maximum.

I bread boarded the LFO/rotary switch with an LED indicator so....I was only able to achieve a visual of the speeds.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on August 25, 2015, 05:56:44 PM
Here you go Larry... as requested.

Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on August 25, 2015, 06:09:56 PM
Perfect!

Thanks for that Nick!

It sounds like a pretty good, linear collection of speeds.

That's what I saw with the LED.

I would imaging that the pedal pot would be adjusted to "lose" that fastest speed.

Like I said, I'll have to play with it a bit to see what is "useable"
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on August 26, 2015, 02:47:48 AM
Something I've been thinking about regarding the expression pedal.

How about an external expression pedal that has a pot of a nominal (probably best higher) value.  Then have a microprocessor that can read the resistance from the pot.  The microprocessor can apply a multiplier to the value of resistance and then using a digital pot, 'output' a new resistance value.

I hope that made sense, but if it does then the treadle could be calibrated by reading the min and max possible values so that the full range of output values are possible.  Because the multiplying value is variable, then the output range of resistance could be changed.  Also, the microprocessor could actually be a bit more clever and apply log, linear and reverse log logic to the output.

Title: Re: What Does the Foxx Phase?
Post by: nickbungus on September 04, 2015, 02:42:02 PM
I've just been messing on with all the bits I socketed, which is basically the differences Larry noted between the Studio Model 7 and the 1482.

For MKII I basically went with the Model 7 parts.  I cycle to and from work every day which is about an hour in total and whilst on this project I've been listening to Queen bootlegs from the 70s.  Brian May never had his fOXX switched off during that period.  Anyway, with the Model 7 components, I felt like the Phaser was doing too much phasing and not sounding like what I've been listening to. 

Also, I've felt that although I can hear lots of phasing of noise, the actual guitar signal wasn't that involved.  I take it that's what trimpot R2 and pot R7 are trying to manage?  I tried adjusting these but wasn't that happy.

Anyway, I just changed C16 and C21 back to 0.01uf from .1uf and then I changed the notorious R34.  On the 1482 schem its rated as 2M2 but Jim informed me this was causing an uneven sweep.  Larry using his skills, noted the Studio Model 7 used a 6M8.  Anyway, using Jims advice from a previous post, he said this should be 'Select On Test' and I think he is right.  I went with a 4M7 and although the sweep wasn't as smooth, it did sound a lot more authentic.
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on September 04, 2015, 03:25:48 PM
Well Nick...

All I have to say is everything that is written about Brain May's equipment lists his phaser as a Foxx Studio model 7.

I spent quite some time with multiple board images verifying the components.

Lowering the value of the two capacitors that you mentioned (C16 & C21) will only cut back on the bass response a bit. (less apparent phasing) The .1µf value has been verified.

R34 is 6.8M on every Foxx Model 7 and Regal RE-35 phaser that I have images of.

If you are hearing strong phasing without the signal being affected, I would look elsewhere for an issue.

If you recall, we added C23 (.1µf) to the feedback path.
Try lifting one side of C23...see if it makes a difference.
I was planning to do just that when I get around to building this thing.

Did you use a 300K for R13 in the LFO?
The 330K could make a difference in the sweep.

(https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/IC%201%262.jpg)

(https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/FFP1.jpg)
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on September 04, 2015, 03:44:12 PM
Thanks Larry, you know I don't understand electronics!!  I'm just going off my ears!

There's a guy called Mike Ryde who's got a whole website dedicated to the Brian May tone who I've had a few correspondences with.  He told me that the earlier models are deemed the most authentic according to the Brian May forums he's on.  Even I'm not that much of a geek to be on them!!  Whether they mean the 1482 or the Studio Model 7 I don't know. 

Yes I went with the 330K I had rather than the 300K you noted.  I'll give that a go. I'll play with C23 too.

One thing I've discovered is how subjective your ears can be, this can also change from day to day without making any changes.

Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on September 04, 2015, 03:50:54 PM
I just had a look on this site:
http://www.brianmayworld.com/PeteCornish.htm

It looks like two knobs on the left of the pedal in two of the images.

The Sears 1482 has one knob and one toggle switch.

The original Foxx phaser was called Foxx Foot Phaser.

(https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/FOXX%20PHASER.jpg)

The first issue of the Model 7 was a completely different circuit board.
This model included two ring modulator settings on the rotary switch.

The Model 7 was changed to the original board and circuit of the Foxx Foot Phaser.
I guess the ring modulator settings didn't go over very well!
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on September 04, 2015, 04:06:28 PM
Another possibility is that there is no clear divide between the 1482 and the Studio Model 7 and the thing just evolved. 
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on September 04, 2015, 04:23:37 PM
As far as I can tell...the Sears 1482 is a castrated version of the Foxx Foot Phaser.

There are many examples where goods that are manufactured for a mass market chain are the cheaper, cut down versions of the original.

During WWII, the United States developed the "super charger" technology.
This was introduces on the P-38 Lightning.

The British witnessed test fights of the Lightning and placed orders for 667 of these fighters.

Three Lightnings were delivered sans superchargers.

The British promptly cancelled the remainder of the order.

These three aircraft were appropriately nicknamed....castrated Lightnings.

Sorry Nick! :)
Title: Re: What Does the Foxx Phase?
Post by: Luke51411 on September 04, 2015, 04:36:42 PM
I've browsed this thread a bit but haven't paid that close of attention. At any rate, I just came across a "broken" studio model 7 on ebay. Is this circuit sorted out or are there still some unknown values?
Title: Re: What Does the Foxx Phase?
Post by: Luke51411 on September 04, 2015, 04:38:35 PM
http://www.ebay.com/itm/311436905869?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT (http://www.ebay.com/itm/311436905869?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT)
Here it is, there are some gut shots in there too.
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on September 04, 2015, 04:54:34 PM
http://www.ebay.com/itm/311436905869?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT (http://www.ebay.com/itm/311436905869?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT)
Here it is, there are some gut shots in there too.

Thanks Luke.

I collected these shots the other day.

This is an example of the original Model 7 with the ring mod settings.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on September 05, 2015, 02:52:18 AM
Thanks Luke.  The eBay item does not ship to the UK, otherwise I'd be on it

I've modded my board to be able to satisfy both the 1482 and the Studio Model 7.  I've printed 2 out and I'll be etching soon.  Apart from the ICs, the only thing I plan to socket is R34.  I'll also use Larrys speed control on both, but I'll make each model.

I'll then be able to compare them side by side. 

I'm guessing the SM7 will be a better everyday phaser but for the authentic Brian May sound, it will be somewhere between the two.
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on September 05, 2015, 05:12:40 AM
Hey Nick...

I just read something about Brain May's Foot Phaser that came as a bit of a surprise.
From your previous statements (reply #44), I was under the impression that Brian's phaser was rehoused in a different enclosure, and the speed pedal wasn't used.
If Brian didn't use the pedal speed control...then Pete Cornish went through a lot of hassle incorporating the cry baby pedal for the speed control....and the cry baby speed controller would have been a waste of space on Brian's pedal board. 
It would make sense that Brian adjusted the speed of the phaser for different songs/passages with the pedal.

"A modified Foxx phaser pedal was added with foot operated speed controller. The modifications were as follows:
The potentiometer was fitted into a CryBaby chassis, as the original speed control pedal was badly worn, along with a replacement heavy-duty bypass switch. The CryBaby chassis was fitted on top of the pedal board. The original Foxx circuit board was too large to fit in the CryBaby chassis so Pete incorporated it into the pedal board with a built in 9v DC power supply to power it. He did not do any audio modifications to it."


If you scroll down, you can see an image of the pedal board that Pete Cornish built for Brian.
It includes the Cry Baby shell that controls the speed of the Foxx circuit.
http://www.brianmayworld.com/PeteCornish.htm
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on September 06, 2015, 04:26:18 AM
Its a good point Larry.  It also asks the question as to why he didn't just buy a new one.  Even if they were no longer in production, someone like BM, with the resources available to him at the time could have sourced a new one.
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on September 06, 2015, 02:13:17 PM
"why he didn't just buy a new one."

I think one of the key sentences is:

"As Queen moved on to bigger things, so did their stage show. Brian needed a more up to date system that would withstand the rigours of life on the road. In June 1982, Pete designed a pedal board and routing system that Brian could take anywhere in the world."

Pete Cornish built Brian a pedal board that  "consolidated" his effects into one user friendly module.

The pedal potentiometer in the Foxx phaser controls voltage for the sweep and resistance for the LFO speed control.

If the pot were worn...it would not have the same linear response of a new pot.....but it would still be usable.

This does not hold true with a worn wah pedal pot which "carries" the audio signal.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on September 12, 2015, 05:04:18 AM
Well V2 is housed and sounds awesome.   I stuck it in with a Brian May Treble booster from Tonepad as the enclosure I had was so large. 

Like Jim reported, I also had a lot of interference and noise, so I made the cap mod suggested by Jim and when housed its as quiet as a mouse.

I wish I used a 1M log for the Feedback (I used a 1M Rev Log as that's all I had).  Its only effective from minimum (7 o'clock) to 8 o'clock.

I tried to do a video last night but couldn't get a descent tone going straight into a crappy sound card.  I'll sort something.
(http://dirtmonkey.org/foxx/foxx2.jpg)
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on September 13, 2015, 02:54:20 PM
Hey Nick,

I don't see a selector switch for the speeds. Which speed did you jumper?

Also, I'm sort of curious how you connected the "Depth" control.

I experimented adding a Depth control to the LFO on a breadboard....

There was only one configuration that truly worked. It's the "standard" pot to ground or reference voltage, attenuating the LFO signal.

I tried connecting lug 1 to ground, 1.8 volts, 6 volts, and a 1/2V divider. I didn't see much difference on the scope so....I ended up connecting it to ground.

Note: R21 (100K) is removed.

You might want to add a 4.7K resistor between lug 1 and ground....just to leave a touch of "wiggle" when the Depth control is fully CCW.

(https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/Foxx%20Foot%20Phaser%20Mod.%207%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20Depth%20mod.jpg)

Title: Re: What Does the Foxx Phase?
Post by: pinkjimiphoton on September 13, 2015, 03:00:54 PM
I just designed a new fuzz circuit! It almost sounds a little different than the last fifty fuzz circuits I designed!


sorry larry... just saw this... BWAHAHAHAHAHAHAHAHAHA.... when did i say that?
<j/k, all my fuzzes sound the same>
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on September 13, 2015, 03:12:30 PM
I just designed a new fuzz circuit! It almost sounds a little different than the last fifty fuzz circuits I designed!

sorry larry... just saw this... BWAHAHAHAHAHAHAHAHAHA.... when did i say that?
<j/k, all my fuzzes sound the same>

No Jimi....I can't credit you for that one!

It's a little dig to all of the Fuzz connoisseurs out there.
as I work on yet another Flanger and Phaser!   ::)

Title: Re: What Does the Foxx Phase?
Post by: nickbungus on September 13, 2015, 04:19:15 PM
Sorry Larry.  A bit misleading.  I used lies for the depth control.  It's just the 100k 'speed' pot.  I used the same labelling used by Greg Covington on his version.  The one labelled speed is the rotary switch.

I didn't want to have a label for 'speed' and then 'more speed'.
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on September 13, 2015, 04:37:12 PM
I see...
Why label things as what they actually are???? Because....that's what they would be expecting!  ;)

Title: Re: What Does the Foxx Phase?
Post by: nickbungus on September 14, 2015, 02:56:49 AM
It's just for me and in really happy with it.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on September 14, 2015, 06:36:20 AM
Actually Larry, that got me thinking and I had a look at the controls as stated on http://www.effectsdatabase.com/

For the 1482 Phaser:
•(treadle in mode 1)controls the depth/amplitude of the modulation (the size of the range in which the effect sweeps).
•(treadle in mode 2)sets the position of the effect when the LFO is in the center position or controls the effect when the LFO is switched off
•Modeswitches between the 2 treadle modes
•Range (Slow-Fast)controls the speed of the LFO wave that controls the phaser in mode 1
•Depthcontrols the depth of the LFO wave that controls the phaser in mode 1

And for the Studio Model 7:
•(treadle in mode 1)controls the depth/amplitude of the LFO that controls the phaser
•(treadle in mode 2)sweeps the phaser like a wah pedal
•Modeswitches between the 2 treadle modes
•Range (Slow-Fast)controls the speed of the LFO wave that controls the phaser in mode 1
•Depthcontrols the depth of the LFO wave that controls the phaser in mode 1

Clear as mud!

Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on September 14, 2015, 04:40:43 PM
Yes...I'm not sure who came up with that overview of the controls but...there are some discrepancies.

Even the name Foxx uses..."Phase Depth" isn't exactly correct.

Even though turning the control CW will "thicken" the sound...the control, as you are aware of is feedback.

This is probably a better description of the controls.

(https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/Foxx%20Phaser%20image.jpg)

Question Nick:

When you tried the 6.8M for R38, did you leave in R25 and C12 as in the 1482 drawing?
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on September 14, 2015, 04:55:58 PM
Yeah I did.  I said I wouldn't and would socket them, but I was on a soldering roll!!

I looked down at my picked parts and went 'BOLL#*KS!!'.

Like I said in an earlier post, I'm making another 2, side by side - one for a friend and one for the hell of it.  I'm going to make one strictly 1482 (except R38) and one Studio Model 7 without R25 and C12.  I've got a Rat and a Boss CE-2 to finish first.

Regarding the word Depth, I was happy enough to use it on my decal even though I knew it wasn't right.  Any suggestions for the correct wording?

For the 'Phase Depth' as in the image, I liked Jims description, 'Swampy'.
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on September 14, 2015, 05:28:47 PM
I would go with the label "Speed Select"
One turn of the knob and any questions one might have about the knob's function will disappear.  :icon_wink:

This last weekend I was "playing" with the LFO on the breadboard while viewing the changes on my scope and taking voltage measurements with a DMM.

I tried including R25, C12 with R34 value 2.2M. (1482)

I then changed R34 to 6.8M.

Then removed R25 and C12...leaving R34 value 6.8M. (Model 7)

I found that the LFO in the 1482 configuration had a slightly higher amplitude at pin 7 of IC3.

Now let's get into some details.

With R25 and C12 in place, and R34 6.8M you will have less phasing because the LFO will have a lower amplitude....why??? because R21 (100K) and the R25, C12 combo make up a voltage divider.
With R34 at 2.2M...the gain is increased at IC3....so...it works.
When Foxx removed the R25, C 12 combo...they decreased the gain with the 6.8M

Now there has to be a reason why Foxx did this. Maybe the original component values were causing an issue with the upper end of the LFO slamming into the top rail of the IC, or causing distortion with a hotter signal. I'm not sure but...they were so adamant about changing the circuit that they sourced a not so common 6.8M as the only carbon comp resistor in the build.

If you remove the R25, C12 combo, and replace R34 with a 6.8M....you are probably going to have stronger phasing than you have now with the voltage divider and the 4.7M that you went with.


Title: Re: What Does the Foxx Phase?
Post by: nickbungus on September 15, 2015, 02:41:41 AM
Without the scientific electronics knowledge I was wondering the same thing too. I'll crack on with my definitive versions and play them side by side.  Shame I soldered in the extra components. 

I think I'm going to label the 100k pot 'Rate' going forward.  It means the same but at least I won't have two 'Speed' controls.
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on September 15, 2015, 06:33:20 AM
I can lose sleep over what name to put on a knob. On the usual stomp box, I would probably put 2 related controls side by side, put "LFO" centred over them and "Range" and "Rate" under each. Rate could be speed but I use rub-down lettering. Applying the lettering is tedious so I want little words! If I was running out of "R" on the sheet I'd use "Speed" instead, unless I was running out of "e".

I made a delay with an LFO that would change between fast & slow rate, rotary speaker fashion, over variable time. Simulating the fact that the mass of a rotor cannot change between speeds instantly. Took me ages to decide what to call it. I settled on "Inertia".
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on September 15, 2015, 09:55:41 AM
I'm going to add a few more knobs: tempo, pace, velocity, rapidness  anti-slowness, fastness, and quickness.
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on September 15, 2015, 02:18:20 PM
I found something interesting today.

A decent gut shot of the reissue.

There is a Blue, Grey, Green, Gold (6.8M) resistor, with a 1M resistor next to it.

Since there are no other 6.8M resistors in this circuit....I would imagine that these are R34 and R38.

So...the reissue uses the same values for the gain of IC3. (LFO signal gain)

(https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/reissue%20comp.jpg)

Also....I was comparing the 1482 drawing and my drawing....

Did you use a 270K for R1 as in the 1482 drawing?
I've verified R1 as 100K on the reissue board as well as the older model 7 boards.
A 100K for R1 will give you gain of 1, the 270K will give you about a 1/3 of that.
That may have been the cause of your volume drop.
I recall you addressing that issue by raising the value of R49
The differences that I see between the 1482 and the model 7 all appear to be improvements or fixes.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on September 15, 2015, 06:48:39 PM
Actually Larry,  because it was early in the build, before I'd got myself in a soldering frenzy,  I actually socketed this.  I've currently got a 270k in but, I believe I did try the 100k,

Because I tend to do this stuff late at night with minimal volume,  I can't really report any difference but I don't believe it affected the tone at all, which is what I'm listening for.

I'm away on business until Friday, but would happily do a side by side test when I get back.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on October 01, 2015, 04:41:39 PM
I'm on a build, using Larrys spec.  Although I'm pretty sure I bought loads of them, I can't find a 180pf cap for C20.  I've got a 150pf but not 180pf.  Will this would make much difference?  I could put 150pf in parallel with a 47pf for 197pf.  Would this be better?

I usually measure all components before soldering and I have noticed the tolerance on caps is a joke.
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on October 02, 2015, 10:37:46 AM
You can use the 150pf.

This is a filter to cut some of the harsh highs.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on October 02, 2015, 10:39:27 AM
Thanks Larry, excuse my ignorance.  What's the ramifications of using a higher or a lower value?
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on October 02, 2015, 11:26:03 AM
If you raise the value of C20, the cut off frequency will be lowered.

Less highs will pass through the filter.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on October 05, 2015, 06:58:46 AM
This isn't a question or anything, just a note if anyone is interested (I doubt it) and for me.

For what I need and want, I don't need the treadle aspect of the pedal but if you do, here is how to wire the dpdt switch to toggle between auto-phasing and manual. (Going off the original schematic and not Larrys much improved one).

2 | 1
5 | To Treadle Pot (100K)
3 | 4

So if, like me, you don't want to use the treadle and just have a 100K pot, place a jumper between 2 and 5 and then wire 1 to the 100K pot, grounding the other 2 pins on the pot.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on October 08, 2015, 06:40:56 PM
Thanks to Larry (armdnrdy) and a big congratulations for the brilliant tracing he has done on the fOXX Studio Model 7.

I've just built it using my board but his specification and it sounds great.  I'll post a video soon.

I had a few issues which for the first time ever on a fail, I managed to debug.  Larry also helped considerably with that.

Thanks again!
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on October 22, 2015, 11:35:23 AM
Going of Larrys schematic:

(http://dirtmonkey.org/foxx/c2c25.png)

Do I really need C2?  Larry traced C25 as an offboard component, I presume because C2 wasn't cutting it.  On my current board I've added it along side C2.

It would free a bit of space up on my board if I could bin C2 and then lay flat C25.
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on October 22, 2015, 12:44:13 PM
I like to distribute capacitance rather than have just one big one, so maybe C2 could be close to the LFO chip supply pins. I don't think this particular LFO is a "clicky thumper", but it can't harm.

C25 at 220uF isn't particularly large value for it's duty, but if space is tight you can...
Hunt for smaller caps. A 16V rated one would be smaller that a 25V rated one. Maybe at most 6mm dia 11mm high.
Radial lead or axial  could offer different space usage options. Hight versus diameter?
Have 4x 47uF distributed around the board (and lose C2).

Absolute panic solution.. a surface mount Tanatalum cap on the solder side of the board.


Title: Re: What Does the Foxx Phase?
Post by: nickbungus on October 22, 2015, 03:38:06 PM
Thanks Jim.

What is the purpose of these caps?  I'm sure this is week 1 stuff at pedal building school.  My guess is they smooth the DC (which probably means to level out any fluctuations).
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on October 22, 2015, 07:15:59 PM
The board layout that I drew shows the placement of C2 and C25.

C25 (220µf) is the incoming power filter cap.

C2 is the local op amp decoupling capacitor.

C2 handles IC1 and IC2. (the signal op amps)

I would say that it is needed. While IC3 is oscillating up and down, C2 keeps a power reserve for IC1 and 2. If you delete C2...there might be issues with ticking in the signal section.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on October 23, 2015, 02:25:56 AM
Thanks Larry

On your schematic they are in parallel, going between V+ and ground.  So are we saying they do 2 different jobs?  From what I have read, wouldn't they just work together to give 230uf capacitance? 

"The board layout that I drew shows the placement of C2 and C25." (Note that the text editor tools and icons don't work with MS Edge/Windows 10).

Are you saying Larry that schematics don't always show the desired position of components even when it matters?

Remember I am a novice trying to understand a little so please go easy on me!
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on October 23, 2015, 06:57:10 AM
They do 2 jobs, smoothing out any noise and ripples in the supply voltage is one. That resistor R53 is making a low pass filter with C25 to do that, but there's another effect and that's helping to stop other parts of your circuit that share the same power supply from interfering with each other via that common power supply.

All paths in a circuit have some resistance - be it in fractions of an ohm. When something switches on and pulls current there is going to be a voltage drop across the path proportional to the resistance. Other parts of the circuit downstream will "see" that volt drop and it could be audible. Capacitors across the power rail are storing electrical charge. If placed close to parts of the circuit that draw significant current, they directly supply that current without the resistance of the upstream supply path causing a volt drop. In IC based circuits, the chips are often the only things that draw current, so the chips power pins are the place to situate the cap.


Where all the circuit is only audio and especially one using op-amps, the supply input cap is all you need (and you will probably get away without one at all - it just isn't best practice not to) and Op-amps have very good immunity to power supply noise. With an LFO present, there is often an element that switches on or off every time the sweep changes direction. That sudden switching, if passed via the power rail to the audio side, will be heard as a ticking at the LFO rate. Very annoying. It needs a "local" supply cap.

I would raise the component count with a 100nF ceramic cap across each of those electrolytic caps. Electro's are good, but at high frequencies start to slow down  due to the way they're made. Ceramic are cheap and nasty but are fast. So I think of the electro as catching the hum and audible noise and the ceramic stopping the radio noise.


Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on October 23, 2015, 08:36:26 AM
Are you saying Larry that schematics don't always show the desired position of components even when it matters?

I am saying exactly that.

There are many drawings that show IC power pins connected "directly" to the output of a voltage regulator...when in reality...they are connected to the "power rail" on the other side of the board.

Same holds true with voltage divider resistors for voltage reference.
The resistors will be depicted on the schematics as being directly connected to the voltage regulator output....when once again...they might be on the far side of the board.

Schematics are the drawings of the circuit...a board layout can be something completely different.
When you are dealing with LFOs and clocks....placement of components and traces make a difference between a nice "quiet" effect and complete failure.
I learned this from mistakes in my early board layouts.  ;)
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on October 23, 2015, 09:29:30 AM
Thanks Guys.  I always enjoy the lessons.  Slowly it is getting in. 

Good news then, with the way I have got it on both my 1482 and Studio Model 7 boards I have no clicking/noise!
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on November 20, 2015, 06:40:16 AM
Probably one for Jim as he coined the term when he had my v1 but all suggestions are welcome.

When Jim had my v1, he said that with the Feedback pot at minimum (or maximum - depending on which way it was wired), you could get a really 'swampy' sound.

I've built 4 fOXX phasers now, 1 with the original schematic (Sears 1482), 1 with mostly the original schematic and then 2 with the components that Larry brilliantly traced for the Studio Model 7,

The Studio Model 7 has a much better sweep and a clearer sound but I can't get them to get that swampy sound that I could get from the other 2.  Listening to Queen bootlegs from the 70s, the swampy sound is what makes it.

Is there any way I can mod either design to increase the swampyness? 

I've got a new board/Layout that I am currently building that accommodates both the Sears 1482 and the Studio Model 7 plus all the suggested enhancements from you guys.
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on November 20, 2015, 11:13:40 AM
I can't see anything different in the 2 schemes around the feedback. Both lack the cap in series with the control that I'd added, but then Mr May's examples probably lacked it too. The cap would have changed things a bit, since it would have cut some of the bass in the feedback, and in the Foxx, both the phase shifted AND clean signal get fed back.
The feedback is positive, which, where the clean signal is involved, usually leads to uncontrolled howling, so you get quite a small range of adjustment between a useful feedback amount and rampant squeel. The cap I added probably gave a bit more useful range.
The original reason for adding that cap, was to isolate the first amp from any ground or DC voltage sneaking in from the output and changing the bias of the first amp. Normally, you would hope whatever it's plugged into would have a cap on it's input to stop this ever happening anyway. In the real world, you can't guarantee this is always the case, so I would add a cap in there anyway.
Title: Re: What Does the Foxx Phase?
Post by: armdnrdy on November 20, 2015, 12:46:02 PM
Nick,

Without reading through this whole thread.....I'm not sure if it was ever outlined how to adjust the feedback path.

I'm assuming that you will "calibrate" TR1 (feedback trimmer) with a guitar instead of a signal generator.

The feedback control (P1) is connected one way....the correct way.
You should have less feedback (thinner sounding signal) when the control is CCW. You should have a "thicker" sounding phase when the control is CW.
Looking at the pot from behind, with the lugs facing down, the lugs are numbered 3, 2, 1, from left to right.
My drawing depicts the correct lug connections.

With the feedback control CW, the feedback trimmer set around the 50%, and the speed control around 50%, strum your guitar...sort of hard, to emulate the hottest signal that this circuit will see.

If the phaser starts to oscillate, adjust T1 CCW until the oscillation stops.
If it isn't to the point of oscillation yet....adjust T1 CW until it oscillates and then back it off a bit.

Check for oscillation at slower and faster speeds and adjust T1 accordingly.

With the feedback set correctly...you might achieve that "swampy" sound that you're searching for.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on November 20, 2015, 02:17:20 PM
Cheers guys.

I've played with the trimmers to no avail on builds 3 and 4.   I don't own these anymore though.  I've only got my second build which is a mash up and this is the one with the nice swamp.

I'll do the build with the new board and then experiment with the feedback and the added cap to see if I can get a resolution.  Perhaps just for testing omit the trimmer and have a temp 2M pot.

Thanks again Larry and Jim,  the education is always appreciated.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on November 22, 2015, 05:58:14 AM
The feedback control (P1) is connected one way....the correct way.
You should have less feedback (thinner sounding signal) when the control is CCW. You should have a "thicker" sounding phase when the control is CW.
Looking at the pot from behind, with the lugs facing down, the lugs are numbered 3, 2, 1, from left to right.

That is really interesting and I take it, it holds true for the  trimmer.  On my board, I've been using multi-turn trimmers and just putting them in without regard for CW/CCW.

Looking forward to my next build!
Title: Re: What Does the Foxx Phase?
Post by: anotherjim on November 22, 2015, 06:21:57 AM
CW or CCW only matters for control panels where we want the common intuitive action of CW=More, CCW=Less. Also Log or Anti log pots will only give their intended sweep when CW=More, as in a Volume control.
In practice, with ordinary linear pots and trimmers, it makes no difference which direction More & Less is as long as YOU know.

It may be the 2 builds that didn't have a strong Q effect had a fault, such as one phase shift stage not working, but still passing clean audio. That would mean fewer notches -  but still sounding like a working phaser.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on December 01, 2015, 05:31:29 PM
Just a quick update on the Feedback control.  I got my hands on one of the builds I wasn't happy with and played with the feedback trimmer some more. 

This is what I did

1)  Turned the pot to max Feedback
2)  Adjusted the trimmer until I achieved squeal
3)  Backed off the trimmer a tad

Much better.  Getting a lot of control now.
Title: Re: What Does the Foxx Phase?
Post by: lovetone on July 05, 2018, 06:07:12 PM
Hey

Can anyone re post the schematic please?

I know this is an old topic but it would be nice to see what your all talking about
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on July 09, 2018, 04:41:08 AM
I've got a newer board layout which is much neater.  I've also verified it. I keep meaning to post it so give me a day or so and I'll get both the schematic and new board up.
Title: Re: What Does the Foxx Phase?
Post by: njkmonty on July 09, 2018, 05:20:33 AM
 :)
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on August 16, 2018, 12:16:24 PM
Sorry - I promised this a long time ago and never got round to it.

Heres a PDF (https://drive.google.com/file/d/1o5g83AXMsbRjBXlRRaHMLL-STz4NTdOy/view?usp=sharing) showing my final version and notes etc.

Any changes please let me know.
Title: Re: What Does the Foxx Phase?
Post by: bcruzin2 on September 17, 2018, 01:04:13 PM
Hi Nick, I know this is an old post, but I have built the Foxx Phaser per your pdf. The only thing I had an issue with was it distorted quite a bit. I did change the R49 to 39K to reduce the distortion. I did  not do the calculations what the gain is actually. Also it looks like it does not mention the jumper that goes on the board next to C21. other than that, it sound great, I might mess with some of the cap values mentioned earlier in this post. Great Job!
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on September 17, 2018, 02:34:21 PM
Hi.  I'll have a look at the pdf and that jumper. The only time I've had distortion is because I've got a 10k or a 100k value wrong. Check you've got your component values correct and if you post your voltages I'll check with mine.
Title: Re: What Does the Foxx Phase?
Post by: bcruzin2 on September 17, 2018, 06:32:32 PM
Wow that was fast, thanks I will check that tonight! I can see where a 10k or 100K could cause a mess. Also, earlier in the thread it talks about a 4 way rotary switch for different speed setting, do you happen to have a jpg of that handy, if not no biggie, I can experiment, I know where it goes. so  I can figure out the layout.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on September 18, 2018, 04:41:09 AM
Yes - Because its just a sea of 10k and 100ks,  after I build one I now just quickly check them all before I even try it out.

I've added the jumper to the document - good spot.  I've also added the wiring for the rotary switch - although I think its not necessary

 Thanks
Title: Re: What Does the Foxx Phase?
Post by: bcruzin2 on September 18, 2018, 06:15:29 PM
For the voltages I get
From the Voodoo Labs Power 9.35v
at  pin 4 of the chips 8.55
at the D4 I get 1.86v
Z3 pin I get +6v
For the FETS 
1= +6
2= +6
3= +2.5v
I did not have a 12 ohm so used a 18ohm and for the 560, it is a 580.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on September 18, 2018, 06:36:25 PM
If you give me all the voltages on all pins on all chips we'll probably be able to see there the issue is
Title: Re: What Does the Foxx Phase?
Post by: bcruzin2 on September 18, 2018, 06:47:00 PM
Found it! R46 and R47 need to be swapped on the board. Just the labeling needs to be changed so the correct values are used.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on September 19, 2018, 07:40:05 AM
Brilliant - That is such a good spot.  Much appreciated.  I've amended the PDF

Thank you so much
Title: Re: What Does the Foxx Phase?
Post by: DMgremlin on September 26, 2018, 02:53:35 PM
About to be repairing this Studio Model 7, thought I would share pics.  Right now it has output signal with no phasing.  Read the entire thread and looks like Larry's schematic with updates is no longer visible?  I should be able to figure it out anyway, I think...

(https://i.postimg.cc/kV56NYs3/20180923_155027_2.jpg) (https://postimg.cc/kV56NYs3)


(https://i.postimg.cc/kV8NzXzF/20180923_155044_2.jpg) (https://postimg.cc/kV8NzXzF)

(https://i.postimg.cc/HrFD3V4Y/20180923_155051_9.jpg) (https://postimg.cc/HrFD3V4Y)
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on September 28, 2018, 02:05:59 AM
Oh wow.

If you could get some high quality shots of the top and bottom and also some side shots on the component side I'm sure we can figure it out
Title: Re: What Does the Foxx Phase?
Post by: DMgremlin on September 28, 2018, 09:43:45 AM
I can definitely get more pics and will update progress. 

The voltages "seem" to be correct all over the place...9V, 6V, and 1.8V everywhere it should be.  The gate and drain voltages of all the FETs match each other, and the source legs all seem to hover between 5.5-5.6 volts or so...will hafta double check those readings, going off memory. 

The threadle pot smoothly measures between about 1k-70k with no weird jumps.

The IC doing the LFO has swinging voltage (between ~1-3 volts if I recall) on the output pin. 

The mode switch and rotary speed switch don't seem to do anything at all...no audible click or effect to the non-phasing output signal that does get through the pedal. 

The Q knob does increase bandwidth (or volume anyway?), sounds a little louder with more perceived bass content.

Again I could be wrong and hafta check again, but possibly Z2 pin 9 (inverting input) did not have audio with a probe...and was thinking it should.

.......

I recapped all the electrolytics with new ELNA audio grade 10uF's throughout, and the 220uF filter cap with a new one.  I may replace the 6M8 carbon comp with a metal film just for posterity.  I have a 180p silver mica I can swap the ceramic with, not that it ought to, but that cap looks seriously funky and I don't happen to have any ceramics in that value.  I am going to add the pulldown resistor at the input and 100n cap on the feedback loop to get rid of switch pop, because it's definitely a loud pop! 

I already have a brand new set of LM324N's and a bag of J112's in case the opamps or FET's end up needing replacing.  You would want to assume a transistor failed but right now I don't see it.  Only had a short time with the unit, and no time on the scope yet.  I'll be excited to get this up and running as it was always a bit of a white whale for my personal collection!
Title: Re: What Does the Foxx Phase?
Post by: DMgremlin on September 30, 2018, 10:46:16 PM
Got it fixed!

Basically there were a couple suspect/bad solder joints, and the speed caps for the rotary needed replacement.  Then reset the FET bias trimmer to factory calibration.

I added a series 100n decoupling cap and resistor to ground (where the feedback loop connects to the pedal switch) to prevent DC at the output jack.  So it still has all the stock IC's and transistors!  Now I just need to clean up the treadle pot internally (or replace if track is worn thru) and it's 100% good to go.

Personally, I think the longest phase time should be MUCH slower and I could probably put a larger cap there, but leaving it all stock values for now.  I have a Small Stone that I added an ultra slowwww speed mod for that type of sound anyway...

Anyway, just reporting the successful repair!  If anyone needs new gutshots or help with one, you know where to find me.  - GREMLIN

(https://i.postimg.cc/fkSs4J3H/IMG_20180930_210818_062.jpg) (https://postimg.cc/fkSs4J3H)
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on October 01, 2018, 04:32:26 AM
Brilliant.  Well done.

I'd love to see the gut shots please.

Do you know what year this model is from?
Title: Re: What Does the Foxx Phase?
Post by: DMgremlin on October 11, 2018, 11:36:35 AM
Sent you a link to pics, Nick.  I will hafta investigate further for possible date.
Title: Re: What Does the Foxx Phase?
Post by: nickbungus on October 12, 2018, 04:55:28 AM
Thank you so much
Title: Re: What Does the Foxx Phase?
Post by: bcruzin2 on October 19, 2018, 04:39:22 PM
Finally had a chance to box up my Foxx Phaser. I added a KAT (Knight Audio Technologies) treble booster http://www.deacyamp.com/index.php?route=information/information&information_id=12 , added a selector switch for the different cap values and since I had extra lugs added a few lower caps. I left holes on the box debating if I want to add a "deep" switch adding 100nf for c16 and c21 and a hole as soon as I figure out how to add an led for lfo speed.  Any suggestions for that?
(https://i.postimg.cc/VdwV596X/20181019-114650.jpg) (https://postimg.cc/VdwV596X)
Title: Re: What Does the Foxx Phase?
Post by: bcruzin2 on October 21, 2018, 01:00:30 PM
I forgot I had this handy little circuit from another discussion in this forum Connected it pin 7 of ic3
(https://i.postimg.cc/3d7s7Kwh/9944131423-3c8df85587.jpg) (https://postimg.cc/3d7s7Kwh)