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I've been messing around with a Phase90 circuit on my bb and came up with this. I am using 2N5457's and 3x TL062 and so far everything is sounding great to me.
I wanted the bias trimmer to be a pot so I figured out a way to do that with a B50k between the extra resistors, 39k and 180k.
I also used a 15k and B100k series resistors to make a variable feedback adjustment.
I had to put a 3k on the Rate control because it will go way too fast and sound weird, then stall out. Maybe because I used a C500k pot? I still can't decide if I want to change that top speed or not.
Here's a vid: https://youtu.be/uq767wDtcaM
EDITED schematic, removed 1N914 and re-arranged bias resistors:
(http://i68.tinypic.com/6rhdhw.png)

I am wondering about some of it though.

1) I am using my standard power filter/protection/LED plan, which is permanently installed in my bb, along with that I also threw in the 1N914 protection diode (D2) but it probably isn't necessary, right? I removed it and I didn't notice any changes, should I have noticed something?

2) Is it ok to use my U1 as a buffer and 1st phase stage? My U3 as last phase stage and LFO? Should I be worried about weird noises leaking through or something?

Some wise person said something like if it sounds good it is good. Sounds cool in the vid. The bias adjust is especially cool, which could be swept for an effect unto itself. Looks like you nailed the parameters in good ranges. Itsa keeper.

sounds cool....a nice mod is to turn the lfo off, and have a manual sweep filter...

nice with OD/DIST in front... 8)

2 things i'd like to add:
1) the 1N914 (D2) isn't necessary because the 1N5817 protects the circuit from reverse voltages and the Zener doesn't need any protection.
2) I like to put my LED after the reverse protection circuit so any reverse voltage won't damaging it.

It sounds great by the way.

Look at the section around R4 you have 39K in series with the Vref output and "top" of the bias

The other schematics I looked at on the web show the Vref connected to rest of the circuit without a series resistor

So you are not connecting the sources and emitter with a low resistance node
Q4 emitter current will wiggle the Vref and bias voltage

R3 the 10K sets the current in the zener shunt regulator, 9VDC - zener voltage / 10k for  3.9VDC / 10 for about .39ma

Have you tried moving the Vref to the other side of the 39K?

You might have found a different adjustment for the p90

Are you using a tant for C12?

can I arkse, what's the caper with Q1? how come it's connected to the Vref line?
sorry, half- and mis-read.

Thanks Gus, good catch.  My mistake in drawing the schematic... oops! it's not like that on my bb, I will fix my sloppy schematic later.
EDIT: I am using a tant for C12 15uF, is that the only kind that works right there?

Thanks everyone else too, what do you all think of the top speed? I think most people would say to let it go bonkers-fast at the top end like an alien ray gun battle. I tend to think just "musically fast" and no more than that.

Duck, I think Q1 is drawn correctly, as are all the others. It seems Vref and Vbias wiggle them all except the output mixer Q, which only gets + from Vref to e

Here's a link to the schematic I started with:
http://www.electrosmash.com/images/tech/phase-90/mxr-phase-90-script-logo-schematic-parts.png

QuoteThanks everyone else too, what do you all think of the top speed?  I think most people would say to let it go bonkers-fast at the top end like an alien ray gun battle. I tend to think just "musically fast" and no more than that.

In my builds i tend to have a "headroom" for the controls. I mean when i build something i almost always scale the values so that i don't want to max out them (and neither go to the minimum in some cases). So i never end up with the "i just want a tiny bit more on this knob" situations.

At 2:10 in my vid I show top speed with the 3k stopper, I like this, it's really just slightly above any speed I would ever use.
At 4:30 I pull out the stop and show a sample of the possibility to include optional "un-musical" speeds  :P

Quote from: Ben Lyman on August 20, 2016, 12:25:34 PM
At 4:30 I pull out the stop and show a sample of the possibility to include optional "un-musical" speeds  :P

I loved that part :P So i would go with a really small resistor for setting the minimum like 100R. :D
Being serious i would say that something between 3k and 1k would be the ideal for ME.

Quote from: TejfolvonDanone on August 20, 2016, 03:22:22 AM
2) I like to put my LED after the reverse protection circuit so any reverse voltage won't damaging it.

Reverse voltage doesn't damage leds. They're diodes. Insensitivity to reverse voltage is one of their defining characteristics.

LEDs have a reverse breakdown voltage so it is safer to move the led +power after the 1n5817 or you could place a Si diode across the LED to conduct if reverse voltage is applied

QuoteReverse voltage doesn't damage leds. They're diodes. Insensitivity to reverse voltage is one of their defining characteristics.

Diodes have a reverse breakdown characteristics which essentially means that if you apply voltage big enough in the reverse direction high current can flow. Zeners usually work in this reverse breakdown area with set breakdown voltage and they are used as voltage reference and shunt regulators.
For most diodes there is a rated reverse voltage at which they are guaranteed not to break down. This value isn't always specified for LEDs and they are usually much lower than for a regular diodes. So LEDs aren't so forgiving to reverse voltage as diodes are. You may blow only the LED with a reverse voltage. Protecting the LED doesn't need a lot of effort: you just put it after the Schottky and you are done. It's better to be safe than sorry. You could put a antiparallel Si diode with the LED as Gus mentioned but why bother when you already have reverse voltage protection?

Interesting. Learn something new every day. I've reversed dozens of leds without killing them, so I didn't realize it could be a problem, but the internet agrees with you. I stand corrected.

• R35 (3M9 as shown) sets the current feeding the FET gates, and ultimately the sweep width.  MXR opted for a one-size-fits-all-speeds sweep-width so it is fixed.  Faster speeds want less width, and slower ones want wider.  So, consider using 4M7 for R35, and a toggle to strap in one of two other fixed resistors in parallel to achieve other widths.  Try not to go any lower than 3M.
• The bias current coming through R7 (1M) sets the initial starting point of the sweep, and the LFO simply adds to that.  Varying the value of R7 adjusts the "offset" or range of the sweep, so that it can be gurgly to swirly.  Consider replacing it with a 680k fixed resistor in series with a 500k variable resistance.
• Higher feedback tends to results in cumulative noise.  So what many manufacturers do is include a cap in the feedback loop of one or more phase-shift stages.  So consider a .001uf-.0015uf cap in parallel with R22.

It becomes your choice as to whether things like feedback, width, mix, or offset/range should be set with pots or toggl;es (2 or 3 position).Prsonally, I find that 3 settings each for width and feedback are good enough for me, while a vibrato/phase switch is sufficient for mixing.  Offset, however, is really more of the sort of thing that wants a variable control, since it really changes the character of the phasing  a lot.

LEDs do reverse breakdown BUT they also "forward breakdown". So we "always" have a resistor in series to limit the forward current. In general, this will also limit the reverse current.

Some quibble. Forward breakdown is say 2V and reverse breakdown is something over 5V. If the forward current limit is "melt down", and the supply voltage is significantly higher than 5V, you can get to a point that heat in reverse breakdown (due to higher break voltage) causes melt-down.

I don't think this can happen with 9V or 12V supplies. So an LED plus its resistor can be safely and frequently "reversed" in car, PC, and pedal applications.

I did once "prove" it could be a problem for 110V AC supply. Though at that heroic level the resistor ratings get awkward first.

2) Is it ok to use my U1 as a buffer and 1st phase stage? My U3 as last phase stage and LFO? Should I be worried about weird noises leaking through or something?
« Last Edit: Yesterday at 06:16:54 AM by Ben Lyman »

Question 1
Buffer and first stage should be fine using a dual op amp.

Question 2
U3 as a dual oppy.
I would not.
Maybe use 2x single op amps.
UA741 TL022 see below
Having said that while you have it on the breadboard you could try it and see for yourself.

It's a good idea to use a low power op amp for the lfo.
Such as TL022.

Look at some other. Phaser schematic's for parts.
Also take a look see the bi phaser for those caps in the feedback loop.

http://experimentalistsanonymous.com/diy/Schematics/Phasers/Mu-Tron%20Bi-Phase%20Phase%20Stage.gif

Then take a look at the univibe cap values for some different ideas. I think I read some where they're chosen for octaves. Maybe I imagined that.

Congratulations on some good mods mate.
Some really good advice here from the guys.
Keep up the good work

Wow! Thanks guys, some great info here. I've been having a  lot of fun experimenting with all those ideas.
I have made some very slight changes but not too much, as I really like the sounds as it is but I got some parameters to go a little further out there.
Still not sure if I really want sonic ray gun noises but a 1k8 for R33 allows for crazy buzzy noise without stopping altogether, backing the knob down a tiny bit returns to more normal vibey speeds.
But then, as D'Astro says, stopping it is pretty cool when you can sweep the other knobs around and get manual settings. It seems I don't even need a switch if I just leave out R33.
My main problem now is with the layout, AARRGGHH!!! What a complicated circuit to do on a perf.
I hope I can figure out something because I really like the sounds and I really want to build this thing bad!

finished at last!
(http://a65.tinypic.com/essqcj.jpg)
(http://a63.tinypic.com/286tn9l.jpg)

Gotta revive this for a minute, rather than start a new thread.
I love this pedal and use it constantly, however I want to simplify it a bit, maybe come up with something I can make for friends and family, maybe a smaller box.

I tried a PHASE 45 on the BB and I love it! I don't know why people bag on the P45, it sounds perfect.
I also tried one part of the JC Maillet Vibe Mod, just the 2x 50nF caps swapped out for a 10nF and 100nF.
I guess it's more vibier, I dunno, it was late, I'll check it again later.
Pulling the dry lead made a nice vibrato, not worth putting on a switch if you ask me.

Here's my question: Before I build this, is there any new developments I should be aware of? Any errors in the schematic?
Mark Hammer: I used your schematic (THANKS!) from Ampage: http://www.ampage.org/schematics/mxrphase45.pdf
I also tried to read the GGG schematic, it looks about the same but it was a little difficult for my rookie eyes to suss: http://www.generalguitargadgets.com/pdf/ggg_p45_sc.pdf
Here is JCM's: http://www.lynx.bc.ca/~jc/phase45modded.gif

I'm thinking of replacing the 1M (depth resistor?) with something bigger or a pot?

Other changes of mine include:
2x TL072
2x 2N5457 or 2N5458
Series 1n5817 polarity protection
Series 100r power filter and bypass caps 100uF & 100nF

I think thats it
Thanks!

The JC Mallet modded version mixes the dry and wet signal via the 22k pot a IMO useful feature that get that vibe or phaser feel to the pedal.
You could get this in a 1590b with 3 pots side by side (no dust covers) or triangulated.
Maybe even have room for a battery too mate.
Breadboard the mix pot and see if you think it's worth it.
What op amps are you using?

Thanks Rich, I will look into that mix pot, it does seem like it might be useful.
Maybe I wouldn't need a depth control if I had the mix pot to tame it a little bit.
I'm using a couple TL072's and I have a variety of FETs but none of those weird old kinds in the schematics.

I'm gonna post these links again here since we've gone on to page two:
Mark's schematic (THANKS!) from Ampage: http://www.ampage.org/schematics/mxrphase45.pdf
the GGG schematic: http://www.generalguitargadgets.com/pdf/ggg_p45_sc.pdf
Here is JCM's: http://www.lynx.bc.ca/~jc/phase45modded.gif

I'm thinking of replacing the 1M (depth resistor?) with something bigger or a pot?
Or is the mix knob a better way to go?

Other changes of mine include:
2x TL072
2x 2N5457 or 2N5458
Series 1n5817 polarity protection
Series 100r power filter and bypass caps 100uF & 100nF

Well, I tried the 22k mix pot, maybe I did something wrong but I don't see how, it's such a simple thing and written so clearly in JCM's schematic. Results were this:
Far CCW turn= no effect at all, just loud clear guitar
Middle= nice effect with volume drop
Far CW turn= volume returns with very subtle vibrato effect

best results seem to be from 9:00 to 3:00 ability to do some mixing but I am not 100% convinced it's worth it... nor am I 100% convinced I wired it right  ;D

I think I will start working on a layout for a 1-knob, 2-switch version:
Speed knob, plus switch for vibe/phaser caps, and switch for deep/shallow phase.

while I am working on that, hopefully if anyone has anything to say, please speak up  :)
Thanks!

Edit: I just had a thought. Look at JCM's 22k mix pot. it goes straight from the IC out (buffer?) to the output cap. No wonder I got dry signal, right?
Hmm... maybe a 10K pot with a 10K resistor? 

external bias pot?

[edit :] that kipper fella, didn't he add a switch wot changed the wet phase into the out mixer? that might be a thing here.

Good idea Duck. JCM has the external bias pot so I started with that. I don't know if it's my choice of FETs & ICs or just the nature of the P45 but my 250K bias pot has a very narrow working range, about 10k-50k. As a result JCM's 100K bias pot (2x 47K straddling) was pointless, I pulled it out and got a better working result with a 50K pot in between a 120K & 81k, even better still with a 25k between some resistors I can't remember. Pulled it out, which I so often do when I listen to the results and weigh it against drilling a hole in an aluminum box. lol  :P

Here is another test I ran which I liked, just like in my previous experiment with the P90 and a variable feedback resistor. Look how the dry path goes around through a 10K in the P45 schematic. JCM uses the mix pot, some others might break the link with a switch to get straight vibrato, so I put a 100K pot in series with the 10K wired with just the wiper and one other lug for variable resistance. This seems the best way to my ears, pot fully turned offers no resistance allowing for full phasing mix, turn the other way resists the dry signal and emphasizes only vibrato. Basically a mix control without the volume drop in the center.

Again, I am still not even sure it's worth drilling a hole to be able to do this when I get the same amount of satisfaction by stomping my foot on something and playing guitar with or without switches and knobs!  ;D

On to one more stupid question: Is there a way to get more volume out of this?
I don't really want to add a booster transistor but it seems like the pedal is just barely equal to the bypassed volume.
It would be nice to be able to adjust it up or down a tiny bit.
Why no "output mixer" like in the P90? Just cost cutting or it doesn't need it?

This is what I'm starting with, it will be a little easier for me to suss out, providing I've drafted it correctly.
Thinking of keeping it very simple, C6 and C7 will be replaced permanently with 10nF and 100nF respectively.
R16 (10k) will have a 100K (or higher) pot in series wired as a variable to cut out the dry signal.

Any bold faced errors?
(http://i67.tinypic.com/2reihpw.png)

Okay, you guys convinced me the bias control is pretty cool  ;D
So to keep it simple, I am only having two knobs, speed and bias.
I couldn't see the point of having a 100K bias pot that only has an effect right in the middle, so using my DMM I was able to find that the bias pot was only working in a range of about 44K.
Here's the updated schematic including all mods, they aren't a lot.
Bias is a 50K pot with 100k fixed on each side.
note the 27k R10 for added volume, I think?
R25 is 3M3 for more deeper and R29 is 5k1 for more ultra super mega fast
(http://i64.tinypic.com/rvest0.png)

Quote from: Ben Lyman on October 12, 2016, 06:27:09 PM
Okay, you guys convinced me the bias control is pretty cool  ;D
.....
I couldn't see the point of having a 100K bias pot that only has an effect right in the middle, so using my DMM I was able to find that the bias pot was only working in a range of about 44K.
.....
Bias is a 50K pot with 100k fixed on each side.

oh, we thought you knew, this is the way it's done. you can measure the voltage range of usable bias, then pick a pot value, like 50k, 10k, 5k, whatever is close handy, and do the resistor string and Ohm's law to work the top and bottom resistors, if you are the trainspotting type, but your way works.

And your Q1 Q2 are? please.

Quote from: duck_arse on October 13, 2016, 09:42:41 AM
oh, we thought you knew...

You presume a lot there, Duck  ;D
I tried a few resistors on each side of my 50K pot but settled on 100K each, because the pot bias functions about dead center anyway.
The end result is that the pot has a small spot at each side where the modulation seems to go away completely but I can live with that.

Rich, the Q1/Q2 are 2n5457 today. I didn't notice any difference from putting in 2n5458, I think either kind should work.
I also have not bothered with any matching, though I have read plenty about how important matching them is... I just don't want to 

Thanks Ben When I get the chance I'll bread it.

R25 sets the width of the sweep.  You'll find some issues that use 3M9, for a narrower sweep, ideally suited to faster rates, and some use 3M3, for a wider sweep.  Keep i mind that MXR aimed for a one-size-fits-all approach with that pedal/design.  One fixed sweep width, one fixed wet-dry mix, one fixed feedback setting.  When people express a preference for this issue or that, they selecting the P90 issue where the fixed feedback and width settings more closely match what they usually aim for.

By "wider", I mean that each cycle sweeps higher up before coming back down again.  Typically, on any two-knob modulation effect, whether flanger, chorus, or phaser, the faster you set it, the narrower you set the "depth" (more accurately, sweep width) control.  The usable range would seem to be between around 2M5-4M5, so a 2M2 fixed resistor with a 2M log pot would provide a usable range of sweep widths.  Alternatively, a 4M7 default value, with two other fixed resistors strapped on in parallel, via a 3-position toggle, would provide 3 different sweep widths, tailored to different LFO rates.  For a higher-feedback slow sweep, you'd probably want somewhere in the 3M-3M3 range.  Of course, with a 2-stager like you show, there IS no feedback, but still one would generally like a less boing-ey sound from faster sweeps so a narrower sweep width helps.

Thanks again Mark! It's amazing how much I've learned since starting this thread.
And yes, I have changed the topic to that of a P45 with some of the vibe mods from JCM.
I think for now I am going to stick with what I have already started assembling but in the future I will mess around some more with the width mods.
This one might get a spst for one deep mode but for now just the bias pot and speed.
It might take a few more days but I will make a quick sample vid to show how good it sounds.
I'm very impressed at the sound this thing gets compared to the headache of building the P90.

After a few hiccoughs I managed to get it working on the breadboard.
No 4v7zeners in stock, so used a 5v1zener seem the mxr used the same.
I subbed in some 2n5458 it sounded and worked better.

All I can say Is you must have got really lucky with the fets Ben. (Jammy dodger).
I could hardly get the 5457 to work and then they where thumping.
I had to make R32=122k to get them to even go on.

Something strange happens though. When I play hard It stops phasing.
And the speed range is a bit too much IMO.
Too fast, Too slow. I guess its a suits your needs thing. YMMV.

I'll mess with it some more later
Cheers

Edit.
"Something strange happens though. When I play hard It stops phasing."
My fault. turns out its my breadboard connections shorting,

I tried the Hammer mod.
swapped R25 for 2M2 and series (varistor) B1M pot. That works ok actually nice for the faster speeds to be able to make it smoother.
Is it worth an external pot. I dunno maybe a descreet one.
It has a dead spot at one end too.


I tried it with a 3M3 and A1M pot (not sure if the pots dodgy) but it wouldnt work.

"All I can say Is you must have got really lucky with the fets Ben. (Jammy dodger).
I could hardly get the 5457 to work and then they where thumping."


wait wait.
I take that back now too.
Since sorting out the shorting they work ok.
Same Vb as above 100k 120k
I still think the the 5458 sound better somehow though.

Quote from: Kipper4 on October 14, 2016, 10:22:21 AM
I tried the Hammer mod.
swapped R25 for 2M2 and series (varistor) B1M pot. That works ok actually nice for the faster speeds to be able to make it smoother.
Is it worth an external pot. I dunno maybe a descreet one.
It has a dead spot at one end too.

I tried it with a 3M3 and A1M pot (not sure if the pots dodgy) but it wouldnt work.

Think of it like carrying a 2x4 vertically.  If it's long enough, you need to carry it low for it to fit under the ceiling.  If it's short, you have the option to carry it high or low.
By analogy, the sweep width option really needs to be complemented by the offset option.  And the offset is provided by two means, one of them being the trimpot, and the other being the 1M resistance that feeds the FET gates.  Varying the value of that resistance shifts the sweep range upwards or downwards.  In tandem with the sweep width, you can arrange for the sweep to stay low and gurgly (by having a narrower sweep width), high and swirly (also a narrow sweep width but starting higher up), or wide and majestic (start low, sweep high up).  Having it set for too wide a sweep, given the offset and bias, will bump the sweep against the ceiling.

Gottya. I'll experiment some more thanks Mark.

Overall, whadya think Rich? I like it a lot. Did you use the JCM caps for C6 & C7? I would make a vid but my BB components are already being transferred to the perf.
I did put sockets in for the FETs so later I can try the 2n5458s again.
Here's what I'm working with, not verified yet but if it all works out I will have the two pots mounted on the board and it should fit in a 125B, maybe even a 1590B.
(http://i63.tinypic.com/2ibgck5.png)

Overall It's great mate.
I really enjoyed not having to match fets. I guess one could carry it on with a further dual op amp and make it a p90 style, even p180.
I'm gonna try the jc Mallet mix pot too while it's on the breadboard.
Good work mate.
I still want to investigate the bias pot further as It seems on my breadboard right now theres still only a very narrow part of the rotation that gets results.
Thanks

At some setting there appears to be a bit of fet distortion. Bear in mind it could just be my breadboard.
I swapped to the 2x 100k Vb resistors you used and the full rotation of the 50k bias pot works ok now (still using 2N5458s)
The bias pot makes some nice tonal changes especially when you have the Hammers Mod pot too. Much easier to dial in the sweet spot.

I did make a few changes to the lfo
4u7 charging cap (C12)
slow enough to make a cup of Tea between cycles at the slowest speed.

Make R29 (your 5k1) to a 22k still plenty of speed there for me. 15k would likely work well too. 10k was a bit too fast for my taste.

YMMV

I like the mix pot mod too. All the way from vibe through phaser to very subtle phasing ,almost dry.
I reckon one could get a TL074 model in a 1590b with 4 knobs
Speed, Bias, Sweep, Mix.
I'd have to try my std perf (5cmx7cm) for a layout
I used a 10nf and 100nf caps btw Ben

They're 10x the price (uk) but 2SK30 fets work in this too.
Unless they're cheaper near you.
They make a viable alternative.

If you want to add a flashing indicator led.
from the U2a pin 1 put a 3mm red led anode and from the cathode put a 10k to ground.
It will wink in time with the lfo. Wire it to come on with the effect.
If you need help with this hit me up.

reread last Ben I edited a mistake. Op amp name and pin.

Very cool Rich, thanks!
So a couple things:
For me the mix pot made the volume change way too much... not so for you?
Even a switch to pull the dry path out and go straight vibrato created a big volume boost that I wasn't crazy about.

If you have a chance can you make a vid showing the deepest effect of using that 2M2 and how crazy you can make it sound at a fast speed? and slow speed? Please? How low can that resistor go Mark? Is there a limit?

The goal here is to make it cover ground from so slow that you get bored waiting for it... to so fast a wavy weavy warbly that it sounds like a million rubber balls fired from a cannon inside a metal trash can... over and over again. When we have achieved this range of operation, it will be complete.

Will do. Check back in a bit.

https://youtu.be/Fn8d1HuILDo

I love it Rich, great job! thanks
I'm thinking a simple switch to go from vibe to Phaser, volume jump be damned!
And a simple switch to go from 3M3 to 2M2 for shallow/deep... hmmm maybe less than 2M2?

If you wanted to combat the volume jump you could use a dpdt and change the value of R10 at the same time as you change the 3M3 to 2M2.
Kill 2 birds with 1 switch.

By the way I'd breadboard the 3M3 to 2M2 before you pcb it. I only say it because when the Hammer pot is all the way to the ends it went dead. It'll probably be alright with set resistors.
Double check the values Mark suggested before.

For the vibe to phaser mod just take out the dry signal path from input to output (R16). Boom Vibe.

Given that 3M3 still gives a reasonably wide sweep, I'd opt for 2M7 to set my maximum sweep width, and add resistance from there.  On the other hand, it may be wiser to start out with a 1M8 in series with a 1M trimmer, set to max, and see where the sweep limit is.

Quote from: Kipper4 on October 14, 2016, 05:37:09 PM
...combat the volume jump... ...as you change the 3M3 to 2M2...

This is not when I get the volume jump

Quote from: Kipper4 on October 14, 2016, 05:37:09 PM
...take out the dry signal path from input to output (R16). Boom Vibe.

This is the problem with volume jump for me. Also, big jump, dip and swing when using a mix pot.
My mix pot was 25K... can 3k off the proper value make a difference?

Here's the way I see it so far, no mix pot is needed, no vibe/phase switch is needed. My bias pot gets nice and strong in the center, turning to either side changes the flavor and mellows it out almost to the point of inaudible to the far left, far right.
I know it is doing something completely different than vibrato or a depth control but I think it provides enough sonic flavors.

I most definitely am going to experiment further with Mark's depth control ideas, but I almost feel that to have a depth pot will require the ability to have straight vibrato.
It should sound like two jack rabbits on a 1958 Flying V with a Bigsby or it's not worth building  :icon_mrgreen:

Also, perf is laid out, soldered and working. I ordered a 125B yesterday and the post predicts delivery tomorrow!
I love this particular parts supplier that I have no affiliation with!  8)

Being able to adjust sweep width is VERY useful for vibrato.  Sometimes you want it boing-ey (wide sweep) and sometimes you want it quivering (narrower sweep).

Rich- You were right, I got lucky on the fets. After swapping some around I realized not only did the two match but they were the only two I had that matched, and they biased dead center of the trim pot! What are the odds of that? So, the 5458's didn't work out for me because of my 50k bias pot plus 2x 100k on each side. I plan on starting another vibe P45 vibe asap because this thing sounds great! I am going to pay more attention to matching gets this time and adjust the bias accordingly.

Mark- You are absolutely right, I need a sweep depth control and then I can probably throw on the vibrato toggle to make it boingy. I'm still not sure if I want the mix control, I want to keep it down to two knobs so the bias will go back to the trimmer as well... "Less knobs equals more music"  ;)

So up next is a P45 vibe mod with sweep and rate knobs, possibly a vibe/vibrato switch.
In the meantime, I will try to post a vid of this one but I don't really see the point as Rich has already covered it plus so much more with that breadboard vid of his.

Ponder this for me if you will:
How can we make this... um... "V45" if you will, into a stereo contraption? What is stereo anyway?  :P

I just added a further 2 phase stages to mine. V90 and its much less musical.
maybe all the fets where not close enough matched.

Stereo to my way of thinking is the two output signal out of phase with each other.
So spilt the input signal after the input buffer to go to the two x2 V45s but invert the output signal of one of the outputs, Jfet or bjt buffer will do.
That's where i'd start anyway.
You may find it more intresting to invert the lfo signal to one of the V45s instead of inverting the output signal.
Duck showed us how to do this with vactrols in the Dub1 magna recently. Although the final project name might have changed.
I hope this makes sense, It made sense in my head when i was writing it.

Why do you want a stereo phaser?



Going back to the V45, I could make all the non matched fets work. 57's, 58's, 2sk30 work.
Didnt try the j201 or mpf103 or 2N3819's.

"So up next is a P45 vibe mod with sweep and rate knobs, possibly a vibe/vibrato switch. "

Do you mean a vibe/Phaser switch?

Go ahead mate put a video up. Show us with your great chops and the super fast rate too please.

Ok Rich, here ya go. I tried to show the speeds and all  the "voices" from the bias knob.
Yes, i meant vibrato/phaser but in the end it still has the JCM 10:1 phase caps, 10nF and 100nF instead of 2x 47nF, I don't know what that means but it sounds great  :P

I like your idea of stereo, it should create a very strong vibe. I think maybe the original Uni-Vibe had a dry signal output on the mix knob for a different kind of stereo effect but i'm not sure. It might be easier to do that but maybe not as lush sounding.

Why? I dunno, just something to do i guess... plus i have two amps  :)

I tried 7 different fets, a mix of 57's and 58's.
Combinations of the 57 and 58 together. 2x 57's together, 2x 58's together and all worked fine.
Definitly different sounds depending on the assortments. especially with moving the bias pot.
my fake j201s would hardly work. You could just hear something but not good.

I took voltages too.
input buffer and both phase stages all 5v1 (reflecting the zener I used)
lfo output 2v7-7v
the other two lfo pins wiggling around 4v5

fet volts
D 5v1
S 5v1
G 2v4-3v1 depending on bias pot setting.

I'd made a mistake with the biasing on the input buffer initially which is why the V90 version was so funked up.
Now I have it breaded right the V90 works good too. However its much better if i use all the same fets (my case 57's for this experiment).
It does however make less of the bias pot usable. Much less of the rotation works.
So less range of sounds there. but at least we know it will work.
And if one was to make it with a bias trimmer it wouldn't matter.

Edit.
Thanks for the demo Ben. Another good job done.
That enclosure is crying out for a swirly paint job.......

Ha! I can't do swirly paint jobs, I've seen the youtube tutorials... argh, forget that!
Most of my own pedals are boring, black, white, or no paint... I only paint them for my friends

Another idea, cause if your gonna drill a hole for a vibrato/phaser switch you might as well do a pot.
First change R9 to 10k or 12k. (upping the gain of U1b)
instead of putting a switch between phase and vibe
wire the U1b output to one side (lug 1) of a 20 or 25k mix pot.
Wire the phasers stages output to the opposite lug 3 mix pot.
Med sized cap from lug 2 to output (470nf maybe)

rotate completely one way; Dry signal.
rotate tother;                   Vibrato only
to 12oclock                       Phaser
Anywhere between those setting you get to mix in what you want, more dry, more vibrato.

When you breadboard it again. give it whirl mate I think you'll like it.

Thanks, I like that idea! I will try it and see if the volume stays constant for me

QuoteMost of my own pedals are boring, black, white, or no paint...

no, no, no, Ben, please don't say boring black and white .....

and on this stereo business, why don't you do that thing kipper did? no, not miscount the holes. and no, not that gnat mis-connection, the other thing, when he did the phase inverting mixer on his fibe-er thing. maybe if you jamb in a pair of opamp mixers, and have one normal and one kipper inverted, send nomal to out one, and inverted to out two.

and then we'll be calling you "five vibes Lyman".

"maybe if you jamb in a pair of opamp mixers, and have one normal and one kipper inverted, send nomal to out one, and inverted to out two."

Yer that was a cool mod. Completely different feel to both.
it's in the treadle phaser thread.

Nothing wrang with the Gnat Duck you need to wire it up right. Ahem.

Nothing wrang with black Ben. Blakie did a great job on his multiFX. Did you spy that?

Thanks guys, is there a link explaining how to add the opamp mixer?
Will a single dual opamp like a TL072 do the trick?

reply #50 switch sw1 A


http://www.diystompboxes.com/smfforum/index.php?topic=115042.40

Thanks Rich, i will look into that. Right now i have it back on the board with 2n5458's and a trimmer for the bias, it has to be turned more off center than i did with the 5457's so my previous bias network wouldn't have worked without adjustment.

I got a nice sweep pot going here, tried a 2M2 fixed with a B1M pot, then a 2M fixed w/same pot.
Now it is 2M fixed with B500K pot and i think i like it.

You'll probabaly get more rotation usage from the bias pot by adjusting the 2x 100k Vbias resistors.
try a 100k + series 22k to ground (R32) . If its worse adjust the other 100k (R31).

offsetting the bias resistors might help.
if 22k aint enough try bigger eg 33k
or smaller depending eg 10k

I'll go listen now.
Good work mate.Did you try swapping the 58's in after listening to the 57s. I get different tones. I find the 58's more Chewy. Technical jargon.

Yes, chewy  :)

If you like chewy.
Try making R5 bigger. I only got as far as 2M2 and got seasick

Thanks Rich. It's funny how everything Mark already told me was in the back of my mind, it all made sense, the starting point and the point where it rises before falling again, etc. but I couldn't really make use of it until you said bigger R5=chewy
I think i avoided it before because i didn't want an external bias AND a variable R5 but I really like it. I think I can be happy with this extra chewiness as long as i have the sweep control, it sounds great. I think the sweep control covers even more ground now for some reason, goes super thick and chewy all the way down to very subtle. The vibrato can be quite enhanced with the sweep control now too.

I think if I was to offer such a pedal for sale. I'd advertise it as tuneable for your rig.
I.e. The bias is set up for the customers needs. trimmer and inside  the box
Because the phase/vibe set up through a bright fender and a dark Marshall will sound totally different.
Or if the customer where a distance away you could advise on setting it up.

The sweep control is nice especially when in vibe mode.
Btw I'm currently using 1M2-1M5 R5
I might change back to 1M. I'm gonna go look at different versions of the p45.

Quote from: Ben Lyman on October 18, 2016, 04:36:04 PM
Thanks Rich. It's funny how everything Mark already told me was in the back of my mind, it all made sense, the starting point and the point where it rises before falling again, etc. but I couldn't really make use of it until you said bigger R5=chewy
I think i avoided it before because i didn't want an external bias AND a variable R5 but I really like it. I think I can be happy with this extra chewiness as long as i have the sweep control, it sounds great. I think the sweep control covers even more ground now for some reason, goes super thick and chewy all the way down to very subtle. The vibrato can be quite enhanced with the sweep control now too.

The irony here, Ben, is that all of the mods described are normal parts/controls of many standard phasers.  My 30 year-old Pearl PH-44 phaser has variable sweep width, variable feedback, and an offset ("Manual") control, in addition to two speeds and ramp up/down between them.  The MXR units have the misfortune of originating during an era when having two kobs was a really big deal.

Wow Mark, "gnarly" is the only word i can think of for that thing... maybe "insane" as well... yeah, gnarly and insane, that's what that is  ;D

the other irony is that, for me two knobs is still a big deal!
I'm pretty happy to have something on the bb now that looks like it will be good enough with two knobs and a switch.

And now it sounds pretty lush with the recent resistor changes, I will try to make a new vid soon

Quick question.
What is the purpose of R8 ?
Is the op amp not biased by R9 ?
(http://i67.tinypic.com/2reihpw.png)

Quote from: Kipper4 on October 19, 2016, 09:59:58 AM
Quick question.
What is the purpose of R8 ?
Is the op amp not biased by R9 ?

I really don't know, maybe someone else can answer that
I just copied it from GGG(20k) and JCM(22k) schematics

R8 - I'll have a swing. being as it is wired as a non-inverting amp, we set the gain (mostly) with the feedback resistor and the (-)in resistor, which has to go to a low impedance point, in this case V/2. and as we still need to centre bias the output, the (+)in gets a resistor to V/2, also setting the input impedance. it's just drawn different, and so perhaps confusing.

ben - are you keeping the external bias pot? and if you give me the day, I'll draw the mixers circuit I was thinking of.

Whats confusing to me is when i take R8 out. It sounds brighter than with.
Maybe some trickery going on.
If the - input is at V/2 wont the +input try to maintain that and also the output?


edit
defo some trickery. It's not brighter.

Quote from: duck_arse on October 19, 2016, 10:38:00 AM
ben - are you keeping the external bias pot?

Not for now Duck, I messed around with it last night for an hour and wasn't too happy with the results. I figured out the working range, again it was about 50K but this time with a 160K to ground and a 39K to VR. It made some good sounds but I think I will leave it on an internal trimmer this time.

I changed R5 to 2M and R25 to 3M with the B500K sweep pot, I like it a lot. When the bias trimmer is set just right I can get a wide range of speeds and depths.

One problem remains: When I pull the dry path and go for vibrato only, BIG volume jump. I think I have to leave the vibrato switch off this one too, I can't see myself ever using it if I have to adjust my amp volume every time. I haven't tried the mix pot yet, I will test it out next but I expect a volume drop in the middle of the pot with a boost at each side.
Maybe a B10K mix pot in between a couple of 5K resistors?

Quote from: Kipper4 on October 19, 2016, 10:58:04 AM
Whats confusing to me is when i take R8 out. It sounds brighter than with.

I've noticed that sometimes when I change something I have to pay a quick visit to the bias pot

This is where I'm at.

Extrenal pot for Bias

(http://i.imgur.com/JMC8qVR.png)

Quote from: Ben Lyman on October 19, 2016, 11:14:44 AM
One problem remains: When I pull the dry path and go for vibrato only, BIG volume jump. I think I have to leave the vibrato switch off this one too, I can't see myself ever using it if I have to adjust my amp volume every time. I haven't tried the mix pot yet, I will test it out next but I expect a volume drop in the middle of the pot with a boost at each side.
Maybe a B10K mix pot in between a couple of 5K resistors?

Now that's weird.  I tend to have the opposite problem.    On the one hand, killing the clean/dry signal for vibrato means the overall sum of the two signals is reduced.  On the other hand, in phasing/Uni-vibe mode, a big wide dip is created (Vibes create dips, rather than notches), which, in principle, should reduce the overall signal amplitude.

Looks great Rich, mine is very close. I like how you have the external bias pot and a simple switch for the sweep. I also like my sweep pot so i'm still undecided at the moment.

Mark, when I made my P90 I did not have the volume prob; could it be somehow related to the P90 "output mixer" stage? Could it be you haven't had this problem because you included the mixer?

I'm more inclined to think it has to do with whether dips or notches are being created.  Vibes create wide shallow dips that are much less focussed than phasers.  The "dreaminess" they produce is partly a function of how that aspect almost yields a tremolo effect at the same time as it is doing other things.  That's also why Vibes sound better ahead of clipping pedals.  The broad shallow dip moves whole regions away from and closer to the clipping threshold.

So, my gut sense - which can always be corrected by empirical evidence to the contrary - is that the broad shallow dip reduces overall signal amplitude moreso than a few narrow steep notches do.  So, remove the dry signal, such that all you have is the subtle pitch-shifting of the whole signal, and the volume level will appear to increase.

The drawn schematic shows a bit of boost in the input stage.  The RC network around each JFET serves to reduce increase headroom, so it is feasible that a vibrato/phaser switch could simultaneously cancel the dry signal AND adjust the gain of the input stage so as to maintain level balance.

Ok, thanks Mark, I was afraid you might say that  :P  ;D
You know me, simpler is betterer... less knobs equals more music.
I think i will leave out the vibrato switch and stick with my magnavibe for that job.

As for the increased gain at the input, I am very happy with my decision on that for the vibe because as JCM had it, there was a very slight drop below unity when the effect was engaged. I think when stomping on a pedal it's better to have the volume come up a tiny bit if you can't have it stay equal, but not down.

Thanks for clearing that up, I can actually understand what you are saying and I guess the MXR phaser can have a 10k on that input but maybe a vibe needs a little extra

This has a 2M R25 and 3M R5 (my schematic)
pretty good sweep control. Could probably even replace the pot with a 3-way toggle.

Bias is still just a trimmer, i'm not sure when i last adjusted it so it may not even be in the optimal position right now.



Some failed experiments with mix pot:
B25K pot, U1 out to U2 out and wiper on output cap
B10K pot with 10K on one side to U1 out
B10K pot with 10K on other side to U2 out
B10K with 5K1 on both sides

gonna stick with the Magnavibe for all vibrato tasks, though if trying to sell pedals it would be a good gimmick for the customer who wants more options.

on the topic of output mixers and stereo outs, I've hacked this outta wot kipper had, with that switch.

(http://i.imgur.com/gKhaI2b.png)

I dunno if it is right, or will go, but there it is. the second version might be more interesting than the first. assume all resistors are 33k, as per kippers, but as I've said before, I'm not good with gain around opamp mixers.

Quote from: duck_arse on October 20, 2016, 09:47:03 AM
on the topic of output mixers and stereo outs, I've hacked this outta wot kipper had, with that switch.

Very cool Duck, thanks! I can't wait to try this out and see what I get. In the meantime, I've put together my layout for the next mono vibe.
It's pretty close to my last layout except the bias trimmer and now with "Hammer Sweep"  :)
(https://s12.postimg.org/aczquozdp/V45_w_Hammer_Sweep_Layout.png)

Quote from: Ben Lyman on October 20, 2016, 11:40:30 AM
It's pretty close to my last layout except the bias trimmer and now with "Hammer Sweep"  :)

It isn't "Hammer Sweep".  I was just recommending something the Commander Keen drew up 15 years ago on the GEOFEX site.

For this demo
Bias is a set 50k trimmer
R5=1M2
Hammer Sweep mod (so called for reference to this thread, Thanks to Commander Keen too.)
R25= 1M5 + series B1M i prefered the 1M+1M pot though
R29=12k
C12=4u7 I'm gonna change this back to 10uf
R9=12k

Quote from: duck_arse on October 20, 2016, 09:47:03 AM
on the topic of output mixers and stereo outs, I've hacked this outta wot kipper had, with that switch.

(http://i.imgur.com/gKhaI2b.png)

I dunno if it is right, or will go, but there it is. the second version might be more interesting than the first. assume all resistors are 33k, as per kippers, but as I've said before, I'm not good with gain around opamp mixers.

I can confirm the upper schematic as working, Duck.
I'm using it in my stereo pedals...
R1 may be tossed...

Please Ben what dimensions are you using for the DIYLC resistors?

Quote from: Mark Hammer on October 20, 2016, 12:19:25 PM

Quote from: Ben Lyman on October 20, 2016, 11:40:30 AM
It's pretty close to my last layout except the bias trimmer and now with "Hammer Sweep"  :)

It isn't "Hammer Sweep".  I was just recommending something the Commander Keen drew up 15 years ago on the GEOFEX site.

OK, sorry Mark. I was actually just going to call it "Depth" because I think the average guitar player can better understand terms like that.
Hmm.. but maybe I'll call it the "Commander Keen Control"  ;)

Fender3D, thanks for confirming, I will try the upper one and see how I like it.

Quote from: Kipper4 on October 20, 2016, 01:42:01 PM
Please Ben what dimensions are you using for the DIYLC resistors?

0.2 inch x0.125 inch. I squeeze the legs gently with needle nose pliers to make them fit the "3-hole" spaces but sometimes I span "4-hole" lengths.
I don't know if it's bad practice but I've been doing it for a few months now with no ill side effects yet. 1n914 diodes can be squeezed into a "2-hole" space

Thank you man.
I dont think i'll squeeze the legs.
When I use them in 2 or 3 holes i tend to put them upright in a hair grip kinda thing.

thanks, fender. I'd be interested to know what comes out of the second circuit, if anything.

sounds good, kipper.

Thanks mate :)

This is what happens when you do it wrong.
(http://cdn.akamai.steamstatic.com/steam/apps/9180/header.jpg?t=1447351096)

^^
I thought it was an emitter follower...

Dang! I didn't know Commander Keen was already a real thing  :P
I guess I will just call it the "Captain's Knob"  :icon_mrgreen:

RG and I have known each other since this was a popular sidescroller game (actually before.  I think CK came out in '93 or 94).  I use the title "Commander Keen" tongue in cheek because, as a very authoritative source, he IS a commander, even if still a kid at heart.  :icon_smile:

> I think CK came out in '93 or 94

'90-'91 in the US; but perhaps banned in Canada and Texas for some years.

Actually, now that you mention it, my older son was playing it in early 1991...in Canada.

Banned in Texas?  Nah.  Id software was based in Dallas (actually Garland, I think).

After all that, I decided to just put a simple "S" and "W" above the knobs... and then forgot to do it  :P
Oh well, at least it still sounds good  :)
(http://50.6.73.68/picit/1477288200.916.jpg)

(http://50.6.73.68/picit/1477288301.7683.jpg)

Well, I'm back on the P90 again, I searched for threads about matching the JFETs but I turned up some discussions that I'd rather not be the one to revive  :-X
Note that this old thread has gone from P90 to P45 into a "V45" and now I'm talking about the P90 again. So much useful info here that I'm glad I had another look at it.
I'm making a much simpler version of my previous P90 with all the knobs, this one is more traditional with just one speed control and a switch to break open the dry path for vibrato.
I've figured out what changes I want to make to the rate control and the (preset) depth, thanks to Mark Hammer's posts in this thread.

Now, as to matching the FETs... I must've been very lucky to get such a thick sound out of my first one with the FETs that I threw in it.
This one, not so great at first. I had a look at the GEOFEX FET Matching link but when I got home I tried something else:
I put in one 2N5457 and turned the trimmer until it was swooshing.
Took it out and put in another (without touching the trimmer) and another... and another... and so on...
Then, bingo, I found another FET that starting swooshing with the trimmer in the same spot as the first one.
Lot of work I guess to find two that matched? DO they match?
Does that make sense, anyone else do this?

I set those two aside and continued until I found another, then finally a fourth.
Put all four in and blammo, a real P90 sound issued forth from my breadboard!

to complete that dataset, you now have to put those good fets into the matcher circuit, and see what numbers turn up.

Can someone take some pics of their FET matcher with detailed instructions how to use it?
Maybe a video? I can't find anything on youtube

Quote from: Ben Lyman on February 18, 2017, 12:13:34 PM
Can someone take some pics of their FET matcher with detailed instructions how to use it?
Maybe a video? I can't find anything on youtube

Look at Figure 10 on the Fetzer Valve webpage. http://runoffgroove.com/fetzervalve.html (http://runoffgroove.com/fetzervalve.html) It's very simple.

Quote from: reddesert on February 20, 2017, 11:17:54 AM
Look at Figure 10 on the Fetzer Valve webpage. http://runoffgroove.com/fetzervalve.html (http://runoffgroove.com/fetzervalve.html) It's very simple.

Thanks!