Seeing as there are only two trace side gut shots, and no one is willing to post components, I took some time to look at this.
(http://i214.photobucket.com/albums/cc196/digi2t/Select-a-fuzz/foxx_select-a-fuzz_006_zpsam2imlag.jpg) (http://s214.photobucket.com/user/digi2t/media/Select-a-fuzz/foxx_select-a-fuzz_006_zpsam2imlag.jpg.html)
(http://i214.photobucket.com/albums/cc196/digi2t/Select-a-fuzz/foxx_select-a-fuzz_003_zpssv2pjc8p.jpg) (http://s214.photobucket.com/user/digi2t/media/Select-a-fuzz/foxx_select-a-fuzz_003_zpssv2pjc8p.jpg.html)
The pictures seem clear enough to make out what might be a resistor, or a cap. Cap polarities are fairly clear as well. Even a diode symbol can be made out. Wire connections to the board seem to be bigger solder blobs. Transistor E and C letters are there. So looking at, I get this;
(http://i214.photobucket.com/albums/cc196/digi2t/Select-a-fuzz/Select_a_fuzz%20schematic_zpsjww6aert.jpg) (http://s214.photobucket.com/user/digi2t/media/Select-a-fuzz/Select_a_fuzz%20schematic_zpsjww6aert.jpg.html)
Two things that pop out at me, are the resistor/cap in series between B and C on Q2. Never seen that before. The Sustain pot set up is a new one for me as well. At least, the way I see it from the pictures it is.
Anyone interested in flinging some component values at me? I'm game to throw this on the breadboard and play with it.
This could be fun to figure out
I would guess it might be the same transistors used in other Foxx effects
The one picture shows an B10K sustain control
The resistor cap reminds me of the big cheese schematic.
It is hard for me to read the marks on the PCBs with my monitor to check your work
(http://i1033.photobucket.com/albums/a420/TGP39/image.jpg3_zpswmxcjfwq.jpg) (http://s1033.photobucket.com/user/TGP39/media/image.jpg3_zpswmxcjfwq.jpg.html)
(http://i1033.photobucket.com/albums/a420/TGP39/image.jpg1_zpsktgbvbiu.jpg) (http://s1033.photobucket.com/user/TGP39/media/image.jpg1_zpsktgbvbiu.jpg.html)
(http://i1033.photobucket.com/albums/a420/TGP39/image.jpg2_zpsnbnnxluz.jpg) (http://s1033.photobucket.com/user/TGP39/media/image.jpg2_zpsnbnnxluz.jpg.html)
These were the only other pictures I could find. Sorry, it's not much help.
Steve.
I think the purple fuzz is part of the secret, it's come alive and is growing inside the box. I hope you can get this sorted for preservation sake. Too bad no one will open it up for us but what challenge would that be?
I took a stab at cloning this a while back. One of my many started and forgotten projects. I will see if I can find my notes.
Thanks for the pics Steve, they help validate some of what I thought I was seeing.
I won't be able to breadboard this until Sunday, but if someone could explain the sustain set up, I'd appreciate it. Looks kinda like a tone control to my noob eyes.
Hey Gus, this is what I see. Hope it helps you;
(http://i214.photobucket.com/albums/cc196/digi2t/Select-a-fuzz/image_jpg3_LABELS_zpsze6fy2hj.jpg) (http://s214.photobucket.com/user/digi2t/media/Select-a-fuzz/image_jpg3_LABELS_zpsze6fy2hj.jpg.html)
I did a quick scan. I can see two errors:
- R9 goes from the base of Q3 to ground, not to the -ve side of the cap
(ie. Q3 has a standard feedback + divider bias).
- There is a resistor missing R5 and the connection to resistors R6 and R11 needs to be fixed as follows:
- +9V to one sideof R5
- the other side of R5 forks off to R6 and R11 (no other connections at the fork point)
the other side of R6 goes to the collector of Q2 (and R2 etc)
the other side of R11 goes to the collector of Q3
The sustain pot is 10k linear.
The volume pot is probably 50k
[Added]
The wiper of the sustain pot goes to the base of Q3; interestingly that changes the bias of Q3
I think the Fuzz switch labels are reversed. Heavy fuzz is on the electrocap
I've updated the schematic including the designators but I don't have an account to post it.
Quote from: Rob Strand on May 23, 2015, 06:15:57 AM
I did a quick scan. I can see two errors:
- R9 goes from the base of Q3 to ground, not to the -ve side of the cap
(ie. Q3 has a standard feedback + divider bias).
- There is a resistor missing R5 and the connection to resistors R6 and R11 needs to be fixed as follows:
- +9V to one sideof R5
- the other side of R5 forks off to R6 and R11 (no other connections at the fork point)
the other side of R6 goes to the collector of Q2 (and R2 etc)
the other side of R11 goes to the collector of Q3
The sustain pot is 10k linear.
The volume pot is probably 50k
[Added]
The wiper of the sustain pot goes to the base of Q3; interestingly that changes the bias of Q3
I think the Fuzz switch labels are reversed. Heavy fuzz is on the electrocap
I've updated the schematic including the designators but I don't have an account to post it.
All duly noted, and here is the updated schematic;
(http://i214.photobucket.com/albums/cc196/digi2t/Select-a-fuzz/Select_a_fuzz%20schematic_zpsz4gxrdhe.jpg) (http://s214.photobucket.com/user/digi2t/media/Select-a-fuzz/Select_a_fuzz%20schematic_zpsz4gxrdhe.jpg.html)
Guess I should have gotten more sleep before drawing 8-P. I've added the designators. The look over is greatly appreciated Rob. Thanks.
Looks good digi2t!
First stage looks like a FF type with added C to B cap and C to B cap and series resistor
So I would GUESS
R3 of 47k to 100k bias feedback
R4 2.2K
R1 10k to 47K
R6 8.2K and up
R5 has both stages coupled HOWEVER there is no bypass cap at the R5,R6 node and no cap at the battery +9 so maybe it a feedback mix thur the power supply
C8 1uf and up
I could keep guessing but without more information on the parts it is only a guess AND with circuits like this every resistor and cap value selected will change the sound
Output stage is the type bias you find in a BMP input stage without an emitter resistor HOWEVER as Rob Strand posted the sustain also changes the last stage bias
EDIT did a DC sim for operation points and sent it to digi2t
This might be a fun circuit
I think it is safe to say the transistors are silicon. It is not clear if they are high gain or low gain types.
The diode type Si vs Ge is not obvious.
C6 150 to 220p would be a good start for a proto
C7, R2 and and C10 are hard to guess. So too is the biasing around Q3.
However, I suggest listing to the sound sample on youtube. It sounds like Q3 could be biased close to cut-off. It shouldn't be hard to tweak the biasing to get that sound.
Did you see this Dino?
http://www.musicparts.com/products.asp?Company=Foxx
Nick Bungus and I separately tried to contact the proprietor of this site to see if he could "ready" the offline Foxx Phaser pedal schematic.
Nick's request was answered but still no schematic posted. I have yet to hear from him after two emails.
The select-a-fuzz schematic is listed as "offline" but you might try to contact him. You might have better luck than we did.
There is also a phone number with the suggestion to call if you do not get a reply by email.
I listened to the two Videos linked at http://www.effectsdatabase.com/model/foxx/selectafuzz
The fuzz seems to be tuned more to the bass side. Makes sense with the FF like stage with C to B caps and the lowpass part of the tone control.
The videos did not have the sustain changed, one changed the input caps
anyone know of a video sound sample with the sustain control being used?
A GUESS for the range of input caps 10uf, 1uf, .1uf .047uf .01uf hard to tell from the recording
It sounds like a Si fuzz with lowpass filtering( C6, C7 R2, C10) and an edge added from the operation points of the transistor(s). Rob Strand posted about the biasing and a starting point for the FF stage caps.
I sent digi2t a DC sim and some GUESSES for part values HOWEVER being a fuzz you can bias "wrong" and get a sound and my guesses could be off.
EDIT
I was changing values in the sim even if it is not a clone this could be a fun base to build another fuzz
Quote from: armdnrdy on May 23, 2015, 10:42:22 PM
Did you see this Dino?
http://www.musicparts.com/products.asp?Company=Foxx
Nick Bungus and I separately tried to contact the proprietor of this site to see if he could "ready" the offline Foxx Phaser pedal schematic.
Nick's request was answered but still no schematic posted. I have yet to hear from him after two emails.
The select-a-fuzz schematic is listed as "offline" but you might try to contact him. You might have better luck than we did.
There is also a phone number with the suggestion to call if you do not get a reply by email.
Like I mentioned in my first post, this sucker has been on the perifiery of my mind for a while. I did contact musicparts about two years ago, but the the response was that it wasn't available (no reason supplied). Maybe they simply compiled a manufacturers list, and put online what they have.
Quote from: Gus on May 23, 2015, 11:08:37 PM
I listened to the two Videos linked at http://www.effectsdatabase.com/model/foxx/selectafuzz
The fuzz seems to be tuned more to the bass side. Makes sense with the FF like stage with C to B caps and the lowpass part of the tone control.
The videos did not have the sustain changed, one changed the input caps
anyone know of a video sound sample with the sustain control being used?
A GUESS for the range of input caps 10uf, 1uf, .1uf .047uf .01uf hard to tell from the recording
It sounds like a Si fuzz with lowpass filtering( C6, C7 R2, C10) and an edge added from the operation points of the transistor(s). Rob Strand posted about the biasing and a starting point for the FF stage caps.
I sent digi2t a DC sim and some GUESSES for part values HOWEVER being a fuzz you can bias "wrong" and get a sound and my guesses could be off.
EDIT
I was changing values in the sim even if it is not a clone this could be a fun base to build another fuzz
Crap! I hadn't noticed this video;
He switches through the whole range of caps, but I think the Sustain is pegged. These must be the only two videos around.
As for the cap choices, that's definately a good starting point, but there's one angle though; of the five caps loaded on the board, only one (heavy fuzz) seems to have the +/- marked on the board. That leads me to believe that there might only be one electro on there. At least now, with the video mentioned above, I have a better idea of what to aim for.
Anywho, got some deck work to do today, but I'm retiring to the breadboard tonight to experiment with this. This is going to be sweet!
I noted the electro +- marking but I did not think 70's I was thinking a 1uf film. So maybe a .47uf film etc.
Sounds like heavy filtering maybe C10 is something like a .1uf with the values I sent
I sent values that should move Q3 closer to cutoff like Rob Strand posted. I would adjust the bias feedback resistor maybe make R10 a 100k with a 1 meg rheostat for a 100K to 1.1meg to find the value
QuoteI noted the electro +- marking but I did not think 70's I was thinking a 1uf film. So maybe a .47uf film etc.
Sounds like heavy filtering maybe C10 is something like a .1uf with the values I sent
The size and the fact it is only 100V makes me think C10 is 470n (0.47uF). But the circuit function makes me things it's less like 100n or 220n.
The other thing to notice is, either C1 or C2 (ie. near the cap-switch) looks about the same size. Perhaps C1=100n and C2=470n? or is it C1=470nF. Hard to tell.
My money is on 100n. Zooming in, it looks like the top of a "1" peeking out from behind the wire. Like it would say "0.1 M" or something.
As for the other jelly bean, hard to say without knowing the voltage, but for production purposes, yeah, could be another 100n as well.
Anyway, so far, I'm getting some pretty gnarly fuzz on the breadboard. I just need to play with some values some more to tame it, and get the sustain pot to be more effective. It's looking (sounding) promising right now.
Dino,
I just got off the phone with the guy from MusicParts.
I requested an offline schematic for the Foxx Foot Phaser.
While I had his attention...I asked him if he could pull and "ready" the Foxx Select-A-Fuzz schematic as well.
He said that it might take about a week. Hopefully, my phone call lit a fire under his rear and prods him to get these drawings loaded up on his sight!
Quote from: armdnrdy on May 26, 2015, 06:36:38 PM
Dino,
I just got off the phone with the guy from MusicParts.
I requested an offline schematic for the Foxx Foot Phaser.
While I had his attention...I asked him if he could pull and "ready" the Foxx Select-A-Fuzz schematic as well.
He said that it might take about a week. Hopefully, my phone call lit a fire under his rear and prods him to get these drawings loaded up on his sight!
Larry... super kind of you to pass that on. Every little bit helps. A tip of the hat to you brother! :icon_wink:
I figured that I would just sit back with the schematic and go.....nope...but you're getting warm! :icon_lol:
I am surprised that this thread is not more popular.
is there an update?
Yesterday I sent another email to MusicParts requesting a schematic I need. I included that a friend wants to purchase the Foxx Select-a-fuzz drawing as well.
It doesn't seem as if the individual at Musicparts runs a tight ship!
Maybe he pulls requested drawings, scans them, and uploads them to his site only when he runs out of drinking money! :o
I called three weeks ago, and got a very nonchalant attitude ("Yeah, I'll see if I can get it out to you in a few days"). Last week I sent another email request, but no answer.
I think I'm going to spam him. :P
I've dealt with them in the past, they're (very) slow but will eventually come through.
Quote from: Nocaster Cat on June 14, 2015, 05:29:11 PM
I've dealt with them in the past, they're (very) slow but will eventually come through.
Oh....Dino and I will make him come through alright!
This MusicParts character doesn't want us on his bad side! :icon_eek:
I don't think he quite understands...We have pedals to build for goodness sake!
Dino....rough him up! :icon_evil:
Bump
Any news?
How did the experiments with the guesses at the circuit go?
Quote from: Gus on June 27, 2015, 11:57:10 AM
Bump
Any news?
How did the experiments with the guesses at the circuit go?
Since I received the Rand-o board, I've been working on that. I still have the Select-a on the breadboard, and have not abandoned this project. I've also harrased the Musicparts guy too, but to no avail.
Once the Rand-o is figured out, I'll come back to this. Just seems that I've been chewing into some ball busting projects of late. Can't get a break.:icon_confused:
Thanks for the update. I find this fuzz thread and the bigger muff thread to be the current interesting threads.
It is funny to work on a puzzle like this.
Puzzles? Fun? I dunno chief, the Rand-o is giving me fits and starts right now. There's blood on the bricks, and my head is sore. :icon_lol:
any news?
Quote from: Gus on August 29, 2015, 09:41:03 AM
any news?
Nope. I'm sorely disappointed with the guy at Musicparts. The process went something like this;
- Emailed asking for schematic. No answer.
- Two weeks later, called. Was told that it would be up "in a few days".
- Two weeks went by, nothing on web site.
- After a couple of more weeks, sent another email. No response.
- Waited a couple of more weeks, emailed again. No response.
I know I can be like a "dog on a bone" annoying at times, but I don't think I was being unreasonable here. Especially considering what the guy at Musicparts told me on the phone. :icon_sad:
I've thus set this project aside for now. It's still on a breadboard, but I'm working on other stuff for now, until my enthusiasm for this project gets recharged.
I wonder if the first stage is a copy of the colorsound 1 knob or Vox circuit or other one knob fuzzes
maybe something like reply 10 http://www.diystompboxes.com/smfforum/index.php?topic=111894.0 (http://www.diystompboxes.com/smfforum/index.php?topic=111894.0)
http://www.diystompboxes.com/smfforum/index.php?topic=93762.0 (http://www.diystompboxes.com/smfforum/index.php?topic=93762.0)
Maybe using the 82 ohm 4.7k node as the supply for the 2nd stage and taking the output from the collector or it could be the "standard" values in a FF like circuit(add the C to B cap at Q1 and RC C to B at Q2)
Any update on this?
Another belated bump on this. The YouTube video has me salivating!
See this thread: https://www.diystompboxes.com/smfforum/index.php?topic=120622.msg1130577#new
Oh man. I had no idea.
I've read many posts from you, dino, jimmy etc. Assumed/felt you were all indestructible.
There are more important things in life.
Woah! Been a while.... :icon_biggrin:
After a long hiatus, I decided to throw some new values on the breadboard. Gus had sent me a sim way back, which I tried, but it just wasn't really blowing my skirt up. I think I have a winner with the new values (jammin' in my jammies)...
Here's the new setup. Low gain transistors to the rescue!
(https://i.postimg.cc/tY49tG45/Select-a-fuzz-schematic-FINAL.jpg) (https://postimg.cc/tY49tG45)
dude, that sounds @#$%in RIPPIN'!!!
downloaded.
maybe i get wyld hair crosseth mine arse, and whip up a vero version and try it. looks great, sounds freakin killer.
well done, yet again, mr digi2t! :icon_mrgreen:
Are the parts values from a traced select-a-fuzz or is this still a guess?
It does sound good
Are you getting any oscillation from the circuit with the heavy fuzz setting and humbuckers at full guitar volume? (R11 connection at R5, R6)?
I am not a fan of about 1/2 supply voltage at a FF like distortion 2nd collector.
Nice noise. Nice PJs. :icon_cool: :icon_cool: :icon_cool:
Quote from: Gus on April 14, 2019, 09:00:34 AM
Are the parts values from a traced select-a-fuzz or is this still a guess?
It does sound good
Are you getting any oscillation from the circuit with the heavy fuzz setting and humbuckers at full guitar volume? (R11 connection at R5, R6)?
I am not a fan of about 1/2 supply voltage at a FF like distortion 2nd collector.
Guess. Here are the values that you had sent me;
(https://i.postimg.cc/KRDCV8QL/foxxfuzzidea-DC.png) (https://postimg.cc/KRDCV8QL)
It wasn't performing like it does now. Your sim was actually rather poor in the sustain department.
No oscillation whatsoever. The 1n cap across Q1 takes care of that, and the high end still has lots of spank. The 12K/332 cap combo reacts like a drive control. Using a cap bigger than 2u2 makes it sound really mushy, hence the 3K3/2u2 combo.
Quote from: bluebunny on April 14, 2019, 10:23:50 AM
Nice noise. Nice PJs. :icon_cool: :icon_cool: :icon_cool:
Muchos gracias hefe! :icon_biggrin:
Greetings from Australia.
First of all, great to see you back on deck Digi2t!
Secondly, have built this with mixed results. It's fuzzing but single note leads show a consistent octave down and lack thickness. Ironically I'd be very pleased if this was another harmonic perc build! :icon_lol: Voltages in the fuzz face section are close (Q1 1.43, 0.65, 0, Q2 5.3, 1.43, 0.76), but the collector on Q3 reads about 4.5v with the fuzz pot set halfway.
Regarding Q3, i've thrown some values into the guitar science simulator (http://www.guitarscience.net/calcs/cecbmf.htm). Inputs- Hfe 150, Vcc 8.65v (measured), Vc 4.5v, Rc 12K, Rb2 8.3k (39K//(1/2 x 10k pot + 5k6). These values calculate Rb1 at 47K, which is right on the money from the schem. Substituting the posted Vc of 1.96v, Rb1 calculates out at 16k. So not sure if the posted values are ok or if I've made an error?
I'll need to break out the audio probe to see where the octave is being generated, but I'm wondering about the single diode on the output. I seem to recall reading a comment about asymmetrical clipping potentially resulting in an octave, so could this be an issue? Has anyone seen an unwanted octave on a fuzz face build before?
Cheers,
Brett
Quote from: bmsiddall on May 27, 2019, 06:41:09 PM
Greetings from Australia.
First of all, great to see you back on deck Digi2t!
Secondly, have built this with mixed results. It's fuzzing but single note leads show a consistent octave down and lack thickness. Ironically I'd be very pleased if this was another harmonic perc build! :icon_lol: Voltages in the fuzz face section are close (Q1 1.43, 0.65, 0, Q2 5.3, 1.43, 0.76), but the collector on Q3 reads about 4.5v with the fuzz pot set halfway.
Regarding Q3, i've thrown some values into the guitar science simulator (http://www.guitarscience.net/calcs/cecbmf.htm). Inputs- Hfe 150, Vcc 8.65v (measured), Vc 4.5v, Rc 12K, Rb2 8.3k (39K//(1/2 x 10k pot + 5k6). These values calculate Rb1 at 47K, which is right on the money from the schem. Substituting the posted Vc of 1.96v, Rb1 calculates out at 16k. So not sure if the posted values are ok or if I've made an error?
I'll need to break out the audio probe to see where the octave is being generated, but I'm wondering about the single diode on the output. I seem to recall reading a comment about asymmetrical clipping potentially resulting in an octave, so could this be an issue? Has anyone seen an unwanted octave on a fuzz face build before?
Cheers,
Brett
Thanks Brett. Good to be amoung the living.
If I may ask, which schematic are you drawing on, mine or Gus'?
I used yours.
Cheers,
Brett
With the transistors I've listed on the schematic, same resistor values, I range between 1.8 and 2.2 volts at the collector.
Mind you, this is a very fussy circuit when it comes to transistors. It just doesn't seem to like the run of the mill 2N3904, or worse yet, 2N5088. I've tried BC108's and 2N3700 in here as well, and the results were not stellar. The 2N2222A's were just... OK. Just. The 2N2219 or 2N3903 are really nice, but the 2N3965 2N3569's are the cat's ass. Don't know why, but the ear candy is there. 2N3903 is a nose hair behind in second place, followed by the 2N2219 a quarter length back. Of course... those are my ears.
Deleted
You had me confused there--some of the posts in the thread have subbed 2N3965 for 2N3569 -- but that wouldn't work at all, now would it? But a glance at the schematic set me straight. It's the NPN one.
It's all cool--I get a touch of dyslexia now and again, too. But Dino and Brett--you might want to edit above to keep from leading the flock astray.
I note for purposes of the conversation that Small Bear lists hfe for the 2N3569 as 60-150. Fairchild's (https://www.datasheets360.com/pdf/-4148855286439080078) and Central Semi's (https://www.datasheet4u.com/datasheet-pdf/CentralSemiconductor/2N3569/pdf.php?id=538889) datasheets say 100-300. And, FWIW, my stash of 2N3904s tend to test at the high end of its spec range for hfe, or even slightly, above. So maybe low gain really is the key.
Oups! Yes... dyslexia indeed! I've corrected my offending post.
i win- have deleted my offending post :icon_lol: