Peach Fuzz variations which option(s) to go for?

[matopotato]

I am interested in building Peach Fuzz so I searched for layouts and schematics and found that there were a few variations.
As a reference I add two schematics:
Cherry Fuzz (from pcbguitarmania.com): https://pcbguitarmania.com/wp-content/uploads/2020/06/Cherry-Fuzz-Building-Docs.pdf Page 5
And this 2007 schematic: https://www.freestompboxes.org/viewtopic.php?t=1273

I then compared the schematics with (mostly for reference, my questions ought to be possible to understand from the schemas above. Hopefully...)

• tagboardeffects versions 1 and 2 http://tagboardeffects.blogspot.com/2012/03/frantone-peachfuzz.html
• dirtboxlayouts http://dirtboxlayouts.blogspot.com/2019/06/frantone-peach-fuzz.html
• sabrotone https://www.sabrotone.com/frantone-peachfuzz/
• effectslayouts http://effectslayouts.blogspot.com/2015/08/frantone-peach-fuzz.html

My questions (or "requests for comments")

• There is a variation of Diode use at the 9V point. 1N4001, 1N5817 or nothing. I am assuming they are quite interchangeable, and better to have one in than not.
• All except Cheery have a 10R right after 9V, so I assume this is better to have than not. Not sure of its purpose and one blogger mentioned that they fried easily.
• C10 in the Cherry schema in the power section after Diode, 10R, 9V is either 100uF or 1000uF electrolyte. Why so big as 1000u? I am aware that component tolerance make detailed selection on value less relevant if the difference is small, but this is 10 times? (Tried searching here, but not skilled enough. Yet.)
• Cherry, R3: Either it is 560k or 567k. Here 7k diff is almost within the tolerance interval I guess, and 567k a bit odd to find. But the majority have it. What would be the difference? I can make a 567k out of 2 R's, just curious to know why the 567k seemed the preferred selection.
• Cherry use a RPD 1M to kill switch noise I guess. But none of the others? Would there be any negative side to adding it?
• Cherry R4 is 9k1, and most of the build examples have that, but tagboardeffects ver2 have 4k7 and dirtboxlayouts have 8k2. Seems 4k7 allows for better clean up of the fuzz?
  There is also a mention in the comments on sabrotone page: "Major- R6 moved to L14>M14 (4K7 in schematic I used), R6 moved to K13>Q13. Fuzz pot now works 2>3>1." which I do not understand. Both the move(s) and how 2>3>1 would work.
• In the 2007 schematic IC3 has shorted pins 1 and 5, none of the other layouts seem to have this. What would be the purpose or effect of doing or not doing this?
• The R8 in the Cherry schema varies between 39k, 41k, 47k. And between at least 39k and 47k is a significant jump (?). What would be the reason for choosing either one? The tagboardeffects v1 and v2 go from 41k to 47k and the previously mentioned 9k1 to 4k7. But I doubt the two changes are related or a compensation for each other.

Any help on any of these questions is much appreciated.

[GibsonGM]

1.  Yes, for 400X diodes, reversed and to ground for reverse polarity protection....I believe most ppl put the Schottky diodes (5817) directly in series with 9V tho.  Introduces a small voltage drop, but it's usually nothing worth worrying about.

2. The 10R limits the current that can possibly enter the circuit, 900mA at that point  (9V/10 ohms). Unlikely to work in that role unless catastrophe strikes lol.  This R works with 1000u cap to filter power fluctuations down to about 16Hz.   A slightly larger R here can provide better filtering, say 33r or 47r. 

3. if the cap is 100u rather than 1000u, working with the 10R resistor, the cutoff of the filter thus made is 10x higher, ~160Hz....so you won't get (as) much power filtering.   Most expected noise on the power line would be 50/60Hz, or 120Hz, plus any extraneous garbage floating around from lights, computers etc.

4. Don't think the 7k is enough to make an audible difference, wouldn't make a 'custom' R out of two.  Maybe a measured resistance from a working model?

5. I see no down side to adding a 1 meg pulldown.

6. Maybe the different values of R4 are to change the feel of the fuzz pot and limit absolute signal input? So, higher R4 = lower input signal = less hot...

7. Not sure about direct short on pins 1, 5 of a 386. That's usually done with an RC network to boost bass - don't know if a short will kill it...some guru will probably come tell us soon.

8. R8 differences are tone stack tweaks for 'preference'...try both!  May be related to the 1-5 short (??) if that increased bass or something?


HTH! 

[anotherjim]

I don't know what a 386 direct link 1-5 does either. I could try my usual ploy of suggesting something stupid, and then someone is sure to leap in to put me right, but I have no suitably stupid ideas at the moment.

One thing not addressed after being brought up in the otherplace thread is the unused opamp. Just link pin5 to pin 3 and then link 6-7. As a CMOS opamp, it definitely shouldn't be left to flap around in the breeze.

[antonis]

IMHO, by shorting pins 5 & 1 turns LM386 to a unity gain buffer..
(which, IMHO again, isn't the the wiser application due to LM386 is only compensated for closed-loop gains greater than 9)

[GibsonGM]

Thanks for that clarification, Antonis!  A simple op-amp buffer may be a better choice, it would seem.  Maybe it makes some magic mojo with the tone?

[anotherjim]

The circuit earned points from me by being one of very few LM386 distortions that haven't included the Zobel compensation for a speaker output.

[Axldeziak]

I think the variations in the parts comes from them using the different schematics that were posted as the pedal was being hashed out (Several of which are no longer available in the thread at all.) For instance the V5 schematic mentioned on the tagboardeffects layout can be found here:
https://web.archive.org/web/20090321050949/http://supervelcroboy.wordpress.com/2008/08/20/frantone-peachfuzz-schematic/

The last posted schematic (on page three) by MonkeyXX on 11/23/11 appears to be the final correction.

For even more variation check out this schematic posted five years later:
https://www.freestompboxes.org/viewtopic.php?p=257370#p257370

Personally, I would just breadboard the circuit and play with it until you find the mix that makes your ears happy. That's the only thing that is important in the end.

[antonis]

@Jim: A Zobel network, without speaker, makes no harm..
(other than cost/space issues..)

@Sir Mike: Dunno if almost down to zero frequencies boost (actually, highs cut) is some kind of mojo thing.. 

[matopotato]

1.  Yes, for 400X diodes, reversed and to ground for reverse polarity protection....I believe most ppl put the Schottky diodes (5817) directly in series with 9V tho.  Introduces a small voltage drop, but it's usually nothing worth worrying about.

2. The 10R limits the current that can possibly enter the circuit, 900mA at that point  (9V/10 ohms). Unlikely to work in that role unless catastrophe strikes lol.  This R works with 1000u cap to filter power fluctuations down to about 16Hz.   A slightly larger R here can provide better filtering, say 33r or 47r. 

3. if the cap is 100u rather than 1000u, working with the 10R resistor, the cutoff of the filter thus made is 10x higher, ~160Hz....so you won't get (as) much power filtering.   Most expected noise on the power line would be 50/60Hz, or 120Hz, plus any extraneous garbage floating around from lights, computers etc.

4. Don't think the 7k is enough to make an audible difference, wouldn't make a 'custom' R out of two.  Maybe a measured resistance from a working model?

5. I see no down side to adding a 1 meg pulldown.

6. Maybe the different values of R4 are to change the feel of the fuzz pot and limit absolute signal input? So, higher R4 = lower input signal = less hot...

7. Not sure about direct short on pins 1, 5 of a 386. That's usually done with an RC network to boost bass - don't know if a short will kill it...some guru will probably come tell us soon.

8. R8 differences are tone stack tweaks for 'preference'...try both!  May be related to the 1-5 short (??) if that increased bass or something?


HTH!

Thanks Mike!
1. Check
2. Good, I might raise it then.
3. Good, I'll keep the 1000u then. Even if I raise the 10R to 33 or 47? It is no big deal, it is just bigger in size, but I can fold it down a bit. Should work.
4. Yes, what I suspected. Just that when many build refer to 567k (not very standard?) I was not sure if it would matter after all...
5. Check
6. Good. Seems the 4k7 came in later in history and the comment indicated some improvement. I'll probably go with that.
7. Yes, got some guru replies below. Btw, to me you also count as a guru 
8. Yes, will experiment a bit, now I know what too listen for.

[matopotato]

I don't know what a 386 direct link 1-5 does either. I could try my usual ploy of suggesting something stupid, and then someone is sure to leap in to put me right, but I have no suitably stupid ideas at the moment.

One thing not addressed after being brought up in the otherplace thread is the unused opamp. Just link pin5 to pin 3 and then link 6-7. As a CMOS opamp, it definitely shouldn't be left to flap around in the breeze.

Thanks,
So pin 5 to VR like the 3 on the other opamp? 6 to 7 but nothing to ground, right?
(I've seen quite a few variations of how to tie down a leftover opamp)

EDIT: Seems from the V5 schema found by @Axldeziak indicate that the leftover pin5 should go to ground instead?

[matopotato]

IMHO, by shorting pins 5 & 1 turns LM386 to a unity gain buffer..
(which, IMHO again, isn't the the wiser application due to LM386 is only compensated for closed-loop gains greater than 9)

Thanks,
I am ok leaving them. If I breadboard it it would be ok to test though? No risk of harm to the LM386?

[GibsonGM]

An LM386 ISN'T an opamp!!!!  < Ok lecture over.   

It's an audio amplifier IC, it's not the same. 

Connect the pins as shown...Antonis' reply suggests that it's OK, but not ideal, to connect pins 1 + 5. If the designer specified that you do it, I would ASSUME it's ok, if the schematic is verified, or has been 'put out' by someone.   I'd try it.  Pin 1 is 'gain', and 5 is the output...probably does a negative feedback thang that reduces gain, sort of like a buffer. 


Changing the 'power input resistor' up to 33 or 47r is fine, it decreases the filter cutoff as the cap stays the same.  1000u cap is MORE than sufficient, LOL. If it works for you, just use it, good filtering.  The resistor value is less critical here.  As you go on, you will want to know how this power filtering works - if you make a new post asking, you will get lots of great info about it - probably more than we should get into here tho!  It's how Rs and Cs are used together.  Try searching the forum/internet for it, too. 
"Filter cutoff" , "RC Filter" and so on.   

I'm not really a guru, but you can call me "Sir".  (inside joke, j/k!) lol

[matopotato]

I think the variations in the parts comes from them using the different schematics that were posted as the pedal was being hashed out (Several of which are no longer available in the thread at all.) For instance the V5 schematic mentioned on the tagboardeffects layout can be found here:
https://web.archive.org/web/20090321050949/http://supervelcroboy.wordpress.com/2008/08/20/frantone-peachfuzz-schematic/

The last posted schematic (on page three) by MonkeyXX on 11/23/11 appears to be the final correction.

That was quite interesting, the 9k1 just before the Fuzz pot changed to 4k7 as in some of the later versions I found.
The IC3 pin 1 to 5 short removed (should settle that if not already done)
And the 41k vs 47k in the tonestack. Just have to try it out.

For even more variation check out this schematic posted five years later:
https://www.freestompboxes.org/viewtopic.php?p=257370#p257370

Thanks again,
The "HF-stabilizing components" would that be the C16, C17, C18 of 100nF each on the PSU?
Or the C5, C9 56p before the LM386es
Or C6, C10 1uF from LM386es pin 7 to ground
Or even the C7/R8 and C11/R10 (10R + 47nF from pin 5's to ground)?
Or perhaps "all of the above"

I also noticed this schema had A100k for volume. I thought B100k as in the (most of?) others worked less well. I have not yet come across a Lin Volume pot I preferred to Log when testing... (YMMV)

Personally, I would just breadboard the circuit and play with it until you find the mix that makes your ears happy. That's the only thing that is important in the end.

Yes, of course. One should always breadboard and find what is most pleasing to one's own ears.
My only issue with that is that I have only been electric for 2 years and DIY pedals about 1-1,5 years back. And I have noticed that many things are too subtle to me. Until some time has passed, when I have learned a bit more what to listen for.
My first delay pedal (Boss DD-8) I could not tell the difference between Standard and Analog setting.
Now it is hard to remember how I couldn't
Similar with compressors, full squish or bust rather than the more subtle settings still. But I'm working on it...

What I appreciate from this thread and many other threads is that the discussion teaches me new stuff. I can benefit from other's experience and deeper knowledge so I buy the right components to try out, instead of feeling my way in the dark. Yes, frying components is also a learning process and I am doing my share. If I had stocked enough components, then maybe trial and error would have been my way of working, but I am a bit more cautious and not all components are easy to come by
I also have a thing for trying to be close to an original design and sometimes tweak or mod what I might have liked less.
My most common mod is to put another pot or switch on the enclosure so I can control more things. In the end I leave most in one setting and that is that.
My own designs are filled with rotaries and switches to cover as many options as possible. And that is not always a good thing. (23 diodes in an overmodded Dist + ?)

[matopotato]

An LM386 ISN'T an opamp!!!!  < Ok lecture over.   

It's an audio amplifier IC, it's not the same. 

Oh of course not :-o I hope I didn't sound as if I thought so...
The TL2262 though...

Connect the pins as shown...Antonis' reply suggests that it's OK, but not ideal, to connect pins 1 + 5. If the designer specified that you do it, I would ASSUME it's ok, if the schematic is verified, or has been 'put out' by someone.   I'd try it.  Pin 1 is 'gain', and 5 is the output...probably does a negative feedback thang that reduces gain, sort of like a buffer. 

Seeing the second schema V5 linked by @Axldeziak suggests that the 1-5 link was abandoned. And since the Rev1.0 is the only one having it I am happy to drop it (or cut it...)

Changing the 'power input resistor' up to 33 or 47r is fine, it decreases the filter cutoff as the cap stays the same.  1000u cap is MORE than sufficient, LOL. If it works for you, just use it, good filtering.  The resistor value is less critical here.  As you go on, you will want to know how this power filtering works - if you make a new post asking, you will get lots of great info about it - probably more than we should get into here tho!  It's how Rs and Cs are used together.  Try searching the forum/internet for it, too. 
"Filter cutoff" , "RC Filter" and so on.   

Last December I got two 900+ pages books on electronics. Good bedtime reading. I am on page 300-something in the one easier to read.
So by 2027 I'll be seeking guru apprentice internship here

I'm not really a guru, but you can call me "Sir".  (inside joke, j/k!) lol

OK, will do.

...Sir 

[antonis]

7. Yes, got some guru replies below.

Elementary circuit analysis has nothing to do with guru instict..



By shorting R8 (NFB resistor) you effectivelly turn the circuit into a P-N-P Darligton emitter follower..

[GibsonGM]

All of the above, primarily R10/C11, the 'zobel network'...without that the things like to go crazy, but as noted - that may be mitigated if it's not driving a speaker.  I don't do that much w/386s so nope, no guru here, but there ARE tricks like that which are commonly known.

Unless a cap is there strictly for removing treble, for audio purposes...it's safe (but not 100% CERTAIN) that its job is probably helping to limit the amplifying device's bandwidth, which results in more stability.  Esp. if going from power pins to ground ("bypassing the power pins").  What they're actually doing will come in time as you build and play with more circuits!   

I'm only kidding about "sir", Antonis calls me that, it's a joke.  PS - I'd use the MOST RECENT schematic, always - is usually means they found trouble & fixed it, or improved the circuit!

[matopotato]

7. Yes, got some guru replies below.

Elementary circuit analysis has nothing to do with guru instict..



By shorting R8 (NFB resistor) you effectivelly turn the circuit into a P-N-P Darligton emitter follower..

Of course! (What he said...)

I think I will make it an early night so I can ream more in my electronics book. The circuit above flew right by me. At first I tried to see where the Peach was, but the tail wind knocked me off my chair.
But thanks

EDIT: Sorry for my ignorance. I now understand it is the LM386...

[matopotato]

All of the above, primarily R10/C11, the 'zobel network'...without that the things like to go crazy, but as noted - that may be mitigated if it's not driving a speaker.  I don't do that much w/386s so nope, no guru here, but there ARE tricks like that which are commonly known.

Unless a cap is there strictly for removing treble, for audio purposes...it's safe (but not 100% CERTAIN) that its job is probably helping to limit the amplifying device's bandwidth, which results in more stability.  Esp. if going from power pins to ground ("bypassing the power pins").  What they're actually doing will come in time as you build and play with more circuits!   

I'm only kidding about "sir", Antonis calls me that, it's a joke.  PS - I'd use the MOST RECENT schematic, always - is usually means they found trouble & fixed it, or improved the circuit!

Thanks, I guess I am in for some more breadboarding than I bargained for.
"Mitigated", I assume that means still no harm in trying it out? (Zobel, new word today...)

Yes, I also like to follow "latest and greatest", but there is also a very slight chance that a strive towards "perfection" might lose some of the original "mojo".
Anyway, what began as "I want one of those" has now again turned into a tweak-o-rama on my poor breadboards, but you are right, that is how to learn.

EDIT: ...Sir... 

[GibsonGM]

"Mitigated" in this case probably equals "is irrelevant"...   I'm not sure if you would hear a noticeable difference with the zobel in or out of circuit - maybe YOU can try it on breadboard, and tell US!  ha ha

Tip: start getting some data sheets for parts you use often.  Here is the LM386. Go to the 'Applications and Implementations' near the end...note that the Zobel network shows up a lot...and so do bypass caps (pin 7).    https://www.ti.com/lit/ds/symlink/lm386.pdf

These also tell you the max voltage for the part, how much current it can sink or source (important) and other great info you'll need as you go along!  Many of us keep a folder on the computer with lots of these babies in it.

[bluebunny]