My First Fuzz...

[eatyourguitar]

I think you have the aggitate pot set differently on one of them. also I would suspect that 2M2 with %20 or %10 tolerance can make the difference in gain between two silicon transistors even more noticeable. even R4 and P2 are +/- %10. the 2N3904 is about +/-%10 Hfe. set both pots to 0 check voltages. set both pots to 10K check voltages

not sure if you saw this after I edited my post

[HighDeaf1080p]

Oh thank you! I missed that. The 2m2s measured out at 1.81 and 1.81. I got all 1% resistors so I'm surprised at the 1.81 measurement. I didn't, sadly, measure the hfe on the transistors that I soldered to the board.

[HighDeaf1080p]

Resistors were:

22k = 21.13 vs 21.98
47k = 46.97 vs 46.92
1k = 994 vs 1001
12k = missing vs 11.99
100k = 100.5 vs 99.6
2.2m = 1.81 vs 1.81

Agitate is a C1k with pin 3 to the emitter, and 1&2 both to ground...but that is the one that works backwards on the veroboard for no apparent reason. *Cries*

To me after checking 30 times, they appear to be hooked up identically. I cannot see a difference.

[HighDeaf1080p]

I feel like just ripping out the transistors and soldering in the ones from the breadboard and praying that fixes this. Haha

[eatyourguitar]

Agitate is a C1k with pin 3 to the emitter, and 1&2 both to ground...but that is the one that works backwards on the veroboard for no apparent reason.

if it is backwards then the reason is that it is backwards. you measured the resistor but not the pot. that pot is the problem. it is like having 1K on the emitter or emitter to ground. this also affects the voltages. measure the CBE of Q1 with the pot each way on both breadboard and vero. I want 4 sets of voltages.

[HighDeaf1080p]

oops, you said agitate and I was thinking incubate. Let me check agitate too, but it's incubate that works backwards, sorry for the confusion. I'll check both Q1 and Q2 with both their pots and voltages and see what's up.

I bet you're right. Since that pot is the thing that's working differently between the two, that's most likely where the problem is.

[HighDeaf1080p]

Just hooked the "incubate" pot up to the breadboard, and guess what.

The breadboard now exactly mimics the problems the veroboard had!!!!!! We have a defective pot! Thank you so much for helping me find that, Eatyourguitar. I knew that one pot was acting screwy but would have never dreamed it was causing all the other pots to not behave correctly, and cutting the volume by 50% on the whole circuit.

I just put the WORKING C1K on the veroboard and it works like a dream. Sounds exactly how the breadboard did. I'm so happy! What a kick ass pedal this is going to be.

I'm not 100% sure I have the values on the pots ideally selected, because it seems they all have their sweet spots pushed a bit to one end or the other, but all my kick ass sounds are behaviors are back and I'm LOVING it!!

[HighDeaf1080p]

I'm working with dminner to get an enclosure made for it, and when it gets here and I get it all boxed up, I will take it upstairs to my big amp and recording gear and make a nice thorough sound clip to show off all the different sounds it can make.

[HighDeaf1080p]

And I'm a complete spaz. I just realized the pot on the breadboard for "incubate" works backwards as well. So I guess the only thing screwy about that "bad" pot is its resistance value.

Maybe I should get a couple A1K for that location and swap them out.

[eatyourguitar]

I think 1KC is correct for Q1 emitter but you did not label agitate lug 2 in the vero layout you posted. I would suggest if you have 1 & 2 soldered together on the pot then change that to 2 & 3. that will give you maximum gain for Q1 when agitate is fully CW. when the pot is %50 it will be about 300 Ohms or less. this is the middle gain sound we want in the middle of the range of the pot. try that. there is a similar mod I do on a muff where I use a 1KB with a 1K resistor in parallel to make an improvised 500R pot. it could work here but it would have no low gain setting without the 1K pot. you can also put a 470R resistor in series with a 500R pot to target the other half of the range, all the low gain sounds with more control.

[HighDeaf1080p]

Ah ok! Right now I have a C10k for agitate and a C1k for incubate. I will try a C1K there for agitate instead to see if I like that range better, and tie pin 2 to pin 3 because as you guessed, I have it tied to pin 1 now on the C10k that is there. I just have to make sure whatever I use there, it still gives me cleans, through overdrives, and into distortion, because I get a whole range of exciting things happening when I hit Q2 with less distorted sounds, and crank Q2 to do most of the dirt duty. If that doesn't get me there I'll give that 500R and 470R in series a try.

Likewise I need that same fine control on Q2 emitter, for when I hit it with a fully saturated sound from Q1 and want to dial back the additive effect of Q2 on it.

Then graft kindof works as a blend control and sets the ratio of Q1 to Q2 in the final sound. I really like the function/range on the graft pot as well as on the calibrate pot (though I'm not sure the value of the calibrate pot matters since it's just blending two extremes.

[eatyourguitar]

You need to put the 12K resistor back if you want it to reduce the pregain for Q2 all the way at the fully CCW. Look at devi ever all her stuff has pregain controls with 1K to ground to prevent dead silence at CCW

[HighDeaf1080p]

Yes, I left the 22k on Q1's pregain, and the 12k on Q2's. I had forgotten to ever put it on the breadboard version, but I do like it on the soldered one now that I can test the difference. And you're absolutely right...1K is right for Agitate as well as Incubate, so I'll do C1K for agitate and an A1K for incubate, and for Agitate I went with your pin 2-3 connection insteadof the 1-2 connection I had.

I tried B100K for the Inject, as well as A10K for the Graft, and both worked well but started changing the sound of the pedal it seemed so I reverted back to the B500K and A100K's for now. I may make some more tweaks to the pots after it has been boxed and I spend some time with it, but I'm pretty happy right now. I'll update the schematic on Tuesday when I get back to work with all these last minute changes, and post it up here.

I will update as the enclosure manufacture and install process happens.

[HighDeaf1080p]

Been playing through it all morning and I just LOVE it, but...the pots still may benefit from some refinement I think before the schematic is "final". Some of the pots still have big swaths of useless swing, and all the useful stuff is at one end...but it seems like that moves based on how other pots are set, so it may not be easily fixed. For example, when inject and agitate are maxed, nearly the full swing of graft is useful, but when you back off those, you lose most of the swing and just the last 20% or so is of any use because of volume loss. Haha...this thing makes amazing sounds, but there is no doubt it has some rookie errors throughout it. I still love it though, and if I can improve it further, I'll just love it that much more.

If I need a pot that swings from 100k to 80k on pin 2, can I literally put a 20K pot in series with a 80k resistor on pin 2's output and achieve that?

[crochambeau]

If I need a pot that swings from 100k to 80k on pin 2, can I literally put a 20K pot in series with a 80k resistor on pin 2's output and achieve that?

Yes, every single component is essentially a circuit element. Sometimes the appropriate circuit element requires more than one component.

However, think about where that 80K is from the electron point of view. Such a series resistance is generally not the function of a potentiometer (while it *would* be the function of a rheostat). Whenever I am addressing a potentiometer, I usually graft onto either pin 1 or 3 and consider a series resistance on pin 2 part of a larger circuit element (one which the pot may be part - but not one considered the pot)

I hope that is not hopelessly obtuse, hahaah.