Made 2 Fuzz Faces 1 rig they work great but other rig pot levels problem

[TheButcher69]

I just built 2 Dallas Arbiter Fuzz Face silicon pedals. Both pedal do the exact same thing. On my one rig dsl40 plugging straight into guitar, Fuzz Face, amp it works like it should. My other rig jcm2000 same chain order my "Volume" control (500K z Log/Audio Taper) & "Fuzz" control (1K Linear) right at 2'oclock both pots reach maximum volume (meaning that it's at the loudest point on the pot) & if I goes pass until the potentiometer reaches the end where you can't turn it no more it gets quieter & loses bottom end & the fuzz just farts out. If I plug the Fuzz Face into my pedal board (first in chain) it acts normal. There is Boss pedals in the chain so it it possible my jcm does't like the the Fuzz Face or vice verse?

[antonis]

Hi & Welcome..

it it possible my jcm does't like the the Fuzz Face or vice verse?

Try to make Fuzz Volume pot 100k to see if your amp is more happy..

[TheButcher69]

Hi thanks! I'll give that a try. Do you think that will possibly correct the "Volume" pot too? Also any ideas on how to tame the silicon transistors? It farts out a lot. I tried BC108b, NTE 123a (which are a Crossover of a BC108C) I tried 2n5088 all seem to do this but the 123a & 108b are really bad. I got a heavy pick hand & they are far worse.

[aleks_tedstone]

I just built 2 Dallas Arbiter Fuzz Face silicon pedals. Both pedal do the exact same thing. On my one rig dsl40 plugging straight into guitar, Fuzz Face, amp it works like it should. My other rig jcm2000 same chain order my "Volume" control (500K z Log/Audio Taper) & "Fuzz" control (1K Linear) right at 2'oclock both pots reach maximum volume (meaning that it's at the loudest point on the pot) & if I goes pass until the potentiometer reaches the end where you can't turn it no more it gets quieter & loses bottom end & the fuzz just farts out. If I plug the Fuzz Face into my pedal board (first in chain) it acts normal. There is Boss pedals in the chain so it it possible my jcm does't like the the Fuzz Face or vice verse?

The Fuzz Face circuit is simple, and as a consequence has a low input impedance, so places a significant load on your guitar pickups when first in the chain. This is 'normal' behaviour, so when you place it after any other pedal, you will get unusual behaviour.

Hi thanks! I'll give that a try. Do you think that will possibly correct the "Volume" pot too? Also any ideas on how to tame the silicon transistors? It farts out a lot. I tried BC108b, NTE 123a (which are a Crossover of a BC108C) I tried 2n5088 all seem to do this but the 123a & 108b are really bad. I got a heavy pick hand & they are far worse.

In order to get the most out of your transistors, they need to be correctly biased. This is often achieved with a trimmer potentiometer (around 50K) between the power supply (+9V) and the collector of your second NPN transistor (Q2). This can be adjusted by ear, but you will also find that the collector voltage is probably about +4.5V for the most 'even' sound. Some people like to deliberately bias this transistor 'wrong' to achieve the sputtering farting sound you describe, although not necessarily as extreme. Also, not every Fuzz Face uses NPN BJTs so this advice comes with a caveat, but from the information you have provided this is what you have made. Note also that many people like to put a lower hFE transistor in Q1, and a higher hFE transistor in Q2.

[TheButcher69]

Hi and thank you for the reply. I was researching biasing & that is my problem. On Q1 I'm getting 3.8v on the collector & on Q2's collector I'm getting 3.12v. I have the 330ohm next to the 22uf & the 33k in the middle & the 8.2k after that. My Hfe's are 405 & 416 on this website I used the calculator & it gave me these values that I should use in (R1 6.97K) (R2 4.7K) & (R3 220) 



My voltage readings are as follows: (Input 2.2uf .7v) (100K 3.03v) (Q1 3.78v on collector) (Q2 on collector 3.03v) (8.2K 4.9v) Battery 8.28v to board.

[Electric Warrior]

Just use the stock resistor values and you'll be fine.

[pinkjimiphoton]

Hi thanks! I'll give that a try. Do you think that will possibly correct the "Volume" pot too? Also any ideas on how to tame the silicon transistors? It farts out a lot. I tried BC108b, NTE 123a (which are a Crossover of a BC108C) I tried 2n5088 all seem to do this but the 123a & 108b are really bad. I got a heavy pick hand & they are far worse.

you're driving your tubes into cutoff it sounds like. them nte's are frankly GARBAGE.
that said... add a hi pass filter inline with your input signal. dialing out some bass will make it tighter. fuzzfaces have a lot of bottom end to begin with BUT for a marshall to marshall, it can't HANDLE that much bass without getting sputtery and weird. that's why klons are so popular... treble boost to add harmonic complexity and clean boost to make the valve break up.

attenuating the bass will get rid of most of the flub. try about a b100k pot and maybe 22n cap. that should work for most guitars with humbuckers just fine. this will focus the fuzz upwards more into the midrange than the fuzzy bottom end and make it tighter.

don't trust them "calculators". i've used 'em, and they may function, but to my ear, they never sound right.

broken record time: remember too, you can tune the gain of the transistors by using e to ground(ish) resistances.
say, 220r between e of q1 and ground and maybe 150r or so on two similar hfe transistors will offset them and drop the gain down, if in this case they're around 400hfe or so. then either use trimmers for c to find the bias point, or temporarily wire in a pot and sub the closest standard value you have to where the pot sounds best.

[pinkjimiphoton]

Just use the stock resistor values and you'll be fine.

well, i'd say that about the volume pot, anyways
smaller values can make it bassier imho

[TheButcher69]

Thank for the reply guys! I much appreciate the help. I took some test voltages & turns out being I when off the picture of the silicon fuzz face from fuzzcentral showing a picture of the 330 in R1 & the 33K in R2 my bias at Q1 was 3.82v. I swapped the resistors around & now I'm getting 1.28v at Q1 & 3.2v at Q2 sounds much better but you're right lots of bottom end which I don't like & I'm getting a radio station over my amp went the volume on guitar is off or I max the volume & fuzz. My hfe values are 412 & 423 with the 2n5088. I'm thinking of trying the S9018.

I was concerned with the calculator. The values seemed wrong. A guy on YT told me to put the resistors back in normal order & I should be good. I agree stay with regular values. Thank again!

[pinkjimiphoton]

5088's are really too hot for a good fuzzface imho, but if its fuzzing, congrats!  next time, try mpsa06, mpsa6515, 2n2222, etc

now... noise. there's a couple ways to combat it.

first, put a small cap, say 2.2-4.7nf across the power rails. this should shunt the rfi to ground.

a small resistance, say 47r to 220r or so in line with the + voltage will help act as a filter. works best with the cap above.

a big ass filter cap across the rails can help too. start about 100uF, you may have to go bigger. i had a ff once that acted weird til i put about 2200 uf there.

if none of that works, next bet is to add snubbers between b and c on one or both of the transistors. anywhere from about 47p to 3.3nf will work. the bigger the cap, the more highs will be reduced tho.

to fix the mud,  smaller input cap will do the trick.  4.7nf will give you a treble booster and you can use any value you like up to BIGGER than the stock, but around 100 to 330n is a good area to start.  smaller cap value = less mudd. there's distinct sweet spots you'll find along the way.

between this, you should be able to tailor the tone to something more useable.

hint: if you use trimmers to bias, set the bias by ear with the guitar turned almost off. set the bias until you get the clearest kinda compressed tone. now, when you crank the guitar, you'll get a whole spectrum from crystaline clean to kinda crunchy to overdriven to distortion to fuzz to mud all from your guitar. ymmv and should, there's lots of ways to skin a cat... the "tune to 4.5v on c of q2" thing is bunk, imho, based on giving ya max voltage swing by going to half voltage. but i've heard ff's that sound great up close to 6 v there. it depends on the transistors, the gain, etc etc... i've spent about the last 15 years studying these suckers. endless builds. chickenscrathed schematics... the one rule of fuzz is there ARE no real rules. if it sounds good.... it is.

props on figuring it out! had faith in ya!

rock on!
PjP

[TheButcher69]

Thank you for all that advise! I will try what you said. I have some 2N2222's. It's my first build & I thought how hard can it be to build this? I'm finding out even though it's a simple circuit there are many things that come into play to make it sound good. I did notice now after biasing it at Q1 I'm not getting the cleans with the guitar volume I was before so I agree by using your ear is a much better way. I didn't install in trim pot but was thinking of pulling the 8.2K & putting one in place of it. I wish I thought of that before I put the finish on the box. I could of had an external bias.

[pinkjimiphoton]

external bias is really only useful if using germanium, or if ya like really gated farty sounds.
stick a 10k-50k trimmer in place of the 8.2k.

a lot of times, i'll use a small resistor and a trimmer both... say, maybe 2.7k resistor and 10k trimmer. why?
cuz that way you can decide where you want to put the output cap. you can put it at the junction of the resistor and the transistor, at the junction of the trimmer and the resistor, or at the junction of the trimmer and the resistor feeding it. all three will sound different, and all three will have different volume levels and all three can be quite valid. i used to make fuzzfaces with a boost function, just by having a switch move the connection point of the output cap. do a search for schizoid face here on the forum.

remember... this is FUZZ. most legitimate EE stuff goes out the window when working to create distortions rather than minimize it. shit, sometimes a reverse biased transistor will even do the trick in a fuzz. my old friend devi did it all the time in some of her weirder fuzzes.

the only rule is... if it passes signal and sounds good... it is

[TheButcher69]

Thank for that info it's good to know. I ordered from Mouser the MPSA06-AP from Micro Commercial Components (MCC) 833-MPSA06-AP the hfe is 100. I'm hoping this is the correct one as the datasheet states EBC from MMC but other Mfr. datasheets state CBE. I know I can reverse it but just curious as to if they are all the same? All the values except for the saturation are the same but ONSemi/Fairchild gives the saturation & MMC don't. I couldn't find anything with the Motorola datasheet. Also I looked up the MPSA6515 & nothing comes up. A MPS6515 does though.

I was wondering how you get the Q1/Q2 ratio of 66-75% of the gain if you're using the same transistor & the same hfe/beta?

[pinkjimiphoton]

by adding resistance between e and ground. bigger resistance = lower gain. when i did the schizoid face thing a couple years back, i think it was 47r on q1 and 120r on q2 to get two mpsa06 to come out about the right gain ratio to actually bias well with stock values on the passives. the mpsa06's were all about 200 hFE that i'd gotten. the two resistors were close enough for rock and roll, and them things sounded great!


i believe some of them are indeed an opposite pinout. there's a few manufacturers. i got in the habit of always checking pinout on a cheap little chinese tester thing from ebay.

[TheButcher69]

Thanks for explaining that. I'll have to look into one of those on ebay. Takes forever using a DDM. The other transistor MSPa6515 are those MPS6515? What were the hfe?

[pinkjimiphoton]

sorry, mps6515. hfe was around 150 as i recall.

also... if ya feel the fuzz needs more oomph, AMZ/Jackie Orman has a mod that's brilliant.. take the voltage divider feeding q2 and reverse the order of the resistors in the voltage divider... put the 8.2k one in place of the 330r one and vice versa. gives more output that way, too.

i listened to your videos on youtube, ain't NOTHING wrong with this fuzz you built! sounds great!

edited cuz i'm a @#$%in moron lol

[TheButcher69]

Thank you for the info! Very useful. I'm order some of those & give them a try. Thanks I never had a fuzz face & wasn't sure if that's what it the original silicon sounded like. Plus it's my first build.

[pinkjimiphoton]

http://www.muzique.com/lab/yaff.htm

look what jack did here... exactly what i suggested. r7 and 8 drop the gain to the point where almost stock values work well.

[Ben N]

Hi thanks! I'll give that a try. Do you think that will possibly correct the "Volume" pot too? Also any ideas on how to tame the silicon transistors? It farts out a lot. I tried BC108b, NTE 123a (which are a Crossover of a BC108C) I tried 2n5088 all seem to do this but the 123a & 108b are really bad. I got a heavy pick hand & they are far worse.

I'm pretty sure Antonis meant the Volume pot. 100k would make no sense for the Fuzz pot.