Fuzz face "too bright"

[pinkjimiphoton]

SACRILEGE!!!



buffers work fine after fuzzfaces. if your guitar is on 10, they work fine. if you HAVE to have a wah first, they help... tho a simple 50k pot works as well and is way cheaper.

but a buffer before a fuzz face?

most of the time, a buffer before a fuzzface will make it even MORE of a treble booster in my experience

Well...
I agree to disagree, sir. 

well, you are free to disagree sir,
but you are wrong.   

and you proved my point quite well. the guy never touches the guitar knobs. he's playing with the guitar on 10 and varying the pedal pots. that's not the same.
if your guitar is pegged, it cannot interact with the fuzz the way we are all talking about (old timers)

find me a video of the guy turning the guitar up and down to control it, and we can talk, but this one doesn't prove anything.
it sounds like a fuzz pedal thats being adjusted, not like the guitar actually adjusting the circuit.

two totally different applications.... and completely different resulting sounds.

making a silicon fuzzface that don't suck is one of the holy grails of fuzzdom. i've been on it for over 10 years now and have gotten close....  the proper interaction with the guitar is the determining factor of success.

anybody can make a fuzz that sounds decent when the guitar is pegged.

getting it to interact properly so you can express whatever tonal color you need or want from your instrument and fingers is completely different.

[Perfboard Patcher]

Hey guys.. I built a germanium fuzz face with OC71 transistors a year ago, and the thing is, it sounds great, but I have to change my amp settings before it does.
I play through an old super reverb, and when I play, I usually have treble on 5, mids around 6, bass on 2,5 - with these settings, the fuzz sounds very harsh and bad, but if I put everything on 3 and volume around 5-6, the fuzz sounds great. But when I do this, my clean sound is muffled and unusable. Is there a way to modify my fuzz, so I don't have to touch the amp settings? The voltages on the fuzz are good, so I think I basically need some low pass filtering.. The values are almost stock, except I have a 250k volume pot and a 1uf input cap - I was thinking of 500k volume and a bigger input cap, but is there anything else I can do?

Artr, it kinda depends on what the circuit is we're dealing with. The "sundial" part as in the schematic by pinkjimiphoton doesn't seem to be right to me. If R4 is 470 ohms then when the taper is at ground the circuitry will eat the battery (20mA). I guess the sundial's sole purpose is to adjust the DC potential across the collector of Q2?

The best "sundial" I can come up with:




I've slightly modified the "Sundial" part of the schematic but you can ignore that. I take your question as how to tame the high end AFTER the distortion (=fuzz). The simplest solution I see available is to insert one of the component options 1 (C), 2 (C + Potm) or 3 (C + R) between A and B or between B and C. Perhaps it's a challenge to find a good soldering spot for B on the printboard but A or C should be easy. This solution works predominantly as post-distortion eq because of the (ac-)voltage divider consisting of the 470 (small) and 2k2 (big) ohms resistors.   

I've just put some values for 1 and 3 to give you some idea of the order of magnitude. So start somewhere at 100nF and go bigger or smaller depending on what you hear. Or likewise use 3 to limit the losses at the highest frequencies (-6db) and cut more frequencies in the high mid. 

[pinkjimiphoton]

hey dudem
not my schematic or design. to me its not a good one at all.

battery killer with 470r? its 330 r in my dallas arbiter. i use it every gig. change the battery once every couple years.

the "sundial" is nothing more than an external biasing control for q2.

analogman is in CT where i live (bethel) and the reason it was added to the basic fuzzface circuit is cuz here in new england, the weather changes too fast and too often.

germanium doesn't like change. as the temp goes up, it will head toward thermal runaway. as it goes down it starts getting farty and splatty.

what to do? well, i used to carry an embossing gun with my live board. if it got too cold, a few seconds of heat into the jack would bring it back to life. seriously.

but its easier to just change the damn bias, which is the same solution i ultimately came to. the sundial is nothing special, its a bias control with a fancy name.

personally, i find the sunface doesn't interact as well with the guitar, and i don't care for their choice of biasing. it fuzzes, but it doesn't fuzz RIGHT to my ears or taste.

so the point is... i got lame circuits of my own to blame me for, this one ain't one of 'em! 

rock on

ps most peeps building a FF don't wanna add a lot of circuitry. i like your idea and how ya presented it, but @#$%ing with the tone there will also @#$% with the bias of the stage and change the character of the fuzz drastically. to do what you're going for, literally the easiest way is a simple cap between c and b in my experience. at 100p enough high end can be removed to make it fairly noticeable. you can go bigger. you can fake a variable cap (search function) too there and control the tone.
how the thing is biased, particularly in a hybrid ge/si circuit can change the tone. there's more than one point you can bias the circuit at if ya mess with it long enough (multi turn trimmers) and with some q's things can start to work backwards..

but the real key i believe is that when ya turn the guitar down to make it clean but not too brite. thats a tall order in a fuzzface circuit due to the design. very sludgy when the guitar and fuzz are cranked, but more clean and treble boosted the more ya turn the guitar down. he needs it to be darker.

lotta ways to skin a fish

the "sundial" as you have drawn .... and i like it, btw.. is cool  but as a combo high and low pass filter its gonna change the tone and the distortion level and the character of the fuzz too much. it looks great i agree, but in practice...

try it on a breadboard and see what ya think.

as electric warrior stated earlier, the actual circuit is not what was in the schematic i posted. i never bothered to build one of these, cuz the couple i tried didn't impress me at all. i find the design a little off for my tastes.
but in the end, a fuzzface is a fuzzface.

the more you add to it, the less it sounds and acts as it should.

generally, proper biasing is about half way up. the sundial circuit would likely not be grounding the battery, it would likely stop running completely unless it was really cold or hot at the extremes of the pot.

peace out and nice solution... welcome to the forum man!

[Electric Warrior]

I like to set the bias at Q1C. Both collector voltages mostly depend on Q1. When leakage increases with the temperature, the voltage on Q1C decreases, which in turn brings up the voltage on Q2. By tweaking the 33k you can make up for both. Just keep in mind that if you put a pot there it's probably a good idea to limit it's range by putting a resistor in series with it.

[mac]

Tone control,



http://www.diystompboxes.com/smfforum/index.php?topic=102639.msg910766#msg910766

mac

[pinkjimiphoton]

I like to set the bias at Q1C. Both collector voltages mostly depend on Q1. When leakage increases with the temperature, the voltage on Q1C decreases, which in turn brings up the voltage on Q2. By tweaking the 33k you can make up for both. Just keep in mind that if you put a pot there it's probably a good idea to limit it's range by putting a resistor in series with it.

speaking of bias, you ever try the "brit face" mod with the reverse biased ge diode between e and b of q1 with GE? it does work, tho i think the tone suffers some.

[pinkjimiphoton]

Tone control,



http://www.diystompboxes.com/smfforum/index.php?topic=102639.msg910766#msg910766

mac

hey bro, that looks hip!

[Electric Warrior]

I like to set the bias at Q1C. Both collector voltages mostly depend on Q1. When leakage increases with the temperature, the voltage on Q1C decreases, which in turn brings up the voltage on Q2. By tweaking the 33k you can make up for both. Just keep in mind that if you put a pot there it's probably a good idea to limit it's range by putting a resistor in series with it.

speaking of bias, you ever try the "brit face" mod with the reverse biased ge diode between e and b of q1 with GE? it does work, tho i think the tone suffers some.

No, but I tried leaving away the diode in a MKIII/IV Tone Bender and the tone suffered a lot. I haven't looked any further into it. Do you know what happens voltage wise when you put it in?

[Perfboard Patcher]

....
the "sundial" as you have drawn .... and i like it, btw.. is cool  but as a combo high and low pass filter its gonna change the tone and the distortion level and the character of the fuzz too much. it looks great i agree, but in practice...

...

as electric warrior stated earlier, the actual circuit is not what was in the schematic i posted. i never bothered to build one of these, cuz the couple i tried didn't impress me at all. i find the design a little off for my tastes.
but in the end, a fuzzface is a fuzzface.

...

Thanks for the warm welcome, pjp. I've been following diystompboxes for quite some time now but apart from a few posts I stayed in lurk mode. Yeah, I should have said as posted by pjp. I know you present your own designs by means of a YT demo. If seen some of them. You put a lot of effort in it, man.

I myself am not into building fuzz faces at all. Not my niche. I have no ambitions in the "sundial" business, merely a one-off suggestion. It's become clear to me that it's my fate to be in a never ending process of finalizing my guitar preamp + cabinet simulator thingies. Those "hardware" cabinet simulators, why is it so hard to make them sound like the real thing?

To clarify about the cap between the 470 and 2k2, I was more thinking of a cap value like 10uF to minimize signal loss when dialling in a less negative voltage for Q2's collector. So no high pass but only a low pass filter which will give the result the OP wishes for.

[mac]

hey bro, that looks hip!

I was searching for old radio recorders schematics, and some have a FF kind of circuit right after the AUX or MIC input, and a treble cut at the base of Q2 -> a cap and a series pot to gnd.

mac

[pinkjimiphoton]

I like to set the bias at Q1C. Both collector voltages mostly depend on Q1. When leakage increases with the temperature, the voltage on Q1C decreases, which in turn brings up the voltage on Q2. By tweaking the 33k you can make up for both. Just keep in mind that if you put a pot there it's probably a good idea to limit it's range by putting a resistor in series with it.

speaking of bias, you ever try the "brit face" mod with the reverse biased ge diode between e and b of q1 with GE? it does work, tho i think the tone suffers some.

back when i had messed with it years ago, i was too dumb to keep notes on it or measure things. i'd just solder stuff together til it sounded good or fell apart... which was usually what happened by tthe time it sounded good

i believe in the brit face article he goes into the voltages and stuff but tho i often cite it i haven't looked at it myself in years.

if you or anyone needs or wants a copy in pdf, let me know and i'll up it to my google drive and post a link.

as i recall, i tried it on my very first ff... it was great until the temperature changed, but it changes every 5 minutes here in new england. the diode helped with that.. a little. it was more stable, but i felt it changed the tone a bit so i ended up taking it out.

knowing me, i did it wrong, so, ymmv

i mean, on my first fuzzface i had the bias for q2 BEFORE the 330r resistor separating the two stages. hey! it still worked!

and sounded pretty good... but it was biasing both q's i think.   eventually it evolved into a starve control

No, but I tried leaving away the diode in a MKIII/IV Tone Bender and the tone suffered a lot. I haven't looked any further into it. Do you know what happens voltage wise when you put it in?

[pinkjimiphoton]

EW, here's a link
http://www.reocities.com/sunsetstrip/studio/2987/britface.html

I've come across another mod that won't alter the sound but is intended to increase the stability of the biasing of the transistors. The FF is famous for working fine sometimes, bad a lot of times, and simply don't working when you most need it (in SRV words, "sometimes it just dies"). The main reason is the variation of the transistors parameters with temperature.
There are three main parameters that will affect the bias when the temperature changes: the gain (HFE), the magnitude of the base-emitter voltage drop (VBE) and the saturation (leakage) collector current (IC0). Gain will increase with temperature, VBE will drop at a rate of -2.5mV/oC and IC0 doubles for each 10oC increase in temperature. Ge devices have much greater values of IC0 than Si (about a thousand times), so for Ge devices the most important variation is that of IC0, while for Si VBE is what cares most. This is one of the reasons that Si transistors became more popular than the Ge ones: it is much more stable and as a consequence it can also stand more power before thermal runaway.
There's one trick designers used to do at the golden era of Ge transistors to compensate for the variation of IC0. It consisted of placing a Ge diode (reverse biased) in parallel with the base-emitter junction of the transistor:

Since the diode is reverse biased, the current through it will be its leakage current I0. Current through the base will then be IB=I-I0. Collector current will be IC=HFE*I-HFE*I0+(HFE+1)*IC0. If HFE is much greater than one and I0 varies with the temperature the same way as IC0 does, then one variation will cancel the other, leaving IC constant.
This stabilization is most necessary at the input transistor of the FF. At the output transistor, there's the 1k pot at the emitter that will help to stabilize variations in all three parameters. You should not note any difference in sound, unless you have a very leaky transistor or diode. It will only make any difference the next time you have to play that gig at some beach's Summer festival... If you only play in studios or in your bedroom, it's better not to make this mod, to avoid the risk of damaging your precious Ge transistor while you are soldering the diode!

[Electric Warrior]

That was an interesting read.
Looks like he was starting out at the end of the useable voltage range. For some reason the MK1.5 Tone Bender was set to bias pretty much exactly like that. They're notorious for gating a lot in warm environments, but they can still sound quite good sometimes:

I guess they were not going for the most symmetrical distortion. 

It's funny that this circuit can be so unstable to begin with. The range of bias voltages that can turn out a good sounding unit isn't so small that changes in temperature will shift it out of that range (if it's not already sitting right at the edge), but the tone still can change dramatically.

I'll try putting a diode into my Fuzz Face clone today to see what happens..

[PRR]

> old radio recorders schematics, and some have a FF kind of circuit right after the AUX or MIC input

"FuzzFace", with different values and lower signal level, was a VERY common low-level preamp.

[George Moore]

  There are many ways to vary R and C, piggyback, series, switches, desolder points, component sockets, some can be done offboard.
  FF's sound completely different to themselves, depending on the set up.
  R.G. explained the FF, worth a sweep read to find the parts that can be understood, somethings about the source/input and next stage being critical to what the final result becomes.
  I found them very fun to play with and and through, but hard to work with. I spent a great deal of time setting up FF's, amps, speakers and pickups. I found the FF to be highly variable and sensative to anything/everything else in the chain, depending on what it's driving could be harsh or sweet, sweet spots requiring everything else to be 'just so'...and I got there, lots of fun !
  Because I liked the FF with certain efx. that were great and fun, but needed other things to happen [such as being able to bypass the FF without resetting/testing/dialing in, even with a loop switch box.
  I built a second pedalboard with modded, DIST+ or other similar circuit for Dist/fuZZ ''engine''.
 

[Electric Warrior]

I'll try putting a diode into my Fuzz Face clone today to see what happens..

Interesting. Not much of a difference in tone. Q1's collector voltge increased a little, possibly because I had to touch the diode, but even if not it would be easy to make up for.

[pinkjimiphoton]

when i had messed with it years ago, the cranked up fuzztone was pretty much unchanged but turning it down it was kinda weird.

i'll have a play at it later if i get a chance and see if my memory is as dodgy as i expect it is

[Electric Warrior]

That would explain. I may not have tried turning it down.

[pinkjimiphoton]

sorry EW, to be clear i  meant the guitar, not the fuzz. i tend to keep fuzzes pegged most of the time and just tweak the guitar.

sorry for being unclear  

[Electric Warrior]

I meant the guitar as well. I never use the pot on the pedal.