Fuzz Face on the fritz

[CJ]

cool info, Thanks! 

it has been mentioned that the Ge transistors respond better to a drop in the guitar volume knob? where did i hear that, Mike Fuller maybe,

 

[Bo Deadly]

I agree with Wildfara. Collector of Q1 should be more in the middle so that the clipping is vaguely symmetric. Otherwise it starts to make squishy squeaky balloon noises (that the best interpretation I can give of what I hear in my mind anyway).

I don't know much about Silicon fuzz but I messed around building fuzzes for a time and I was always disappointed until I stumbled across a few low-leakage low-bandwidth Germaniums. The ideal part IMO would be something that has a Beta of around 70 and leakage of ~40uA (not to be confused with Icbo values commonly posted in Ebay listings which is actually leakage / beta). If you can get a Germ in said range it might drop into that pedal nicely.

But most Germs are going to be either alloy junction which are too good (leakage is too low and bandwidth is too good) or super high leakage because they're simply what is left over after 50 years of being picked over and resold over and over. There is a semiconductor reseller company in the UK that has been around for a loooong time (used to advertise in WW). Folks who have been around for a while will know who I mean so I won't say the name. If there is a chance of finding something that hasn't been totally picked over it will be with them. Something like Mullard OC4X, OC7X or whatever. Still total crap shoot though.

 

[Bo Deadly]

cool info, Thanks! 

it has been mentioned that the Ge transistors respond better to a drop in the guitar volume knob? where did i hear that, Mike Fuller maybe,

Yes, large series resistance with the base actually sounds nice. Not sure why. Maybe related to huge grid stoppers in guitar amps?

 

[CJ]

what box do you use for the " Spirit in the Sky"  fuzz?

sounds like some weird gating action,

https://www.youtube.com/watch?v=swIcX57vYDI

heard it was an onboard home made thing,

 

[Bo Deadly]

what box do you use for the " Spirit in the Sky"  fuzz?

That's not the fuzz. They might be using a fuzz somehow but that burping gate is not something I would attribute to a Fuzz Face.  You Shook Me by Led Zeppelin is also the same gating effect. I don't know what it is. Sounds like maybe low passing followed by overdriving something (maybe biased badly). I would also love to know what it is actually.

 

[CJ]

check this out>

https://www.thegearpage.net/board/index.php?threads/spirit-in-the-sky-fuzz.425563/

here is the maestro fz 1b .  seems to have some gating going on.

the record sounds like a touch sensitive fuzz, might be able to use a comparator to switch in the fuzz when volume goes high, or maybe just use a low battery,

 

[Jarno]

Enough people realised that the difference between a lousy FF and a much better one is bias:
http://www.diystompboxes.com/biascalc/ffbias.html
http://www.diystompboxes.com/analogalchemy/emh/emh.html
http://www.muzique.com/lab/fuzz_face.php

http://www.geofex.com/Article_Folders/fuzzface/fffram.htm

I Like fuzzes, they are nice in a nasty way

 

[midwayfair]

http://www.geofex.com/Article_Folders/fuzzface/fffram.htm

This here's the bible for this circuit. You guys are about 20 years late to the party.

Ya'll should hang out with us at DIYSB or Madbean once in a while, we got every fuzz you can imagine and then some.

Spirit in the Sky probably did not use an FZ1. The guitarist claimed the effect was built into his guitar. It was probably similar and it probably also had a dying battery. I'm on my way out the door so I can't find the post right now, but it was someone on DIYSB that actually gave the quote from the guitarist. I think it was either Luciferstrip or Warriorpoet, those guys seem to know almost everything there is to know about old fuzzes.

 

[Bo Deadly]

I don't give much weight to claims like that gearpage thread. Clearly no one knows.

My best *guess* just from listening to it would be that a BE diode junction is off-biased for some reason (temperature maybe) so it clips the signal but causes the coupling cap to charge up in the process and that momentarily biases the transistor on until it discharges through the feedback / bias resistor (or in the case of the leakage-biased Tone Bender, back through the guitar itself and source resistance of backed-off vol control). Something like that would explain the gating anyway.

I don't think it has to do with a dying battery because Fuzz bias actually doesn't change much with supply even down to only a few volts. I think temperature would be more likely responsible.

There's some kind of envelope filter effect going on. That is clearly different from the simple heavy modulation characteristic of just about all Fuzz boxes.

 

[user 37518]

I don't give much weight to claims like that gearpage thread. Clearly no one knows.

My best *guess* just from listening to it would be that a BE diode junction is off-biased for some reason (temperature maybe) so it clips the signal but causes the coupling cap to charge up in the process and that momentarily biases the transistor on until it discharges through the feedback / bias resistor (or in the case of the leakage-biased Tone Bender, back through the guitar itself and source resistance of backed-off vol control). Something like that would explain the gating anyway.

I don't think it has to do with a dying battery because Fuzz bias actually doesn't change much with supply even down to only a few volts. I think temperature would be more likely responsible.

There's some kind of envelope filter effect going on. That is clearly different from the simple heavy modulation characteristic of just about all Fuzz boxes.

Maybe you can ask the author http://www.spiritinthesky.com/contact.html

 

[Bo Deadly]

Maybe you can ask the author http://www.spiritinthesky.com/contact.html

Ask him what? About circuits and transistors and such?

 

[user 37518]

Ask him what? About circuits and transistors and such?

What pedal or effect did he use.

 

[Bo Deadly]

Well the gearpage thread has responses from someone who claims to have been on tour with them at the time and said that it was a custom fuzz builtin to a telecaster but that the guitar was sold and they have no further info about it. So if we believe that then it is telling in that it was a fuzz circuit with nothing in front of it.

 

[CJ]

great links up there, thanks!

one thing that is not mentioned is screening the Q1 transistor for their  V-c  at saturation,

in other words, that 1.2 volts on the collector might move around quite a bit for a batch of the same transistors.

do not know what effect, if any, this would have on the sound.

 

[Newmarket]

I just put them in whatever enclosure i can scrounge or build...Anyone who pays more than 100 bucks for a Fuzzface I would think was foolish...its 10 bucks or less of parts and some labor

Well I think that what people are paying for (or at least asking big £££s for) is the retro sci fi vibe of the enclosures.
As you say - circuit component and assembly cost is minimal. The basic circuit is common currency and whilst design and expertise are of value pushing prices to  astronomical levels goes too far imo.
Nice link to your stuff btw 

 

[abbey road d enfer]

it has been mentioned that the Ge transistors respond better to a drop in the guitar volume knob?

That is true. The reason is Ge transistors have much less gain than Si types; as a result the input impedance is much higher, so the volume pot, instead of seeing an almost dead short (about 10k) sees about 30k, which doesn't hammer the pot's taper as much.

 

[abbey road d enfer]

That's not the fuzz. They might be using a fuzz somehow but that burping gate is not something I would attribute to a Fuzz Face.  You Shook Me by Led Zeppelin is also the same gating effect. I don't know what it is. Sounds like maybe low passing followed by overdriving something (maybe biased badly). I would also love to know what it is actually.

Truth is much simpler; use the p/u switch on a LP/SG with the volume pot of the neck p/u all the way down as a kill switch. Bash a chord and shake the switch to taste.

 

[Bo Deadly]

Truth is much simpler; use the p/u switch on a LP/SG with the volume pot of the neck p/u all the way down as a kill switch. Bash a chord and shake the switch to taste.

I think we're talking about two different effects. The distortion sound by itself is unique and not something characteristic of a typical fuzz which usually has a lot of high frequency buzz.

 

[midwayfair]

I think we're talking about two different effects. The distortion sound by itself is unique and not something characteristic of a typical fuzz which usually has a lot of high frequency buzz.

It's a Tonbender MKII. Page's guitar effects have been researched to death, you don't have to guess about most of this sort of stuff.

Also, you're surely off base with guessing that an envelope effect of any sort was used on Spirit in the Sky. They simply didn't exist in stompbox form at the time. (Also fuzz bias does change when it's starved. I have a fuzz on my gigging board that does that intentionally, and some fuzzes sound like completely different pedals when the supply drops too low.)

It takes 10 minutes to breadboard a fuzz. Why don't you get out the testing rig and play around some with some circuits?

 

[Bo Deadly]

It's a Tonbender MKII. Page's guitar effects have been researched to death, you don't have to guess about most of this sort of stuff.

You sound so sure.

Also, you're surely off base with guessing that an envelope effect of any sort was used on Spirit in the Sky. They simply didn't exist in stompbox form at the time.

I don't say it was an envelope filter circuit. I speculated that the coupling cap could be charging because the diode junction of the transistor was rectifying the input. That changes the bias until it has time to discharge. That is effectively a builtin envelope filter. That can and definitely does happen in lots of transistor circuits. In tube preamps it's call "blocking distortion". Is that the cause of this "Spitit in the Sky" / "You Shook Me" distortion effect? I don't know. Again, I'm just thinking-out-loud.