vintage fuzz circuit

[O'malley's Alley]

my dad has this old electronics manual that is dated 1971 that has a fuzz circuit in it, so I figured I might as well build it to see how it sounds. Let me just say, that if this fuzz pedal had a name, it would be the electric ham sandwhich. I personally dont really like the sound of it, cause it like looses it seems a ton of dynamics, so when you pick softly it doesnt go through. It's very distorted, and is a really simple design. I just thought I'd see what you fella's think of it, and if for some reason any of you want the schematic, I'll scan and post it. Here are some clips. My recording techniques arent the greatest. I plugged in through my friends Marshall AVT-50 and from on the headphone jack on the pannel, I plugged that into a tascam, which went into my sound card. Anyways, here they are:

Clean Channel:
No fuzz
With Fuzz

Distortion Channel:
No Fuzz
Fuzz

Just hit the play button over to the right.

[Nasse]

There are lots of people like me in this forum that want urgently see old schematics, so if you can please scan the circuit and post it.

[O'malley's Alley]

sure thing man.  Ill have to do it tomorow though, when I can use my brothers computer.  What did you think of the sound though?

[Peter Snowberg]

Before passing too much judgement on the circuit, it could sure use some biasing first. I doubt there's a real sonic gem in there for most, but it might be sonic nirvana for somebody.

Looking forward to the schematic.

Take care,
-Peter

[Nasse]

I could hear only distortion, although the sample was named "clean channel, no fuzz" or something. Maybe I have something wrong...

Take your time, I dont need more schematics but I like them :wink:

[O'malley's Alley]

Before passing too much judgement on the circuit, it could sure use some biasing first. I doubt there's a real sonic gem in there for most, but it might be sonic nirvana for somebody.

Looking forward to the schematic.

Take care,
-Peter

I'm a bit new to effects making, and I really dont know how to bias something?  How do you bias something?  What will it do to the sound? Thanks.

[b_rogers]

good to see you vamp hunter..it is a way of setting the correct voltage to the transistor,either using a resistor or trim pot..i think thats it. lol

[Mark Hammer]

One of the biggest complaints about fuzzboxes when I was a teenager was that many of them produced a sputtery sound if you weren't picking hard.  In other words, they'd sound great for most of the note but sound awful once the note had decayed a bit.

I take this to mean that a great many normally sounded the way the one you are describing sounds.

[Peter Snowberg]

Take a look at this thread for some more information:
http://www.diystompboxes.com/sboxforum/viewtopic.php?t=16153&highlight=bias

In most audio cases, when a transistor is sitting at idle, you want the transistor to be about 1/2 on. If it sits at only 1/8th on or 7/8th on (for example), the input wave will end up either saturating the base (causing clipping), or it will fall below the base-emitter threshold voltage (~.6 volts for silicon) which stops the transistor from passing any current, clipping the output. The level a signal can rise or fall while still landing in the range where it will get amplified is called "headroom".

Sometimes it's a good thing to clip and you want to over exaggerate the clipping effect (fuzzface being the best example), but when that's done, you want to have control over where that clipping happens.

When you have a fuzz that sounds like it "farts out" at the end of a note, that's a good indication that a transistor is biased to a level that stops it from passing any signal when at idle. That effect is commonly called "gating", but it isn't too musical. You only want the tops and/or bottoms of the wave clipped, and not the middle. When the bias is off, you only pass the tops or the bottoms, but no middle.

Biasing is conceptually just about balancing the base voltage between the emitter and collector voltages, but because NPNs and PNPs run off current rather than voltage so the topic of what to adjust and where is very specific to the circuit.

With single stage amp designs you usually adjust a resistor or two to set the bias on the base.

Lots of fuzzes are compound circuits that use a second transistor to multiply the response of the first one. In that case you can't just adjust the voltage on the base, so you have to adjust the voltage on the collector or emitter so that they line up with what the base is seeing.

When you get the schematic posted I can tell you what to try.

Take care,
-Peter

[Gringo]

Great post Peter, cleared up some doubts i had.

Thanks!