madbeanpedals::forum

Projects => Build Reports => Topic started by: pickdropper on March 16, 2019, 09:27:26 PM

Title: 4-Knob Fuzz Face
Post by: pickdropper on March 16, 2019, 09:27:26 PM
I think I posted a built like this a number of years ago, but this is a bit different so I'll post again.  I slightly tweaked the board so I can use ribbon cable for the footswitch I/O wires.

I used a gold enclosure and backfilled the text.  It's a PITA, but the combination is usually one of the better color looks.

(https://i.imgur.com/keyKYtk.jpg)

(https://i.imgur.com/v1F6r41.jpg)
Title: Re: 4-Knob Fuzz Face
Post by: Leevibe on March 16, 2019, 09:31:14 PM
I really love that laser etch ink fill technique. It looks superb on this. Guts are perfect right down to the fillets on the 3PDT board. Everything about this looks perfect.
Title: Re: 4-Knob Fuzz Face
Post by: culturejam on March 16, 2019, 09:33:59 PM
That's sick.
Title: Re: 4-Knob Fuzz Face
Post by: jimilee on March 16, 2019, 09:54:49 PM
Immaculate as always!


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Title: Re: 4-Knob Fuzz Face
Post by: diablochris6 on March 16, 2019, 11:07:54 PM
Oooh, so nice! Great job, as usual.
Title: Re: 4-Knob Fuzz Face
Post by: matmosphere on March 16, 2019, 11:31:02 PM
Dang, those guts, sooooo good.
Title: Re: 4-Knob Fuzz Face
Post by: jjjimi84 on March 17, 2019, 12:35:22 AM
Just beautiful, nice work
Title: Re: 4-Knob Fuzz Face
Post by: peAk on March 17, 2019, 03:35:43 AM
Holy Crap!

So kewl
Title: Re: 4-Knob Fuzz Face
Post by: TGP39 on March 17, 2019, 06:20:48 AM
So professional.  I thought you burned the bias trim, but quickly realized you're just marking where the bias trim should be set.   You are definitely one of my favorite builders.  Steve. 
Title: Re: 4-Knob Fuzz Face
Post by: cooder on March 17, 2019, 08:34:40 AM
Right in yer face.... 8)
Title: Re: 4-Knob Fuzz Face
Post by: JackSkellington on March 18, 2019, 08:13:11 AM
I'm figuring the schematic, nothing new, I supposed.
The transistors should be the modern germanium, right?
A classic Fuzz Face with a charge pump; a Body control, maybe the Mid control like in the Fulltone 70? Voltage is the Bias, I guess.
I'd like to build something like that, but I didn't think about the charge pump, is it worth?
I wont't find proper hfe of AC128, probably. What about AC126, or AC125 (of this I'd have a larger range of hfe)?
Title: Re: 4-Knob Fuzz Face
Post by: somnif on March 18, 2019, 08:58:16 AM
Quote from: JackSkellington on March 18, 2019, 08:13:11 AM
I'm figuring the schematic, nothing new, I supposed.
The transistors should be the modern germanium, right?
A classic Fuzz Face with a charge pump; a Body control, maybe the Mid control like in the Fulltone 70? Voltage is the Bias, I guess.
I'd like to build something like that, but I didn't think about the charge pump, is it worth?
I wont't find proper hfe of AC128, probably. What about AC126, or AC125 (of this I'd have a larger range of hfe)?

The charge pump is there as an inverter. The Fuzz Face was from an era where transistor technology meant it was easier to design with a Positive Ground in mind. Makes using one with a modern power supply a pain in the ass, so adding little extra circuitry to get around the headache is worth the "mojo" cost.
Title: Re: 4-Knob Fuzz Face
Post by: pickdropper on March 18, 2019, 11:53:02 AM
Quote from: somnif on March 18, 2019, 08:58:16 AM
Quote from: JackSkellington on March 18, 2019, 08:13:11 AM
I'm figuring the schematic, nothing new, I supposed.
The transistors should be the modern germanium, right?
A classic Fuzz Face with a charge pump; a Body control, maybe the Mid control like in the Fulltone 70? Voltage is the Bias, I guess.
I'd like to build something like that, but I didn't think about the charge pump, is it worth?
I wont't find proper hfe of AC128, probably. What about AC126, or AC125 (of this I'd have a larger range of hfe)?

The charge pump is there as an inverter. The Fuzz Face was from an era where transistor technology meant it was easier to design with a Positive Ground in mind. Makes using one with a modern power supply a pain in the ass, so adding little extra circuitry to get around the headache is worth the "mojo" cost.

Yep, exactly this.

And the voltage control is a voltage reduction not a bias control.  It allows you to run the circuit at a lower voltgae, as if the battery is sagging.
Title: Re: 4-Knob Fuzz Face
Post by: JackSkellington on March 19, 2019, 08:15:16 AM
Quote from: somnif on March 18, 2019, 08:58:16 AM
Quote from: JackSkellington on March 18, 2019, 08:13:11 AM
I'm figuring the schematic, nothing new, I supposed.
The transistors should be the modern germanium, right?
A classic Fuzz Face with a charge pump; a Body control, maybe the Mid control like in the Fulltone 70? Voltage is the Bias, I guess.
I'd like to build something like that, but I didn't think about the charge pump, is it worth?
I wont't find proper hfe of AC128, probably. What about AC126, or AC125 (of this I'd have a larger range of hfe)?

The charge pump is there as an inverter. The Fuzz Face was from an era where transistor technology meant it was easier to design with a Positive Ground in mind. Makes using one with a modern power supply a pain in the ass, so adding little extra circuitry to get around the headache is worth the "mojo" cost.

Ok! ;) So it can works at 9v with a standard PSU, but it has positive ground, if I understand. Cool!

Quote from: pickdropper on March 18, 2019, 11:53:02 AM
And the voltage control is a voltage reduction not a bias control.  It allows you to run the circuit at a lower voltgae, as if the battery is sagging.

Yes, it was that I meant, I just told wrongly! ;D Bias and Voltage controls are two different kind of mod.

Thanks! ;)
Title: Re: 4-Knob Fuzz Face
Post by: somnif on March 19, 2019, 08:22:59 AM
Quote from: JackSkellington on March 19, 2019, 08:15:16 AM
Ok! ;) So it can works at 9v with a standard PSU, but it has positive ground, if I understand. Cool!

With the charge pump inverter, the thing has a normal negative ground (so you can use a normal power supply, daisy-chain it with other effects, all that fun stuff). The power portion of the circuit just "wraps around" the classic FF circuit. So the FF "sees" -9V, but you power it with a normal +9V power adapter.