freestompboxes.org

I thought it WAS a fuzz face? Just a particular flavor? : BC108

What I mean is; why can't we use fixed resistors where the trimmers are?
Because of variability in the transistors?

And instead of trimmers, most diy-ers measure the transistors to get close to what they want?

Well it's not a Fuzz Face, it's a modded Fuzz Face with a couple of part value variations and trimmers (and a switchable buffer of course). Remove the trimmers and you have a Fuzz Face

You can always replace a trimmer used as a variable resistor with a resistor if your prepared to take a gamble on the fixed values used and hoping it hits the sweet spot for you, or de-solder and replace if not (or socket the resistors of course). But it does seem to be overcomplicating things modding a modded Fuzz Face back into a Fuzz Face. If you don't want trimmers just build a Fuzz Face and use the resistor values you like to bias the transistors of your choice. But as trimmers cost about 10p each it's certainly a worthwhile variation to have I think.

Haha, No I wasn't going to mod the Classic 108 back into a fuzz face.

I was just checking out the design and wondering how it relates to fuzz face, why the trimmers?

So if you just build a fuzz face you measure the transistors, or swap out resistors until it sounds right?
Or you measure voltages? do some transistors not bias right with"stock" resistor values?

I guess I need to go re-read "Technology of the Fuzz Face.."

I actually think this circuit is fairly forgiving when it comes to biasing, but tweaks to the bias can make the difference between an ok sounding pedal and a great sounding pedal. If I didn't use a trimmer for something like this, then I'd at least want to socket the collector resistors.

That makes sense. Thank you!

I think I'll build a FF pretty soon, and maybe put the bias on an external knob.
And maybe a buffer in front... (Hmm.. BJT or JFET ??)
Know a good perfboard layout?

I have a question regarding how you would wire up the buffer and the fuzz circuits. I am new to pedal building so please excuse the noob question.

I presume you need to wire the buffer in series before the fuzz; if so am I right in thinking that you would have the usual DPDT switch (foot or toggle) wiring for the buffer circuit, but with both the bypassed output and the buffer circuit output going to the input of the DPDT switch for the fuzz circuit?

Or is there a better/correct way to do this?

Forgot to mention that I am using dpdt millennium bypass for my stomp switches, but not sure that makes a difference.

What I'd try is this:

Wire your bypass switch as usual. The input to the circuit goes to your second switch. This you wire to buffer input and fuzz input as the two options in the same way as you wired effect and bypass on the first switch. This will leave the MBP control lug unconnected.

I just picked one of these fuzzes. I really like it! I use it with the buffer on and off. I've been looking for a fuzz I liked for a long time. This one nailed it!

Where would be a good place to add an input trim pot?

matt239 wrote:Where would be a good place to add an input trim pot?

On the actual MXR board, I mean.?

Revive thread.

Reading thru the thread, I am left wondering if the solution was identified in which (how) the buffer system was implemented within the schematic?

Was the last schematic by Harold, along with the BOM correct?