Fuzz Face Bias

[Schappy]

I built a Fuzz Face from general guitar gadgets(69 boutique).

When I turn the trimpot I can bias it by ear but when I go to check the voltages Im getting readings of less than a volt on my DMM.

This being my first PNP build and the wiring being a little different Im not sure Im placing the probe of my DMM in the right place.

Like I said it sounds good and I dont think it would sound this good with the collector of Q2 below a volt.

http://www.generalguitargadgets.com/pdf/ggg_ff5_lo_b69.pdf

The pinout of the transistors is base(middle), emitter(near tab on the can), collector.  Is this correct?

[Earthscum]

That is right. Q2 collector should be maybe half a volt or so. It biases the Q1 base at about the same. When you turn up the distortion, it passes all AC signal throught the cap to ground, but still retains the DC bias through the resistor. The base of Q1 being biased this close to ground is what causes the first side of your waveform to clip.

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

[Schappy]

I thought you had to bias q2 collector at 4.5V.

[Earthscum]

Q2 Collector should be around 4.5-6V, the Emitter should be at .5V.Sorry about that. Still get them backwards. Either way, where the gain pot and the (positive) side meet should be around .5 to .6V, depending on what you like for sound. I was getting some pretty awesome sounds, although not as fuzzy as I'd like, with my Q2 E sitting around 1V on a breadboard build. I had to really play around with the collector resistors to get everything right for the transistors I use (NTE158), so don't give up.

Oh, and I guess you've already checked it, but you have your transistors plugged in correctly, aye? Also, don't forget to try swapping the transistors around (Q1 for Q2) and see how that sounds and how it biases for ya. A transistor will work upside down, but won't quite function properly. Also, I guess I assumed you are using PNP Germaniums? If so, your ground is positive, not negative. This screwed with me the most, so I put heat shrink over my power leads for the test build in reverse colors, lol. Almost got me when I forgot to remove it before next board project.

[newfish]

Any Ge FF Circuit I've ever built has been tuned by ear.

Whenever my pedals are in use, I don't think, "Oh, will you listen to that perfect 4.5v bias?".

Given that any Ge devices we're likely to find these days will be as leaky as any multi-holed thing you might care to mention, I'm just pleased that the Ge FFs work, and sound great.

0.02

[Schappy]

Ived wired it with this layout

http://www.generalguitargadgets.com/pdf/ggg_ff5_lo_b69.pdf

With one exception. I hooked it up with a battery only.

I wired the negative lead of the battery clip to the 9v on the board. I wired the red lead to the ring of the input jack.

Im confused because in this diagram everything else is grounded at the sleeve when usually I ground everything on the ring.

Did I do it correctly?

[Schappy]

Im pretty sure everything is hooked up correctly since it sounds very good.

Like I said I can dial the trimpot in by ear but for some strange reason I cant get any voltage readings.

When I place the red lead of my DMM on the collector of Q2 and the black lead on the sleeve of the input jack I get no voltage reading at all?


I

[Gus]

http://www.diystompboxes.com/analogalchemy/

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