Fuzz Face Transistor Voltages Way Too High

[meyerdanielw]

Hey everyone,

1.What does it do, not do, and sound like?
I'm building a Dallas Arbiter Fuzz Face Clone using the NPN SI transistor schematic from Fuzz Central

http://fuzzcentral.ssguitar.com/fuzzface.php

The transistors I chose to use are a BC108B for Q1 and a BC108C for Q2.  Right now the tones I'm getting are extremely harsh and compressed. I haven't made any modifications or substitutions to the original circuit. However I am using a 3PDT switch with an LED.

I've measured the voltages at each of the pins on the transistors and they've come out as follows

Q1 E  0.00v    Q2 E  6.81v
Q1 B  0.63v    Q2 B  7.57v
Q1 C  7.58v    Q2 C  6.83v

These values seem to be much higher than they should be and I haven't read anything that would suggest what could be wrong. Any help would be appreciated.

Thanks

[PRR]

Welcome.

Look at the 820r, 8K2, and 1K pot. If these were the right values, you could not have 6.8V on Q2 E.

First thought is bad connections to 1K pot, though there are other possibilities.

[snap]

pinout problem?

( http://startingelectronics.org/beginners/components/transistor/ )

[meyerdanielw]

I've checked the pinout of the transistors multiple times. Seems like that's a pretty common error. I've currently got it all put together on a breadboard. I'm tempted to pull it all apart and start over hoping that I've made some error I just haven't seen.

[smallbearelec]

Hi--

I'm glad that you are doing this on a breadboard. Please compare your work with the layout in this article:
http://diy.smallbearelec.com/HowTos/BreadboardSiFF/BreadboardSiFF.htm. I used NPN devices as you did, though lower gain.

This looks like a mixture of wiring problem and mis-biasing. If the power busses on your breadboard are split, be sure that they are jumpered together. If your layout is not clean, make it so so that errors are easy to find and fix. Once we get it wired right, we can tend to the tone.

[mac]

...and sound like?

http://www.mikepiera.com/samples/GregV_SunFace_Jam1.mp3

mac

[meyerdanielw]

I feel like an idiot, but during my reconstruction of my circuit according to small bear's instructions I noticed that the pack of resistors I bought was 33 ohms instead of 33k ohms.   

[smallbearelec]

I feel like an idiot

So does almost everyone here, at some point...just means you are normal. How does the circuit sound with those devices? If the tone is still harsh, (as I would expect), try some of the tweaks in the article.

[meyerdanielw]

With the correct resistor in place it sounds good. I love it. Thank you for all of your help. If I hadn't taken it all apart I might never have noticed the resistor was the wrong value.