Pulsar Distortion Issues

[strungout]

I breadboarded the Pulsar from Tonepad.com. It tremoloes alright but there's some distortion going on, any ideas how to get rid of it? I tried changing the value of R4 (from 33k to 15k) but all it did was make the disortion sound better...

V readings:

Q1 E=0V  B=0.26V  C=0.005V

Q2 E=0V  B=0.48V  C=1.9V

Q3 E=0V  B= -1.20V  C=1.72V

U1 1=1.37V  
    2=0.95V
    3=0.92V
    4=0V
    5=1.82V
    6=1.97V
    7=1.41V
    8=7.81V

I don't get that neg reading on Q3 base... anyway I'd appreciate any help.

Ciao.

The schematic in question:
http://www.tonepad.com/getFileInfo.asp?id=29

[claydavis]

i haven't built this one, but you should have 9V at pin 8. try a fresh battery and see if that fixes it.

[strungout]

I just went and tried it, I had 9.2 V at pin 8, but no change.

Little precision: the pedal sounds like the signal from my guitar is coming out clean, but the pulsing effect has distortion...

An odd thing happens with this circuit also, when I take the battery out and clip it back in, the sound is clearer but becomes distorted (splattery) when my picking is stronger (and the distortion slowly levels in). I had this sort of thing happen with the first pedals I built, sort of like I had to "force" the distortion out. But the distortion becomes smoother when I take out R4 and put it back in.

Ciao.

[claydavis]

does it distort with the depth turned all the way down? if it does, look for a problem around the op amp. if it doesn't, there's probably something funny around Q1, and you should doublecheck the resistor and cap values around it, or maybe even swap it out. like i said, i haven't built it. maybe someone who has can chime in. good luck!

[strungout]

It distorts with any setting. I'll go check Q1. Thnx for the help

Ciao.

[strungout]

strungout enters and sits down silently, a vaporous cloud of embarassment floating over his head. ¬_¬;;;

-So? Says Clay.

-So, what?

-You figure out the problem?

-Yes.

-What was it?

-...

Nobody could've made it out through his muddy mutter, but rumour has it that it was the misbiased input that was cause for the distorted pulse...

                                                ***

Augh ¬_¬;; ....after reading your post I went to work on the pulsar, checked Q1 and everything around but couldn't see any problems, so I figured I'd check the opamp anyway, which led me to check if I was indeed getting 1/2 the power from the voltage divider. I did. But it connected to pin 6 instead of 5, which is my signal input... I don't get how I made that mistake, but I'll be making sure I quadruple check next time.

Thanks alot for your help, Clay.

Ciao.

PS: Oh, this tremolo is great  

[claydavis]

glad you got it working.