Hi, I've been reading this site for a while but this is my first post. I've only built a few pedals and still consider myself new at this. The few I've done in the past were single jfet or mosfet boosters. This is my first attempt at an IC.
I have tried to build the DOD 250 and it seem to make a bad noise. Instead of nice distortion, there is a crackling like sound when the gain is turned up high enough that the IC begins to clip. Even with the clipping diodes removed, it still makes this noise when the gain is turned up. It's worse at lower frequencies.
I tested all the parts before the build and everything seems to be within reason. Most of the parts are socketed and I've checked the caps again, they all check out. Also, I've tried about 10 different LM741CN opamps as well at 4 different TL071 and they all make the same noise. I've changed the cap on the feedback loop between pin 2 to 6 from 10pf, 20pf, 47pf, 100pf, and 120pf, all have the same noise.
Here are my voltages:
1: 0
2: 4.24
3: 3.03
4: 0
5: 0
6: 4.54
7 9.01
8 0
I've made an audio probe and the signal is clear up until it comes out of the IC at pin 6. Also, there's a lot of noise coming form pin 2. It looks like the voltage is too low at pin 3 and I think it's causing the amp to work way outside the linear range...but I'm not sure. What I can't figure out is what is causing this to happen.
Images:
http://1drv.ms/1JoRYYOhttp://1drv.ms/1JoS3Mdhttp://1drv.ms/1A6U1ichttp://1drv.ms/1A6U7Xjhttp://1drv.ms/1JoSmGPhttp://1drv.ms/1JoSrKphttp://1drv.ms/1JoSuWShttp://1drv.ms/1JoSCpaI've tried to solve this problem on my own with no luck. Any help would be appreciated.
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