I built the dipthonizer today. It seems to work ok, but 3 out of the 4 settings on the rotary have a background whine that is killing the fun of this circuit. Do I have a bad chip? Any help? I did a quick search but didn't find much at all on this particular problem.
Just out of curiosity, have you measured the voltage coming out of your power supply? Serms to be going around. Don't know if there was a global surge or what. Also Jon frequently says whines are indication of power issues.
Search Honey Dripper Noise in the forum. There you will find a fix to reduce the noise. Something about 100n caps on the power pins of most of the ICs. On mine it reduced the noise quite a bit.
Power shouldn't be an issue. Im using a BBE Supacharger.
Well, the noise drops considerably when I put the pedal in the FX loop.
I'll search the forum some more about those 100n caps.
The issue appears to be power supply noise coupling into the audio and being amplified by the filters in narrow frequency bands. To reduce the power supply noise, you can put 100nF ceramic caps from the power supply pins to the ground pins of the amplifier IC's. In this case, that would be all the IC's except the LT1054. You can do it directly on the pins of the IC.
Edit: You can get a hint if the whine is coming from the power rails and into the amplifiers if the frequency is dependent on the effect settings. The other possible source of a whine here is the charge pump. If the clock in the charge pump is interacting with another clock somewhere, that can cause whine too. Since it changes depending on where you put it in your effects chain, maybe this is the cause.
Thank you very much. I will most likely try those fixes.
Necro posting here. I just accomplished the mod suggested here of placing 100n caps across power and ground pins of all ICs except the charge pump. For the duals I went pin 4 to 8 and the quads pin 4 to 11. It didn't seem to help. I still get quite a bit of noise on 3 of the 4 settings and there is a faint higher pitched I guess squeal on all of them that kind changes with the envelope, that's not too bad as it's pretty faint but I'm thinking that part of it may be the charge pump. Aside from the noise, it's working like it should.