"crackling" noise problem

Started by The Iron Chef, December 17, 2008, 10:21:05 PM

Previous topic - Next topic

The Iron Chef

I built and boxed a Foxx Tone machine (gaussmarkov) and used NOS 2n3565 transistors in a t-106 package. The circuit worked fine but had a noticeable crackling noise.  Listen to it  http://home.comcast.net/~kgraydon15/ftmcrackle.wav.  I tried to get rid of the noise by rebuilding the circuit using the GGG layout and used all new, quality components except for the transistors. (I used the same ones) Guess what. It still crackles. Other than that, I think that it works fine.
     Can transistors make this kind of noise and still function as they're intended?

tia
-Keith      see photo below

http://home.comcast.net/~kgraydon15/2n3565.jpg
-Keith
I build stuff everyday.

Electron Tornado

Great phonograph record simulator you've got there!  :icon_biggrin:

I just repaired a TS808 clone from GGG that was doing about the same thing. Turned out to be the transistor on the input was the source of the noise. The pedal worked fine and the noise was only audible when I wasn't playing. You can use an audio probe to determine where the noise starts. You can also use sockets for the transistors. I do that for prototyping, but not for a final build, and over the years I've only had trouble with one transistor.

Tell us what you find.
  • SUPPORTER
"Corn meal, gun powder, ham hocks, and guitar strings"


Who is John Galt?

The Iron Chef

so,
I replaced all 4 2n3565 tranistors  with 4 others that I had.  the crackling "phonograph record" (heh) sound is now :icon_smile: gone!I didn't have time to investigate each transistor to find which one was the problem. sorry. anyway, here's a pic.
thanks, -Keith

-Keith
I build stuff everyday.

R.G.

Nota Bene:
"Crackling" noises are a good example of the class of flicker noise or 1/f noise. This is a not-well-understood (at least the last time I checked) noise mechanism. In BJTs it's often associated with surface contamination or damaged B-E junctions.
R.G.

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.