Siren sound from my DOD 250 +Thunderchief??

[uan]

just built DOD 250 preamp to use in front of my thunderchief. Yeah nice sound but a bit noisy.. the problem is when i switch on both circuits, the sound would slowly fade out and then a wierd sound like siren can be heard. After a few seconds, it back to normal until another few secs, it begin to sound bad again..(that siren sound)

any idea?

one more, can anybody suggest me a good project for noise filter/supressor?

[chunks717]

sounds like some crazy cap thing?!
its periodic continuously/ consistently?
did you decouple between stages?(10uf-.01uf cap)

[uan]

its periodic continuously..

I replace the DOD circuit with DIY micro amp in front tof the thunderchief, same thing happened but less often. Than i changed to DIY Tubescreamer and it dissapeared. All the circuits is not covered by enclosure.. i plan to do testing 1st and if everything goes well, then i'll put them into enclosure.

i dont understand what do you mean by decouple between stages..? (sorry, my english is not good)..

[chunks717]

actually, perhaps I mean blocking caps, but either way,
If you look at just about any of these projects, the signal enters
through a capacitor, and exits through a capacitor.  this also happens
between stages (different parts of a circuit) I have no idea if this
is related to your problem.....
I just took a peak at the thunderchief, and you may want to try
putting a 1uf cap, positive lead toward the fet, negative lead toward
your dod/tubescreamer/etc's  output............

may do nothing...are you totaly sure its wired correctly? check all
your caps-sizes, orientation, etc.  a problem like that seems to me
to be cap. related............