wistling sound

[dead99]

A few hours after I finished my crack with speedball i noticed a wistling sound, its not consistent slowly changing in loudness (but not in frequency) ranging from 30-45db. It doesn't change in loudness when I turn the volumecontrol.
It happens in both channels but mostly the right one, if there is a wistle it is purely in 1 channel, never in 2 at the same time. It's a high-mid wistling sound. sometimes it is only one sound but I noticed up to 3 sound at the same time.
I've already tried disconecting everything in my room and turning of the light but it didn't help.

And another question, I noticed that with the transistors with heatsink (not the MJE350) the impedance between transistor-heatsink is infinite in one and around 29k ohm in the other. could this be the cause of the wistling?

Any advice?

 

[dead99]

I've resoldered some spots where I didn't heat the solder enough but it didn't make any difference

 

[Paul Birkeland]

It sure sounds like you have a loose wire, that was probably bumped when installing the Speedball.

Since it can happen in both channels, I would be looking at the wiring remaining from the stock Crack build.

As far as the heatsinks go, either you used all the parts supplied in the kit and mounted them properly, and they are working, or you left parts out and burned up your amp. 

-PB

 

[Doc B]

If you haven't yet, try unplugging and replugging the tubes. Sometimes a dirty pin can create that kind of whistling oscillation, and doing a R&R on the tube can often clean the contact area.

 

[dead99]

sorry  for my late reaction
what is a r&r?

 

[Doc B]

Remove and Replace, pull them out and plug them in again.

 

[dead99]

a r&r didn't remove the wisteling sound. I have noticed that tapping on the tube or the surounding cassis the wistling gets less.

 

[Doc B]

Next step would be to carefully invert the amp and gently tap on different wires and components with a non-conductive instrument like a wood chopstick near the tube sockets while listening to see if any of them affect the whine. If you find one that does reheating the solder connections on that part might solve the problem.

 

[dead99]

I'm back wih my tediously slow response time. The wistling changed most when tapping the octal tube socket. but reheating all solderpoints connection to it didn't help.
sidenote I also thightened all screws.

 

[Doc B]

Hey, response time is not a problem! We all have lives that have to be lived. Tapping the socket influencing the noise kinda leads me back to the idea that there is a tube pin that might have something on it that is creating the capacitance between it and the socket that could induce the whistle. At the risk of sounding like a broken record, it might be worth it to pull that tube out again. You might try scrubbing the pins a lightly with some steel wool, or a scotch brite pad, or some really fine sandpaper or an emery board - you get the idea. A little contact cleaner or alcohol wiped on the pins might be worth trying too. Worst case is you spend a little time futzing around, best case is it might help. Let us know if that helps and if not we'll figure out the next step.

 

[dead99]

I cleaned the contacts with contact cleaner and the sound is almost gone, its now inaudible when listening music. I will clean them more thorougly later today in hope that it disappeares completely.
Thanks Doc 

 

[dead99]

but god says no and so after a few hours the wisteling returned.  :-\ but now it isn't there all the time but it keeps dissapearing and re-appearing.but now when I tap the cassis it doesnt sound like someone throwing the microphone on the floor.

 

[Doc B]

There is a possibility that if the noise is definitely from the tube it will go away completely with more play time. Not sure how many hours you have on the tubes at this point. But if it's under 20 try running them for a week or so and see if the problem improves.

There is still also the possibility that the sound is some kind of outside interference that just hasn't been tracked down yet. Run it with the volume control turned all the way down, and try moving it to a different location. If the sound changes or goes away it may be coming from an external source.

 

[dead99]

I gues I have about 10 hours on it, so I will run them a little longer.