Whistle in my tweed build?

[Giraffecaster]

Finished a tweed harvard (5F10) build and I have the oddest problem.

When the volume is between 0-1 or 9-10 or the tone is between 9-10 I get a really high pitched whistle. It sounds fine and checks out otherwise.

Tried swapping all tubes with known good ones so those aren't the problem. Also tried the chopstick method of moving wires around to no avail.

Anyone else have that problem before? Seems odd it would only whistle at 0-1 or 9-10! :jo

[Trout]

Finished a tweed harvard (5F10) build and I have the oddest problem.

When the volume is between 0-1 or 9-10 or the tone is between 9-10 I get a really high pitched whistle. It sounds fine and checks out otherwise.

Tried swapping all tubes with known good ones so those aren't the problem. Also tried the chopstick method of moving wires around to no avail.

Anyone else have that problem before? Seems odd it would only whistle at 0-1 or 9-10! :jo

It is very possible that the primary transformer leads are reversed. If you lift(Unsolder) the feedback wire at the output jack and the problem disappears, There is a very high probability that is the issue.
Happens a lot on homebrews.

Thats generally the first thing I check as well as making sure all my joints are solid and grounds are good.

Trout

[PRNDL]

>> When the volume is between 0-1 or 9-10 or the tone is between 9-10 I get a really high pitched whistle.

In both of those cases, the signal is nearly shorted to ground.

It may be that a tiny amount of power supply ripple is in your tone stack ground. I'd look at the ground scheme and isolate the preamp ground from the power supply ground.

[Giraffecaster]

Thanks guys!

I tried PRNDL's advice first since I put the power amp ground close to where the pots ground to thinking that was the problem. The whistle was still there so I did as Trout suggested and swapped the brown and blue wires and that did the trick!

I now have a quiet amp that sounds great. Thanks once again PRNDL and Trout!

[Trout]

Thanks guys!

I tried PRNDL's advice first since I put the power amp ground close to where the pots ground to thinking that was the problem. The whistle was still there so I did as Trout suggested and swapped the brown and blue wires and that did the trick!

I now have a quiet amp that sounds great. Thanks once again PRNDL and Trout!


I have seen this a lot, for some reason, if you use the common fender layout pictures to build an amp, and you put the brown and blue wires where they say in the layout you get a whistle. I am not certain this applies to all of the newer transformers, but it is common of several brands.
Glad it helped!!

Trout