trinityamps.com

I built a 18 watt plexi, and am haveing a problem with a whistling sound on the plexi channel, voltages are all fine, normal channel sounds great, but plexi tmb channel sounds good with volume and master dimed with treble less than half way up its still sounds good, but past halfway on the treble the amp starts to give a whistle like sound is the best way i could describe it, any ideas on whats going on here? thanks mark

In the trouble shooting section of the manual there is a section on squealing/feedback. Usually step 5 reversing the leads to the OT will take care of the issue but you may need to go through the other steps as well.

_________________
Les

http://www.soundclick.com/unimind

Hi,

I had this problem with my TMB build back in March (see my post "Debugging a squel on a TMB build" on March 18). After following all the pointers in the manual, I eventually tracked it down to the routing of the wires from the gain and tone pots to the circuit board. By re-routing these, I was able to completely eliminate the problem even at high gains.

Hope this helps

Hey Stratguybri

do you have a picture of how you routed the wires?

Lindsay

Sorry for the delay in replying - I'm on vacation.

I don't have pictures with me, but I ended up routing the wires down low(at the level of the circuit board) vs up high (at the level of the pots). There was clearly feedback between the input and pre-amped signal. The squeal was directly correlated with high gains. Re-routing the wires solved the problem completely. I diagnosed it by removing the pots, which moved the wires, then turned the amp on.

Good luck

Brian