Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Solid State Amplifiers => Tubes and Hybrids => Topic started by: Psabin8951 on August 15, 2020, 09:51:48 AM

Title: Blackstar HT5 noisy Clean channel
Post by: Psabin8951 on August 15, 2020, 09:51:48 AM
I have an early (non reverb) Blackstar HT5 here which has a noisy clean channel which occasionally has volume drop but mainly has a crackle and hiss that appears after about 10 mins of being on.
Both valves have been replaced with new matched ones and all connections have been cleaned, checked and resoldered to eliminate them.
Any thoughts what it could be?
At initial switch on it sounds great.
Title: Re: Blackstar HT5 noisy Clean channel
Post by: Jazz P Bass on August 16, 2020, 01:19:15 PM
I have attached the input circuit diagram.
The signal branches off of IC2A to the Clean and the Crunch channel.
Either of those is selected by jfets. (Clean/ Fet1: Crunch/ Fet2)
You will need to track down where in the Clean circuit the signal is failing.