I bought a used 120 Volt US Invective 120 Head manufactured in China 08/2018.
I put in Ruby EL34BHT tubes and the highest the bias reading was 12 mv at the test points.
The JJ 6L6GC had a range from that to mid 30mv when I adjusted them.
I have been reading that there are a few resistors that need to be changed to increase the range for other tubes and it is an issue Peavey is aware of and had a service bulletin on it and a recommended procedure for their authorized repair personnel.
***********UPDATE**************
I was able to locate the correction for the resistors BUT AFTER EXTENSIVE PLAYING I have decided that 6L6's are the ticket so Im leaving it as is.
Peavey design team really nailed it with this amp and I think its as good as anything out there now. KUDOS
Invective 120 Bias Defect fix UPDATE
- guitarman59
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Invective 120 Bias Defect fix UPDATE
3120, 6534+, JSX 120, Invective 120, XXX 120
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- JamesPaul
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Re: Invective 120 Bias Defect fix UPDATE
Good to see that you found the service bulletin. Also, thanks for reporting that the amplifier does sound best with the 6L6's.
James Paul's PeaveysEnzo wrote:I find if the amp is working, that is a good point to stop fixing it.
Decade, Classics, Ecoustic, Windsors, VYPYR, Triple XXX, XXL, VKs, Bandit, JSXs, VIP, Piranha and a Penta.