Invective 120 Bias Defect fix UPDATE

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Invective 120 Bias Defect fix UPDATE

Post by guitarman59 » Sun May 15, 2022 10:39 pm

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.


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

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3120, 6534+, 5150 412 B, Invective 120
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Re: Invective 120 Bias Defect fix UPDATE

Post by JamesPaul » Tue Jun 14, 2022 12:32 pm

Good to see that you found the service bulletin. Also, thanks for reporting that the amplifier does sound best with the 6L6's.
Enzo wrote:I find if the amp is working, that is a good point to stop fixing it.
James Paul's Peaveys
Decade, Classics, Ecoustic, Windsors, VYPYR, Triple XXX, XXL, VKs, Bandit, JSXs, VIP, Piranha and a Penta.

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