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The 'Mule Project'- learning about valve/tube amps on a B25.
#3
Well I had a chance to play through it earlier and while channel two was reasonably quiet and sounded okay at low volume, it quickly farted out big time when I cranked it up.

By the way, I'm playing bass through it and the cab is a fEARful 15/6.

Channel one had a lot more hiss but it had a 12AX7 as opposed to the 12AU7 in channel two.

Again, channel one seriously farted out at higher volumes, I mean really bad.... The 15" speaker was really suffering so I backed right off....

BassHog queried as to whether I had the output valves biased too cold - they were...... My bad.

I adjusted the bias, with a high plate voltage of 530v I set the current at 39ma and that tightened the sound up a bit. However, it was still distorting badly.....

The 15/6 isn't a sealed cab which won't help with poor damping issues I know.

Cheers
Grahame
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RE: The 'Mule Project'- learning about valve/tube amps on a B25. - by pentode - 05-10-2015, 09:54 AM

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