Comments on: How to Bias a Marshall Tube Amp

By: 8x26x08

8x26x08 — Sun, 07 Feb 2010 17:46:22 +0000

do ALL tube amps …
do ALL tube amps have to be biased before retubing?

By: thomsil1

thomsil1 — Sun, 07 Feb 2010 17:46:22 +0000

hi is this the same …
hi is this the same with the dsl 50? please reply

By: danicgibson

danicgibson — Sun, 07 Feb 2010 17:46:22 +0000

I have a tsl 122 …
I have a tsl 122 combo that has the same problem… these amps are very unreliable… I was about to say check cap 46 but i see you already did… I think I will have to take mine to service

By: henryjimmix

henryjimmix — Sun, 07 Feb 2010 17:46:22 +0000

The tubes on my …
The tubes on my TSL100 are glowing blue! And getting really hot to the point at which it burns my fingers if I touch them after being on for just 30 seconds.
I know this ain’t right, it also hummms like a mother fucker, and doesn’t hum any louder or quieter after adjusting the volume..
I changed the bias to as low as it can go (turning it counter clockwise) and it seemed to help as far as the valve’s cooking is concerned..
I also opened it up and done away with cap C46, still no change?

By: m0pX

m0pX — Sun, 07 Feb 2010 17:46:22 +0000

You NEED a load of …
You NEED a load of some kind plugged in, but not necessarily a cab, some kind of dummy load would work.

By: chevyvan10

chevyvan10 — Sun, 07 Feb 2010 17:46:22 +0000

Just a shameless …
Just a shameless plug for this guy… I’ve pretty much exclusively bought tubes from him for the last 3 years because his customer service is so good. I’ve experimented with alot of tubes, and IMO, JJ’s are the best sounding new-stock tubes for the money. Don’t be fooled by rebranded Sovteks/Chinese garbage.

By: andyman95023

andyman95023 — Sun, 07 Feb 2010 17:46:22 +0000

can you do a video …
can you do a video biasing a 77 JMP 50 watt amp w/6550’s

By: stevothepsycho

stevothepsycho — Sun, 07 Feb 2010 17:46:22 +0000

When you’re biasing …
When you’re biasing a head do you need to have it plugged into a cab as well? I only ask because Marshall say you shouldn’t run the head off standby without a cab plugged in, and I can’t see the output jacks clearly on this video…

By: speedfreak808

speedfreak808 — Sun, 07 Feb 2010 17:46:21 +0000

You should never …
You should never ever have a tube amp turned on when it’s not plugged into a speaker

By: benellidown

benellidown — Sun, 07 Feb 2010 17:46:21 +0000

that is Marshalls …
that is Marshalls standard recommendation, however you have to know the plate voltage and compute your setting. MOST DSL50’s will plate voltage around 450-470. You take 17.5/450×1000 to get your bias setting. Most DSL’s I’ve ever worked on had settings 36-39mV. 45mV is really really high and too high for most tubes.