#1
Hey I just bought Mesa Boogie EL34 Power Amp tubes. But I have no clue what to set the bias at. I have a Randall Rg50TC amp. If anyone could help that would be great. Also Randall doesn't have great customer service so they probably couldn't help me much.
Edit they are Sovtek tubes if that helps any.
Last edited by Guitar Guy21 at Jun 18, 2007,
#2
get a multimeter and measure the reading off the tubes. and adjust
I traded in my Real Books for Robbins and Cotran Pathology Textbooks
#3
My dad has a multimeter. So do I get that reading just by testing the tubes without putting them in the amp or what?
#4
yea first get reading, then adjust
I traded in my Real Books for Robbins and Cotran Pathology Textbooks
#6
oh yeah and don't waste money on Mesa Tubes, IIRC they are rebranded Sovteks.
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#7
Well that's the only thing the guitar store had and I needed tubes bad. Besides they have a 6 month warranty.
#8
^they do their job right for what they are meant for, mesa fixed bias amps. I've tried jj's and they just dont work for mesas.
I traded in my Real Books for Robbins and Cotran Pathology Textbooks
#9
yeah but the guy has a randall, but if its all they had I guess theres nothing to be done about it, just be mindfull of that in the future.
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#10
But they would still work with my amp right? So how do I know what tubes work good with Randall when they have crappy customer service?
#11
they they should, but next time, buy tubes from a place that specializes in them like steve's tube store or eurotubes(both online)
I traded in my Real Books for Robbins and Cotran Pathology Textbooks
#12
Quote by Guitar Guy21
But they would still work with my amp right? So how do I know what tubes work good with Randall when they have crappy customer service?


yeah the brand of tubes doesn't really matter for whether or not it will work in certain amp (even with Mesas, though using non-Mesa tubes might void the warranty or something) as long as it is biased properly.
make Industrial and/or experimental electronic music? Join my group!

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#13
Quote by Kid_Thorazine
oh yeah and don't waste money on Mesa Tubes, IIRC they are rebranded Sovteks.



They are still good tubes.
Major of 7 String Legion 7 > 6

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#14
Quote by MESAexplorer
They are still good tubes.


yeah, but you can get the non-rebranded sovteks a bit cheaper.
make Industrial and/or experimental electronic music? Join my group!

Last.fm
#15
Quote by Kid_Thorazine
yeah, but you can get the non-rebranded sovteks a bit cheaper.


I just stick with Mesa Tubes because I have a mesa, F-100, which has no biasing features, therefore, I intend on keeping the warranty even though I'd really like to tube it with JJs.
Major of 7 String Legion 7 > 6

Carvin DC747
Ibanez RG2228
Schecter Avenger Custom Shop
and my baby....
Gibson Explorer Studio
#16
Quote by MESAexplorer
I just stick with Mesa Tubes because I have a mesa, F-100, which has no biasing features, therefore, I intend on keeping the warranty even though I'd really like to tube it with JJs.

the JJ high gain pre amp tube package is great but i wasnt too thrilled at their powertubes.They worked wonders for my jsx tho
I traded in my Real Books for Robbins and Cotran Pathology Textbooks
#17
I'm sorry to bring this thread back up, but I can't get a reading from the tubes with a multimeter.
#18
Mesa tubes are tested to work correctly under Mesa's fixed bias, that's the advantage of using them with Mesa amps. If you are going to use another tube, the dealer or store should know Mesa's bias and test their tubes accordingly for it. You cannot adjust the bias on Mesa amps without hardwiring in a pot or changing resistors.

Quote by Guitar Guy21
I'm sorry to bring this thread back up, but I can't get a reading from the tubes with a multimeter.

What are you reading?

You need to find the plate voltage for your amp(pine 3 to ground), and then you use the plate dissipation for your specific tube(usually around 22W for 6L6/EL34), and divide the plate dissipation by the plate voltage of your specific amp. This will give you the maximum current you should NOT exceed. P=VI, I=P/V You normally take between 70-90% of that plate current, and use that value for each of the power tubes. Assuming your bias is adjustable, the easiest way is to use a bias probe and a multimeter.

If you don't feel comfortable doing it, it's best to take it to a tech.
"The fool doth think he is wise, but the wiseman knows himself to be a fool." - W.S.
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