Biasing a Mark III?

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tripstan

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Everything I've seen online says I can just buy some Mesa Boogie tubes and I will be fine without biasing. It currently has all EH 6L6's. And I want to go back to 6L6's and 34's.

So can I but a pair of Mesa 6L6's and a pair of Mesa EL34's and just pop them in? I don't see any bias points or a trim pot of any kind inside the amp. I have an pair of Ruby 34's that I could try in the outer sockets but I don't want to mess anything up. I don't care if the tubes blow but I don't want to damage the amp.
 
Yep thats right.

Wont be an exact science though, can't imagine it would be too much of a problem. Head over to the Boogie Board forum there is loads there on non mesa tubes. Ive just done my Mark III (green stripe).

As the amp is fixed bias oiginally the amp would have colour coded power tubes depending on their draw, the idea being you buy the same colour Mesa brand tubes and pop them straight in.

If your amp is Simul Class Mesa now recomend you run two EL34s and two 6L6s. In the bingining they advised you could run a pair of each or all 6L6s...

I went for all Svetlana Winged-C, EL34 & 6L6. Sounds amazing! :rock:
 
Thanks, I've been lurking over there but I'm not a member. I tried to reigster but it won't accept my email address. So I just thought I'd ask the RT brothers first. And yes it is Simul-Class. So do know if it would be o'k to try the Ruby EL34's in the outer sockets?
 
tripstan":272ip8zp said:
Thanks, I've been lurking over there but I'm not a member. I tried to reigster but it won't accept my email address. So I just thought I'd ask the RT brothers first. And yes it is Simul-Class. So do know if it would be o'k to try the Ruby EL34's in the outer sockets?
Click to expand...

I'd imagine so, give it ago. See how it goes. EL34s in the outside and 6L6 on the inside :thumbsup:

I'm sure you can check bias levels and internal voltages just to make sure its not going to cause any damage.
 
How would I do that? I do have a DMM but I don't see and bias points?
 
tripstan":1jhfqmrt said:
How would I do that? I do have a DMM but I don't see and bias points?
Click to expand...

Oh im note sure tbh.

Maybe not then, ive not done it myself but im sure theres a way you can check plate voltages and bias.

Pretty risky poking around a turned on amp... :confused:

Id check on the Boogie Board if you want to. But i have and people are swapping tubes with no problems. I wouldnt worry about it.
 
tripstan":1mga9tcp said:
How would I do that? I do have a DMM but I don't see and bias points?
Click to expand...

It's not a bad idea to check the bias. A bias probe is what you need like the compu bias. It will give you plate voltage as well.
 
They don't have a trim pot on the inside, boogies uses a resistor
So you could use a multimeter and tube socket adapter only to
Check draw , nothing else. The color code used to mean something as
Well, but it is mainly used to separate groups of tubes for matching.
I experimented with my Mark III and finally ended up putting
Boogie tubes back in and sounded fine. Just remember to put
EL34s in the outside sockets if you have a simul-class, you will
Be burning up fuses and tubes in no time.
 
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