Power tube replacement, on boogie amps in general

Mark I's, II's, III's and the almight IV

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cisspcism
Mark I
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Power tube replacement, on boogie amps in general

Post by cisspcism » Wed Jan 14, 2009 10:28 am

Ok accordign to the manuals, no boogie amp has to be rebias as they indicated that they have biased it perfectly already for you and then locked in place so it wouldnt ever drift.

However they then stress that you HAVE to use Mesa Boogie power tubes all the time,
Now is the above statement about the boogies tubes true or is it just them wanting you to buy boogie tubes making them more money?

I have a matched set of TAD 6l6STRs in my Mark III and they sound great but I do notice the tubes seem to be glowing wamrer and seem hotter in the back of the amp, I definitely play with the fan plugged in now.

So is it safe to use any 6l6 tube in a boogine amp? Or for proper operation and correct tube hardness do you really have to keep using the lesser quality mesa boogie tubes

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jonarobb
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Re: Power tube replacement, on boogie amps in general

Post by jonarobb » Wed Jan 14, 2009 4:45 pm

You have to check the current draw(bias) when you replace the power tubes regardless if they're Boogie tubes or not. Mesa won't tell you about all the returns they take with their precision matched and bias rating system tubes. It's kind of run away with itself at this point.

Example being, if you call them to order tubes for say a 1979 Mark IIA. They'll tell you that the tubes for that amp are STR 415's and will cost you $350 for a matched quad. If you can't afford that then they tell you you'll have to send the chassis to them to make a "circuit modification" to handle the newer Russian and Chinese tubes. Guess what that "circuit modification" is? They adjust the bias by putting in a new resistor....

Mesa is a company out to make money like any other business. It will serve you well if you have a qualified tech put in a pot or trimmer in the bias circuit and then you can more effectively experiment with different power tubes and the tones they offer...
"Are you properly trained to use that thing?"

cisspcism
Mark I
Posts: 40
Joined: Tue Apr 29, 2008 12:39 pm
Location: Chicago

Re: Power tube replacement, on boogie amps in general

Post by cisspcism » Wed Jan 14, 2009 5:17 pm

jonarobb wrote:You have to check the current draw(bias) when you replace the power tubes regardless if they're Boogie tubes or not. Mesa won't tell you about all the returns they take with their precision matched and bias rating system tubes. It's kind of run away with itself at this point.

Example being, if you call them to order tubes for say a 1979 Mark IIA. They'll tell you that the tubes for that amp are STR 415's and will cost you $350 for a matched quad. If you can't afford that then they tell you you'll have to send the chassis to them to make a "circuit modification" to handle the newer Russian and Chinese tubes. Guess what that "circuit modification" is? They adjust the bias by putting in a new resistor....

Mesa is a company out to make money like any other business. It will serve you well if you have a qualified tech put in a pot or trimmer in the bias circuit and then you can more effectively experiment with different power tubes and the tones they offer...

But will just using any old 6l6 tubes and not worrying abut the draw harm the amp?

I know for best performance I should but will it harm the amp if I dont.
I have a soldano slo100 and Bill Sundt told me that the slo100 are bias cold that I dont have to worry about biasing the amp when swapping poqwer tubes

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