Bias blunders

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Bottle Rocket
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Bias blunders

Post by Hockeydog » Wed Aug 05, 2015 10:57 am

I found an old thread and revived it, but it was on the Lonestar page - re-posting in the correct thread.

I just joined the Electra Dyne party as of last night ! I am bringing this thread back to the top as it relates the issue I discovered when I got the amp home. The bias switch was set to EL34 but the am has 6L6's in it. When I bought the amp I played it for maybe 20 minutes that way. On top of that one of the 6L6's had actually fallen out and was laying broken on the bottom of the combo. It sounded really good when I played it and the seller was motivated to sell so based on the deal I got I went ahead and bought it.
I didn't smell anything getting overly hot - but my question is what long term damage could be done? I should have given it the once over before playing it but it was one of those situations where the guy had the amp all ready to be played with guitar plugged in when I got there- still no excuses on my end.

I have two follow up questions.
As I only have 3 tubes at the moment, which tube would I pull out - or need to have in place - to run at 45watts?
If I don't go with Boogie tubes, what do I need to look for in values in a 6L6. I've not been down this road before with non-bias amps.

Even despite the above, the amp sounds really good. Like a 2x12 combo in a 1x12 ( 27" model ).

Thanks for any help/advice/opinions !!

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Re: Bias blunders

Post by screamingdaisy » Wed Aug 05, 2015 4:02 pm

To the best of my knowledge, having the tubes on the wrong bias won't hurt the amp but may damage the actual tubes. Hopefully someone will correct me if I'm wrong.

In 45w mode it's the middle pair of tubes that are on.

If you tell any reputable tube vendor you need tubes for a Mesa they'll select the correct grade for you. Different vendors use different labelling systems so your best bet is to just ask them.

The stock Mesa 6L6s are Ruby/TAD 6L6GC STR. So far as current production 6L6s go they're hard to beat, and Mesa tubes have a six month warranty.
Ignore the hype and trust your ears. Play more, buy less = better tone.

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