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Running different tubes

fauxpas

Member
2007-11-15 3:09 pm
Runnung different tubes

Is there any danger in running different branded tubes in my amp? If they are all 6L6 tubes, should it be OK?

I should explain. I received a couple of tubes (RCA) and want to hear what they sound like. Can I run them on one side of my amp?
 
Re: Runnung different tubes

fauxpas said:


I should explain. I received a couple of tubes (RCA) and want to hear what they sound like. Can I run them on one side of my amp?


Did someone call? :D

In 6L6`s there were low power types 6L6 metal or 6L6G (ST glass bottle) that only have a plate dissipation power of around 19 watts. Then there was a high powered version called 6L6GC, common in guitar amp applications good for about 30 watts dissipation. If you are planning to use 6L6GC`s you ought not run any risks.

Depending on how your amp is wired to bias the output tubes you may be OK (self bias) or can adjust the amp to use the lower power 6L6 types (adjustable fixed bias). I suspect your RCA`s may be the low power type if they have the ST shoulder style glass envelope.

I think you mentioned that your amp came with 6P3P`s. In that case plug in your 6L6`s and keep a close eye on them in a darkened room. If the plate (the outermost mettalic structure inside the envelope) shows any dull glowing red or orange areas shut down immediately and do not use these tubes without further consultation. When I say glow, I am not referring to the normal filament glow in the center which all these tubes have.
 

fauxpas

Member
2007-11-15 3:09 pm
They are all 6L6GC tubes. The RCAs differ by having the getter on the sides, where the mesa tubes the getter is on the top...

I did a side by side run. The RCA tubes on the left and the mesas on the right... The old RCAs sound pretty good.

Some have suggested in these forums that preamp tubes will likely have more affect on the sound than the power tubes. We'll see as I have a russian pair coming to replace the chinese ones.

Thanks...