Lower or higher milli-amp "better"?

[lockbody]

If I was buying NOS 6L6s for my DC-5, all other things being equal, is there a better side of the range that will work in my amp? For example, a 20ma tube will have character a in clean and character b with dist, while the 30ma tube will have y and z.

Thanks,

 

[212Mavguy]

There is room for several different, workable answers here...

If that amp were mine I'd go ahead and have a bias pot and possibly test jacks installed. That is the best way to get the "best to your ears" NOS, vintage used, or modern production power tube tube sound out of it. I'm not the only one who can hear a difference in two different bias settings set only 3ma's apart in a 6l6 amp. You don't have to worry about voiding a warranty. Might be also a good time while it is opened up to have the tech evaluate and possible replace filter caps as well. Peace.

 

[stokes]

Simply put,the tubes that draw 20ma's will have a later breakup,the tubes that draw 30ma's will have a quicker breakup.Which is better? Only you can say,either tube will be "safe" in your amp.Personally,I like a little "edge" in my clean channel and a little "softer" distortion in my lead channel.That would seem to be a "contradictory" condition,but I set my bias at about 35-40ma's and use 5751"s in the pre amp of my MKIIC+ and my SOB and it gets me there.

 

[lockbody]

Simply put,the tubes that draw 20ma's will have a later breakup,the tubes that draw 30ma's will have a quicker breakup.Which is better? Only you can say,either tube will be "safe" in your amp.Personally,I like a little "edge" in my clean channel and a little "softer" distortion in my lead channel.That would seem to be a "contradictory" condition,but I set my bias at about 35-40ma's and use 5751"s in the pre amp of my MKIIC+ and my SOB and it gets me there.

Thanks, this is the kind of information I was looking for. I just don't care to install a bias pot and bias the amp myself, although it's certainly within my abilities to do so. I think I would like to experiment with some NOS tubes, however.

 

[stokes]

Best to do the adjustable bias mod,you get a good set of NOS tubes,you want to find the "sweet spot".I have done the mod for guys who insist on using stock Mesa and current production tubes and it is still extremely beneficial with those tubes as well.Real simple,just get a 150k-250k cermet pot and replace the appropriate resistor in the bias supply.I believe the DC-5 has an 82k in paralell with a 20 or 22k.The 82k is the one to replace.When doing this mod I use a pot that has 2x the value of the resistor thats in there.That way the bias voltage that is stock is about in the middle of the pots range,giving eneough adjustment in either direction.In your case you could use either the tubes that draw 20ma's or the ones that draw 30ma's or any other tube for that matter and dial it in.I have found that even the tubes that are graded to be "safe" and "matched"tubes that were previously used in a Mesa amp can vary up to 20ma's.So you think you are buying tubes that match what you had in there and find them to be sterile sounding,because they are 10 or more ma's colder.

 

[Tommy_G]

I bought 3 different sets of 6L6's =C= from thetubestore...17's, 21's and 27's.

The 17's and 21's are cold and brittle; the 27's are warm and delectable.

 

[stokes]

I bought 3 different sets of 6L6's =C= from thetubestore...17's, 21's and 27's.

The 17's and 21's are cold and brittle; the 27's are warm and delectable.

With an adjustable bias,they would all be "warm and delectable",the 27's could even be warmer and delectabler.

 

[212Mavguy]

+1 for Stokes. Once you have heard your amp with adjustable bias set to the output tubes' sweet spot you will most likely never be content with going back to non adjustable bias. And that sweet spot varies according to what kind of tones you desire, too.

Offers new opportunities for choosing from a much larger selection of power tubes for your personal tones. 8)