JJ 6l6 GC without biasing the amp?
- Thread starter m@tstr@t
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jbird
Well-known member
Mesa amps are fixed bias, no bias needed! But you should state to a reputable tube dealer which amp you are ordering tubes for! They should give you a matched set of tubes that are within a specified range suitable for your Mesa. Did you order from a reputable dealer and state what amp these tubes are for?
Shep
Well-known member
they have to be baised for the mesa REcto amp or they won't last as long..
disassembled
Well-known member
Shep said:
Whoaaaaaa!!!!!! Not so fast there bud. This is not a true statement. You can place just about any matched set of tubes (6L6 or EL34) in your amp and they will be in safe operating mode and last as long as if they were graded to a specific amp. The Rectos are biased a bit colder to extend tube life, to give the amp a certain tone or feel. and to prevent premature tube failure. Most amp manufacturers do this as a compromise and since most people like the tone of their Mesa amp it would be safe to assume they picked a decent window to operate in.
The deal about getting tubes that draw a certain amount of current is that they will give a certain tone you are after (IE more grind, headroom, warmth, early breakup, etc). What this equates to usually is you want the warmest set of tubes to get you out of crossover distortion territory but you really can't get this with the 6L6 setting on a rectifier without modding the Bias circuit. If you read the link below it states that if you get a colder set of 6L6's and run the amp in EL34 mode it puts the tubes where they should be according to Bob at Eurotubes to have a warm responsive power section with as little crossover distortion as possible.
http://eurotubes.com/euro-n.htm
What you need to be worried about is if the tubes are matched well or not. Matched tubes draw similar amounts of current. Unmatched sets draw different amounts of current and can add excess hum to the output section and affect tone. Without a Bias meter from weber or alessandro you can know for sure if the tubes are matched well for sure but, heck, if it sounds good to you then you shouldn't worry about it.
Don't believe everything you read. Do your own research and come to your own conclusions. The info is out there.
jbird
Well-known member
m@tstr@t said:
Well, good if you mentioned what amp they are going in!
jbird
Well-known member
No, not all are the same! Which is why you should state ( to the dealer) what they're going in!
jbird
Well-known member
Who's support center?
disassembled
Well-known member
The only way to be sure is to measure how much current the tubes draw. My advice is to invest in a unit like the BR-2 octal:
https://weberspeakerscom.secure.powweb.com/biasrite/br_page.htm
That way you can see if you are safe or not. It's hard to rely on people sometimes.
If you are not able to measure the tubes on your amp then I strongly suggest that you DO NOT switch to the EL34 setting.
https://weberspeakerscom.secure.powweb.com/biasrite/br_page.htm
That way you can see if you are safe or not. It's hard to rely on people sometimes.
If you are not able to measure the tubes on your amp then I strongly suggest that you DO NOT switch to the EL34 setting.
disassembled
Well-known member
JJ tubes vary in current draw. That is why when buying from someone you tell them what you are after and hopefully they will handselect and test something for your application. I hope if you are retubing one thing you are doing the rest of the amp as well(ie Preamp tubes and Rectifier). It would be like changing 2 out of 4 brakes on your car. Yeah sure, it will stop better than before but those 3rd and 4th brakes will probably help a bit more. Then again you may not notice. I guess it depends on how in tune you are with your equipment.
jbird
Well-known member
Reference www.eurotubes.com.
disassembled
Well-known member
Well, safe range is stock in the 6L6 position. Anything else, well you're on your own. It is up to your ears and wallet in the end. If you run the tubes hotter they will not last as long (meaning they will lose their tone faster) and if ran too hot you could risk damaging some things. This is the beauty of a tube amp, kinda like a stick shift where you are in total control. Go ahead drive it nice and easy the drive train can last a while OR drive it like an ******* and replace everything in 10 thousand miles. Atleast you will get a good rep if you drive like an ******* 
It's ok to experiment as long as you know the consequences. If you are a warranty fearing owner then I do not recommend messing with the Bias.
All amps are different too, like my old PV 5150 I ran at like 45 ma's most of the time to get a usable clean channel. My Triple XXX was ran at 40 Ma's to give it more volume and to smoothen out the gain channels. The measurements don't really tell you much unless you know plate voltage and the max dissipation of heat your tubes can handle.
Maybe you are misunderstanding the point of delving into the adjustment of the bias switch. I am not talking from an operational standpoint but more of a PERSONAL taste of tone. You may hate the way it sounds warmed up because it may take some of the edge off. Bias is more like a fine tuning, in all honestly it is just like setting the idle of an engine. I think for now you should just stick with what you have and run the amp in the 6L6 setting. Besides, I am running out of car analagies
It's ok to experiment as long as you know the consequences. If you are a warranty fearing owner then I do not recommend messing with the Bias.
All amps are different too, like my old PV 5150 I ran at like 45 ma's most of the time to get a usable clean channel. My Triple XXX was ran at 40 Ma's to give it more volume and to smoothen out the gain channels. The measurements don't really tell you much unless you know plate voltage and the max dissipation of heat your tubes can handle.
Maybe you are misunderstanding the point of delving into the adjustment of the bias switch. I am not talking from an operational standpoint but more of a PERSONAL taste of tone. You may hate the way it sounds warmed up because it may take some of the edge off. Bias is more like a fine tuning, in all honestly it is just like setting the idle of an engine. I think for now you should just stick with what you have and run the amp in the 6L6 setting. Besides, I am running out of car analagies
Most of the JJ 6L6GC's have a very soft current draw. They tend not to draw huge amounts of natural plate current, unless you get someone to pick some out for you that do. So, you should be fine.
Also, when biasing an amplifier, one should take into account what the Output Transformer is able to handle. A Mesa Recto isn't going to be able to handle MASS amounts of current. Sure, Mesa's run a lot colder, but that is by design.
As it has been stated earlier, it all boils down to what tones you like hearing. It's your amp! Do what you want to do with it.
Dale
Also, when biasing an amplifier, one should take into account what the Output Transformer is able to handle. A Mesa Recto isn't going to be able to handle MASS amounts of current. Sure, Mesa's run a lot colder, but that is by design.
As it has been stated earlier, it all boils down to what tones you like hearing. It's your amp! Do what you want to do with it.
Dale
Shep
Well-known member
disassembled said:
..i just find running them at the wrong set bais makes them sound really bad and in some cases burns up the tube quicker than wat the right bais would ...
