jehu
Active member
what are the effects on the amp when this happens?!? i had 6L6's & somehow i THINK i failed to have it on the right bias setting. what does that do to your amp?!?
thanks
thanks
jehu said:what are the effects on the amp when this happens?!? i had 6L6's & somehow i THINK i failed to have it on the right bias setting. what does that do to your amp?!?
thanks
disassembled said:Mesa amps are biased in a fairly safe range so running in the EL34 was probably a nice "warm" setting for the 6L6's. Like siggy said no harm no foul so you should be good to go. If I were you I would get a bias meter to make sure the tubes you are using are matched and are operating at the proper current levels.
Greg
FPFL said:siggy says, "up to where the bias should be"
Should be? I had no idea it was wrong from the factory. Bias is just like tone, the only wrong settings are either -
1. The ones you don't like
2. The ones that blow your tubes
Everything else is tube salesman talk. I love the now common thinking that Mesa are "too cold" from the factory. Hysterical. One of the most popular amp companies in the world just can't get it right! Thats why they overcompensate by nailing it to a certain setting - they don't believe in themselves. Ha!
I love that they are set and if you buy tubes from them you'll know they are a good match. Of course you can buy tubes from others too. It isn't like a computer company made it and only lets their own stuff in.
-P
FPFL said:siggy says, "up to where the bias should be"
Should be? I had no idea it was wrong from the factory. Bias is just like tone, the only wrong settings are either -
1. The ones you don't like
2. The ones that blow your tubes
Everything else is tube salesman talk. I love the now common thinking that Mesa are "too cold" from the factory. Hysterical. One of the most popular amp companies in the world just can't get it right! Thats why they overcompensate by nailing it to a certain setting - they don't believe in themselves. Ha!
I love that they are set and if you buy tubes from them you'll know they are a good match. Of course you can buy tubes from others too. It isn't like a computer company made it and only lets their own stuff in.
-P
I'll accept the above post! Most of it anyways? What gets me is the disregard towards putting unknown, old tubes in; "Like from the late 60's probably, & well used"! And now someone's worried about the well being of they're amp? I tell you what, go get a meter, and start poking around in there! With the disrespect you have towards an instrument made to last forever, maybe you'll get a little jolt of reality! How 'bout not treating your amplifier like a toy! :roll:jehu said:nothing blew. and the 6L6's were definitely old, like from the late 60's probably & well used. thanks for putting my mind at ease Siggy.
Boogiebabies said:FPFL said:siggy says, "up to where the bias should be"
Should be? I had no idea it was wrong from the factory. Bias is just like tone, the only wrong settings are either -
1. The ones you don't like
2. The ones that blow your tubes
Everything else is tube salesman talk. I love the now common thinking that Mesa are "too cold" from the factory. Hysterical. One of the most popular amp companies in the world just can't get it right! Thats why they overcompensate by nailing it to a certain setting - they don't believe in themselves. Ha!
I love that they are set and if you buy tubes from them you'll know they are a good match. Of course you can buy tubes from others too. It isn't like a computer company made it and only lets their own stuff in.
-P
I agree about the tube salesman pitch, but Mesa's from the factory are shipped with the bias set to -51 volts. Since this value does not change, it is the tube that draws whatever bias it can from -51 volts. Most Mesa tubes will draw between 17-25ma of bias. In laymans terms this is considered cold, but the amps are loud with good headroom. Settings of 11 to 17ma will produce a crossover distortion, but this is not necessarily a bad thing. If you run the power amp open the rise in current will eventually reach a point in plate dissipation thats not so grainy. Mesa's are designed around this principle. A set of Mesa STR-415's only draws -22ma at -51 volts at 483 plate volts. A GT 6L6GE # 6 draws -22ma. You can call them cold, but they sound incredible. Even adding a bias pot to a Rectifier, IMO is a waste of time. Once you get to -40ma the amps turn to mush. You get to the point where you realize that the biasing of a Mesa at 75% MPD it sounds like a blanket was thrown over the cabinet. I have enough amps that I can sit around all day and play with the tones from different bias settings, but it is just an eventual realization that a good Mesa or GT tube will do the trick. If you want a faster interaction with the power amp, use a Mesa Grey, Blue or White. A GT, especially the American made, a 3-5 will warm the amp up a bit. You have to account for the fact that not every tube amp owner has the ability to take a plate voltage reading and adjust a bias pot. There is absolutely a reason that Mesa's ship with colder tubes. If you sell 10,000 DR's in a year, it's cheaper to replace a tube than a $150 output transformer. The moral is, you can spend a week trying bias settings, or you can just pop some tubes in and play. Once you let the bias bug, you spend more time thinling about every other detail except playing. My method is to leave the Mesa's at a factory bias and use tubes that get me between -20 to -35ma for Simul's and Rectifiers. For my adjustable amps, I never go over 50 % MPD. 75% just drops your headroom and compresses way too quick. Mesa's are about preamp gain and the power amps are just an extention to amplify it. Altering the power section to the point where you leave too little room left for your tube to blossom, you're basically making your amp sound like a dark, flubby amp with a side of suck. I can attest that if you run a tube in a DR at -17ma, if you run with the loop master on and raise the master volume while lowering your preamp output, a cold tube will still offer you sustain and a very pleasant feedback.
Just remember if your a Simul owner, the outer tubes draw much hotter, just like the current Road Kings so you may want to find an EL-34 that does not run too hot. A green or blue would get you within the ballpark where you want to be.
Restless Rocks said:I can only be thankful and humbled that Randall Smith came to the realization (or revelation), that in designing guitar amplifiers worthy of the worlds most competant and innovative musicians, would also have to make them childproof. Does John Pettruci worry most about how many milliamps of current his tubes are drawing or if his pick is still sharp, or either?
disassembled said:Restless Rocks said:I can only be thankful and humbled that Randall Smith came to the realization (or revelation), that in designing guitar amplifiers worthy of the worlds most competant and innovative musicians, would also have to make them childproof. Does John Pettruci worry most about how many milliamps of current his tubes are drawing or if his pick is still sharp, or either?
There are many manufacturers that share the same view as Mr Smith. I used to be an mA junkie (i had to rebias everything because I was told it would sound best that way) but to be honest the only amp that I felt ever benefitted from it was a Peavey Triple XXX head which gained some volume but the tone remained similar to what it was when I first got it.
I still like to tinker and still am curious as to what the % of MPD the tubes are running at but I no longer am stuck on the mindset that it HAS to be at this number or that number. Part of the fun of tube amps for me is the fact that this maintenance affects the longevity and performance of the amp (kind of like tuning a car for max power, gas mileage, and drivability, etc to get the most out of it) but I would not recommend the masses dive into their favorite tube amp since the risk is pretty great for personal injury and IMO isn't worth the small gains you possibly might incur.
These topics usually have firm believers on 1 side or the other and those that are stuck in the middle that listen to the first credible source they encounter (either their favorite tech, Mesa rep, tube distributor, etc) without even researching any of the facts before they get diahrrea of the keyboard and spread misinformation to countless people.
The fact of the matter is: if you want to run your tubes at 75% of MPD then go ahead if it keeps you happy. There's nothing wrong with it as long as you like it. Finding the right tone is a journey that is never ending for some so experimentation is a must in some cases.
Just my .02 cents
Greg
siggy14 said:Some what true on your statements.
But i disagree about the bias at 40 will not sound good. I have a set of tubes in my rackrecto running in EL34 mode that are at about 40 to 45 MA and the amp sounds great! Better then any recto ever did when the bias was to low.
I don't see what can be "Some What True" about an opinion. If it was a fact, then I would be lying. This is basically another " Chasing the Dragon" thread on biasing. Now I personally like Bob at Eurotubes, but even having a quad of # 26 6L6's draw -40ma in EL34 mode does not equate to the fact that your amp will not have crossover distortion. Just because the bias is where someone thinks it should be does not guarantee anything. The fact is that your can bias out a certain degree of notch, but you may never truly eliminate it in a Class A/B power section, regardless of your % of MPD. In Class A/B amplifier designs the negative feedback loop has been used to cover up, or mask crossover distortion.
Some people would not know crossover distortion if it was sleeping in their bed with them. Even if you bias using a scope, you can eliminate, or almost eliminate crossover distortion, but you may find yourself running 92% MPD.
There are many opinions, misnomers and just plain untruths about biasing. You can ask 10 amp techs and get 12 different answers.
For tube amp owners who do not understand the entire principal, they are at the mercy of opinions and varying ideals. This is where the bias debate gets people in trouble. If you tell someone your intrpretation on bias, it may be right, or it may be wrong and cause damage. In my previous post I gave a safe opinion to everyone who wants to have a good sounding amp without the fear of damage and does not want to chase the " Dragon" of amplifier biasing.
jbird said:I'll accept the above post! Most of it anyways? What gets me is the disregard towards putting unknown, old tubes in; "Like from the late 60's probably, & well used"! And now someone's worried about the well being of they're amp? I tell you what, go get a meter, and start poking around in there! With the disrespect you have towards an instrument made to last forever, maybe you'll get a little jolt of reality! How 'bout not treating your amplifier like a toy! :roll:jehu said:nothing blew. and the 6L6's were definitely old, like from the late 60's probably & well used. thanks for putting my mind at ease Siggy.
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