Mesa Bias Question

Beyond Black

Well-known member
When running EL34’s or KT77’s in EL34 mode on a Dual, am I supposed to use tube instead of diode, because diode runs to hot?
 
Beyond Black":1w7edx9f said:
When running EL34’s or KT77’s in EL34 mode on a Dual, am I supposed to use tube instead of diode, because diode runs to hot?

Depends on the grade you get. It'll only run hot with a much warmer grade. I put a 32 rated quad of JJ 6CA7's in a Dual Multiwatt, and it never got hotter than 36mA in any mode. They sounded damn good in it, too.. I loved that amp, but it had to be stupid loud to bring the goods. Just for reference, I had a quad of 6CA7's rated 15, and they only got as hot as 19-20mA in the same amp.

Did you buy them already? Do you have a way to check it? I know the stock 6L6's it came with were only running 19mA. Uggg….

If you haven't bought them yet, buy them from Eurotubes, and let them know what they're for.. They'll send you a grade that will be spot-on. They've never let me down in 15 years.
 
napalmdeath":2up6phth said:
Beyond Black":2up6phth said:
When running EL34’s or KT77’s in EL34 mode on a Dual, am I supposed to use tube instead of diode, because diode runs to hot?

Depends on the grade you get. It'll only run hot with a much warmer grade. I put a 32 rated quad of JJ 6CA7's in a Dual Multiwatt, and it never got hotter than 36mA in any mode. They sounded damn good in it, too.. I loved that amp, but it had to be stupid loud to bring the goods. Just for reference, I had a quad of 6CA7's rated 15, and they only got as hot as 19-20mA in the same amp.

Did you buy them already? Do you have a way to check it? I know the stock 6L6's it came with were only running 19mA. Uggg….

If you haven't bought them yet, buy them from Eurotubes, and let them know what they're for.. They'll send you a grade that will be spot-on. They've never let me down in 15 years.
That’s what I did! :thumbsup: Bought a quad of KT77’s from Eurotubes and told them they were for a Dual. On one side they say 6.0, the other side says 38 (on all of them). Doesn’t the Dual run at like 50 in EL34, Diode and Bold settings? It gets quite a bit louder like that compared to 6L6 setting.
 
Beyond Black":y48b7bmq said:
napalmdeath":y48b7bmq said:
Beyond Black":y48b7bmq said:
When running EL34’s or KT77’s in EL34 mode on a Dual, am I supposed to use tube instead of diode, because diode runs to hot?

Depends on the grade you get. It'll only run hot with a much warmer grade. I put a 32 rated quad of JJ 6CA7's in a Dual Multiwatt, and it never got hotter than 36mA in any mode. They sounded damn good in it, too.. I loved that amp, but it had to be stupid loud to bring the goods. Just for reference, I had a quad of 6CA7's rated 15, and they only got as hot as 19-20mA in the same amp.

Did you buy them already? Do you have a way to check it? I know the stock 6L6's it came with were only running 19mA. Uggg….

If you haven't bought them yet, buy them from Eurotubes, and let them know what they're for.. They'll send you a grade that will be spot-on. They've never let me down in 15 years.
That’s what I did! :thumbsup: Bought a quad of KT77’s from Eurotubes and told them they were for a Dual. On one side they say 6.0, the other side says 38 (on all of them). Doesn’t the Dual run at like 50 in EL34, Diode and Bold settings? It gets quite a bit louder like that compared to 6L6 setting.

You're in good hands. Should sound killer!
 
napalmdeath":3ojqhxc1 said:
Beyond Black":3ojqhxc1 said:
napalmdeath":3ojqhxc1 said:
Beyond Black":3ojqhxc1 said:
When running EL34’s or KT77’s in EL34 mode on a Dual, am I supposed to use tube instead of diode, because diode runs to hot?

Depends on the grade you get. It'll only run hot with a much warmer grade. I put a 32 rated quad of JJ 6CA7's in a Dual Multiwatt, and it never got hotter than 36mA in any mode. They sounded damn good in it, too.. I loved that amp, but it had to be stupid loud to bring the goods. Just for reference, I had a quad of 6CA7's rated 15, and they only got as hot as 19-20mA in the same amp.

Did you buy them already? Do you have a way to check it? I know the stock 6L6's it came with were only running 19mA. Uggg….

If you haven't bought them yet, buy them from Eurotubes, and let them know what they're for.. They'll send you a grade that will be spot-on. They've never let me down in 15 years.
That’s what I did! :thumbsup: Bought a quad of KT77’s from Eurotubes and told them they were for a Dual. On one side they say 6.0, the other side says 38 (on all of them). Doesn’t the Dual run at like 50 in EL34, Diode and Bold settings? It gets quite a bit louder like that compared to 6L6 setting.

You're in good hands. Should sound killer!
It sounds totally killer, but I just now blew a fuse. I was playing, reached around and switched from silicone to tube, and the fuse blew. I’ve done that before with the 6L6’s and coke bottles without a problem, now with the KT77’s and GZ34’s this happened. What gives?
 
Beyond Black":iphvxxcv said:
napalmdeath":iphvxxcv said:
Beyond Black":iphvxxcv said:
When running EL34’s or KT77’s in EL34 mode on a Dual, am I supposed to use tube instead of diode, because diode runs to hot?

Depends on the grade you get. It'll only run hot with a much warmer grade. I put a 32 rated quad of JJ 6CA7's in a Dual Multiwatt, and it never got hotter than 36mA in any mode. They sounded damn good in it, too.. I loved that amp, but it had to be stupid loud to bring the goods. Just for reference, I had a quad of 6CA7's rated 15, and they only got as hot as 19-20mA in the same amp.

Did you buy them already? Do you have a way to check it? I know the stock 6L6's it came with were only running 19mA. Uggg….

If you haven't bought them yet, buy them from Eurotubes, and let them know what they're for.. They'll send you a grade that will be spot-on. They've never let me down in 15 years.
That’s what I did! :thumbsup: Bought a quad of KT77’s from Eurotubes and told them they were for a Dual. On one side they say 6.0, the other side says 38 (on all of them). Doesn’t the Dual run at like 50 in EL34, Diode and Bold settings? It gets quite a bit louder like that compared to 6L6 setting.
Do you have a bias tool/meter? I bought one years back that plugs in to my multimeter. Tells me what ma my tubes are running. My F Triple, the Mesa 6L6s were running at around 50ma. A little hot for me...but within range. I usually find a sweet spot between 30-40ma with any amp. This one measures at 485v so I set the bias to 39, sounds better now...not as harsh at higher volume.

How did I re-set the bias you ask? This one had a bias mod done...by a previous owner at some point. I find it pretty darn useful I must say.
:rock:
 
Beyond Black":2j2rb0c3 said:
napalmdeath":2j2rb0c3 said:
Beyond Black":2j2rb0c3 said:
napalmdeath":2j2rb0c3 said:
Beyond Black":2j2rb0c3 said:
When running EL34’s or KT77’s in EL34 mode on a Dual, am I supposed to use tube instead of diode, because diode runs to hot?

Depends on the grade you get. It'll only run hot with a much warmer grade. I put a 32 rated quad of JJ 6CA7's in a Dual Multiwatt, and it never got hotter than 36mA in any mode. They sounded damn good in it, too.. I loved that amp, but it had to be stupid loud to bring the goods. Just for reference, I had a quad of 6CA7's rated 15, and they only got as hot as 19-20mA in the same amp.

Did you buy them already? Do you have a way to check it? I know the stock 6L6's it came with were only running 19mA. Uggg….

If you haven't bought them yet, buy them from Eurotubes, and let them know what they're for.. They'll send you a grade that will be spot-on. They've never let me down in 15 years.
That’s what I did! :thumbsup: Bought a quad of KT77’s from Eurotubes and told them they were for a Dual. On one side they say 6.0, the other side says 38 (on all of them). Doesn’t the Dual run at like 50 in EL34, Diode and Bold settings? It gets quite a bit louder like that compared to 6L6 setting.

You're in good hands. Should sound killer!
It sounds totally killer, but I just now blew a fuse. I was playing, reached around and switched from silicone to tube, and the fuse blew. I’ve done that before with the 6L6’s and coke bottles without a problem, now with the KT77’s and GZ34’s this happened. What gives?
Those are new from Eurotubes? Blown fuse? Probably got a bad tube...it happens. I bought a quad of KT88s from the Tube Depot and one was bad...measured at 14ma while the rest biased up just fine. I would put the 6L6 back in, set it like you had it before with a new fuse and see if it holds up. Chances are one of the new tubes are bad; or they are just too damn hot. That or it could be a transformer problem but since it coincides with the tube change, probably just tubes.
 
Racerxrated":2owtbqsz said:
Beyond Black":2owtbqsz said:
napalmdeath":2owtbqsz said:
Beyond Black":2owtbqsz said:
napalmdeath":2owtbqsz said:
Beyond Black":2owtbqsz said:
When running EL34’s or KT77’s in EL34 mode on a Dual, am I supposed to use tube instead of diode, because diode runs to hot?

Depends on the grade you get. It'll only run hot with a much warmer grade. I put a 32 rated quad of JJ 6CA7's in a Dual Multiwatt, and it never got hotter than 36mA in any mode. They sounded damn good in it, too.. I loved that amp, but it had to be stupid loud to bring the goods. Just for reference, I had a quad of 6CA7's rated 15, and they only got as hot as 19-20mA in the same amp.

Did you buy them already? Do you have a way to check it? I know the stock 6L6's it came with were only running 19mA. Uggg….

If you haven't bought them yet, buy them from Eurotubes, and let them know what they're for.. They'll send you a grade that will be spot-on. They've never let me down in 15 years.
That’s what I did! :thumbsup: Bought a quad of KT77’s from Eurotubes and told them they were for a Dual. On one side they say 6.0, the other side says 38 (on all of them). Doesn’t the Dual run at like 50 in EL34, Diode and Bold settings? It gets quite a bit louder like that compared to 6L6 setting.

You're in good hands. Should sound killer!
It sounds totally killer, but I just now blew a fuse. I was playing, reached around and switched from silicone to tube, and the fuse blew. I’ve done that before with the 6L6’s and coke bottles without a problem, now with the KT77’s and GZ34’s this happened. What gives?
Those are new from Eurotubes? Blown fuse? Probably got a bad tube...it happens. I bought a quad of KT88s from the Tube Depot and one was bad...measured at 14ma while the rest biased up just fine. I would put the 6L6 back in, set it like you had it before with a new fuse and see if it holds up. Chances are one of the new tubes are bad; or they are just too damn hot. That or it could be a transformer problem but since it coincides with the tube change, probably just tubes.
Sounds good, I’ll do that. I’ve been playing it with these new tubes for a few days now in diode, and it’s been fine. This just happened tonight when I switched to tube. Wouldn’t a bad tube make itself known before then?
 
Beyond Black":2ythnimy said:
Racerxrated":2ythnimy said:
Beyond Black":2ythnimy said:
napalmdeath":2ythnimy said:
Beyond Black":2ythnimy said:
napalmdeath":2ythnimy said:
Beyond Black":2ythnimy said:
When running EL34’s or KT77’s in EL34 mode on a Dual, am I supposed to use tube instead of diode, because diode runs to hot?

Depends on the grade you get. It'll only run hot with a much warmer grade. I put a 32 rated quad of JJ 6CA7's in a Dual Multiwatt, and it never got hotter than 36mA in any mode. They sounded damn good in it, too.. I loved that amp, but it had to be stupid loud to bring the goods. Just for reference, I had a quad of 6CA7's rated 15, and they only got as hot as 19-20mA in the same amp.

Did you buy them already? Do you have a way to check it? I know the stock 6L6's it came with were only running 19mA. Uggg….

If you haven't bought them yet, buy them from Eurotubes, and let them know what they're for.. They'll send you a grade that will be spot-on. They've never let me down in 15 years.
That’s what I did! :thumbsup: Bought a quad of KT77’s from Eurotubes and told them they were for a Dual. On one side they say 6.0, the other side says 38 (on all of them). Doesn’t the Dual run at like 50 in EL34, Diode and Bold settings? It gets quite a bit louder like that compared to 6L6 setting.

You're in good hands. Should sound killer!
It sounds totally killer, but I just now blew a fuse. I was playing, reached around and switched from silicone to tube, and the fuse blew. I’ve done that before with the 6L6’s and coke bottles without a problem, now with the KT77’s and GZ34’s this happened. What gives?
Those are new from Eurotubes? Blown fuse? Probably got a bad tube...it happens. I bought a quad of KT88s from the Tube Depot and one was bad...measured at 14ma while the rest biased up just fine. I would put the 6L6 back in, set it like you had it before with a new fuse and see if it holds up. Chances are one of the new tubes are bad; or they are just too damn hot. That or it could be a transformer problem but since it coincides with the tube change, probably just tubes.
Sounds good, I’ll do that. I’ve been playing it with these new tubes for a few days now in diode, and it’s been fine. This just happened tonight when I switched to tube. Wouldn’t a bad tube make itself known before then?
Maybe...the only experiences I had with blown fuses were always a bad power tube; the one exception being a Ceriatone Fortin mod that the PT went south in. I had gigged both Fri/Sat with it; and on Sunday I plugged in and an hour into playing a fuse goes.
When I got the Monomyth back after 2 days of playing POOF! Fuse goes. Put a new one in, played again for a bit when I noticed one of my Winged Cs started to glow differently so I immediately shut it off. Put that 34 in my tube tester and it was in the fail zone. Put another pair in and no problems since.

Really no telling when a tube is going to go...when its happened to me the amp always worked great up and until the fuse failed.
Good luck!
 
yeah man I've had several brand new tubes go out on me recently. I had one in my 2204 before it was modded go out when I tried to crank it to get some power amp breakup. It was my first Ceriatone and I put Classictone transformers in it so I was kinda freaking out. I didnt have any replacement fuses either so I had to wait a couple days before I got one. I switched tubes to an old pair I had laying around and switched the fuse. Played great. Put the new tubes back in and blew the fuse again. I had played the amp for over a week with no issues prior. Had a similar issue with some TAD 6L6's in my Orthos. Pretty much a similar scenario except different fuse(that I didnt have extras) than my 2204. I played for about 30 minutes then I got a bunch of popping then a blown fuse.

One thing this did teach me is dont buy Tubes from places that wont let you return them. Mojotone were awesome handling it. ZZounds was basically saying tough shit. I need to check out Eurotubes. I have a Molecular being shipped this week minus the tubes so I need to get a set.
 
LP Freak":3fxjmzq3 said:
Jeff, maybe it’s your rectifier tube
Those are also new. I’m gonna put all the old ones back in, then reintroduce the rec tubes first, then the power tubes, see what happens. Paul’s got a tube tester, so I’ll check that out too. When tested, the numbers should match the numbers Eurotubes wrote on the tube, right?
 
ClintN667":31vwizq8 said:
yeah man I've had several brand new tubes go out on me recently. I had one in my 2204 before it was modded go out when I tried to crank it to get some power amp breakup. It was my first Ceriatone and I put Classictone transformers in it so I was kinda freaking out. I didnt have any replacement fuses either so I had to wait a couple days before I got one. I switched tubes to an old pair I had laying around and switched the fuse. Played great. Put the new tubes back in and blew the fuse again. I had played the amp for over a week with no issues prior. Had a similar issue with some TAD 6L6's in my Orthos. Pretty much a similar scenario except different fuse(that I didnt have extras) than my 2204. I played for about 30 minutes then I got a bunch of popping then a blown fuse.

One thing this did teach me is dont buy Tubes from places that wont let you return them. Mojotone were awesome handling it. ZZounds was basically saying tough shit. I need to check out Eurotubes. I have a Molecular being shipped this week minus the tubes so I need to get a set.
My fuse blowing when I switched from diode to tube rectification led me to believe it was something other than a tube. Like, you have to switch to standby before switching. But, I’ve switched it many times with the old tubes without a problem. I’m sure it’s a bad tube. Hope Eurotubes will replace it.
 
Beyond Black":2ugq56ha said:
LP Freak":2ugq56ha said:
Jeff, maybe it’s your rectifier tube
Those are also new. I’m gonna put all the old ones back in, then reintroduce the rec tubes first, then the power tubes, see what happens. Paul’s got a tube tester, so I’ll check that out too. When tested, the numbers should match the numbers Eurotubes wrote on the tube, right?
New doesn’t mean a thing. As you know they can go bad in 5 minutes or 5 years.
 
LP Freak":1ygjcyhl said:
Beyond Black":1ygjcyhl said:
LP Freak":1ygjcyhl said:
Jeff, maybe it’s your rectifier tube
Those are also new. I’m gonna put all the old ones back in, then reintroduce the rec tubes first, then the power tubes, see what happens. Paul’s got a tube tester, so I’ll check that out too. When tested, the numbers should match the numbers Eurotubes wrote on the tube, right?
New doesn’t mean a thing. As you know they can go bad in 5 minutes or 5 years.
Yep. No telling with new tubes...failure rate these days is silly. Most places will replace though. For yrs I've been trying to buy used vintage tubes, they seem to last forever compared to new, even when they are used.

OP, if you put the 6L6 back in and switch between diode/tube and the fuse stays intact I think you can safely say it's a power tube.
 
Racerxrated":35pan6fp said:
LP Freak":35pan6fp said:
Beyond Black":35pan6fp said:
LP Freak":35pan6fp said:
Jeff, maybe it’s your rectifier tube
Those are also new. I’m gonna put all the old ones back in, then reintroduce the rec tubes first, then the power tubes, see what happens. Paul’s got a tube tester, so I’ll check that out too. When tested, the numbers should match the numbers Eurotubes wrote on the tube, right?
New doesn’t mean a thing. As you know they can go bad in 5 minutes or 5 years.
Yep. No telling with new tubes...failure rate these days is silly. Most places will replace though. For yrs I've been trying to buy used vintage tubes, they seem to last forever compared to new, even when they are used.

OP, if you put the 6L6 back in and switch between diode/tube and the fuse stays intact I think you can safely say it's a power tube.
Sounds good, that’s what I’ll do. Thanks guy, appreciate it! I love this place. :thumbsup:
 
Ok, so I put in a new fuse, all the old tubes, and switched back and forth between diode and tube, all good.
Put in the new rectifier tubes, switched back and forth again, all good.
Put in the new KT-77’s, switched from tube to diode (this is when the fuse blew last time), all good.
So I’ve got all the new tubes installed, switched tube to diode, back and forth, multiple times without blowing a fuse, and the amp sounds killer. Does this mean it’s fine? Was the fuse blowing just a freak thing? :confused:
 
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