Bias on a Mesa Mark series

[BesaMoogie]

T

Thanks for the post. Ya, right now I'm running green 6l6's in the outer slots and grey in the inner slots. That's what Mike B recommended for those tubes when I got the amp serviced. I also got some yellow code 6l6's and more grey code tubes that I'll use when it's time to change them out.

Brings me to another question, how often do you change your power tubes? because I've had mine in the IV for a good 5 years now and they still seem to be running strong.

The official stating of Mesa is to use red or yellow labeled tubes in the outer sockets. But I guess Mike B knows his stuff.

 

[anomaly]

T

The official stating of Mesa is to use red or yellow labeled tubes in the outer sockets. But I guess Mike B knows his stuff.

Ya, he does. These tubes sound really good too, and they're just the cheap Mesa labeled ones, str440's. I think they're relabeled JJ's, correct me if i'm wrong. For some reason they don't sound like JJ's though. I've got some JJ's that I got for a Peavey VTM a while back, they must be 15 years old now but they have little use on them and they sound like they're hotter than typical Mesa tubes.

 

[GJgo]

Like I said, the IV and VII have relatively cold Class A slots which is why going up to GRN is generally speaking fine.

Mesa regularly ships Simul amps with the same color in all 4 slots, which to me makes no sense. Seems lazy.

The STR440s are Chinese. The STR 445 are JJ. (The new STR448 Redbase are TAD, which are a 415 copy).

Generally speaking, JJ 6L6 are VERY cold. it's takes quite a bit of work to find a set that's hotter than Mesa YEL. Although, in the last couple years it would seem that production is putting out some hotter tubes.

At the end of the day, the correct answer is always to test for your amp! For example, while most of my C+ A/B have been good to go with GRN, I have one that YEL is pushing 70%. Thee is definitely variance in the IIs and IIIs. (Though I've never seen significant variance in the Rectos.)

 

[BesaMoogie]

Like I said, the IV and VII have relatively cold Class A slots which is why going up to GRN is generally speaking fine.

Mesa regularly ships Simul amps with the same color in all 4 slots, which to me makes no sense. Seems lazy.

The STR440s are Chinese. The STR 445 are JJ. (The new STR448 Redbase are TAD, which are a 415 copy).

Generally speaking, JJ 6L6 are VERY cold. it's takes quite a bit of work to find a set that's hotter than Mesa YEL. Although, in the last couple years it would seem that production is putting out some hotter tubes.

At the end of the day, the correct answer is always to test for your amp! For example, while most of my C+ A/B have been good to go with GRN, I have one that YEL is pushing 70%. Thee is definitely variance in the IIs and IIIs. (Though I've never seen significant variance in the Rectos.)

Yup, the STR440 are chinese (from the burned down shuguang factory?). You find the same tubes for example labeled as ruby.

I did my measurements in a MKIII green stripe loaded with TAD 5880. While the inner pair was sibirian cold (like 12mA) the outer tubes were running fairly hot, more like double the mA reading if I remember right