Are these STR 415's ?

[Tyrant]

Is it possible to tell with the photo and marking "IS 188-5" to tell if these GE tubes 415's?

 

[Shep]

the one on the left looks like one.. the rest are all different..

 

[Tyrant]

Thanks for hitting this thread up Shep. I know it's difficult if not impossible to tell from some photos. Too bad there weren't at least 2 of em. I think I'll pick up some KT77's and give them a whirl.

Thanks again!

 

[Shep]

it looks like the GE's are matched see if they are ok to run in a mesa before you try...

 

[stokes]

it looks like the GE's are matched see if they are ok to run in a mesa before you try...

If only it were that easy.Tubes arent "matched" by looks.You must have the current draw checked to see if they match.

 

[Tyrant]

So what about the tube determines "okay" to run in the Mark IV? Do you have a range of a specific value? I was under the impression that any 6L6 would run in the Mark.

 

[stokes]

Any 6L6 will "run" in any amp designed for a 6L6,but it must be biased properly.Mesa uses a fixed bias supply,just like many other amps do.Mesa buys huge lots of tubes and checks the current draw and then grades them to match a particular performance in their amps.Makes it easier for your average guitar player to change his tubes,but doesnt neccessarily give you the absolute best performance from the tubes.Tubes must also be "matched",which means a pair of tubes or a quad will all draw the same current in a given amp.Just because 2 tubes are labeled 6L6 doesnt mean they will have the same current draw.

 

[Tyrant]

Thanks for the info stokes. I've read about the STR415's on these forums and how good they are. I am trying to find a pair. I am under the impression that they were rebadged Sylvania's.

So buying a matched pair is essential. It's a bit daunting for the tube novice to know what I'm looking at let alone if they will be optimal in my Mark. There are a lot of claims about tubes out there. Any places to start looking would be appreciated. thanks

 

[stokes]

I am pretty sure the 415's are Sylvania 6L6GC's.I dont use Mesa's tubes so I aint 100% sure,but one of the better tubes they offered were the Sylvanias and most likely is the 415's.You can find matched pairs of Sylvania 6L6GC's on ebay for reasonable prices.The only catch is it is hit or miss as to them matching the current draw of your amp.You would have to have a tech check the bias if you cant do it yourself.I did the adjustable bias mod on both my Boogies years ago,so using NOS tubes is not a problem.Its an easy affordable mod and well worth the cost to have somebody do it if you cant.It is only a matter of changing one resistor to an adjustable pot.Even if you choose to use the Sovtek or Chinese tubes that Mesa offers,you can get them at half the price Mesa charges.