MK III Blue Stripe Tubes~!!~

[slowdownyourday]

When I was a much younger man I played in a power trio that was a cross between Slayer and Public Enemy, but my best friend (and guitarist in the band) went down the wrong path and passed away from an overdose. Years passed and I kept in touch with his parents and sister. Both parents passed about three years ago, and a week ago I got a text from his sister asking for my address. This showed up on my doorstep yesterday, his 1988 Blue Stripe MK II! with a note that said "I always wanted you to have this, I knew it's what he wanted. She'd gotten it serviced and cleaned and it's AMAZING looking, even pro packed. All this to say one tube is shot, and it's pictured below. My questions are 1- What's best to replace this with, 2- Where's best to buy from and 3-Should I buy a set, or could I buy just one, what's a better idea? Thanks in advance, Paul

 

[Darkstar2]

That's an EL34 you have pictured above. Is that amp a Simulclass? If so, it's got EL34s in the outer 2 sockets. For the best, I'd see if Mesa still has any of those vintage 416's to sell you. @bandit2013 can better offer advice than myself. The inner two tubes should be 6L6GC's and the outers EL34 for Simulclass. Great score. Sorry to hear about your former bandmate.

 

[bandit2013]

My condolences on the loss of your friends, and his parents. That was a nice gesture from his sister to give you his amp.

As for the one bad tube, best to replace both outer tubes as a matched set. Mesa only sells tubes in matched pairs. As tubes age after use, the characteristics will change over time. Trying to replace just one is not a wise choice as that will result in an unbalanced condition.

If you want the original tubes for this amp, that would be the STR415 Sylvania 6L6 in the center and the STR416 in the outer, not what brand they are. Send Mesa customer service an email inquiring if they still have any of those tubes available. The means to get a message through is to use the link below. You should get a response in a few days. If they have the tubes in their hidden inventory, it is a special order to get them. My first attempt was to try back in a few months as they do have them but will not be able to get them ready for a while. I assume tested and packaged. That requires a work order to process them and some sort of invoice to get them. The STR415 and STR416 (assuming they have them) are not a cataloged or stocked item for resale. If they were, they would have sold out years ago.

The person I was communicating with at Mesa: Kris Dilbeck (MESA/Boogie). Best to use there portal to get through. At the bottom of the page, click there to initiate a request.

https://mesaboogie.zendesk.com/hc/en-us


For current production tubes. Hard to say how the amp will respond with what is out there now. TAD red base tubes like the Mesa STR448 (6L6GC) and the STR446 (EL34) may work out. If I still had the Mark III DGR, I would be able to recommend what works best. The STR448 is very close to the STR415. The STR446 is an EL34 tube and not a 6CA7 as those tubes have beam forming plates like a 6L6GC tube. The alternatives for the STR416 would be either the JJ 6CA7 or the EH 6CA7. Then there is the Gold Lion KT77 that will sound similar to the 6CA7.

Now I wish I never sold my Mark III DRG combo. I sort of miss it. See what Mesa says as a response to the inquiry. I am sure others who favor the vintage amps will chime in with some recommendations for you as well.

 

[CoG]

My condolences, man. Weird feeling when an old brother goes like that.

bandit2013 knows his power tubes for sure but STR416s from Mesa's back room are a pretty expensive choice and it's the kind of thing that you might notice in the room, for the first five minutes you're playing, if you have golden ears.

I have EH 6CA7s from thetubestore.com in the simul-class sockets of my green, perfectly happy with them for high gain stuff, I just told them what they were for when I ordered.

 

[slowdownyourday]

That's an EL34 you have pictured above. Is that amp a Simulclass? If so, it's got EL34s in the outer 2 sockets. For the best, I'd see if Mesa still has any of those vintage 416's to sell you. @bandit2013 can better offer advice than myself. The inner two tubes should be 6L6GC's and the outers EL34 for Simulclass. Great score. Sorry to hear about your former bandmate.

Thank you so much!

 

[slowdownyourday]

Thank you so much!

My condolences on the loss of your friends, and his parents. That was a nice gesture from his sister to give you his amp.

As for the one bad tube, best to replace both outer tubes as a matched set. Mesa only sells tubes in matched pairs. As tubes age after use, the characteristics will change over time. Trying to replace just one is not a wise choice as that will result in an unbalanced condition.

If you want the original tubes for this amp, that would be the STR415 Sylvania 6L6 in the center and the STR416 in the outer, not what brand they are. Send Mesa customer service an email inquiring if they still have any of those tubes available. The means to get a message through is to use the link below. You should get a response in a few days. If they have the tubes in their hidden inventory, it is a special order to get them. My first attempt was to try back in a few months as they do have them but will not be able to get them ready for a while. I assume tested and packaged. That requires a work order to process them and some sort of invoice to get them. The STR415 and STR416 (assuming they have them) are not a cataloged or stocked item for resale. If they were, they would have sold out years ago.

The person I was communicating with at Mesa: Kris Dilbeck (MESA/Boogie). Best to use there portal to get through. At the bottom of the page, click there to initiate a request.

https://mesaboogie.zendesk.com/hc/en-us


For current production tubes. Hard to say how the amp will respond with what is out there now. TAD red base tubes like the Mesa STR448 (6L6GC) and the STR446 (EL34) may work out. If I still had the Mark III DGR, I would be able to recommend what works best. The STR448 is very close to the STR415. The STR446 is an EL34 tube and not a 6CA7 as those tubes have beam forming plates like a 6L6GC tube. The alternatives for the STR416 would be either the JJ 6CA7 or the EH 6CA7. Then there is the Gold Lion KT77 that will sound similar to the 6CA7.

Now I wish I never sold my Mark III DRG combo. I sort of miss it. See what Mesa says as a response to the inquiry. I am sure others who favor the vintage amps will chime in with some recommendations for you as well.

Thank you so much! I'll reach out and see what they have to say!

 

[slowdownyourday]

My condolences, man. Weird feeling when an old brother goes like that.

bandit2013 knows his power tubes for sure but STR416s from Mesa's back room are a pretty expensive choice and it's the kind of thing that you might notice in the room, for the first five minutes you're playing, if you have golden ears.

I have EH 6CA7s from thetubestore.com in the simul-class sockets of my green, perfectly happy with them for high gain stuff, I just told them what they were for when I ordered.

So the EH 6CA7's would replace the EL34's, correct?

My condolences, man. Weird feeling when an old brother goes like that.

bandit2013 knows his power tubes for sure but STR416s from Mesa's back room are a pretty expensive choice and it's the kind of thing that you might notice in the room, for the first five minutes you're playing, if you have golden ears.

I have EH 6CA7s from thetubestore.com in the simul-class sockets of my green, perfectly happy with them for high gain stuff, I just told them what they were for when I ordered.

 

[Darkstar2]

So the EH 6CA7's would replace the EL34's, correct?

Yes, that is correct.

 

[user 41014]

Scratch the 416's off the list. I just dropped a blue stripe off with mb and asked. The 416's are long gone. The 447's might still be around.

 

[slowdownyourday]

Thanks for the info!

 

[slowdownyourday]

Thank you so much! I'll reach out and see what they have to say!

Hi there. So the 416's are gone, as Electric Mayhem was kind enough to let me know after his visit there. Let me clarify what you said. The tube that blew is Mesa-branded, one sider says STR-416, and the other side says 6CA7 EL34. You said that (in general) a pair of EH 6CA7's would work dropped into the outside slots? If that's the case I'll see if the tube store has them. And thank you for your detailed reply. I've heard this amp SO many times, and I can't wait to plug it in and dial it up. Thank you, Paul

 

[bandit2013]

It probably will not make much of a difference. the EH 6CA7 are a bit different from the EH EL34 (what Mesa calls the STR447). The 6CA7 is as close to the original as you can get since it is the big bottle version. I have run the EH 6CA7 in both TC100 and TC50, I know that is a 450V plate voltage. No issue with that, actually sounded good but not a Mark amp. As for the STR447 (EH EL34) can sound a bit harsh depending how the tube is biased or what the plate voltage is. I only had one set of the STR416 which were the original tubes that came in mine when I bought it new back in 1989. Bummer they do not have the STR416 tubes. The alternates were OK, when you could not find any Mesa power tubes in the 1990s and had to use Groove Tubes or Sovtek for replacments. I was buying the tubes from the Mesa dealer that was local to me when I lived in PA.

Based on the hard to read schematics, it does not state what PT is in the amp, 480VDC max but on the power tube section, it lists 478V plate on the 6CA7 tubes, it is triode mode connected. The 6L6 are pentode connected with 479V plate, B voltage for the screens is 460VDC assuming the blurry text is correct. Not much else available online in terms of readable schematics for the amp. At least they call out the tubes used, STR416 and the STR415. First time I noticed that.

 

[woodbutcher65]

That is specifically Sylvania 6CA7sSTR-416s in the outer two sockets. There are a few on ebay. I would strongly recommend getting them rather than attempting to substitute any newer replacement, if the prices are in the same range. The Sylvanias can handle the high voltages in that amp.

 

[mark0]

ffs just get mesa str440 6l6 or str448

str447 for the outer el34 or just run cold 6l6 there

bandits ears will never know

 

[bandit2013]

I hate to say this, agreeing with mark0. It probably will work out fine with current tubes in Mesa's offering. Mesa now has two TAD red base tubes, STR448 (6L6) and the STR446 (EL34). Probably will not have the same character as the old Sylvania 416.

It is not my ears that matter, not my amp.

 

[woodbutcher65]

My recommendation is to leave those STR 416s right where they are if there's no compelling REASON to replace them. Based on their appearance and the getter silvering they're relatively fresh and have tons of life and many years left. Those are some of the longest lasting, most reliable tubes EVER made, and given their value, it makes no sense to swap them out while they're still giving good service.

The 416s also have higher voltage tolerance than most ANY new built EL34 type tubes you can get today.