New Tubes For MKIIc+

The Boogie Board

Help Support The Boogie Board:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Henz

Moderator
Staff member
Joined
May 19, 2016
Messages
343
Reaction score
19
Location
USA Pittsburghish
Greetings, Forgive me if this has beed answered . Plain and simple, I want to replace all tubes in my amp. I have had this amp since 1984 and re-tubed it w/ many different brands over the yrs. The tubes in it are very old.I know good pre's can last a long time but I feel as tho they need replaced. I have been struggling w/ it for weeks trying to figure out what happened to my tone. I want dimension in my tone. I have tried Sovtek's, Svetlana's, GT's and Mesa tubes. I know that the V1 pre socket is the most important but when I view the schematics, they all seem important. I still think to myself do tubes change tones? Or do they just make the amp function? Like PU's, Speakers...ect. They can change tone. Jeesh, anyway, any guidance will be greatly appreciated. I love this forum. Very informative. Thanks for your time, James
 
I was asking myself the same question, especially for the replacement of the power tubes. I was thinking of getting the TAD 6L6GC-STR (RCA-Style black-plate) which are supposed to be kind of a remake of the STR 415. Has anyone compared those 2 tubes?
 
Thanx for the replies. What brand is TAD and how do I get in touch w/ this person for new tubes? Mike Bendinelli sent me two 6L6's 415's many years ago. I have used them in my MKIIc+ w/ other tubes but not consistantly. He said those tubes were made for this amp. They were always in the outer sockets.They run nice. No bias prob. Svetlanas run hot in the outer sockets as do some Mesa tubes.I stumbled on a pair of Mesa tubes 6L6GC STR 430's. I put them in hoping to solve my issue. They run hot but plates dont glow. Seemed to have helped a little. I must add to my other post that one of my issues was notes wud not sustain. Anyone else have this problem? I'm thinkin pre's for this issue.I have switched so many tubes around the last few days that i am goin crazy. I know that this amp can deliver what i want. Will those TAD tubes help me? I know that gettin new pre's doesn't mean it will fix it. Good pre's are hard to find. Sorry for the long post, I'm very frustrated. Thanx for ur time. Sincerely, James
 
The 415's Mike sent you are the perfect tube for this amp. I would end my search right there if it was me. That tube is a holy grail for Mesa users, and you already have a pair
 
I've got Tung Sol 6L6's and nos Chinese military 12ax7's in the c+ HR I bought this summer. Unfortunately the amp got damaged during shipping. While it was in the shop for repairs the tech recommended a bias pot because the 415's it came with were running too hot. I decided to try the Tung Sol's and save the 415's. The Tung Sol's have kind of a tweed tone to them which I really like.
 
Thanx for the replies. But my 415's are very old. As of today, I still have the 430's in the outer sockets in the C+. I put the 415's in my 2:90 (im only using one channel) to see what it wud sound like.Oh, I'm sorry, Im slaving my 2:90. They seemed ok.When all else fails, I always put the 415's back in C+.Still I dont know what TAD tubes r and how to get tubes from Dr Tube. About tose TungSol's, please give me an example of what a tweed tone is...guitarist or band or whatever. I may be interested. Ty for everyones time, James.
 
Tweed tone is like an early Fender amp. Warm and round. If I want more of an edge I just turn up the presence. The rhythm channel on my c+ with a les paul breaks ups really nice, like Jimmy Page's live tone on The Rain Song from The Song Remains The Same album.
 
My Simul-Class amps use either all STR-415 or a 415/416 mix for the power tubes. For preamp tubes I have grown to like the Tungsram 12AX7 in V1 and V2, and the RFT 12AX7 in V3 and V4 positions. Not the cheapest route, I know, but it works every time without fail.
 
I buy my tubes from antique electronic supply. They have great tutorials to get you started and describe the tone of the tubes, TAD 6L6 tubes will run you about $100 for four. Tube sound is very subjective, louder tubes aren't necessarily tubes with more gain. Sweet tubes versus harsh tubes is all in the ear of the beholder.
 
Perhaps it's time to send it back to Mike B. for a go-through and a re-cap job. Made a big difference with my Mark III when it started to sound dull. He replaced some bad resistors as well.
 
Thanx for the reply. i wud luuuuuvvvv to do that. He is awesome. But , currently, I m un able to. I plan on it though. It really needs a good physical. Sincerely, Jim
 
Hello. I recently checked out Mesa's home page and read that amps built before the 90's had 12AT7's in V5 driver. Tho my papers
that came with it ( C+ , purchased in 1984) says 12AX7 in the V5. I put an AT7 in it and it seemed to improve tone. Any thoughts?
Thanx for your time, James
( Update: I was wrong. It was for the Reverb Driver.Should I still use the AT7 in the V5? )
 
Henz said:
Hello. I recently checked out Mesa's home page and read that amps built before the 90's had 12AT7's in V5 driver. Tho my papers
that came with it ( C+ , purchased in 1984) says 12AX7 in the V5. I put an AT7 in it and it seemed to improve tone. Any thoughts?
Thanx for your time, James
( Update: I was wrong. It was for the Reverb Driver.Should I still use the AT7 in the V5? )
My chassis actually has 12ax7 written by all the sockets, but I wouldn't think that putting an 12at7 in would hurt the amp. It just won't have the same output as an 12ax7.
 
Thanx for the reply. My chassis as well. As u mentioned, it did sumthing to the output tubes, they didnt seem to run as they shud. ( I can tell by the color of the output tubes). Anyway, put 12ax7 back in V5. Everything is groovy. Side note, do you at tmes have inconsistences with your tone? This has plaqued me for soooo long. It wud sound great, then the next day, gone. I know that it cud be mood, voltages, this that and the other.Anyway, Blessings be. Sincerely, James
 
I thought I'd post this if anyone was curious about New Sensor Svetlana tubes. I just put Svetlana 12ax7's, EL34's and 6L6's in my DR combo. The Svetlana 12ax7's remind me of Tungrams. Very smooth tone and not harsh at all. I wanted to see if new production tubes could come close to nos tubes. Very happy with the way the amp sounds. I had Mesa/JJ 12ax7's and Mesa EL34's and 440's in the DR but they just made the amp sound like a hot rodded Marshall.
 
Cool. I like to hear of new stuff. I am gonna have to check out Svetlanas pre's. Their power tubes at times, ran too hot in my C+. Thanx!
 
If I put 6L6's in the the outer sockets of my DR the fuse will eventually blow. Doesn't matter what brand. I tried Mesa, Ruby, Tung Sol, JJ, Groove Tubes CHP's, R's and GE reissues. It runs fine with the EL34's. I like the way it sounds with the EL34's but I need to get it checked out. On your side note of the tone changing from day to day, I've noticed the tone changes with the weather. I have a humidity gauge in the basement and when the the humidity drops the amps don't sound as smooth. On another side note, I prefer the Mesa/Eminence MS-12 speaker in my c+'s. The last one I bought sounded a lot brighter than the other ones I have, couldn't really use it in the DR. That amp is too bright as it is. So a couple of days ago I decided to experiment. I applied 2 coats of rubber cement to the outer edge of the speaker cone to see if it would tame the brightness. It worked. The speaker sounds so much better now.
 
Thats strange w/ the fuse issue in the outer sckts. With my Boogie , the bias is -38 to -40vdc. Do u have schematics w/ that amp? A 220 resistor is on my outer sockets. I did try EL34's a loooong time ago. I think I liked them :?: I also thot bout humidity as an issue too. During very humid cond. , my 2:90's circuit board wud arc. I think, over time, residue built up and made everything condusive. Humidity and guitar, as u know, hate each other. May be a factor. The cement on speaker was interesting. Did u think of silicone first? just curious. We did choose a finicky instument. Sooooo many factors involved to achieve our tone. Check the bias voltage on the sockets. Get a copy of schematics online. Please note that lethal voltages lurk inside chassis. If not sure, get someone else to check. Take care, Jim.
 
There's a really good amp tech here in Chicago that repaired the HR combo I bought last summer. The amp was damaged during shipping. I'll eventually have him look at the DR. Never thought about using silicone on the speaker. I did some research online about speaker doping and some guys had good results with the rubber cement.
 
Back
Top