Wed Dec 24, 2014 1:25 am
Wed Dec 24, 2014 2:30 pm
Wed Dec 24, 2014 3:08 pm
helle-man wrote:In the 1980's I started doing sessions and live work in LA. My main amp at the time was a 60's Blackface Fender Twin Reverb.
I re-tubed it one day with Mesa's and for the next few months started experiencing a rash of blowing fuses all the time. I even installed a fan on the back to cool the tubes.
The last straw was on an important recording session and it was blowing fuses so frequently that the producer lent me a Music Man RD-50 which I used to finish the session.
The next day I put the Twin in the paper to sell as-is. A guitarist friend of mine asked me what I may have done differently to the amp and I explained I re-tubed the power tubes with Mesa tubes. He told me the new tubes may be running my amp too hot. I put a different set in and it worked great again, never blew another fuse and I still have the amp.
I've never bought Mesa tubes ever again after that. They may sound great in Mesa's, but they ran my Fender way too hot.
My 2¢
Will
Wed Dec 24, 2014 3:16 pm
Wed Dec 24, 2014 3:17 pm
Wed Dec 24, 2014 3:25 pm
suave eddie wrote:
The Subway Blues has always been a rather noisy little amp which I have heard is to be expected -- there is a fair amount of hiss even with all new tubes.
Wed Dec 24, 2014 8:19 pm
Thu Dec 25, 2014 3:19 am
Thu Dec 25, 2014 4:58 am
Thu Dec 25, 2014 7:38 am
Fri Dec 26, 2014 7:32 am
Fri Dec 26, 2014 12:36 pm
Non-adjustable fixed bias is extremely sensitive to tube parameters and that's why one is restricted to use tubes with the proper specs which can only be assured by tight selection after testing which is a drawback of sorts. The good thing is that you can just plug in a new set of tubes plus the amp will never suffer from bias potentiometer malfunction.
Eddie, you asked how one would know when to replace a rectifier tube; short answer is when it quits. Rectifier tubes are kinda like light bulbs, they either work or they don't. All the rectifier tube does is convert AC to DC and it'll do that until the day it dies. I have the original rectifier tubes in each of my old Fender amps.
Fri Dec 26, 2014 1:05 pm
suave eddie wrote:This is what I have always believed. So my question is for other Mesa users who have swapped tubes with other brands, is how do they know if the new tubes are up to Mesa standards. And how do I know if the Groove Tubes in my newly acquired Lonestar are up to snuff -- other than the fact that it sounds great. I'm tempted to just change out the power tubes on general principal -- I have no idea how old they are -- the owner I bought it from did not touch anything in the two years or so that he owned it.
So it sounds like it would be a good idea to have a spare rectifier tube on hand but there is no need to arbitrarily replace it along with the power tubes as long as it is working.
Fri Dec 26, 2014 1:45 pm
A spare rectifier tube is always a good idea if you are gigging but not likely to ever be needed, unless of course you don't have one with you. Ha Ha. And don't get suckered into paying big money for a rectifier tube.
Thu Jan 22, 2015 7:46 pm
suave eddie wrote:I have a question for you mesa owners out there -- I know Sam and Boogie Bill are known to crank up a Mesa now and then.
Mesa amps have non adjustable bias. Randall Smith has a long article here explaining why they went that way.
http://www.mesaboogie.com/US/Smith/biasadjust.html
Much of the info is over my head, but here is how he starts out:
"Our business is designing and building high performance amplifiers. And for this we need tubes whose variance is within a narrow range. Our warehouse is full of rejects ... oh, they work -- they just don't perform within our tolerance range. We have a very sophisticated computer - based tube testing system (nicknamed "Robotube") that matches and measures tubes over seven important parameters. It can even predict which tubes are likely to have a shortened lifetime -- even though they work perfectly during the test."
I don't know how much of this is hype so they can sell their own branded tubes. Randall Smith says, if you want your amp to sound like it did when it left the factory, then use Mesa branded tubes. I've always done this with my Subway Blues just to be safe and I never had an issue with them.
I do know that some don't like the Mesa branded tubes and use others they consider better.
I was wondering if any of you here that own Mesa amps have used tubes other than the Mesa branded ones.
My new Lonestar already has had the originals swapped for Groove Tubes. I'm not ready to re-tube it yet as it sounds great as-is, but eventually I will need new tubes and was curious about others experiences. How do you know if other brand tubes are within specs and tolerances imposed by Mesa? How important is it actually?
How do you know when the rectifier tube needs replacing? The Subway does not have a rectifier tube but the Lonestar does.
I have another question about the MESA SPAX7 preamp tube.
This is what Mesa has to say about them:
"MESA SPAX7 preamp tubes are a super-premium grade substitute for any 12AX7 positions - They are a "Special Requirement Preamp Tube" that possess an even higher standard of overall performance, due to their incredibly low sensitivity to microphonic noise - This is the ultimate preamp tube to use in all critical gain stage positions - It is the absolute best of the best!"
Does anyone here have experience with these?
The Subway Blues has always been a rather noisy little amp which I have heard is to be expected -- there is a fair amount of hiss even with all new tubes. I wonder if these premium SPAX7s would help alleviate any of that. I wonder if just replacing the one in the first slot would be enough or if I would need to replace all four.
Any of you Mesa users who have any experience experimenting with other brands of tubes, please chime in.
Thanks
Thu Jan 22, 2015 8:15 pm