Tubes and Mesa Boogie

[suave eddie]

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

[helle-man]

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

[suave eddie]

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

The Twin has adjustable bias, correct?

[Fumble fingers]

the twin is adjustable ..... for my Carvin V3m I ordered a tube assortment from Doug's Tubes because I didn't really know what I wanted ..... anyway , the Tubes do make a difference in sound , you can tweak your amp anyway you want , Doug is pretty knowledgeable on tubes , you might give him a call ..... I did have to readjust bias after the tube change

[Elwood]

I wish I had a newer Mesa so I could add more than this funny tidbit I found on the UG forum:

Suckers Pay An eXtra $7

It sounds like well tested (and matched) tubes would be as good as well tested tubes branded by Mesa (they do match them , that's nice),
I'm still learning, good questions Eddie

[Elwood]

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.

Maybe try a 12AT7 at V1 ? you'll lose some gain but sometimes that's not a bad thing.

[suave eddie]

I've been doing more reading on the MESA SPAX7 on the Gear Page as well as the Mesa forum. Lot of good reviews and it appears that Mesa recommends them in the V1 position -- not necessary to swap all of them. I think I will definitely give it a try.

Now which is the V1 tube? The manual doesn't have a layout. Can I assume it is the one closest to the input jack?

[geoff douglas]

Hi eddie,, Re V1 location you are most likely right,
http://forum.grailtone.com/viewtopic.php?f=4&t=55592
Cheers and Merry Christmas all

[patricks]

Short answer:
1) Yup, the V1 tube should be closest to the input jack. I haven't looked under the hood of a Mesa, but that's the typical location. The shortest path between input jack and the first stage minimises noise and interference.
2) It sounds like Mesa have gone to a lot of trouble to define "the Mesa sound". If that's the sound you want, it'll be easiest to go with their tubes

Longer answer:
As far as matching/testing goes, it sounds like Mesa test both the preamp and power tubes. In both sections, any set of tubes that meets Mesa's specs should work just as well as Mesa-branded tubes. Different brands will sound different (and of course quality is usually related to price!). The requirements for power tubes will be much more strict than for preamp tubes; you should be able to swap any 12ax7 with any other 12ax7 and it'll work (you can even usually swap a 12ax7 for a 12ay7/12at7 or similar without problems).

In the power section, Mesa-branded power tubes will (according to their press blurb) be tested to make sure the amp doesn't need to be re-biased (bias should only affect power tubes, preamp stages are usually self-adjusting). If the amp doesn't have a way to adjust the bias, then using Mesa-branded tubes is the easiest solution. If there is a way to adjust the bias and you want to try different tubes, take the amp to a good tech and they can adjust the bias so the amp won't run hot.

If you really want to do it all yourself and experiment with other brands of tubes, you'll need to find out what Mesa's specs are (there'll be more to it than just bias) and get a good quality tube tester. So, if you like the Mesa sound and just want to play, buy Mesa tubes and rock on. If you're interested in the black arts of amp DIY, the world is your oyster!

[GeorgeB]

Technically, Mesa (and eg. classic Hiwatt) use non-adjustable (pre-set) fixed bias for the power tubes, in contrast to (potentiometer) adjustable fixed bias used by Marshalls, Fenders etc. VOX and some Peaveys use so called self-bias, yet another scheme.
The correct nomenclature would be grid bias instead of fixed bias, and cathode bias instead of self bias (and self bias can be made adjustable, too).

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.

Personally, I like user adjustable bias and symmetry pots, with test points to clamp a multimeter to, accessible on the chassis (no need to open the amp). As seen, for example, in the Red Knob Twin.

[Case24]

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.

One other thing about Fender and fixed adjustable bias; Blackface amps have true adjustable bias (except for Princetons) but Silverface amps after about 1970 have adjustable bias balance. CBS did this so they could get away with using un-matched tubes. One power tube will be fixed non-adjustable bias and the other one uses the old bias pot to balance it to the other tube. I had my '79 Vibrolux converted back to true adjustable bias on both power tubes and it made a huge difference on the tone.

[suave eddie]

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.

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.

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.

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.

[Case24]

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.

Well if your tubes aren't red plating and they sound good, they're probably going to be ok.

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 wih you. Ha Ha. And don't get suckered into paying big money for a rectifier tube.

[suave eddie]

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.

This has always been my attitude towards being prepared -- in most cases if I have a spare of anything, it just insures that I will never have to use it. It's got to be one of Murphy's laws. They only cost $25 direct from Mesa which isn't much for insurance.

[Boogie Bill]

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

I like the Mesa system of fixed, non-adjustable bias. It saves me a LOT of money--I don't have to take my amp to a tech when I change the tubes. I pop in a set of Mesa tubes and I'm ready to go.

FACTOID: Saw Mesa endorsee Andy Timmons at a Mesa Clinic. Andy was using the store's amps, He uses a Lonestar Classic and a Stiletto Deuce in an A/B rig. During the clinic, a power tube goes out in one of the amps...lots of screeching and noise. Andy shuts the amp off. Store owner opens up a pair of new power tubes, pulls out the offending tube and it mate and in less than five minutes, the amp is up and running. No biasing. Sounds PERFECT.

There is simply not a lot of amps that you can do that with. Certainly not Fender, or Marshall.

Mesa offers a SIX MONTH warranty on their tubes--the best warranty in the business. I have had to use that warranty on time, on a preamp tube--they back their products. I don't think the Robtube is hype at all. I have been using Mesa amps since about 1994.

Rectifier tube does not need replacement until it blows. The Mesa amps have switchable Diode or Tube rectifiers, so if a Rec tube goes out at a gig, just switch the amp to DIODE and you should be good to go.

If you are using Groove Tubes in a Mesa amp, you should use ones with a 4-6 rating. Anything else, you will have problems. BTW, Groove Tubes' rating standards and QA are not as strict as Mesa's. Duh!

So you can use other brands of tubes. Most of the good tube vendors like Doug's or the tubestore.com know what MA range to send to a Mesa user. Be sure to tell them your order is for a Mesa amp.

I have had excellent luck with the Winged C/SED 6l6 and EL34 power tubes in my Mesa Mark IIIs and Mark IV amp. These are getting hard to find and expensive. I have also used the Groove Tubes 6L6-GE in my Mark IV, along with their EL34 in the Simul-Class sockets. They worked fine.

I will not use the JJ EL34 or 6L6 in my Mesa combo amps, the can quickly develop noise and microphonics in these small, high-powered combos. The SED's handle this easily.

FACTOID: Mesa is the largest buyer of amp tubes in the world. And what do you think Mesa does with all the tubes that don't meet their specs? (Hint: they get re-sold to other vendors. Caveat Emptor.)

In my DC-3 and Maverick 212 combos that use EL84s, I am currently using the JJs. This is one tube I really like tonally, but they are not as durable as the Mesa EL84, which I think is a SOVTEK.


===========================

Re: PREAMP TUBES

I tried a set of JJ 12A7s from Eurotubes in my DC-3 but it made it too dark sounding. Eurotubes is close to me, and one of our clients works there. I have Eurotube JJs in several of my amps; in certain sockets they are fine.

I like the Mesa 12AX7s, but I have amps that also have the JJs, EH, Tung-Sol, TAD and Groove Tubes. You can do what some people call "amplifier blueprinting", and use various manufacturer's tubes in each of the different sockets to fine tune you amp for the tone you like.

My all-time favorite in the all-important V1 socket is the Groove Tubes GT12AX7-M Mullard clone. When you could get one that was noise-free and non-microphonic, they produced a wonderful, creamy, liquid tone. Sheer bliss in my Mark III amp. Unfortunately, these are no longer available. And finding good ones was tough.

FACTOID: If you have a Mesa amp under warranty and you have non-Mesa tubes; and a tube problem damages the circuitry in the amp--Mesa will VOID YOUR WARRANTY.

FACTOID: The Mesa Mark V combo I bought in 2013 is only getting Mesa tubes for the foreseeable future. Mesa amps have a FIVE-YEAR WARRANTY; also one of the best warranties in the biz. And the warranty is transferable.

The SP12AX7 is specially selected to be lowest noise and non-microphonic. I have used these, and they do work. They are wrapped with heat shrink as a further step to keep them reliable. I'm currently using them in two of my amps, and I have a couple on hand as spares.

You should always have spare tubes on hand when you gig, or take a spare amp. I almost always have a spare amp at a gig. I have two 12AX7s, a duet of 6L6s, and a duet of EL34s in my gig bags, and I'm going to be adding a quad of EL84s shortly. And don't forget the spare fuses. CA-CA happens.

Your noise issues could be tube-related, or indicate an more serious problem that would need servicing. Certainly trying the SP tube wouldn't be a bad idea. Tubes do wear out. Preamps tube generally will last a couple of years, but power tubes only 6-months to a year, depending on how hard you run them.

FACTOID: Lindsey Buckingham of Fleetwood Mac has his techs install a brand new quad set of Mesa 6L6s into his Mesa Trem-O-Verb amps before EVERY show. (Sheesh!!!! Wish I had his budget!) He does get a slight Artist Discount from Mesa, but he buys them from Mesa.

Let me know if you have any other questions.

Bill

[suave eddie]

I bought a new quartet of Mesa 6L6s and replaced the Groove tubes on general principal -- I have no idea what they were rated or how long they were in use. I saved them for spares and now I know what is in the amp. I even swapped out the rectifier tube just for the heck of it and now I have a spare -- also as you said, I always have the option to switch to diode rectifier anytime. I have a couple of spare sets of Mesa 12AX7s since that is what the Subway Blues uses also.

I talked to a tech at Mesa about the SPAX7 and my Subway amp. He acknowledged that the Subway is an inherently noisy amp and said the special pre-amp tube might help a little. Since it has now been relegated to my "spare" amp status, I am not going to bother right now experimenting with swapping out the pre-amp tubes.

The more I play this amp the more I like it. What a deal.