Does anyone know someone who can modify Mesa Baron

There is a local modder in New Jersey that I have used for several projects. He is very knowledgable and has a great ear. His name is Igor. The company is called K-Works. I suggest you contact him with your query. His email is: gorkuz@yahoo.com. Tell him Phil Slepian sent you.

Hi Rick,

no idea about these amps but from fooling with the Audiopax, if you can use 12 AT7's as prior post, try some CV 455s. Some nos Mullard CV455s make the CV4204s? or whatever my Pax came with sound positively broken.
Failing that the engineer I use worked at Abbey Road Studios
and although the only authorised repairer for Audio Note uk,
his real labour of love is band gear.
Get it performing to original spec and leave as is

Talk with Mike at Mesa. The most important upgrade is to replace the 10,00uf 16V brown Sprague electrolytics on the audio board. Highly prone to leakage.
Had my amp set up for EL34s many years ago, much smoother than the 5881. Also replaced the .1uf caps on the outputs to Hovland Musicaps and will soon go to Mundorf silver and oil caps. The original Mesa tubes tended to be a little bright in combination with the orangedrops.

Magnumip205, I also prefer EL34's in the Baron. My original 16V caps did leak, and Mesa replaced them. Would you consider upgrading the replacements Mesa used important? They seem better than the originals, but Mesa would never use an expensive "audiophile" cap. re: the eight .1 uf caps, did you upgrade those from the original Sprague 715's, or had you tried the Wima upgrade Mesa offered?

I have had one since 1998. Mine was modified by Mesa to be a tri tube version with WIMA caps. The speakers are Soundlab Dynastat. Tubes are JJ E34L all matched to 1ma, drivers and splitters are Mazda silver plate or (sometimes) Mullard m8137.

This combo is outstanding. I have had musicians and singers that have appeared at the Kennedy Center and the Metropolitan and 9 of 10 said it sounded as if there were at a live performance.

Since you are in California, Mesa might be the best idea...they are expensive however. The reason I had mine done by them was when I bought it from a California dealer they had already made the arrangements for the work ( otherwise I would have done it). I have been restoring vintage gear and nome new products for over 30 years (and have done work for Joe at Tempo Electric), and intend to rework the amp very soon.

What I will do to it includes, hexfred diodes for the 10 cent 1N4007 line up, Muse electrolytic bypassed with small oil caps and some ATOM caps (if I can't fit film caps in), dump the WIMA and Sprague 715 (which are NOT audio caps)and replace with Obbligato or Ampohm, and resistors in the signal path get replaced with bulk metal type. The output tubes a RCA 12 matched Blackplate 6L6GC.

I could modify yours, but as others have said here, you need to listen to yours first...it may just be what and how your want your amp to sound. Then try a Mullard 12ax7 or a Raytheon/RCA blackplate 12ax7 (very similar to a Mazda in sound) and see what that does. It is very important that your outputs be matched to within/no more than 2ma total spread per set of six.