Tubes for .50 Caliber +?

[icycanadianguy]

Hello everyone,

My .50 Calibre is extremely noisey on both channels and I have been advised to change the power amp tubes. The operating instructions call for Mesa/Boogie 6L6GC tubes. I have found some on ebay but they are listed as "rectifier" tubes. Is this the tube I am looking for? What is the difference between a rectifier and reguar tube (if any)? I was also considering picking up a couple of Mesa/Boogie 12AX7s but again they are listed as "rectifier" tubes so I am not sure if they are what I need. Any advice would be appreciated.

Thanks

 

[Sludgenutz]

I recently got my .50 cal + about September or so. I tried a few tubes in the preamp section, and settled on this arrangement:

V1 Tung Sol (Russian) 12AX7A
V2 Electro Harmonix 12AX7A
V3 Electro Harmonix 12AX7A
V4 Electro Harmonix 12AT7 (reverb circuit)
V5 Tung Sol (Russian) 12AX7A, with seller tested "balanced outputs"

JJ EC83s are middy. EH's are very bright. Tung Sols are more balanced, top to bottom.

Power tubes: Mesa STR 440 (tested, and rebranded Chinese mfd. Ruby 6L6MSTR)

I do not care about the clean channel, so this is a combo geared for high gain tones. Running all Tung Sol's (except for V4) did not result in better tone than the list above. The thump I require comes from the cab. Your experience may vary.

 

[Sludgenutz]

Hello everyone,

My .50 Calibre is extremely noisey on both channels and I have been advised to change the power amp tubes. The operating instructions call for Mesa/Boogie 6L6GC tubes. I have found some on ebay but they are listed as "rectifier" tubes. Is this the tube I am looking for? What is the difference between a rectifier and reguar tube (if any)? I was also considering picking up a couple of Mesa/Boogie 12AX7s but again they are listed as "rectifier" tubes so I am not sure if they are what I need. Any advice would be appreciated.

Thanks

There are three broad ranges of vacuum tubes used for instrument amplification:

Rectifier
Preamp
Power

Our .50 caliber + amps a have solid state rectifier section that never needs a thought unless broken/fried. Rectifier tubes are a non-issue. The seller may be offering these as fitting Mesas Rectifier ("Recto") amps, but they are only for the preamp section, by my best guess.

Mesa's current 12AX7 preamp tube is a rebranded (Chinese mfd.) Ruby 12AX7 tube. Preamp tubes of like designation, do not need to be "matched" to each other, or the circuit like power tubes do. The Mesa name does not mean as much, so you might as well go a Chinese 12AX7 by "Shuguang", from what I see on the 'net to save a few bucks by going EH/JJ/Ruby/Shuguang/others...or spend the $15 US each for a Tung Sol 12AX7A.

6L6 designates a power tube. To make things a bit more complex, Mesa/Boogie had an earlier .50 caliber with a set of four low power EL84 power tubes. The later .50 Caliber + (plus) model has a pair of 6L6 power tubes.