12AX7 matching??

[emperor_black]

I'm thinking about buying preamp tubes for my cavin ts100. The amp takes 12ax7 tubes. there are all these different types of 12ax7's...12ax7a, 12ax7ws, etc. I'm assuming the amp should do fine with any 12ax7.

Also, I'm aware that power tubes come in "matched" multiples of two. however, tubedepot.com is offering 12ax7 matching. What the heck is that and should I be buying matched preamp tubes too?

[Recklessrob]

You can change the tonal character with different brands of tubes.
I've had good luck with Groove Tubes, but everybody has their preferences.Ask the people here:

http://www.carvinmuseum.com/forums/index.php?sid=63138cbfd5acbd8aa4205350cdf4dd54

[emperor_black]

yes, i understand about the different tonal characters. but its match or not-match i dont understand

[fett]

Each 12ax7 has two diodes. So there are two sides of the tube that needs to tested. Those numbers should be close to each other. You can also match tubes that test with simular test results. I think that's correct.

[bibz]

Yep when the diodes rate the same its called a 'balanced' 12ax7. These are used as phase inverters for balanced power sections. But as far as I know most guitar amps dont run that so theres no real reason for it.

[marcus]

For most of the positions in the preamp, matching the two triodes of the 12ax7s will get you nothing. They are generally not used in topologies that require them to be balanced. There is some debate about whether they should be matched for the phase inverter, so you may want to get that one matched. For what its worth, I didn't bother the last time I retubed my amp, I just got all unmatched triode 12ax7s and have noticed no problems.

[ezbprimerib]

don't worry about 'matching' 12ax7's. sounds like tubedepot is selling snake oil.

[Bengal65]

Some good reading Myles has here: http://www.guitaramplifierblueprinting.com/Primers.html

[zeegler]

It's quite normal to mix and match pre-amp tubes, so don't worry about it. In my AT-100, I have 3 JJ, 1 EH, 2 Shuguang, and 1 NOS RCA. I have a pretty big assortment of pre-amp tubes, and try all kinds of different combinations until I get the sound I like best.

[Rsmacker]

yes, i understand about the different tonal characters. but its match or not-match i dont understand

Only if you are really really Eric Johnson about having exactly the same tonal characteristics when you change the valves. For everyone else who has a real life too, you should be able to find what you are looking for by having a couple of spares to swap, like Zeegler does, but that's if you even notice any difference at all.

Having changed valves in loooooooadsa different amps, only had one customer who wasn't happy with what he got back in his Fender Twin. (He was right though, it did sound considerably different. Swapped it for another 12AX7, and bingo, job done)

[emperor_black]

yes, I realize it now. thanks. I went ahead and ordered a non-matched pair.