Power Tubes: Matched or not?

[LesStrat]

I just ordered a new set of power tubes for my amp. The question arose, "do you want matched, or unmatched tubes?"

What are the advantages/disadvantages for each?

 

[BigAlTheBird]

Re: Power Tubes: Matched or not?

You read for the vaguest answer ever?

Well some class (B maybe?) needs matched tubes, I believe. Besides that, I dunno.

But I'd guess they're just slightly better.

 

[Dr.Mavashi]

Re: Power Tubes: Matched or not?

Yeah its for the B class amps, if you dont match them at the minimum your tone is gonna suffer ... I believe there are people who believe that unmatched tube over time do some damage to your amp but whether they are right or not I dont know ...

 

[ES350]

Re: Power Tubes: Matched or not?

Depends on your POV---matching is from the audiophile/EE world, but most of what you have heard on recordings since 1937 is probably unmatched tubes. A little nonlinearity is a good thing...

 

[Dr. Lo]

Re: Power Tubes: Matched or not?

If your Amp is Class A/B (most Fenders, Marshalls, and Peaveys) and you don't want to have to rebias your amp everytime you change power tubes, then get a bunch of matched tubes. Otherwise, if you start mixing and matching different power tubes together, your amp's bias may end up being off, resulting in a crappy sound (e.g., distorts too early or too late).

If your amp is Class A (e.g., Vox AC15 and AC30, Matchless, Orange Tiny Terror), then unmatched tubes are fine since these amps do not require biasing.

 

[marvar]

Re: Power Tubes: Matched or not?

Depends on your POV---matching is from the audiophile/EE world, but most of what you have heard on recordings since 1937 is probably unmatched tubes. A little nonlinearity is a good thing...

Keep this in mind- tubes made from 1937 until the 70's were made with much higher standards than the tubes made today- ever see the the letters JAN on NOS tubes? It means Joint Army-Navy.(gov't spec) and most tubes back in the day were of very close tolerances, due to the fact that almost everything used tubes. Even jet fighters of the day had tubes in them. Virtually all communication gear used tubes. Back then, tubes were made so well, that you could probably pick up two different tubes made by the same mfg,(same type of course) and they would probably be within what we would call matched. Hence, the premium prices for NOS tubes. they were just better made
Today's tubes are all over the place, so when I buy new tubes, I get matched ones.
You can look at it like a twin engine airplane- don't you want both 'engines' running as close as possible to each other?
Sure, you make the argument that amp manufactures don't match tubes in their new amps- but why should they- most are out just to make money. And most sharp players will replace their tubes pretty quickly after purchase anyway. But, I'll bet that if you talked to your favorite guitar hero's amp tech- you will find that they use matched output tubes.

 

[Dr.Mavashi]

Re: Power Tubes: Matched or not?

If your Amp is Class A/B (most Fenders, Marshalls, and Peaveys) and you don't want to have to rebias your amp everytime you change power tubes, then get a bunch of matched tubes

So what you mean is that if get a matched pair, match them to a certain level, re-bias the amp for them, and then, when they are finished I just order a matched pair to the same level and just swap as if they were pre-amp tubes?

 

[Pierre]

Re: Power Tubes: Matched or not?

If your Amp is Class A/B (most Fenders, Marshalls, and Peaveys) and you don't want to have to rebias your amp everytime you change power tubes, then get a bunch of matched tubes. Otherwise, if you start mixing and matching different power tubes together, your amp's bias may end up being off, resulting in a crappy sound (e.g., distorts too early or too late).

If your amp is Class A (e.g., Vox AC15 and AC30, Matchless, Orange Tiny Terror), then unmatched tubes are fine since these amps do not require biasing.

The AC15 and 30 at least are not class A.

This has to do with fixed vs cathode bias, I doubt class has anything to do with it. Cathode bias = power valve biased via a cathode resistor. Fixed bias = different system, usually adjustable.

 

[Fresh_Start]

Re: Power Tubes: Matched or not?

The AC15 and 30 at least are not class A.

This has to do with fixed vs cathode bias, I doubt class has anything to do with it. Cathode bias = power valve biased via a cathode resistor. Fixed bias = different system, usually adjustable.

I had the same thoughts and have read that the Vox (and Matchless) amps are not true Class A. Sometimes cathode biased is called "self biased". I believe that a cathode biased amp should not be as sensitive to power tube matching as a fixed bias amp would be (could be wrong about that though).

It's probably good practice to buy matched pairs of power tubes - certainly new production ones. Matching & balancing of preamp tubes is nonsense, IMHO.

Chip

 

[J Moose]

Re: Power Tubes: Matched or not?

So what you mean is that if get a matched pair, match them to a certain level, re-bias the amp for them, and then, when they are finished I just order a matched pair to the same level and just swap as if they were pre-amp tubes?

Errrr... kinda. You more or less have it.