More Tubes = Better Sound


I am wondering if anyone has thoughts on the sound quality of using more tubes to get the same power as an amp that uses less tubes? I had a pair of VTL MB 750 and they had 12 tubes for the output. I am looking at an ARC ref 600, however, it is 250 watts less and uses almost 3 times as many tubes as the VTL MB 750's. does anyone know the logic here? I am thinking of passing up on the 609's due to the expense if the tubes, but is there an advantage to using so many tubes?
128x128richdeben
Generally, I would say the less amplifying devices in an amplifier, be they tubes or transistors, the shorter the signal path and the better the sound. That may explain why, at least in my experience (using Jadis, Krell and ARC amps in the past), assuming a speaker load that's not power-hungry, lower-powered amplifiers by a manufacturer generally have sounded better to me than the same manufacturer's higher-powered offerings using similar circuits, though the higher-powered units might offer superior power reserves and macro-dynamics for difficult speaker loads. I suppose an advantage to using more tubes (assuming they're the same type of tubes) to produce less power might be that the tubes are being pushed less hard and might therefore last longer, but I will defer to those in this community with more technical knowledge than I for the advantages.
@ Rcprince, Hi, That is odd that you have that opinion, My opinion is my New rebuilt, Everything 2014 as opposed to what was available in 2005 new inside and out Krell 700cx has a way better sound than the Krell FPB 200 I had many years ago.
Rcprince,
I agree with your general premise. Assuming equal quality of built and implementation I'd take the lower power amplifier with fewer parts, less circuitry and devices. I do believe that they will most often sound better with an appropriate speaker match. There will always be division on this topic.
Charles,
If you are going to have multiple power tubes, it is best to have a lot, assuming there is a mechanism to allow for current sharing among them.

The bigger problem in dealing with high powered tube amps is actually the output transformer, but that is a story for another thread.
More is usually better if done right. Big if though. ALso more means more expensive. The value proposition may or may not be there case by case.

IT mostly boils down to how much of a tube lover one is. There are many ways to skin the good sound quality cat. Tubes are one way but one that only a small minority of listeners today prefer.
Hi Audiolabyrinth. I was referring to amps from the same vintage, with the same basic circuitry. For example, the Jadis JA30 vs. the JA80 vs. the JA500, or the original Krell KSA50 vs the KSA 100, and the KSA 80 vs. the KSA 200. Subjective observations, of course. You're comparing amps from different generations.

Atmasphere's answer is interesting to me, as he is an excellent designer of some very fine amplifiers of different power ratings. Ralph, what are the advantages to having a lot of tubes, assuming that you have very efficient and sensitive speakers (the OP has some very efficient Klipsch speakers)?
Musing: I have a 4 output tube with 4 input tube classic push/pull design amp. It has more than enough juice (65 watts per side, 85 watts peak) to power the speakers I use in the room I use, and when I think about replacing it with a well regarded amp with twice the output tubes I consider the expense of tube replacement or compulsive tube rolling, and all that extra heat from the amp. I might get more efficient speakers someday and score a small pair of mono single ended or OTL amps, but adding more tubes doesn't appeal to me much...at least this week anyway.
IIRC, Atmashpere's comment has to do with better impedance "matching" between his OTL amps and speakers.
what are the advantages to having a lot of tubes, assuming that you have very efficient and sensitive speakers (the OP has some very efficient Klipsch speakers)?

There is less advantage in this situation. What such speakers do allow is that you can have a situation where clipping the amp becomes impossible (we have lots of horn customers...). That in itself is valuable but not germane to the thread.

IIRC, Atmashpere's comment has to do with better impedance "matching" between his OTL amps and speakers.

This is incorrect; what I said was if one is to have multiple output tubes it is better to have a lot than a few. IOW in a larger transformer-coupled amp this holds true just as it does in our OTLs. This, as I mentioned previously, holds true as long as there is a means to allow for current sharing between the output devices.
Could one take away from this that with the Ref 75 and klipsch speakers, clipping the amp is very unlikely?
"In theory," fewer tubes mean less concern with mismatched tubes, which means less muddled sound. A lot of purist won't even except two output tubes per channel in a parallel single-ended setup for this reason.

But, in practice, there are quite a few advantages to more tubes to achieve a given output. One advantage is not having to run the tubes as hard. When run well under their rated output, most tubes will last MUCH longer, and this may actually mean lower cost for tube replacement than another amp that uses few tubes but pushes them much harder. Using multiple tubes in parallel lowers the output impedance meaning a lower turn ratio for the output transformer (arguably a positive result), or in the case of OTL amps, a lower output impedance seen by the attached speaker (higher damping factor).

One of my all-time favorite amps is a custom-built OTL amp that uses many tubes to achieve a 35 watt output. The tubes in that amp, which is often left on for months at a time, have not been changed in more than ten years and still test new.
My viewpoint is the implementation is better than the actual topology is more or less. Ex most tubes go from single ended to Push pull or Ultra Linear as the power of the amplifier goes up.

When that happens sound quality goes down. Then when you think about topology of tube amps no one really builds them like SS so most have no bottom end weight. Few companies give them enough current to drive them right and just focus on watts per channel

I am more to the camp of the less is more, but when it involves compromise to get more then be wary