Tube type vs Wattage

The circuit design and transformers have as much to do with the sound quality of an amp as the choice of tubes. EL34s are widely beloved for their midrange qualities and the KT88s and 6550s have a reputation for a gutsier sound with better bass. But there are exceptions to any rule of thumb.

I've had several EL34 amps (the most recent a Conrad Johnson MV60) and several KT88/6550 amps. Currently I have an Image 65i with 6550 outputs and prefer it on almost all counts to the CJ I had previously.

However it is very difficult to talk about a topic like this in generalities. It will always come back to the following advice: you need to try the amp you're considering in your system, preferably under circumstances where you can compare it against your current amp or whatever the other contender happens to be.

Bass is going to be a function of the output transformer quality, power supply reserve (in the case of amps that are not class A), condition and quality of tubes and how well the timing constants in the power amplifier upstream from the power tubes are chosen.

It is *not* a function of the tubes. Certain power tubes do have greater linearity, which will account for midrange differences where these things are more audible, but bandwidth is not a function of linearity.

So you will have to listen to the amp in the end :) BTW its possible to have the best bass and midrange at the same time...

Atmasphere: Could you provide a few examples of tubes that you feel are "linear" and those that you feel are NOT linear?

(I imagine some designers are not trying to make a linear result and I imagine some consumers don't want a linear result.)

Can all tubes be made "linear" depending on amp design?

Bjesien:
I do not believe one should buy an amp based on its power tubes. Input tube tube type, driver/phase splitter design , coupling caps, cathode caps and the factors mentioned by Atmasphere affect bass response more than the output tubes.
Above all, there is no substitute for auditioning the amp with your speakers.
Having said that, most EL34 based amps I have heard sounded midrangey to my ears, while 6550 amps are all over the place and KT-88 amps tend to have strong bass. This is all subjective opinion IME.
Personally, I would not buy an EL-34 based high-power tube amp, because it would certainly need at least two matched quartets of EL-34 tubes and probably will require a complex bias adjustment procedure every time a tube drifts.

Also, please let us know your speakers brand/model. Matching tube amps and speakers is not a straightforward calculation. More power does not necessarily mean more bass.
Good luck

Thanks for the knowledge guys! To give a little more information I currently have a pair of Verity Taminos (89db 8-6.4)that I've had paired with an AX7e and VSi-55.

The 50 watt VSi-55 drove these with great authority so I think I'd like to stay with at least 50 watts and definitely tubes. Looking for that organic 3D sound with more transparency than the VSi-55 and Tamino combination. I once had a Mastersound amp in this same setup and it sounded like the players were in the room. It was a 300B and all but the bass was extremely satisfying. I guess this is why I got to thinking about different tubes, but from what some of you are saying it might be more the qualities of the amp too.

I've owned and heard many speakers in the 2-4k used range want to stick with these. Perhaps an Avatar or maybe going for separates at some point?

Jj2468, I found the stock Svetlana 6550's to be more linear than the Tung-Sol in the Vsi-55.

Bjesien, why did you give up the Mastersound?

Bjesien
Those are great speakers, congratulations!
They should be easy to drive with tubes.

You wrote:
" I once had a Mastersound amp in this same setup and it sounded like the players were in the room. It was a 300B and all but the bass was extremely satisfying."
This is the famous SET (single ended triode) magic. Unfortunately it is difficult to achieve tight bass with SET amplifiers, though the midrange is to-die-for.

If you want to try SET, I would recommend 845-based amps, they do much better than 300B amps in terms of power and bass control. 845 tubes do have wonderful midrange "bloom", it more than makes up for the slight lack in bass control.
Art Audio and Dehavilland make great 845 amps.
Unison and Viva from Italy also make great 845-based integrated amps.
IMO, avoid the cheap 845 amps on Ebay, there are several reports of weak bass due to sub-dimensioned output transformers.

If you want to stick with push-pull amps, I love the McIntosh Mc275, it sounds very powerful and "in-control", the latest version has about 90W/channel. Its bass is tight and tuneful after burn-in. It has great soundstaging and midrange. I regret that I sold my Mac, it is a great amp.
I understand it is available as an integrated amp with modern looks, the Mc2275.

I have no first-hand experience with VAC amps.

You wrote: "Looking for that organic 3D sound with more transparency than the VSi-55 and Tamino combination",
You may also want to audition the latest ARC Ref 110 amp, if your source has balanced outputs AND volume control. ARC amps do have transparency and soundstaging in spades.

A friend of mine owns a great class A KT-88 integrated amp, the Unison Sinfonia, 30 Watts/channel. It sounds wonderful, with very controlled bass and amazing soundstaging, specially when listening to vinyl. Class A watts sound very powerful, more like 60W in class AB.
I hope this helps

...why did you give up the Mastersound?

The amp was the 24 watt 300BPSE, very nice, solid build, awesome detail, etc, etc. It was loaned to me by an audio friend that was on an extended trip.

Like I said the only thing I missed with this amp was the control over the bottom end. I started listening exclusively to acoustic and jazz because it sounded so great. If it made me listen to my whole collection I would save my money and be done for a while.

Casouza, seems like you know what I am looking for. I read the review on the Ref 110 a few minutes ago and it sounds perfect. Just about 4k out of my used price range. I'll check out the others you have mentioned. It might come down to saving some $$$ and waiting a while.

Thanks for the input!