Tube amps and speaker ohms

I am fast coming to the conclusion to stop looking at "watts per channel" as an efficient means of determining how powerful an amplifier is.

My experience tells me that the power supply and transformers play the biggest role in this, as opposed to whatever reading was obtained when the amp drove a 1 KHz signal through an 8 ohm resistor, or what a company chose to rate an amplifier. Music is not a test tone, it is dynamic, and loudspeakers are not an 8 ohm "dummy load", they are FAR more complex.

Tubes, also seem to have something to do with this whole thing. For example, a 2A3 has less "measured" power (usually, about half as much) than a 300B, but in my experience, the 2A3 does a better job in providing "real world" power to a loudspeaker than a 300B. Similarly, a KT77 looks SO close to an EL34, but they are very, very different tubes, with very different power characteristics. And, for what it's worth, a KT88 is a strong tube. At least as strong as a 6550 or KT90, though the Ei KT90 tube seems a bit more extended in the lows.

In no way am I saying that measurements are something to completely ignore, but clearly, the engineers designing these tests have yet to figure out what is the important criteria, and the means to go about testing it. Until I am told of a better way, playing music through an amplifier and a pair of speakers, and listening with my two ears is going to be the way I test...

Instead of playing games why not spend 2K and pick up a pair of excellent hurricane amplifiers and put power worries to rest.

Thanks for the responses - seems like a real friendly forum.

To some extent, it looks like almost any tube amp will represent a bit of a gamble as long as I retain the B&W 804S's. That's why I was looking at the more affordable chinese brands first, before I consider investing more.

I've not long had the speakers (love the midrange when paired with my Sugden, but the combo tends towards brightness), but would definitely consider trading them for some similar sized speakers that present an easier load and would widen my choice of amps. I always wanted to audition some Spendors but never got around to it - maybe I should now.

I think I'll probably go for a tube amp first though and just see how it works. Another amp I was considering is the Ming Da MC34-AB. Rated a little higher in terms of wpc, but using EL34's I believe. It seems to be more well known, so there there may be someone here who's tried one with B&W 8 series.

Above all, I don't think I want to stick with a transistor amp as, from what I've experienced so far, tubes seem to reproduce music the way I like. A smoother top end, an open midband and a full-bodied bottom end. I do like a powerful bass, so that may present problems given that my speakers appear to demand a lot of watts to produce that. To be honest, I also like the idea of tubes because I can then experiment with different tubes in order to 'fine tune' the sound - something I've enjoyed doing with my guitar and headphone amps.

Divad, You didn't ask, but what the hell.....

If you want powerful bass stay with an amp that is designed around the 6550/KT88/KT90. EL34's are potentially great mid-range tubes but lack the bass of one of these power tubes. In my systems the KT88 has more 'color' (as does the EL34) than the 6550 or the KT90. It reminds me, somewhat of an EL34 with balls.

In your place I would start with an amp designed around the KT88. There are a lot of different brands with different tone available for substituting in KT88's, most new production are quite good.

Re Chinese tube amps (I've got three) be mindful of a couple of things which can be important. Support is #1! If you're not a techie type and can't maintain and fix things yourself, get something which can be serviced without a return to China.

Also, one of the things that some Chinese amps are starting to appear with are on-deck bias meters and bias pots for each tube. Highly recommended feature! Allows you to easily maintain proper bias, follow tube wear, and replace or substitue tubes. Auto bias curcuits are also good for new tube amp users, but IMHO, in the long run manual bias with post for each tube are far more beneficial to the user.

Also, some Chinese amps are now coming with fuses that protect the bias curcuit in case of a tube short. Very important unless you can solder in new resistors. The sonic compromise by having a fuse is, IMHO, minimal if any for most folks.

Hope that helps you a bit.

Thanks for the advice. The Yaqin MC100B that I was looking at has 4 x KT88's and adjustable bias for each tube - access via marked holes in the top plate. I'm not frightened to get into the techie stuff so that appeals to me. A screwdriver and multimeter job, I guess?

Think I'll take a gamble on this one. Can probbaly get hold of one for approx £400 and if I get on with it then I can look to upgrade to something more classy.