High-current tube amps


Are there any good high-current tube amps besides the Bernings? They need enough juice to drive WP7s well.

As background, I understand that WP7s can be driven by a variety of tube amps, even SETs. Just trying to get more info on high-current tube amps here.
bigamp
>>High current implies doubling output into lower impedences.<<

No it doesn't.

>>But, I could be wrong.<<

Yes, you are.
WP7s are an easy load for tubes. The real issue is how much power do you need- and for that, in many rooms, the answer is that 100 watts/channel is a good minimum.

Just because an amplifier does not double power as impedance is cut in half (and no tube amp does that) does not mean it can't be 'high current'.

But first we have to be clear about what 'high current' means. In the world of tubes, there is no good answer for that, especially since in the past, many transistor amp manufacturers used the term to express how many amps were available in their power supplies!

These days 'high current' refers to the ability to provide the needed current when subjected to certain load impedances, for example 4 ohms as opposed to 8. Well, tube amps do not have the same behavior that transistors do, but its easy enough to get them to drive 4 ohms, although there really isn't any good argument for doing so if the best possible sound is your goal.

Tube amplifiers for the most part will exhibit a 'constant power' quality, that is to say they will attempt to make constant power regardless of the load impedance. Of course, no tube amp actually does this, but the more capable ones come pretty close.

This is quite a bit different from the ideal for a transistor amplifier, wherein the goal is 'constant voltage' into any load. Here is where you find amps that double power as impedance is halved.

The question is: what does that have to do with sound? Is that important to our ears? Most people who are looking into tube amps already know that tubes have a quality that is preferable to that of transistors; so it follows that the importance of doubling power is unimportant. IOW that has nothing to do with good sound. Matching speakers to amplifier is.

So- look at the intention of the speaker designer. If their speaker (in this case the Wilson) is designed to be easy for tubes, then the ability to double power ('high current') is unimportant to the designer's intent for best performance.

For more information see
http://www.atma-sphere.com/papers/paradigm_paper2.html
Thanks for the responses. Very informative as always, Atmasphere. I look forward to listening to some of these amps.
First off put your Wilson Audio Tube ports in the head unit to reduce the required damping factor for tube amps. Since you had a Krell amp prior, I would skip the SET unless it is a 45watt or higher SET. Get that sound from your preamp if you crave the SET

I powered my WP7's with a Music Reference RM200 (100watt into 8ohm) which worked pretty good because it put out 145watts (one of the few tube amps that actually increases as ohm load decreases) into 4ohms but this was a very neutral amp.
I preferred the VTL S400 that I heard at my VTL/Wilson Dealer on WP7's but that might be a little large for your listening room (but the autobiasing that is computer controlled and push button Triode feature, made me drool over this amp). Now VTL has a signature version of the MB450's that has computer biasing also (not quite as advanced as the S400's but also very affordable) In my mind that would be the minimum because of the full range nature of the WP7's... Most people that love SET amps (I've enjoyed a few 300B amps too, but they aren't accurate that's for sure) are use to sacrificing the bass and top end but because they are using some monitor or defintely less than full range they don't realize what they are missing. I've heard the big Manley 500's if you want a more tubey (traditional) sound.

My favorite are the VTL's from an operational (not hard on tubes life) and stunning bass (actually stunning full freq range which I find the hardest challenge for any amplifier solid state or tube). If you like the flexibility of high power solid state amps (control, dynamic reserves, ease of matching) The VTL's keep what you like about solid state and add the air and flow of tubes without loosing accuracy. Pair this with a VTL 6.5 or a VTL 7.5 (no fuss tube preamp with Home theater pass through and with only 2 tubes) and you have amazing clarity and incredible soundstaging!
Someday I'll get a VTL preamp for my system.....