[rockadanny]

I was wondering if anyone is using their Fet-Valve Ultra 350 or 550 to drive high efficiency speakers, such a horns. I've been told that to experience all that a high efficient horn has to offer one really needs to use a SET amp, or at least an amp that produces a great first watt. Although my 550 cranks out tons of power, it is rated at less than 0.01% THD from 20-20kHz; is class A for the first 40(?) watts; and as the web site states, "There simply is no roughness or compression in Fet Valve amplifiers." Sounds to me like it should do the job admirably. What say you?

[TomW16]

I can't say that I have heard the FetValve with high efficiency speakers but I do agree with the first watt theory in that if the first watt isn't quality it doesn't matter about the rest.  I would bet that the FetValve wouldn't be ashamed of driving horn speakers and would certainly have sufficent headroom.  I believe that the first few watts are in Class A operation too.

Cheers,
Tom

[modular747]

These amps also have extremely low noise, which is important with very efficient speakers.  Oddly, the grotesquely overpriced SET's aren't very low noise.  That said, the only reason for the reemergence of horn speakers is that they are about the only kind efficient enough for the puny output SETs to drive to reasonable levels.  No matter how well they are designed, no matter how much platinum and asteroid derived iridium they're made of, horns are limited be very audible compression harmonic distortion due to the unavoidable nonlinear properties of air. (That's probably great for SET's as it masks their own extremely high HD.) They still sound like PA speakers.

[Dmason]

Modular,

I hate to say it but your post reads as though written by someone not all that familiar with the actual sound of a good hornspeaker mated to a single ended amplifier of ANY type. What you exclude is the extreme dynamic expresiveness, and ability to convey the emotional content with ease.

As the amp in question is of high quality, the first watt excels and is run in Class A, I would imagine it would be HIGHLY musical with most high sensitivity single drivers. As always, synergy is the "genetic" element in the equation. Not all things to all combinations, to all people, to all ears, etc...

[modular747]

Yes, PA speakers are very dynamic also.  Music, like any other sound, has a dynamic range which can be altered (compressed or expanded) by any part of the reproduction train.  However, "expressiveness" and "emotional content" exist in the listener only, and have as much to do with the emotional state, expectations, and indoctrination of the listener as anything else.

[stereocilia]

No horns, I'm afraid, but I have Legacy Focus 20/20 which are 94.5 (2.83 V), which is on the sensitive side.  They are being driven by a Fet Valve Ultra 350.  The low noise floor is a very useful feature here.

[Wayner]

Some care must be taken driving any high efficiency speakers. No amp/preamp combo is free from noise at some threshold. Depending on location of speakers, efficiency and music source, slight background noise can be heard. I feel very good with the AVA amps driving these types of speakers. The source pre-amp (depending on brand) may also deliver some residual noise that may be hard to deal with If it is bothersome to the listener (in between passages). I would just say to go for it but it depends on the speaker system.

Just remember, a very efficient speaker can be very revealing......hopefully not too revealing. I personally think this is the wrong direction to persue. All AVA amps have more than enough power to drive even the most stingy speakers. If any residual noise is present, it won't even be heard. Many fine speakers are avalible with 85 to 90db ratings.

[avahifi]

The Fet Valve amplifiers are very quiet, typically less than 2 mV broadband noise, and run Class A up to about 20 watts output, so there is no good reason they should not be outstanding high efficiency speaker drivers, unless the users of these speakers are looking for some kind of "sound" from their amps rather than the best that can be done, which is to not screw up or change the source material at all.

Frank Van Alstine

[denjo]

Frank

Is that not akin to driving a Mustang in first gear?

Best Regards
Dennis

[rockadanny]

Thank you Frank, BrianM, Wayner, TomW16, Modular747, Stereocilia, Dmason. As usual, responses I get on AudioCircle are always kind and very helpful.

[denjo]

Yeah, if the quarter mile is the only thing that is important to you. As someone said if the first watt isn't great the rest don't matter.  If you care about music anyway.

Someone also said that if the first watt is great, that's all you need!! The first quarter mile is important to me as much as the rest of the journey. I care for the music, the speakers and my ears!!

I am making a valid point about too much watts into high efficiency speakers. Its a topic that has been covered ad nauseam in many circles, not least Harbeth forum (www.harbeth.co.uk) and many other forums.