looking for a pure "Class A" amplifier

[SoundEngine355]

Hi,

Is anyone aware of any manufacture that does a pure Class A amplifier design? Only one I can think of is Pass-Labs.

[Alaric]

There are a bunch out there. My little Marantz integrated is Class A for the first 25 or so watts. With reasonably efficient speakers you can do great sonic damage with Class A!

[recca]

Monarchy Audio SM-70 and SM-70 pro are pure class A. They sound really nice when run as Balanced Monoblocks. Pretty easy to find used on Audiogon. Stress the balanced part, really makes a big difference for them.

[GregLett]

One of the lines I have access to Audia Flight does.

http://www.audia.it/uk/audia_flight_50.html

[dtb300]

Plinius Audio has amplifiers with a toggle-switch for selectable A/B or A modes.
Pictures for those that need to see...

[Alaric]

If you check the specs on the Audia , you'll notice it "doubles down" as ohms decrease. A pure class A amp generally needs a hefty power supply-never a bad thing in an amp. The Monarchy Audio specs seem similar.
Just bear in mind , Class A amps put out some heat-you'll need proper ventilation. Some of the Krells can double as space heaters!
While I don't know GregLett personally , his posts indicate a familiarity with quality gear-being a forum sponsor doesn't hurt either!

[Hdale85]

I know a couple people that have done business with him and he seems pretty stand up

[Russ L]

Hi,

Is anyone aware of any manufacture that does a pure Class A amplifier design? Only one I can think of is Pass-Labs.

The Krell KAV-400xi is pure Class A. At a good price as well. Note the extra room for the power supply to diissapate heat.



(Edit: I see that Lee has mentioned them already.)

[Alaric]

Russ , that Krell is a beast! I would love to get my paws on one. Good call!

[krek]

xindak?

http://www.xindak.com/english/products/showditail.asp?id=253

This 26 kg unit only costs around 900 euro's in Europe. I would like to hear it perform..

[twitch54]

The Krell KAV-400xi is pure Class A. At a good price as well. Note the extra room for the power supply to diissapate heat.

Calling it 'pure Class A' is some what of a stretch, for it does so UP TO the driver/ output stage only.

[Alaric]

Still want one. Maybe two.

[Alaric]

xindak?

http://www.xindak.com/english/products/showditail.asp?id=253

This 26 kg unit only costs around 900 euro's in Europe. I would like to hear it perform..

A lot of stuff from Red China looks very good. Still the enemies of my country so I'd have to pass. Doesn't affect the sound quality at all , but I'm cursed with patriotism.

[wettou]

One of the lines I have access to Audia Flight does.
http://www.audia.it/uk/audia_flight_50.html

very nice, I would be worried buying Italian electronics QA is not their forte on the other hand design is sublime

[krek]

Red Rose amps are made in China (AKA Dusson). B&W is made in China. The german company Vincent is importing and re-labelling from China (AKA Sheng Ya). Grohe sanitary ware is made in China.

[H.T.C]

very nice, I would be worried buying Italian electronics QA is not their forte on the other hand design is sublime

Sonus faber and opera speakers are italian which produce very good speakers and customer service must be as well or the absolute sound and stereophile mag would have made a statement to the opposite.

[H.T.C]

A lot of stuff from Red China looks very good. Still the enemies of my country so I'd have to pass. Doesn't affect the sound quality at all , but I'm cursed with patriotism.

In the political sense you would have too stay away from b+w/roy hall and just about any consumer electronic giant or manufacturer out there.

[Face]

Here's my Class A baby.

[Victor]

Face,

Nice picture! Looks like a DIY effort. Can you tell us more about your amp and where did you get those heatsinks?
Victor

[Johnloudb]

Hi Face,

Really nice work! To guess, I'd say it is a Nelson Pass F5? Then again I don't see a thermistor, well tell us know what that it is!

[Russ L]

Calling it 'pure Class A' is some what of a stretch, for it does so UP TO the driver/ output stage only.

I'm not the only one to make that "stretch". Here is Philip Beaudette from Soundstage reviewing the KAV-400xi: "A low-negative-feedback design that features a fully balanced signal path from input to output. All circuitry up to the driver stage is pure class A." :W

[twitch54]

I'm not the only one to make that "stretch". Here is Philip Beaudette from Soundstage reviewing the KAV-400xi: "A low-negative-feedback design that features a fully balanced signal path from input to output. All circuitry up to the driver stage is pure class A." :W

Not sure what your point is ????? for what you quoted is eactly what I said ???

FYI, "Pure Class 'A' throught" INCLUDES the output stages !

besides anybody looking at the pics of that thing could easily see that the outputs are not biased class A with those meager heat sinks !!!!

[joetama]

Plinius Audio has amplifiers with a toggle-switch for selectable A/B or A modes.
Pictures for those that need to see...

Those are some expensive looking heatsinks... :T

[Russ L]

Not sure what your point is ????? for what you quoted is eactly what I said ???

FYI, "Pure Class 'A' throught" INCLUDES the output stages !

besides anybody looking at the pics of that thing could easily see that the outputs are not biased class A with those meager heat sinks !!!!

The point is that I was citing "pure Class A" from that quote from the Soundstage! reviewer in response to the OP. If the reviewer and/or engineer feels that enough of the design is Class A to call it "pure Class A" even if its only "up to the output stage" then who am I to argue. I suppose one of you is right or maybe both. I count on you engineers to keep me informed! My last post was made in a lighthearted fashion and in partial jest. Some of us don't take amp topology quite so seriously and are here for the end result- the music!

[dtb300]

Those are some expensive looking heatsinks... :T

It can be expensive, but if you are in the right place at the right time, it can be purchased at a significant discount.

The Plinius has to be one of the best sounding SS amps I have heard to date. Before purchasing I listened to many SS and Tube amps and the Plinius won out handily. None of the amps gave me the sound quality, frequency extensions, and control of my panels all in one package like the Plinius did.

The Plinius in A/B mode it is a very nice sounding amp, but in Class A it is a whole 'nother beast. In A, it has phenomenal midrange, sweet highs, and controlled authoritative bass.

Best thing about the amp is the user gets to select when to run A/B or A, so you have the heater mode when you want it.

[joetama]

It can be expensive, but if you are in the right place at the right time, it can be purchased at a significant discount.

The Plinius has to be one of the best sounding SS amps I have heard to date. Before purchasing I listened to many SS and Tube amps and the Plinius won out handily. None of the amps gave me the sound quality, frequency extensions, and control of my panels all in one package like the Plinius did.

The Plinius in A/B mode it is a very nice sounding amp, but in Class A it is a whole 'nother beast. In A, it has phenomenal midrange, sweet highs, and controlled authoritative bass.

Best thing about the amp is the user gets to select when to run A/B or A, so you have the heater mode when you want it.

I agree, Plinius are some very nice amplifiers. After building my own amplifier heatsinks are one of the things that draw my attention. I remember those type heatsinks being pretty steep. But they look cool and have a lot of surface area which makes them very useful.

[dtb300]

I agree, Plinius are some very nice amplifiers. After building my own amplifier heatsinks are one of the things that draw my attention. I remember those type heatsinks being pretty steep. But they look cool and have a lot of surface area which makes them very useful.

And the Plinius heat sinks really work well. I have measured temps around 150F right where the sinks meet the chassis in Class A. You can put you hand there for just a second or so before it gets really hot But at the very end of the sinks you can keep you hand there for quite a bit longer. A true testament on how well they dissipate the heat. In A/B mode the amps run very cool to the touch - almost no heat at all.

Remember kids do not try the above unless you have direct adult supervision - and then do not try it :rofl:

[twitch54]

Remember kids do not try the above unless you have direct adult supervision - and then do not try it :rofl:

You know Dan, with my 'Plinny' sitting idle in the corner maybe I should fire it up tomorrow AM and cook breakfast !

[dtb300]

You know Dan, with my 'Plinny' sitting idle in the corner maybe I should fire it up tomorrow AM and cook breakfast !

Naw, I think you should sell it to me for use as Mono's in my setup.