[Bemopti123]

IThey seem to be the antithesis of K.I.S.S. I think the Pass 350 has 48 output devices.

I remember a reputable Audio technician who repaired Pass gear tell me that once he had to replace a "slew" of these devices on a pair of Pass monos under factory warranty.  I do not know, but that sort of failure makes me think twice before plunging in money on SOTA amplifiers. 

If you have the money to spare, welcome, but brother, the design of an amplifier should not make an electrical failure render it almost like a high tech anchor, should you be the unlucky one facing repair. 

[eric the red]

The Sensible Sound did something in the same vein years ago as the author did a dollars to watts analysis on a few amps and naturally the pro amps were the best dollars per watts value.

[TONEPUB]

Except the Sensible Sound basically says that all amplifiers sound the same.

Depends on what side of the fence you are on.

[YoungDave]

Let it be clearly understood that Frank is a stand-up guy, basing his designs on sound engineering principles.

The cost/weight relationship is cost/weight, not sound quality/weight.  Sound quality, valid engineering, and performance is a whole 'nother thing and their relationship to a product's weight, be it aircraft, car, or amplifier, is not the point I was making.

There are too many guys on this circle that would bench test a unit to determine if it delivers the advertised performance.

This is great.  Missed the point entirely.  Any manufacturer who makes a performance claim deserves to have that claim validated.  Any of us who can test performance ought to do so.  Now, we should all know that a product's sound is not necessarily determined by measurements - but if a manufacturer states a certain performance, then, by gum, it ought to be true and we ought to test it if we can.  An analogy, and a true story:  A car manufacturer claims 300 horsepower.  His cars only make 275.  This does not mean the cars drive nicely or poorly - it just means that the manufacturer lied.  Likewise, I like to know if an amplifier manufacturer lies.  Krell, for example, claiming 150 watts on a box that craps out in 45 minutes during a Stereophile review (they liked it anyway!?!).

For the record, I am not accusing AVA of lying.  I think they are tops.

[TONEPUB]

Frank makes great stuff and I am sure that he and other mfrs wouldn't stay in
business for as long as they have if their gear didn't pass muster.

My experience has been that most mfrs if anything, underrate their gear so
that no matter who is measuring it, it will meet spec.  Now that there is
so much traffic on the internet, it's pretty easy to expose the non truths...

[dorokusai]

Young Dave - I understand your car analogy but isn't the engine often tested without a drivetrain? It probably does create x HP at a given stage, just like any amplifier will produce the posted results at a given stage or distortion level. I don't think they lie, as much as I believe they interpet the FCC "guidelines" in their own way. There are some manufacturers that are better than others and vice versa.

Mark
Polk Audio CS

[Occam]

3 pages of jibberjabber and no one has tipped to the fact an amp biased in class A (Pass) and one biased AB (AVA) are going to have very different physical sizing requirements for some arbitrary power output? 

Both AVA and Pass amps have appropriate heatsinking and transformers for their respective topologies and implementations.

[ricmon]

Even though Franks amps are of the AB type.  He has said before in a previous post the the Fet-Vale apm are heavly biased to class A until more power is needed.  I forget how much they are biased to class A.

[TheChairGuy]

3 pages of jibberjabber and no one has tipped to the fact an amp biased in class A (Pass) and one biased AB (AVA) are going to have very different physical sizing requirements for some arbitrary power output? 

Both AVA and Pass amps have appropriate heatsinking and transformers for their respective topologies and implementations.

Hey Paul - I'm seeing the body of your work in a whole new light - you know what, you might just be a bigger dick than me   

John

[mark funk]

I think I recall Frank saying the Fet/Valve amps are biased Class A for the first 20 watts. As for the weight of an amp, that does not have a thing to do with how it would  sound! Price/Weight PLEASE what are we buying here? Scarp? Boat ankers? maybe. I have a 550, I would say it not only puts out 250 watts per, to me its sounds and feels like a little more then that!  

[Occam]

Hey Paul - I'm seeing the body of your work in a whole new light - you know what, you might just be a bigger dick than me   

John

John - You're right..... It was totally inappropriate of me not to acknowledge how spot on and comprehensive GBB's (Gary's) reply was-
http://www.audiocircle.com/index.php?topic=43838.msg392219#msg392219
What is truly sad is that no one asked Gary for an elaboration on the requirements for full class A biasing in comparison to AB

[Zheeeem]

I think it's a real advance in the state of the art of audio reviewing to evaluate the presumed sound quality of a product by weight.  That will avoid the need to actually listen to a product before buying.

I think the commenter is comparing apples and oranges. If the Pass amp uses an iron transformer and the AVA uses toroidal, then there will be a significant weight difference.  And the chassis will need to be heavier to support it.

The important thing is to have a big enough transformer.  The rest of the essential parts - transistors, capacitors, resistors, etc. have minimal weight.  So I would venture that >>90% of the weight differential is iron.