Decisions......decisions

[Peter Nielsen]

I think your reading too much into it. Classe has set the transistors to run in class A operation for 33% of the total wattage depending on the amp you buy, taking into consideration heat management. So at low volumes the amp is cool, really cool. Its not either 10watts low bias or 25 watts high bias.

Okay, if this is true, then it sure sounds like Classé is not running in Class A at all.

Technics (by Matsushita Electric Corp) invented many Class A substitution technologies like this in the 80's. You probably remember "New Class A" (1981) and "Class AA" (1986). It was very much about creating an Class A-like amplifier and overcoming the heat output and power requirement problems of real Class A.

Technically speaking, Class A is trivial. It means that the transistors are under CONSTANT load regardless of volume. A "full Class A" amplifier will run continuously at its max power. Its heat output is the same regardless of output volume.

Here's some reading material: http://sound.westhost.com/class-a.htm

Facts, please!

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Update:

I just found this on Classé's webpages:

For Classé amplifiers, output stage DC bias is set to idle at a relatively low level to minimize heat. As the output increases under load, the bias increases, remaining at about 1/3 of the total output power. So for example, a Classé amplifier delivering 100W into an 8Ω load will be operating at about 30W Class A, eliminating any effect of switching distortion normally associated with a Class A/B design.

That settles the issue. Classé is not running conventional Class A. Just like Technics did in the old days, they're monkeying with it.

No offense meant. I owned several high-end Technics "monkey" amps in the 80's and enjoyed them! I was in fact using one of their best "Class AA" amps for 15 years before trading up to Parasound JC-1.

However, I see red when marketing people sell their creations as "Class A" when it is not... Somebody told me that I'm the quintessential engineer, and it is probably true :

Peter

[RebelMan]

Okay, if this is true, then it sure sounds like Classé is not running in Class A at all.

That settles the issue. Classé is not running conventional Class A. Just like Technics did in the old days, they're monkeying with it.

Sorry Peter, I don't mean to get into the middle of this but I am afraid you are coming to the wrong conclusions with regard to Classe's power amplifiers and Class A design. A power amplifier is classified as a Class A amplifier when current is continuously running through its output stage transistors (always on). The amount of current that flows through the transistors does not. Hence, Classe' amplifiers are Class A, perhaps an efficient implementation of Class A, but nevertheless, Class A.

By the way, the article you politely referred to points this out....

This simple model is not really appropriate for general use, since it wastes far too much power, although many Class-A amps still use this principle. The next step is to operate the current source at about 1/2 the speaker's peak current, and modulate its current output to ensure that both current source and power amplifier output device conduct during the entire signal cycle, but are able to vary their current in an appropriate manner. This improves efficiency (which remains dreadful, but slightly less so), and lowers the quiescent dissipation to more manageable levels.

The simple Class-A amplifier described by John L Linsley-Hood and the very similar looking Death of Zen (DoZ) amp on these pages use this latter approach, and it is a sensible variant of the various Class-A designs. As an example, the amplifier will only (?) need to dissipate about 50 Watts when idle, since the quiescent current is reduced to around 1.2 Amps.

Another version of the Class-A amp looks exactly the same as a standard Class-AB (Class-B) power amp, except the quiescent current is increased to just over 1/2 of the peak speaker current. This is thought by some (including me up until I was shown the error of my ways) that this is not a "real" Class-A amplifier. It is real Class-A,...

[Peter Nielsen]

Hence, Classe' amplifiers are Class A, perhaps an efficient implementation of Class A, but nevertheless, Class A.

Yes, you could argue that it still is Class A. However, the Class A drive will vary with time. It is no longer constant. Some of the benefits are lost. To a purist it is no longer Class A.

Also, just think about it. One of the ideas with Class A is that the transistors are run with CONSTANT power. The TEMPERATURE stays the same regardless of volume. Some claim that this is what makes it sound so good. The semiconductors are heated up to constant temperature just like tubes in a tube amp... (Why on earth do people still manufacture and love old outdated tube techniques if they could go with Classé's brilliant power and heat saving inventions?)

Peter

[RebelMan]

Yes, you could argue that it still is Class A. However, the Class A drive will vary with time. It is no longer constant. Some of the benefits are lost. To a purist it is no longer Class A.

Class A in its simplest form is as you described it. Whether this makes a difference (improvement) in sound is a personal (purist) observation not a technical (qualitative) implementation of Class A design.

(Why on earth do people still manufacture and love old outdated tube techniques if they could go with Classé's brilliant power and heat saving inventions?)

Perhaps for nostalgic reasons and hopefully very sensitive speakers.

[Peter Nielsen]

Perhaps for nostalgic reasons and hopefully very sensitive speakers.

If you ask an owner of a vaccuum tube amp (e.g. MacIntosh) why he bought it, I doubt many will say it was for "nostalgic reasons". I bet most will say that it is because they think the tubes sound better than semiconductors...

Peter

[RebelMan]

If you ask an owner of a vaccuum tube amp (e.g. MacIntosh) why he bought it, I doubt many will say it was for "nostalgic reasons". I bet most will say that it is because they think the tubes sound better than semiconductors...

Agreed, it was a facetious remark.

Tube amplifiers do have their place in audio. Perhaps to most owners they do sound better, it stands to reason that they would. Similarly, I find LP's to sound better than CD's but I prefer to own and listen to CD's. Likewise, I am sure many solid state amplifier owners would draw the same conclusions with respect to tubes. The nine JC-1s you own suggests that you did! :lol:

Better in this case is simply a matter of perspective. :wink:

[DrJRapp]

The CD player I own, the Shanling T100 has both SS output (Burr-Brown Op amps) and tube outputs. I've got both hooked up in bypass on separate inputs on my 1098 so so I can switch back and forth at the push of a button on my remote in true A/B fashion. Yes, there is a remakable difference between the tube sound and the SS. The Tube is warmer, fuller, and has better low end weight. The A21 had a lot of the same tube character, perhaps too much, but without the clarity.

So, I listen to the tube output, for SQ and not nostalgic reasons. If you've never seen a Shanling T100, it's far from a nostalgia piece in terms of looks.

[RebelMan]

So, I listen to the tube output, for SQ and not nostalgic reasons. If you've never seen a Shanling T100, it's far from a nostalgia piece in terms of looks.

Hypothetically speaking, if two sources were identical in sound, price and overall outward apperances and one of the those devices sported tubes and the other not, which would you choose?

There are many fine SS devices out there that sound good and look good. I jokingly mentioned nestalgia, but one cannot deny the reality of its existance when choices are made.

[DrJRapp]

That one is easy. The SS for less heat and more longevity.

[DrJRapp]

There are many fine SS devices out there that sound good and look good. I jokingly mentioned nestalgia, but one cannot deny the reality of its existance when choices are made.

I used to think the same, untill I got to listen. James, PLEEEZE take the cotton out of your ears and stuff it in your face till you actually get to hear the differences....lol

[RebelMan]

James, PLEEEZE take the cotton out of your ears and stuff it in your face till you actually get to hear the differences....lol

Jerry, I put the cotton in my ears to hear what you hear (differences). It allows me the opportunity to hear my B&Ws and Rotel simulate the coloring sound effects like that of your Klipsch and Shanling which you are so proud of! :lol:

[nicholtl]

Fellas, it's Saturday night. How about you all go out and enjoy yourselves somewhere outside of a computer room? I know I will be...

[tboooe]

dont mind those two dudes...this is there way of showing their obvious affection for each other....

[RebelMan]

dont mind those two dudes...this is there way of showing their obvious affection for each other....

Perhaps respect would be a better choice of words. :T

[tboooe]

lol...thanks for the laugh...

[RebelMan]

That one is easy. The SS for less heat and more longevity.

Indeed! What reason would there be not to? NOSTALGIC