Krell anticipator circuits of the 1990s

@invalid    What makes you sure the circuit is fast enough?  What evidence do you have?  I know of no evidence that has been published?

Of course it can be compared in the same way any alternative components are compared.  Listen to one, then the other.

How would you compare it to another amp, unless it has the same exact circuit design one with the anticipator circuit and one without.

@invalid    You used the term 'sounds better'.   We are comparing different amplifiers all the time and expressing opinions as to which sounds better (to the listener).  None of these has the same circuit design, yet we express opinions, sometimes vehemently.

By the way, what makes you sure the circuit is fast enough??

Where’d this “anticipator circuit” come from? 
I also don’t think any “green revolution” is impacting class A amplifier design and production. Anymore than it is driving development or sales of  class A/B,D etc….

As I see it, Krell has been attempting to improve their amplifiers by innovation which includes removing/addressing issues with class A amplification while maintaining the benefits. Heat, and efficiency being the problems with fully class A.

I doubt Krell is just tossing about ad claims to sell product. They are not a mass market company looking to move amps and ramp up production.

I do not, I am no engineer, think the OP bass drum analogy accurately describes what Krell is doing here. It is a sort of straw man. The process is patented. It can be proven on the bench and to the ears. It either delivers its goal or it does not.

It is not as some seem to think, a secret circuit that can tell the future. In the end does it deliver on its promise?

https://www.hificlube.net/media/11276/krell_ibias.pdf 

@johnlnyc    Thank you for this input.

As in my OP, the anticipator circuit is claimed to monitor the output from the pre-amp and adjust the bias quickly enough so that the change has taken effect before that output is amplified.  A tall order I think.

At the introduction of the FPB series environmental issues were discussed.  My KRS200s draw more than 1kW per side.

Just because an idea is patented doesn't mean it is effective.

As a manufacturer previously claiming the benefits of pure Class A, if they wished to sell FPB prorduct it was encumbent on Krell to claim they had overcome the disadvantages of Class AB designs.

Yes the circuit could be proven on the bench but it has not been.  The time that the circuit takes to adjust the bias has never been revealed or found.  To that extent it is a secret circuit.

The paper you publish does not speak of the time it takes to change the bias.

I never said it was claimed the circuit could tell the future.  It does claim it can change the bias quickly enough in response to changes in the signal.  We don't know if that claim is true or not.

Krell has never been forthcoming with any of their circuit designs and schematics. They also came out with sustained plateau bias long before the FPB series came out.

@invalid    I am aware of these facts.

Not so long.   I believe the first variable bias Krell was the KSA300S, launched in 1994.  The first of the FPB series started in 1997.

The krell audio standard was the first variable bias amplifier krell made, it was their flagship amplifier at the time 1993 I believe.

Thanks, right.  It was 35,000 1993 dollars.  KRS200s were around $30,000 in the late 80s, so very much on a par.

Looking around the used ads I find KRS200s are regularly priced around double the 1990s FPBs.  I wonder if this is related to sound quality?

It seems like all of A ksa300s weighs 3lbs more than the krell FPB 600,  seems like it should weight more given it's double the power. The only FPB series amp I like are the FPB 750 MCX monoblocks.

I'm not sure one should evaluate amplifiers by weight although when I bought my first CD player I didn't do any auditioning but just chose the heaviest in my (low) price range on the basis it probably had the best build quality.  Little did I (or anyone else then) know that the SQ in CD players (and all digital sources) depends almost only on the clock, jitter and DA converters.  Reading error even in a flimsy plastic 50c computer drive is only a couple of bits per million.

I doubt the anticipator circuits account for much weight, but compromised Class A working should allow some weight reduction as the power supply section accounts for most of the weight.

Both the FPB 600 and the ksa300s have the sustained plateau bias circuit, krell just lightened the power supply on the FPB series.

Very much as I thought.  No point in carrying power supply capacity that will never be used.