@invalid Sorry. I meant to type KRS200s.
Krell anticipator circuits of the 1990s
"Krell FPB-600 Stereo Power Amplifier
This big power amp features the evolution of the plateau biasing circuit introduced in the KSA series of amps. This circuit anticipates the power demands of the output by monitoring the incoming signal as the demand for power increases, the more power the amplifier supplies. After a grace period of fifteen seconds and no additional high current signal demands, the Krell FPB-600 amplifier returns to its appropriate power setting. This feature allows for Class A bias output without all the wasted electricity and heat."
Do you believe the anticipator can up the bias quickly enough? A guy hits a huge bass drum, the anticipator circuit senses this and ups the bias in time for the hit to be amplified in Class A?
We are talking a micro second. Once he hit it the start of the moment was over. This was a con. Created by Krell because they were under pressure from the emerging green lobby to cut power consumption. Qualified Krell service engineers have not been able to explain to me how it can work.
Me? I still have my KRS200s. Pure Class A. So there's my answer.
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@clearthinker Did you watch the video I posted? I think that answers the initial question you posed on this thread. |
I might be in over my head on this, and I really don’t know how Krell actually manages this, but I can imagine that if there was an opto-coupler at the amps input it could possibly alter the bias faster than the speed of sound and closer to the speed of light to adapt the output accordingly. If Krell uses digital manipulation to accomplish this, there might be an issue of close proximity of digital noise contaminating the analog signal, I am curilous to know how Krell actually does accomplish this. |
@yyzsantabarbara Yes I did watch the video. This adds nothing to the story. The Krell personnel say the Class A watts output is varied according to monitoring of the watts of the signal output. It does not say how it is done - 'we've found a way...', 'a very high degree...'., 'this is completely new...'. All this is marketing puff. It does not say how long the amp takes to adjust the bias in response to the measured output. Since Krell must know the length of the delay, we are left to assume it must be relatively long. If it were so short that there is an argument that its effect is inaudible, Krell would surely have told us the details. This is all very unsatisfactory and in the result I continue to use my KRS200s. |
- 63 posts total