Liquid cooled hybrid tube / SB mono-blocks …ROCK solid bias… love them…. and a SS sub :-) 1.2 KW per side… fun
Enjoy the music
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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KRELL is going to release a uber XD amp around Christmas time, KSA 400i. It will be an iBias amp with some new enhancements. It is supposed to be better than the base XD amps. Which makes it a must listen for me. The 2 base XD amps I have owned have been very good to excellent (K-300i and 175XD). The power rating for the new KSA 400i: 400 -> 800 -> 1600 -> 3200 Watts 8 -> 4 -> 2 -> 1 Ohm SoundStageNetwork.com | SoundStage.com - Talks The iBias designer is on this video talking about the new amp. He actually explains how iBias works in this video. |
I owned a FPB-300 for about 20 years. Great sounding amp. This replaced a pair of Krell MDA-300 monoblocks. I thought the FPB-300 sounded as good and ran a lot cooler. I don’t think it really matters if the bias can adjust instantly. In fact, I suspect it odd preferable for the bias to increase gradually. There are many class AB amps that have no problem providing excellent dynamics, so running class AB for a free milliseconds Should not be a problem. At any rate, these were very nice sounding amps and did receive excellent reviews when the first came out. The only real problem is the capacitors used don’t last very long and are time consuming to replace. |
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