There are three basic limitations implicit with all high-end class A power amps, so be certain that you're prepared to cope with the challenge that they present: (1) They're big, heavy beasts that generate a lot of heat, so the installation has to accommodate those needs. (2) Class A amps often use fans, and that noise can be intrusive unless there's enough isolation. (3) Minimizing DC offset at the amplifier output is a common problem with all solid-state class A designs. I'd prefer to see a published spec. limit on the maximum permissible DC offset. The Krell Duo 175XD on-line specs don't list any specification for that parameter, so be wary. I don't like to see any DC offset that exceeds 30mV, and 50mV would be the absolute worst case limit that I'd be willing to tolerate.
Advice on Krell amplifier
I am planning to replace my 20 plus year old Audio Research amplifier with a solid state one (tired of dealing with tubes). I’m considering the McIntosh Mc312 and the Krell duo 175xd. The Krell is highly recommended by a trusted dealer as having a “tube like” sound and going well with my other components. My other equipment: Audio Research preamp and phono stage (which I plan to keep) KEF Reference 5 speakers, Innuous Zenith 3 server. I haven’t seen many comments or reviews of either the McIntosh or the Krell. I would appreciate any advice, including comments from people who have heard these amplifiers. Thanks.
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Numerous responders here are Krell amp. owners, so lets ask them to chime in… Hey Krell guys, what DC offset do you read on your power amps? Simply read the DC voltage present at your amplifier's output terminals under a NO SIGNAL condition. (Use a DC multimeter capable of reading down to the 10mVdc or lower range. Place probes across amp output terminals or across load input terminals, whichever is easier. Be certain that you are on Vdc scale, not Vac.) Advise us of your measurement. And does your reading vary much when amp is cold versus right after a heavy listening session? This DC offset is what your woofer will normally see in use, and it will cause the woofer to be offset from its optimal centered position by that voltage. (It's only the woofer that will see any offset because the crossover network capacitors in series with tweeters will block any such DC bias.) |
Thanks vtvm. I’m the op. Never heard of DC offset until you brought it to my attention and I appreciate your help. Reading the Krell information on the amp (under circuitry), I found the following. Is it of any relevance...I don’t know enough to say:http://www.krellonline.com/stereo-amps.html |
Simply read the DC voltage present at your amplifier's output terminals under a NO SIGNAL condition.Inputs should be shorted and not open circuit, or hooked up to a source, even if no music is playing, you don't know if any dc is coming from the source. So best just to use input shorting rca's or xlr's, then measure the speaker terminals for any DC offset 0mv is naturally best but the amp would have to have a dc servo for this to be stable at 0mV, but < 10-20mV is fine for amp with no DC servos.. Cheers George |
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