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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. 
fast
fast OP
92 posts
 
Last paragraph in the circuitry section.  
georgehifi's avatar
georgehifi
10,312 posts
 
 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
vtvmtodvm
66 posts
 
fast—Yes, the Krell info that you pointed me to is very pertinent; thanks.  And the DC servo correction that they cite should prove of material benefit in minimizing DC offset drift. As a consequence, I still don't comprehend why Krell doesn't publish a true spec limit for maximum DC offset, but I guess that's a separate issue. Regardless, I'd suggest making periodic measurements of DC offset to assure that it's within an acceptable margin during the first few weeks of operation. Measured results, when properly administered, provide the best evidence.

georgehifi—Yes, true. Most preamps (and signal sources) couple to the power amplifier's high impedance input through a coupling capacitor, thus blocking any DC input, but exceptions do exist. So if you don't know what your own setup does, then do assure a "no signal" test condition by selecting a shorted input.
Re. the 10-20mVdc range that you cite for acceptable DC offset…Yes, that's a tolerable offset range for a class A/B amplifier, but lots of class A power amplifiers typically exhibit greater DC offset. For example, the published spec limit for DC offset on many Pass power amps is 50mV, a value that I feel is marginal, at best. (But I applaud the fact that it's published! Of course, many buyers never read that deep.)
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