Moulton Laboratories
the art and science of sound
Power Amps Revisited: The Joys Of An “Audiophile” Amplifier
Dave Moulton
March 1997
1. Our story to date

Dave reviews the R.E. Designs LNPA 150 power amp.

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Power Amps Revisited: The Joys Of An "Audiophile" Amplifier

Our story to date:

Couple years back, when I did some double-blind tests on a bunch of power amps, my basic conclusion was that studio amps were all pretty much alike, pretty good, and that the main issues were power headroom and damping factor. Since that time, I’ve just not been worrying about power amplifier issues. Been there. Done that.

Recently, a guy named Dan Banquer, who builds audiophile-quality power amps (R.E. Designs LNPA 150) brings a pair of amps over one Saturday for your usual critical listening session.

These amps’re big monoblock units. Modest rated power, about 80 Watts, expensive at $2700/pr, but not totally whacked like some of the really pricey audiophile units. Banquer sez they’re really quiet for power amps. We measure the noise floor at around -80 dBu at full gain, which is about 120 dB dynamic range. Not shabby - enough for 20-bit anyway. Also, they have no cooling fans, don’t hum or buzz. Better and better.

Put up some music. System sounds decent, damn decent. Cue up my current “test” CD (Arvo Part “Credo”), which at its loudest it sounds like someone dropping a Mosler floor safe down a stadium stairwell during the 2nd OT of an NBA playoff game. When I run at reference levels during this passage, my usual amp ‘n monitors get just a little, er, “hard.” Banquer’s LNPA 150s sound a good bit more transparent. Set up the TEF ‘n B&K mic, do a Noise Level Analysis. Lmax (the highest level measured) is around 109 dB SPL. Hmmm. Orchestra sounds really solid and full, but definitely not “hard” or even particularly loud.

Listen to some other stuff. Pink Floyd’s “The Wall.” It sounds really open. Phantom images are really solid. Speakers sound great. I’d like a little more level, though. Add three dB. Now we’re getting somewhere. TEF sez Lmax hits 112. Actually, it doesn’t sound that loud.

Put on some laid-back acoustic vocal stuff. Add level. Sounds really nice. Full, accurate, detailed, smooth. TEF sez Lmax is 114 dB SPL! Leq (sorta like 0 VU) is up to 103 dB SPL. Egads! What is going on here?

You gotta understand. My normal listening reference is 85 dB SPL, and peaks might hit about 95-100 dB SPL. When I get to sustained levels of about 95 dB SPL with peaks of around 107 dB SPL, my amp ‘n monitors generally begin to hurt my ears. FYI, I’ve never, repeat NEVER EVER, run that system, with its 250 Watts per channel, at sustained levels of over 100 dB SPL. Yet here’re these 80 Watt monoblocks effortlessly cruising at well over 100 dB SPL. And it doesn’t sound particularly loud, just full! Amazing!

Using These Amps Over Time

Dan left me the amps to try for an extended length of time. They’ve run effortlessly, transparently and cool. A pleasure to have in place. When we showed my monitors to major manufacturers at the AES in LA, we took along the LNPA 150s as our amps of choice (Thanks, Dan!), and once again, they performed beautifully. One designated Golden Ears said that our demo was the best thing he heard at AES! I don’t know quite what I’m gonna do when Dan asks for the amps back.
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