AHAH. that’s what I was talking about
Quoted From that thread:
“…., while getting my goosebumps I noticed some flickering lights from the AHB2, and of course they were the right/left clipping warning lights. I also heard the speakers seeming to be a bit distressed. I immediately lowered the volume of course but I did repeat the episode and clearly at -10 to -15 the amp was clipping.
The Revel's are fairly efficient (high 80s i believe) and in the Audioholics review Larson characterized them as "easy to drive". Especially given the support from the subs I really thought I would never see the amp clip. Based on this experience I clearly need to keep the volume reasonable and preserve my hearing but now I realize I'm closer to the max ouput of the amp than I thought.”
Generally, I think this is true for most listeners more often than they realize, if they listen to truly dynamic recordings (which most are not). The assumption of "operating within their envelope" is less often a reliable assumption than we realize, if the use case is playing music really loudly (dangerously loud for typical compressed content when the average loudness is high relative to the peaks).
I started out listening to 86-dB Advents using a 45-watt Kenwood integrated amp. It's an excellent little amp, and reasonably efficient speakers at a meter or so can be made very loud with it. But less-efficient speakers at 2 or more meters, maybe not so much for spirited listening to content with dynamic peaks. I upgraded to a Spectro Acoustics 202, which was transformational in that it could play effortlessly loud with those Advents in my smaller rooms. When it went up in smoke for the second time, I replaced it with a Carver commercial amp that lacked guts, and may simply have been assuming commercial-level inputs (+10 dBU balanced inputs instead of -4 dBU single-ended inputs), though my Onkyo preamp at the time could certainly crank out some voltage. (Guts = ability to play
peak content loudly without distortion or compression). I switched to a cheapie Samson commercial amp that supplied guts and maybe not much else. It was otherwise fairly crappy, but the ability to drive peak listening levels made a bigger difference in my listening experience than did particularly low distortion. More recently, that amp also failed and I bought a
much-better B&K Reference 125.2, 125 watts into 8 ohms with plenty of headroom. It drove the Advents pretty well, but I still ended up stacking Advents and running the other pair with an identical B&K amp--the equivalent of 250 watts/channel into 86-dB speakers. That fulfilled my use case admirably, but failed in many other objectives, with horrendous comb filtering that would change the sound very noticeably if I blinked or took a breath and nothing resembling real imaging (because of where two pairs of Advents had to be placed in that peculiar room). I switched to the Revel F12's with the amps separately driving the woofers and higher drivers (an illusion that added no power benefit, of course) and the additional efficiency of those speakers made a difference. But the B&K amps ran hot and I didn't have a place for them that made cooling easy, plus it was time to try something new, and that's when I bought the Buckeye amp.
But even at an honest and very clean 330 watts/channel into the (nominally) 6 ohms of the Revel towers, the amp will show the clipping indicators when playing dynamically recorded percussion music at high loudness (the drum solo on the Chesky demonstration CD is my test piece for checking this--it's easily the most dynamically recorded percussion I've ever heard). But only the most dynamically recorded music can tolerate the level required to flash those LEDs--most recorded music would drive even me out of the house if the peaks were that loud, not to mention hearing damage. When I play an only mildly processed recording, such as, say, Rick Wakeman's
Red Planet, I can't make those lights flash at any tolerable listening level. True also listening to, say, Bruckner's 8th Symphony played loudly enough for me to blast along with the brass section on my tuba--I don't see the clipping indicators for that, either. I am playing that music significantly louder than any audience member would hear it.
So, I'm not prepared to disagree with the notion that the AHB2 isn't as powerful as would be needed for some content to be played at reference level in relatively inefficient speakers. (Though two of them as bridged monoblocks certainly would in any residential setting for mortals that I can think of.) But I do think it's easy to overstate how loud that needs to be, especially for normally recorded acoustic music.
Rick "whose Revel F12's play 91-dB at 1W/1M" Denney
