Re: Uli Behringer of The Music Group Q&A
This is a similar issue to loudspeaker power handling, two opposite sides of the same coin, i.e. how to quantify this (not continuous sinusoidal) music power that either speakers can handle, or power amps can make.
Loudspeaker professionals have gravitated toward noise, or shaped noise testing as more useful than sine wave testing. Power amp specification have so far resisted such conventions.
Opinions surely vary about this and consumers are not very good about understanding the nuances of complex specifications. The marketplace has pretty much evaluated amp technology based on how it performs in the real world, with real loads and real music.
I recall the hand wringing decades ago when amp technology evolved from continuous 24x7 duty, to reduced duty cycle music power. The marketplace voted overwhelmingly for reduced duty cycle (with the reduced cost). The rest is history.
Max sine wave power roughly correlates with PS rail voltage. All things equal (similar technology and design rigor) consumers can use this to compare amplifiers. Where they encounter gotcha's is when one model scrimps on how long it can deliver that voltage limited output. The marketplace and word of mouth generally polices where amplifiers end up in the pecking order.
Its actually more conflicted than that. We have had the technology for decades to make accurate and repeatable test stimulus with digital sound files, but the million dollar question is what exactly should be in that 'industry standard" sound file? I have pondered this for a long time and this is a difficult question because the test would effectively determine winners and losers in the amp marketplace based on how you measure against this arbitrary sound file.
Big dog amp designers for decades have not been able to rely upon sine wave testing to fully evaluate their designs, so have used alternate tests like a few favorite CD tracks, and rigorous field testing. Since a CD will generally be more compressed (less dynamic) than live performances this can be useful, and they have been doing that for decades.
Perhaps this was John's actual question for Uli.. i.e., how do his engineers evaluate their amp designs in this absence of industry standard metrics? This is a pretty well discussed topic on professional forums.
This evolution and more than thousand watt power amps have been around for more than 15 years. Over decades there has been an ongoing arms race between amp makers and loudspeaker makers to balance amp power output and loudspeaker driver power handling. At the very highest power points for both, the design task becomes a matter of peaceful coexistence with the SOTA, but in general the very high peak power output systems do not get operated at abusive high average power duty cycles, like lower power systems.
Another confounding data point is the mains power limitation for many users who don't provide their own electrical distribution. So there is an upper limit to how much power we can pull from a typical outlet before popping a breaker or fuse. This has driven technology toward more effective power extraction (like power factor correction) and switching technology to reduce PS losses.
Established players have nothing to gain by publishing their benchmarks. It would only provide those inclined to copy a roadmap for how to compete against them. I don't think consumers are being injured by this status quo, and a fair system of complex power tests along the lines of speaker power handling would be just as confusing to consumers, if not more.
I remin agnostic about the utility and/or need for duty cycle standards. I don't see the need for market intervention with imposed standards like back in the 1970s when the FTC stepped in to squash the ridiculous overstatements of hifi amplifier power. The professional market is efficient enough to sort out the real deal from the fakers, and there isn't one definitive measurement that would be universally meaningful for all musical genre's.
I wish Uli good luck with his new amp. I have seen the progression toward higher efficiency since class A/B was first replaced with class G/H (a huge improvement) and later by class D (a smaller but still useful benefit). With every improvement the amount of waste heat left to recapture gets progressively smaller. Now I suspect the foot race is mostly to make them cheaper.
JR
