Originally Posted by walbert
The points on clipping were well addressed, and your points on program power make sense in their context. The claim about capacitors/transformers (???) magically handling "additional power for transients" was already talked about back on page 1. That isn't true. You keep re-introducing the topic though.
I guess the topic wasn't put to bed for me.
Obviously for you there's not much middle ground, when you say things like:
That's also part of my point. If your current 100W/ch amplifier isn't hacking it, 150W will not do it, 200W might do it, but 1000W is where you'd need to look "next."
Really? If a well-built 100w receiver isn't hacking it, one MIGHT be better served by a 200w XPA-3, but really one should jump to a 1000w amp? Seems a little extreme, to me.
A few dB of compression doesn't sound like much to you, but as I'm sure you know, when you approach the limits of things like amps, the distortion goes up IMMENSELY. Every little increase in volume shows massive rises in the THD. So if one is on the threshold, and only needs a few more dB, it seems like 3dB from an XPA-3, or 6dB from a 400wpc amp would be a big improvement.
Other articles / marketing, like Meyer Sound
suggested there's more to peak handling than just pick the RMS rating that matches your desired peak needs:
Meyer Sound's research has found that, in order to reproduce music without compressing the signal, the power amplifier should be capable of maintaining reproduction of a sine wave at full amplitude (i.e. where the sine wave's peak amplitude reaches the maximum available voltage swing without clipping) into its intended load for at least 500 milliseconds. Meyer Sound refers to the average power during this 500 milliseconds astrue burst power. Peak power output should last at least 100 milliseconds in order to be useful for music reproduction. All Meyer Sound self-powered loudspeakers meet this criterion, and this rating will be included on data sheets for these products. Up until now, Meyer Sound has not published specifications relating to the peak power of this burst.
Here's an article at Enjoy the Music that talks more about peak handling: http://www.enjoythemusic.com/magazin...708/index.html
Regarding capacitors and how few watts they might yield, I agree that the key is in the short amount of time involved. What might be 30 watts for 1 second might be much more for 100ms. Add the transformer to that, and we might be realistically talking about a lot more power for a short duration.
I think the negative attitude towards peak power handling was due to the abuses of not qualifying specifications. And the FTC requirement enforcing a little bit of order, and that being RMS values. That doesn't invalidate other considerations. Conversely, the FTC could've mandated peak burst power for 500ms @ < 1% THD 20-20kHz, and then all the RMS numbers could be all over the place and meaningless, as in the car audio world.
I'm concentrating more on peaks, because I feel there's a disconnect between the realities of the conditions of how we stress amps, versus how we're spec'ing and choosing them.
It seems like there's a difference between two amps that might have the same fully qualified RMS power rating, but one provides more instantaneous voltage for up to 1 second. I'd rather have the latter one, all other things being equal.
I agree that one shouldn't just hope that one will get 1dB to 3dB of headroom for peaks from a given amp. Ideally, one would be able to know which was which.
You aren't going to gain a whole lot having your 100W speakers fed by a 200W amplifier, instead of a 100W amplifier - especially when you're never driving the system to full power anyways.
Are you saying you have trouble imagining a situation where one might need another 100w? I'd say that would come up when someone needs 3dB. If this is not likely, then there are going to be a lot of Emotiva amp buyers who wasted their money!