Re: Peal Power

"William Sommerwerck" <grizzledgeezer@xxxxxxxxxxx> wrote in
message news:5tudnciv-tf-YqjbnZ2dnUVZ_jqdnZ2d@xxxxxxxxxxx
I assume this is to make an amplifier seem more
powerful than it is?

No, PMPO is for that. ;-)

For the young'uns -- that's Peak Music Power Output.

Music Power was based on the unproved assertion that an
amplifier can produce more power for brief periods than
it can continuously (that is, before the output stage
power supply begins to sag).

That is an assertion that can easily be shown to apply to just about any
non-regulated power supply.


The assertion is true -- unless the amplifier has a
regulated power supply for its output stage (few do) --
but musical peaks usually last at least a few seconds,
which is more than enough time for the voltage to drop.

After working with 100's of recordings of music and now even 1,000s
recordings of music, I can't avoid calling that an unproven assertion. In
fact it is an assertion that is easy to disprove.

The largest peaks in recordings are very often very short term freaks of
nature, perfect waves due to chance juxtapositioning of musical sounds.

Next largest are dynamic peaks based on modulated envelopes of tones, such
as drum hits. The over-all wave lasts for many milliseconds, but the peaks
are often of far shorter duration.

It was the abuse of Music Power ratings that got the FTC
to set standards for amplifier output power.

Fact is that other than hypercompressed recordings, the peak-to-average
ratio for general recordings is 15-20 dB, while hypercompression brings that
down to no less than about 8 dB. Bottom line - there's no justification for
expecting a power amplifier to produce rated power 100% of the time for more
than a few seconds, let alone a few minutes or 10s of minutes.

That mostly impacts heat sink sizing, but as power amp power supply
technology moves over to switchmode, it will relate even more strongly to
power supplies - because power supplies will have even more heat-sinking
issues than they have with traditional power line frequency based designs.


.

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