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Hi folks,

While looking at some 5.1- and 6.1-channels amplifier / receiver / speaker
systems to be used with a new DVD recorder, I noticed that power is rated
in the format: "xxx watts @ 1kHz @ .7% THD".

Now, I will admit to being out of the technical end of the audio field for a
number of years, but are ratings no longer based on " xxx watts RMS per
channel @ 20 - 20,000 Hz @ .xx% THD" ?

Looking at a couple of stand-alone receivers (no speakers included) found
the same type of rating.

My impression is that this is related to the use of switching power supplies
in the new systems.
Is it no longer a case of 'good specs' but rather 'how it sounds sitting on
the shelf at BestBuy' ?

Thanks for any opinions.

- --
Ron n1zhi

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In article ,
Ron Cook wrote:

Now, I will admit to being out of the technical end of the audio field for a
number of years, but are ratings no longer based on " xxx watts RMS per
channel @ 20 - 20,000 Hz @ .xx% THD" ?

Some are. Different vendors prefer to mention their consistent, whole
frequency power, and some prefer to mention their peak power at 1kHz.
For home-theater-in-a-box systems, the target market is generally less
informed, less interested in sound quality, and more interested in
loudness, so whatever games you can play to pump up the perceived
'thump' will help you move more boxes.

Looking at a couple of stand-alone receivers (no speakers included) found
the same type of rating.

Look at better receivers. At www.crutchfield.com, they track many specs
on receivers, including RMS power and the frequency range for which they
are rated at that power. They don't do that for home theater *systems*,
though.

Is it no longer a case of 'good specs' but rather 'how it sounds sitting on
the shelf at BestBuy' ?

I think it's still a matter of good specs, although some experimentation
is necessary to figure out what's good enough and what's pouring money
down the drain.

--
Matthew Weigel
the email address is real
the contents of the post are not

In article ,
Matthew Weigel wrote:

In article ,
Ron Cook wrote:

Now, I will admit to being out of the technical end of the audio field for a
number of years, but are ratings no longer based on " xxx watts RMS per
channel @ 20 - 20,000 Hz @ .xx% THD" ?

Some are.

In fact, I took a look at some of the cheapest sets online, and the $90
AMW home theater system at Circuit City.com has its power rated from
20-20k Hz. Not surprisingly, it doesn't come close in its power ratings
to anything else, at 30Wx5, 15W for center. The next lowest power
rating (by price, anyway) is Sony, 70Wx6, rated at 1kHz. There's
probably a lot less difference between those two systems than Watts
suggest.

--
Matthew Weigel
the email address is real
the contents of the post are not

So long as you are looking at a conventional design a good amplifier
specification to look at is weight. Yes, weight. The components that
produce power and dissipate it have to be larger and heavier in proportion
to the power produced. I refer mainly to the transformer, but also to the
power supply, heat sinks, and chassis.

Wylie Williams
The Speaker and Stereo Store
Saint Louis Missouri


"Matthew Weigel" wrote in message
...
In article ,
Matthew Weigel wrote:

In article ,
Ron Cook wrote:

Now, I will admit to being out of the technical end of the audio field
for a
number of years, but are ratings no longer based on " xxx watts RMS
per
channel @ 20 - 20,000 Hz @ .xx% THD" ?

Some are.

In fact, I took a look at some of the cheapest sets online, and the $90
AMW home theater system at Circuit City.com has its power rated from
20-20k Hz. Not surprisingly, it doesn't come close in its power ratings
to anything else, at 30Wx5, 15W for center. The next lowest power
rating (by price, anyway) is Sony, 70Wx6, rated at 1kHz. There's
probably a lot less difference between those two systems than Watts
suggest.

--
Matthew Weigel
the email address is real
the contents of the post are not

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Wylie Williams wrote:

So long as you are looking at a conventional design a good amplifier
specification to look at is weight. Yes, weight. The components that
produce power and dissipate it have to be larger and heavier in proportion
to the power produced. I refer mainly to the transformer, but also to the
power supply, heat sinks, and chassis.

Wylie Williams
The Speaker and Stereo Store
Saint Louis Missouri


Agreed.

(With regard to my original post: I decided to stay with a good solid stereo
receiver which is also used with feeds from three computers.

Oh, to return to the days when a power supply weighed as much as a house and
was powered by half-inch copper lines fed directly from a local
sub-station )

I actually had an opportunity to look at the input power requirement on a
Panasonic 'home theatre' unit at BestBuy this morning. The product is
advertised as 600 watts amongst six speakers (at 1 kHz), including the
sub-woofer.

It's input power requirement is 130 watts on a nominal 117 vac main.

This reminds me strongly of the late 1960s and the early 1970s when I worked
at one of the major hobbyist-consumer electronics stores.
'IHF' power, 'peak power', and a couple of others I don't recall allowed
power 'ratings' of 100, 200 watts or higher with an input requirement of 50
watts.

I do recall that the FTC (Federal Trade Commission) and no-holds-barred
testing and reviews put a stop to that. When the practice resumed I don't
know.

To be fair I have come across a couple of manufacturers (Onkyo was one) not
afraid to list the actual ratings of units with 5.1 or 6.1 channels.

When I'm ready for a full-blown multi-channel home theatre system I'll start
looking at those products.

- --
Ron n1zhi

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