From: logan@ccwf.cc.utexas.edu (Logan Shaw)
Newsgroups: rec.audio
Subject: Re: Watts/channel question (Was: Sony ES vs. Sony A/V receivers)
Date: 19 Dec 92 08:30:49 GMT
Organization: The University of Texas at Austin

In article <1glf7sINNl9v@iskut.ucs.ubc.ca> twong@civil.ubc.ca (Thomas Wong) writes:
>Talking about watts per channel....
>I'm looking at getting a new receiver (probably one of them new A/V Pro
>Logic ones) and one of the salesguy told me that for the type of music I
>listen to, instrumentals and classical, clipping is of an issue hence I
>shouldn't get any receiver with less than 100 w/ch for the front
>channels at least. I was looking at getting a "no so expensive" unit
>with maybe up to 80 w/ch up front, maybe even down to 70 w would do?
>What do you all think about clipping? 
>
>I was also looking at the above mentioned Sony but if it's only 75 w
>up front... and clipping is an issue, I might have to rule this one
>out.

There are several issues to consider:

How powerful is the amplifier, for real?  A simple watts per channel rating
doesn't tell the whole story.  How much is the headroom?  Take, for an
example, the NAD 7240 receiver.  It's rated at only 40 watts per channel,
but it has a 6 dB headroom, which means that on peaks it can deliver 160
watts without exceeding the distortion ratings.  It can even drive 2-ohm
loads to 250 watts on peaks.  Suddenly, it doesn't sound so wimpy just
because it's a 40 watt receiver.  Many receivers have very low headroom
(probably because consumers don't usually pay any attention, so increasing
headroom won't increase sales), not uncommonly less that 1 dB.

Also, ratings are somewhat arbitrary.  Different manufacturers might give
the same amps different ratings - some rate conservately, and others
(mainly car stereo manufacturers) tend to exaggerate their products'
capabilities.

In other words, a 100 watt reciever would be better if all other things
were equal, but probably *not* all other things relating to power output
*are* equal, but only a little better.

Increasing amplifier power by 25% probably isn't going to make much of a
difference.  (i.e. a 100 w/ch amplifier is only negligably better than an
80 w/ch).  Yes, it's a whole 20 watts more, but it's only something like
1.5 decibels difference in actual power.

How efficient are your speakers (or the speakers you plan to get)?  Wasn't
it Paul Klipch who use to brag that the Klipschorns could produce the same
sound level as the Cinncinnati Philharmonic (or something) with around 1.5
watts?  :-)  Speaker efficiency can easily make more difference than
amplifier power ratings.

What are the anticipated surroundings?  If you live in an apartment, you
might be quite satisfied with 20 w/ch - that's what I have, and I can't
come near overdriving my receiver without getting complaints from the
neighbors.  If, on the other hand, the system is going into a giant living
room, maybe you'll need more power.

You may or may not need a really powerful receiver.

I guess ideally you'd be able to try out the system you plan to buy with
all the components together, listening to your music, in a room like yours
(or actually in yours) and see if it really does what you want.  Some
dealers will let you do that, especially if you're making a big
investment.

Hope this helps...

Adios,
  Logan
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From: myers@hpfcso.FC.HP.COM (Bob Myers)
Date: Fri, 18 Dec 1992 20:14:26 GMT
Subject: Re: Mr. Pierce responds to Re: Class C amplifiers, says Mr. Pierce.
Organization: Hewlett-Packard, Fort Collins, CO, USA