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From: gt4586c@prism.gatech.edu (WILLETT,THOMAS CARTER)
Newsgroups: rec.audio.high-end
Subject: Re: Class A amps
Message-ID: <6610@uwm.edu>
Date: 26 Sep 90 13:01:33 GMT
Sender: news@uwm.edu
Lines: 44
Approved: tjk@csd4.csd.uwm.edu


In article <6584@uwm.edu>, KLUDGE@AGCB1.LARC.NASA.GOV writes:
> Class A amplifiers are not ecologically unsound.  They do not make energy
> disappear, they merely transform it into heat.  For example, a 120 watt
> Citation II amplifier pulls 750W idling (and also 750W when in operation).
> This means when it's idling, it dissipates 750W as heat, and it is just as
> efficient in this as an electric space heater.  Granted it is not as 
> good a way of heating your house as possible, but it isn't bad.  So think
> of your amplifier as taking a load off of your furnace in the winter.
> --scott
>    (formerly kludge@pyr.gatech.edu... ask chen@debesys about my amplifier)

Of course, there's the opposite problem in summer, when you have to run your
air conditioner harder to keep your room comfortable.  And then there are
those nice fall and spring days when you can just open your windows to get
your house to a nice temperature - with your Class A heater you've reduced
the number of days in which this is possible and increased the number of
days when you have to run your AC.  Of course from the Second Law of
Thermodynamics we knew we couldn't win anyway.

Judging from a couple of Email responses I received from my original post,
some of you just see red when the word environmental is spoken.  Let me
reassure all of you that I was not about to go before Congress and recommend
that Class A amplifiers be banned as ecologically unsound.  Whether you
care about the environment or not, it seems that idling a Class A amp all
day and night at 400+W is wasteful of money and equipment longevity.  The 
answer I was looking for was finally posted recently - use a variac to 
reduce the voltage given to the amp when idling, and hence reduce the power
dissipated.

Now the question is:  has anybody used their class A amp in conjunction with
a variac?  Does it have any unwanted audible side-effects?  Also, a recent
poster noted that he couldn't tell the difference when his amp had preheated
for half-an-hour versus a whole day.  Has anybody else performed a similar
experiment and would like to comment?

And, as always, let us all try to be polite in our discussions here.


-- 
thomas willett 
Georgia Institute of Technology, Atlanta  
gt4586c@prism.gatech.edu
"Violence is the last refuge of the incompetent." - Salvor Hardin (Foundation)