Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!think.com!mintaka!ogicse!milton!whit
From: whit@milton.u.washington.edu (John Whitmore)
Newsgroups: sci.electronics
Subject: Re: Power supplies for audio amps
Message-ID: <1991May11.005101.5378@milton.u.washington.edu>
Date: 11 May 91 00:51:01 GMT
References: <1991May9.120758.20464@umbc3.umbc.edu> <822@newave.UUCP>
Organization: University of Washington, Seattle
Lines: 19

In article <822@newave.UUCP> john@newave.mn.org (John A. Weeks III) writes:

>Soundcraftsman used to advertise something called class 'H' amps.
>These were basically two stage amps that had a quality low power amp
>plus an extra high power stage.  The high power stage could not run
>continious duty, so it was used only for peaks.  The end result was
>a quality low power amp the acted and sounded like a much more powerful
>amp.

	The 'class H' amps started with Hitachi, I think.  Most
of Carver's units use this same principle (and the highest power
ones have THREE positive and THREE negative power supplies).
	Amplifier efficiency depends on the difference of
the power supply voltage and the output voltage; on the 
average, that efficiency goes WAY up when there are several
possible power supplies (and the least of them is used until
the signal demands more...).  
		
	John Whitmore