mag amp audio

[David Halliday (Volt Computer)]

I have one - it is not magnetic but it is a very clever design.  It is a
very nice and fast 15-watt or so Class A amplifier sitting on top of a
large switching power supply.  It takes a look at the input and says
that the output should be about 63.075 volts and it adjusts the
switching supply to its nearest voltage tap and then uses the Class-A
amp to provide the difference.

Since switching supplies are so efficient ( 95% and better ), you can
output fantastic amounts of power with minimal heat buildup.  The little
Class-A amp is cooking but since it's overall power is so small, this is
negligible.

Very very clever hack!  <grin>

( still use it for my subwoofer - works great!  the high-end is not as
good as a Phase Linear ( another one of Bob Carver's designs ) but it is
OK for a first design! )

> -----Original Message-----
> From:	CGS2510.SEP.STUDENT.UCA at CUB.UCA.EDU
> [SMTP:CGS2510.SEP.STUDENT.UCA at CUB.UCA.EDU]
> Sent:	Wednesday, October 08, 1997 10:04 AM
> To:	synth-diy at horus.sara.nl
> Subject:	mag amp audio
> 
> Recall the postings about controlling the inductance of a ferrous 
> core gadget by applying a dc control to an extra winding...
> 
> Well, a trip to a pawn shop reminded me of something that might be of 
> interest to somebody.  Carver at one point made an audio hifi amp 
> that was a mag amp based item.  I believe the one I read about was 
> about 8x8x6 inches or so and delivered a couple hundred watts.  I 
> suspect it weighed a lot, but was very effiecient and physically 
> small per power compared to the tube amps available at that time.  I 
> think this was circa about 1955 or 1960 or thereabouts.
> Can anyone elaborate on this?