Path: utzoo!utgpu!attcan!uunet!convex!killer!ames!pasteur!ucbvax!hplabs!hp-pcd!hplsla!tomb
From: tomb@hplsla.HP.COM (              Tom Bruhns)
Newsgroups: sci.electronics
Subject: Re: Homebrew audio equipment
Message-ID: <5170019@hplsla.HP.COM>
Date: 28 Jul 88 17:52:42 GMT
References: <1075@gethen.UUCP>
Organization: HP Lake Stevens, WA
Lines: 29

I didn't notice any replies here mentioning "The Audio Amateur" as
a good source of DIY audio articles.  I don't even know if they are 
still in business, but they sure used to have a lot of really nice
articles.  I dropped my subscription for lack of time to do anything,
not because they didn't have lots of neat stuff.  Everything from
the signal source to the speaker, with test equipment on the side.

I did build a few channels of a friend's design -- precursor of the
stuff put out by DB Systems.  It helps a lot to have a PC board
design, but of course you can do it point-to-point, too.  We used
regulated power supplies, because hum on power busses can cause
very significant intermodulation when the amp is driven to clipping.
Probably a better way is a clipper at the input so the amp stays
linear all the time.  We had a switch to go between class AB and
class A; my tin ears could never tell the difference.  I believe we
got typical distortion in the .005% range at all powers/freq's;
DB guarantees a little better than that as I recall.  These are
relatively low-power amps -- 30-40 watts into 8 ohms.  But they
can drive down below 2 ohms with no significant distortion
increase, yielding more like 120 watts.  That, of course, makes them
good for bridging.


Anyway, the point is -- yes, you can build some really good stuff
yourself.  If you keep your mind open as you do it, you will learn
a whole lot!

Tom Bruhns
uucp:  ...!hplabs!hplsla!tomb