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From: hoffman@pitt.UUCP (Bob Hoffman)
Newsgroups: net.audio
Subject: Re: (re)building my speakers
Message-ID: <1036@pitt.UUCP>
Date: Mon, 24-Jun-85 14:45:06 EDT
Article-I.D.: pitt.1036
Posted: Mon Jun 24 14:45:06 1985
Date-Received: Sat, 29-Jun-85 01:40:28 EDT
References: <1123@tekgvs.UUCP>
Reply-To: hoffman@pitt.UUCP (Bob hoffman)
Organization: Univ. of Pittsburgh Computer Science
Lines: 54

In article <1123@tekgvs.UUCP> keithe@tekgvs.UUCP (Keith Ericson) writes:
>	What I've been thinking about doing is blocking the port hole
>that currently exists in the front baffle of the box and re-cutting it
>on the bottom, and then raising the cabinets X inches off the floor,
>where X is "the correct value" to be determined (somehow) later. The
>object is to couple the bass energy to the floor to shake the room up a
>little more. (It seems to me, now that I think about it, that the old
>Heil AMT-1?'s were built someting like this: is that right?)

Well whaddya know.  I still have a pair of AMT-1s, and they do indeed
shake up the room.  I found the resonant frequency of my living room
(accidentally) with them!

The woofers in the AMT-1 were in a "Transmission Line" enclosure.  The
8" speaker faced forward about 2-1/2 feet off the floor, and the tower
enclosure had several baffles in it to lengthen the column of air.  The
port, however, came out at floor level, but faced forward, like the
speaker.  Here's what I can remember of their construction (side view):

	Tweeter (Heil Air Motion Transformer)
	went up here.
	---------------------------------
	|				|
	\				|
	 \				|
	  \----				|
	   |  |				|
	   |  |				|
	  /----				|
	 /				|
	/				|
	|				|
	|	------------------------| <-- Baffles, across entire width
	|				|     of enclosure.
	|				|
	|				|
	|-----------------------	|
	|				|
	|				|
	|				|
	|	------------------------|
	|				|
	|				|
	|				|
	|-----------------------	|
					|
Port opening				|
					|
	|-------------------------------|

I hope this is helpful.  Sorry for taking up so many lines for a picture.
-- 
Bob Hoffman, N3CVL       {allegra, bellcore, cadre, idis, psuvax1}!pitt!hoffman
Pitt Computer Science    hoffman%pitt@csnet-relay