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From: mat@hou5e.UUCP
Newsgroups: net.audio
Subject: Re: Which audio gadgets work (for me)
Message-ID: <540@hou5e.UUCP>
Date: Mon, 6-Jun-83 14:34:33 EDT
Article-I.D.: hou5e.540
Posted: Mon Jun  6 14:34:33 1983
Date-Received: Tue, 7-Jun-83 23:14:17 EDT
Lines: 64

I am replying to a couple of things that appeared in an article recently.
I am proud owner of one of Carver's magic boxes, and I would like to balance
my opinions against these below.

	SONIC HOLOGRAPHY*: ... .  I have found the holography effect to be
	convincing on but a small number of records, primarily small groups.

This is of course subjective.  I find that it improves the imaging on most
stereo recordings, detracts from it on none that I have heard, and makes
a tremendous improvement on a few.  The latter include both Pink Floyd's
Dark Side of the Moon and the Telarc Carmina Burana (Orff).

	Placement of speakers is critical for sonic holography.

Very.  On the other hand, I am now able to check the speaker and chair
position by walking across the room with a familiar recording playing.

	Proper (for holography) speaker placement may by itself improve
	the stereo imaging sufficiently to make the exercise worthwhile.

Best placement for holography is usually closer together than for regular stereo
so this is not always true.  If your speakers are very well placed as it is,
the hologram will probably still require some adjustment.

	Sometimes recordings sound muddy with the holography switched in. ...

I haven't found this, but it is subjective, as well as depending on speakers,
the room, etc.

	Unfortunately, proper speaker placement (for best imaging) may render
	the room useless for other activities.

Sometimes.   Usually there are compromises which can be made on both sides.
It just requires a little work.

	AUTOCORRELATION NOISE REDUCTION: ... To my ears, autocorrelation does
	NOT reduce hiss without affecting instrumental timbers as the
	advertising suggests.

Of course, my ears sre not as well trained as some, but my system seems
to work pretty well.  In fact I have only heard it ``fall down'' once.
This was an old piano recording played on WNCN and the autocorrelator
apparently had to suddenly open every band to let the signal through,
dumping  all of the disk noise through.  Notice that this was cleaning up
not only the FM noise but also the disk surface noise from a 20-odd year
old disk.

In any case, if someone were to offer to buy my Carver preamp for what I
paid, with interest, I would turn him down.  I still have a little work to
do to finish find-tuning the room for the hologram, but it works very
well anyhow.

*SONIC HOLOGRAPHY is a trademark for a process implemented by a set
of patented devices marketed by the Carver Corporation.  This audio
process injects into each channel of a stereo signal a signal derived
from the opposite channel, delayed, inverted, and shaped so that the
added signal just cancels the signal that the ear hears from opposite
speaker.  The result is claimed to be an enhancement of the stereo
illusion, providing depth, height, and apparent sound sources not only
between the speakers, but to the sides of the speaker pair as well.


Mark Terribile
Duke of deNet