[net.audio] Carver holograms etc.

newman (12/21/82)

I heard the Carver sonic holography unit at some length under reasonably
good conditions, and was extremely impressed. It is, however, ridiculously
expensive for an accessory device (the C-1000 (?) outboard unit) and its
inclusion in their new preamp makes for a superb but ridiculously expensive
preamp. Anyway, back to the sound. The description of the device's purpose
recently posted to the net was not too accurate; its purpose is NOT to make
the sound appear to come from points slightly outside your speakers, but to
eliminate (?) the characteristics of sound reproduced by a pair of speakers
that tell the ear that it is a pair of speakers being heard. It is certainly
NOT a cheap matrix decoder type sound enhancement device. They claim that
from a live instrument each ear is first subject to a single primary sound 
arrival, with the time delay between left and right arrivals providing info
on the localization of the source. Further, they say that with a pair of
speakers, each ear first gets two primary sound arrivals, one from each
speaker. The desired arrivals, left spkr --> left ear, right spkr --> right
ear, are heard first, followed by the unwanted arrivals left spkr --> right
ear, right spkr --> left ear. With complex electronic wizardry, the hologram
unit generates delayed out-of-phase waveforms that cancel the unwanted 
arrivals. The effect is easily noticeable as a broadening of the sound stage
and an increase in the apparent front-to-back depth. A good description of
the sound was provided by the salesman demonstrating the Carver boxes; only
a pair of speakers out of 4 or 5 pair were being used for the demo, with
several on both sides of the demo pair. With the hologram unit in, it sounded
as if they were ALL playing! Some instruments seem farther away also. The
effect is quite remarkable. Apparently, with the hologram box, you can tell
in Pink Floyd's Dark Side of the Moon, in the alarm clock cut, that the
clocks were placed in rows.

Drawbacks: 1) you must be as close to the exact center of your pair of
speakers as you can - the effect becomes much weaker off-center.
2) the effect is more noticeable with some recordings than others, and
I think depends on miking techniques. Small groups, like jazz bands, can
sound astonishing, but badly recorded orchestras etc. can sound pretty
ordinary (not sure about recordings that sound best). 3) price.

- Carver tuner - excellent review in recent Stereo Review. Overall impression
was the tuner sets new performance standards in a couple of areas, most
notably quiet stereo reception of distant normally unlistenable stations.

- NAD 4150 tuner - I posted a request for info on the net some months ago.
Uses new Schotz variable bandwidth circuit (?) to attain performance better
than previous theoretical limits (1.0 uv sensitivity at 30 db quieting,
< 1.0 db capture ratio, 80 db S/N). They've been advertising it for a while,
but no deliveries yet. I'm buying the first one I can get my hands on. Maybe
they're having production problems (oh-oh). It's also half the Carver's price.

Ken Newman
utcsrgv!newman

dyer (12/22/82)

Regarding the NAD tuner designed by Larry Schotz, the inside word
is to wait several months more before buying it.  Apparently there
are still a few bugs in the circuitry which keep it from attaining
its best performance (i.e., you won't be buying a clinker, but you
will do better to wait until Spring or Summer '83.)

Steve