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