SOME FUNNY GOINGS-ON I have witnessed at my local friendly hi-fi dealer's but I was quite unprepared for what I saw and heard the other day. There he was calmly dragging a pocket-knife blade across a record as if he were peeling an orange. "You have finally flipped," I exclaimed; "this business is too much for your sensitive soul."
"Not at all," he countered, "I am preparing a record for a special demonstration. It's an old fairly beat-up record anyway."
The "demonstration" turned out to be as surprising as the preparation and a lot more salutary. What my knife-wielding experimenter had done was to add a long series of severe scratches to the disc surface which, when the record was played, were quite audible and utterly annoying. They came through as pops and clicks and rasping noises, the worst kind of audible garbage that record-owners often are bothered with. After a few moments of this he grinned and said, "Now listen carefully." He then threw the switch on a small device patched into the system, to which I had not really paid attention before. Instantly, the noise all but vanished and the music came through with a refreshing clarity. What's more, virtually nothing of the high-frequency response seemed to be lost.
Obviously, the small box was some kind of super noisekiller that was doing a far better job of reducing scratches and the like than any filter I had ever encountered before, and without degrading the highs. It turned out to be a new product from Scientific Audio Electronics known as the model 5000 Impulse Noise Reduction System. The title gives a clue to how it works. In audio parlance, "impulse noise" refers to the clicks and pops that can develop on a record, and the model 5000 is designed specifically to cope with them, and nothing more. The electrical nature of these noises (which show up on a oscilloscope as intense, needle-like signals or "spikes") was founded by S.A.E. to have certain characteristics of rise-time, decay, phase relationships, and more. Accordingly, a circuit was designed to detect and suppress those spikes. Beyond that, the model 5000 also has circuitry that senses the musical material surrounding the offending spike and obligingly fills in this signal as it suppresses the spike. The process happens so fast (in less than one millisecond) that the audible effect is one of musical continuity.
The model 5000 itself is a reasonably compact unit (10 3/4 inches wide, 9 1/4 inches deep, 3 inches high) that is patched into a playback system via the tape-monitor facilities, or - if one doesn't mind additional control adjustment - between preamp and power amp signal connections. It has its own tape-monitor button plus a button to audition the record noise, and a sliding sensitively control to adjust the device for proper operation. Once adjusted, you can convince yourself on the work it is doing by pressing a "defeat" button.
the only aspect of the model 5000 that might give a record owner a problem is its announced price of $200. Admittedly that sum can buy a lot of new, unscratched records. On the other hand, many older cherished records may not be replaceable and may be plagued with pops and clicks. And of course new records, if mishandled, can develop such blemishes. So the serious collector might well consider this device. Certainly a demonstration at a dealer (with or without a pocket-knife) would be an intriguing experience.