1996 by L.A. Audio File - Larry Calhoun on Collecting Music Software:
Getting Rid of That Snap, Crackle & Pop
Lets talk about a major problem with records: Namely, extraneous noises, clicks, pops, crackles, sizzles, etc. Even those of us who continue to support records would love to get rid of these annoying background noises. As we all know, the amount of the background noise can be reduced by cleaning our records with a good record cleaner, such as those produced by VPI and Nitty Gritty. Using a good turntable, arm, and cartridge can further reduce annoying noises. However, that only gets us so far. In the 1970s, a few companies such as SAE, Burwen and Garrard marketed black boxes which claimed to eliminate impulse noises, clicks, pops, ticks. To a limited degree, they were successful in at least reducing such noises especially the ones caused by large scratches. By the mid 1980s, however, these devices were no longer being manufactured. Today the used price for these units vary between about $150 and $400. There are still a few companies manufacturing devices which address record noise, but for the most part they are quite expensive (e.g., the Packburn costs $2,650, and the Cedar $19,000).
I recently became aware of a relatively new product called Surface Noise Reducer (SNR) being sold by Esoteric Sound for $450. Quoting from Esoteric Sound's literature, The Surface Noise Reducer circuit topology employs the latest in modern digital integrated circuits and a design algorithm which can identify and remove most clicks and pops found on records and even 78s and other vintage records... The Esoteric Surface Noise Reducer acts only on the click or pop without effecting program material.
The SNR circuitry is contained in a 12 by 7 by 1 inch box, with an attached 19 inch faceplate which makes the unit suitable for rack mounting. The unit can be connected through a tape or processor loop, or between the phono preamp and the preamp. The front of the unit are two dials, and a toggle switch. The switch is used to toggle between processing and bypass. In bypass mode, the signal path is hard-wired input to output, therefore it shouldn't introduce any noise or distortion. The right hand knob allows you to set the amount of noise reduction, while the left-hand knob is used to limit distortion by curtailing the noise reduction at appropriate times. According to company literature, hum and noise is 95 dB below rated output, THD is less than 0.02 percent at 1 kHz, and response is 20 to 20 kHz +/- 0.20 dB. The SNR is easy to use, as can be seen from the following instructions:
* While playing loud passages, advance the Distortion Limiting control until the THD LED illuminates. Now back off the Distortion Limiting control slightly.
* Advance the Quieting control until the NR LED flashes indicate that clicks and pops are removed.
* Carefully adjust the Quieting control for maximum reduction of noise without introduction of distortion.
* If you notice distortion during loud peaks, advance the Distortion Limiting control further until the THD LED illuminates and thus inhibits the NR LED and resultant distortion. This may require careful adjustment of both controls; some interaction will be observed.
How well did the unit work? During the past few weeks, I listened to dozens of records, in various conditions, using the SNR (for this review, records were played on a VPI HW-19 Mk III, with a Rega RB300 arm and a Blue Point cartridge). The SNR works similarly to the SAE, Burwin and Garrard units in that it identifies the impulse noise, and cuts the signal for a fraction of a second to remove the noise, and then backfills the missing signal to match the surrounding signal. Like the other units, when the SNR removes an impulse noise, it leaves a sonic footprint, n place of the click or tick, in the background behind the music. Id describe the sonic footprint as being a dull or soft pop at a lower volume than the impulse noise. For the most part, the music masks this slight noise; however, when the music is soft, or during the gap between cuts, the noise can be heard. I found the sonic footprint generally much less annoying than the click or pop which it replaced. The unit had little if any effect on other types of surface noise such as sizzle and crackle but then it wasn't designed to remove such noise.
For some records, the results were outstanding, while for others only a slight improvement it depended on the type of background noise on each record. If the problem was clicks, pops and ticks, the unit did a great job; On the other hand, if the problem was sizzle and/or crackle, there was only a slight improvement.
On average Id say there was a full grade improvement on most records. For example, good records became very good records, very good records became excellent. Esoteric Sound informed me that when there are fluctuations in voltage, this could increase the residual noise (soft dull pop) left after the tick/pop has been eliminated. To correct this problem, Esoteric began adding a voltage regulator to the SNR units. After he had added a voltage regulator to my unit, I did extensive listening. While its tough to compare my memory of the units performance before the voltage regulator to its performance after, I believe there was a slight improvement but its a difficult call.
After a while, I became aware that more wasn't necessarily better than less. Sometimes moderation in noise reduction is the best policy. This became clear while listening to George Winston's Piano Solos. This album had a great many very fine scratches, few moderate scratches, a no major scratches. When the quieting knob was turned high enough to identify and process the very fine scratches, the resulting dull pops were more intrusive than the ticks had been. These dull pops could be heard between each note, and were very distracting. By reducing the amount of noise reduction, the dull pops went away, and the volume of the tiny ticks was so low they generally couldn't be heard.
For the first couple of days I was constantly tweaking the knobs. After that, I found that I was generally setting the distortion limiting knob at about 11 o'clock, and the quieting knob at about 1 o'clock. I finally decided to leave them there, and feel I'm getting most of the benefit of the unit without any audible distortion. Now I only tweak the setting when I get an unusual album such as the George Winston album discussed above. I also will probably do some tweaking when I tape a record.
Did the SNR affect the quality of the sound? Did it add or eliminate something? When the SNR was in the bypass mode, there was absolutely no change to the music. This was an easy A/B test. The unit was in the tape loop, so by leaving the SNR in the bypass mode I was able to switch the SNR in and out by using the pre-amp tape button. Whether the SNR, when in the active mode, added or subtracted something from the music is a harder call. I spent a lot of time switching between bypass and active, and didn't hear any difference in the music, but with the background constantly changing (ticks/pops being eliminated/reduced), I cant be absolutely sure that the music remained exactly the same. I cant say for certain that there were no changes. If there were, they were very small.
With devices such as the SNR, its important to have realistic expectations. You cant expect all extraneous noise to be eliminated, but you can expect some improvement. Shortly after I purchased the SNR, Mike Stosich sent me an early version of a cassette tape (C-60, high bias, Dolby B) made on their digital audio workstation which is used to demonstrate what the SNR is capable of accomplishing. The cassette compares the SNR to the Packburn and Cedar noise reducing units four 78 selections, 2 LP selections (the current version has four LP selections), a 1 kHz signal plus scratches selection, and a selection containing calibration scratches. When listening to each tape selection, you first hear the selection with no noise reduction, then the selection as processed through the SNR, then through the Packburn, and finally through the Cedar. Interestingly, the SNR did a better job than the Packburn on the record and scratch selections, and better than the Cedar on the scratch selections. But the Cedar did a much better job than either the SNR or Packburn in cleaning up LP noises. It didnt just stop at eliminating or reducing impulse noise; it also did a credible job on sizzle, crackle and other grungy noises (you get a lot for $19,000).
For those of you who still enjoy listening to records, you should consider adding the SNR to your system. I'm very pleased with mine. If you're interested in purchasing an SNR ($450, plus shipping charge; postage to Northern California cost me $6.50, so I imagine it would be the same to Southern California), receiving the demonstration tape ($5.00), or a free catalog, Esoteric Sound can be reached at 1608 Hemstock Ave., Wheaton, IL 60187 (phone/fax: 630-933-9801).
- Larry Calhoun
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