Behind The Scenes (Mar. 1970)

by BERT WHYTE

SOME YEARS AGO I VISITED THE HOME of an audiophile friend of mine, who wanted to show me his new super-duper, "state-of-the-art" preamplifier. As I walked into his listening room my ears were assaulted by the over bright shrill strings of a "mood" record he was playing. I winced, and asked him to roll off his treble control a little. He looked positively shocked at this suggestion and stated with great emphasis that he "always kept his tone controls perfectly flat." Is asked him if he enjoyed listening to shrill distorted strings. "Of course not, he bristled, but I don't believe in "diddling" with tone controls.

This just confuses things and you never know when the balance is right." Now mind you, this lad lived in one of those fancy modern apartments with a glass "window wall," the furnishing was sparse, and what there was of it was mainly hard surfaces. In essence, a room with hard, over-bright acoustics. The room simply cried out for acoustic treatment via drapes, carpeting, and so on, but you would think that in the absence of such aids, the least he could do would be to utilize his tone controls! Here was a chap who had just laid out quite a sum for this fancy pre-amp, and somehow had become convinced that "purists" just don't use tone controls. In the years since that incident, I've run into similar situations and it is astonishing how this notion persists. But today, in addition to the "flat-tone-control fetish," we have a new whipping boy-equalization-which apparently is a "dirty word" to certain misguided hi-fi buffs.

The reason I mentioned this is that there appears to be the start of a trend towards the inclusion not merely of conventional tone controls in certain new playback equipment, but of bass and treble equalization control for the cut or boost of specific frequencies. It is strange that equalization should be viewed with such suspicion, when it is very much a part of the warp and woof of the fabric of audio, and has been a basic technique for many years. Where would we be without the standard RIAA equalization curve for disc recordings, or the NAB equalization for tape recording, to say nothing of the special new equalization that permits wide response with a reasonable signal-to-noise ratio on 1 7/8-ips cassettes? There are other applications of equalization too numerous to mention and it would be a very rare recording studio that didn't own a Pultec or graphic equalizer or far more elaborate equalization equipment. Not long ago the JVC company of Japan introduced a receiver which incorporated what they call a "Sound Effects Amplifier." This comprises five slide-type pots which afford up to 10 dB boost and 10 dB attenuation of frequencies of 60, 250, 1000, 5000, and 15000 Hz. This is a rather broad spectrum, nonetheless it offers a more versatile approach to sound control than conventional bass and treble controls.

The idea has been well received and while the JVC has the field to itself at the moment, I understand there are similar equalization facilities on some competitive receivers waiting in the wings.

When I was at the Los Angeles Hi-Fi Show last year, I ran across a unique preamplifier made by a small Los Angeles based firm called Scientific Audio Engineering. Their SAE Mark One pre amp costs a whopping $500, making it the most expensive in this country. For this kind of money however, they have built a unit which in finely crafted with much use of MIL/SPEC quality components, deposited carbon resistors, and other similar embellishments. Reliability should be quite high as they offer a five-year guarantee on the unit. This preamp has a fairly elaborate equalization facility in place of the usual tone controls. A rotary switch gives a choice of low-frequency equalization at 60, 120, 220 and 320 Hz.

Another rotary switch handles high-frequency equalization at 2500, 5000, 10000 and 15000 Hz. The rate of slope from these frequencies is 12 dB per octave.

Low- and a high-frequency step controls are provided for left and right channels.

There are six steps of clockwise rotation for each control, each step giving 2.5 dB of boost at the selected frequencies for a total of 15 dB boost. Counter clockwise each of the first four steps gives 2.5 dB attenuation. The final step gives an additional 5 dB attenuation for use as a notch filter. The total attenuation is 15 dB. There are two toggle-type switches, one for low and one for high frequencies which is one position gives flat response and in the other position provides the equalization selected. Thus you can A-B between the fiat response and the equalization on your program material. With such a flexible equalization set-up, you can handle virtually any situation which calls for frequency manipulation. Certain phono cartridges have high-frequency peaks. A few seconds adjusting controls on this unit and the peak is no more.

Some speakers accentuate the middle range and in certain rooms this can spell trouble. Switch in the desired amount of attenuation at 2500 Hz and you've solved that problem. Conversely, in certain rooms the sound from some speakers is on the dull side. A few minutes experimentation with mid and upper frequencies boosted a certain number of decibels affords the desired balance. These are some of the more obvious uses of equalization. The major use of the equalization facility is frequency modification of program sources, and this is what scares many people and makes them shy away from any such devices. Let us look at this concept for a moment. The most simple situation would be a record with excessive high frequencies and corrective equalization could be applied in seconds.

Or we may have a recording which is weak in the mid-bass frequencies. This too, is easily corrected. The people who are afraid of equalization and who always set their tone controls to the flat position, would seem to have an almost blind faith in the omnipotence of the recording engineers and recording directors. They don't seem to realize that while there is plenty of the scientific method in making a recording, with much rigid adherence to certain electronic disciplines, there is also a good deal of "art" and personal judgment in recording. Naturally, much depends on the background of the personnel involved with the recording. For example, the recording director may have played the violin in a symphony orchestra. When this gentleman makes a classical recording, for one thing, he has perhaps an unconscious tendency to pay more attention to the string sound than he does to brass or woodwinds. He usually has very definite ideas of what kind of string sound he prefers. If he played for a numbers of years with the orchestra in the same hall, he has a certain degree of acoustic conditioning which influences his preferences in string sound. Or let us assume that for many years this recording director was an avid concert-goer at Symphony Hall in Boston. Here he has been exposed to the overall sound of the orchestra from the listener's viewpoint.

Again he has been conditioned to a degree, and while acoustic memory is supposed to be fallible, nonetheless he retains an image of the kind of orchestral sound he feels is ideal, and in his recording he strives to duplicate that sound.

Quite apart from all this, there is always the possibility that our recording engineers and directors are faced with an entirely new hall in which they must record their symphony, simply because the hall they prefer is not available for some reason. I've had it happen to me.

In London, I like to record in Waltham stow Town Hall, but there have been times when I had to use other halls, each with it's own distinctive acoustics. You try to cope with the strange acoustics, but, it must be confessed, rarely with complete success. Another variable involved in the recording of classical music is the monitoring situation. Finding a room offstage where there will be no mutual sound interference is hard enough. Further, the acoustics of these rooms are usually just plain awful. If the room acoustics are not modified (as is frequently the case) monitoring is poor.

The whole idea is of course, not to let the acoustics of the room which you are monitoring influence the sound you are hearing from the recording hall. To this end, many engineers heavily damp the monitoring room with fiberglass, burlap, or other suitable material.

The monitor speakers that are used can have a significant influence on the quality of the sound on the master tape.

You would be astonished by what kind of speakers are used by certain recording engineers. I have seem them use 8-in. speakers in small portable baffles which are quite poor in general, and most specifically have little bass response below 150 Hz. Granted, when the master tapes are played back in their studios, their playback speakers are usually of considerably better quality than those they use for monitoring in the recording hall.

This affords them an opportunity to apply corrective equalization which hopefully will improve the sound to the point where it can be issued commercially. As you can readily see, if nothing else, the use of a poor monitor speaker makes unlikely the chance of recording from the master tape directly into the cutter-head, thus forcing them to go to a second- and perhaps a third-generation equalized tape for the disc master. Of course, if the recording engineers were using the Dolby System, they could get away with the noise build-up engendered by the multiple generations of tape. My personal opinion is why use a sophisticated technique like the Dolby System without making certain the master tape is of high quality. Even if the recording engineers, used high-quality monitor speakers, the sound that is recorded is still to the individual taste and ideas of the recording director. Whether his ideas are consonant with yours is a moot point.

I am not suggesting you run out helter-skelter and buy yourself some means of home equalization. Recording companies in general furnish a well-balanced disc or tape. Strictly speaking, in the home you don't really equalize a recording per se.

With a unit of sufficient flexibility you use your ears to arrive at a balance which seems pleasing to you, which if you think about it encompasses your listening room, your speakers, amplifiers, phono cartridge, tape heads, and recording itself. In other words you are either pleased with what you hear in the total acoustic environment and chain of electronics, or you feel it needs modification.

Up to now, such modification was restricted to bass and treble controls. With the JVC unit, or this SAE Mark One preamplifier-equalizer, or the Advent "Frequency Balance Control," the audio buff has the means to effect the frequency modification. The SAE Mark One handles all of the other usual preamplifier functions, and does it with extremely flexible controls, wide-range response, vanishingly low distortion, and very low noise. It is my understanding several other preamplifier manufacturers are investigating this equalization concept, and it will be interesting to see if this becomes popular with audio buffs.

(Audio magazine, Mar. 1970; Bert Whyte)

= = = =