AUDIOCLINIC (Mar. 1989)

Copying 78-rpm Discs

Q. For more than 50 years I have collected and preserved 78-rpm albums in the hope that one day a device would come along that would enhance, to a degree, these wonderful recordings and permit me to tape and share them with others. Do you know of anything of this kind? I have tried using various settings on my equalizer without much success.

-Marshal C. Ramsey, Columbia, S.C.

A. I was faced with the same recording problem, and I made my tapes monophonically. Thus, the procedures I will explain here involve using two channels of a single graphic equalizer; if you plan to make your recordings stereophonically, you would use two separate equalizers.

Connect a monophonic output from your preamplifier to your equalizer's left-channel input. Then, to double the equalizer's potential effect, feed its left output back to its right-channel input.

The right-channel output is then fed, via a Y connector, to the recorder's two stereo inputs.

With all of this in place, you are ready to start work. First, make sure your cartridge's stylus is the right type for the 78's wider groove and that your arm's tracking force is set high enough to avoid distortion. Next, set all equalizer controls to their flat positions. Play one of your discs. If the equalizer has volume controls, set them so that volume remains the same, whether or not the equalizer is switched in. Having all equalizer controls set at flat will help you adjust the equalizer properly.

Listen to the disc critically. Is there enough bass? If not, experiment with various low-frequency controls of one channel until you find one or two which, when readjusted, produce music which sounds good to you. To avoid rumble, I believe that you will wind up setting the lowest octave of both equalizer channels to their maximum cut positions. In most cases, this won't affect the amount of bass heard.

Of course, if you happen to have a well-recorded organ disc, you may have to back off a bit on these controls.

Chances are that no high frequencies will be lost by turning the highest frequency bands of both equalizer channels down to their maximum cut positions. This will remove high-frequency scratch and hiss without removing highs from the music.

Continue listening critically, this time to the higher frequencies and harmonics. If you hear a hint of highs, you may want to boost the controls associated with that frequency range. It is likely that you will want to boost just one channel, and perhaps only slightly.

Naturally, noise will also increase along with the desired highs. I would rather put up with this background noise than have the highs rolled off for the sake of a quieter background.

You may discover that some frequencies sound too prominent. Locate the controls which affect these frequencies and adjust one channel. Often, this predominant frequency range will lie between 2 and 3 kHz.

From time to time, switch the equalizer in and out of the circuit in order to compare your equalized signal to that of the untouched audio.

Many people will suggest that you set your equipment to compensate for the recording curves used when making the original discs. Even when these curves are published, deviations are so great that I believe using your own ears will allow you to make better adjustments. If you do attempt to match the original playback curves, you will have to figure out the difference, in each frequency band, between the original curve and the RIAA playback curve in your preamplifier. Then set your equalizer to compensate for these differences.

(Editor's Note: The Esoteric Sound Re-Equalizer, reviewed in our November 1985 issue, does precisely such equalization corrections. To make 78s sound quieter, the Packburn 323 A dynamic transient-noise suppressor has an excellent reputation among 78-rpm collectors. I've had good results with an old Burwen dynamic noise-reduction system, which has a setting especially for 78-rpm records; it's long discontinued, but you might be able to find a used one. -I.B.)

Overdoing Subsonic Filters

Q. I always leave the subsonic filters on my amplifier and outboard noise-reduction unit switched in. Further, I use my equalizer's 16-Hz band as a subsonic control. Does all this subsonic filtering degrade my system's bass response? I know that such filters are helpful, but how much is enough?

-Name withheld

A. Chances are that all this subsonic filtering is more than is necessary. It is certainly possible that some deep bass (30 Hz and below) is rolled off as a result, especially as the effects of the equalizer's 16-Hz band probably extend to 32 Hz or higher.

Many factors affect the need for rumble filtering. These include the combined resonance of your arm and cartridge, the amount of rumble in your turntable, the amount of warp in your records, the internal circuitry of your amp, and the design of your loudspeakers. Depending on how favorable or unfavorable those factors are, one subsonic filter should suffice, and you may not need any such filters.

One way to check is to remove your speakers' grilles and watch your woofers when you play a record; if the woofers move slowly in and out, you have subsonic problems which require filtering. As to the question of bass response, try playing a recording with good bass and then switch the filters in and out independently, to see what effect each has.

Old Is Better?

Q. Why is it that I have been searching for the last 25 years for the great sound that I had from 1960 to '65, and I just can't find it? You see, in 1960 I purchased-of all things--a Motorola console mono hi-fi set! Its sound was even superior to live music! It had everything: Clarity, stunning impact, and power. It was also distortionless, with terrific dynamic range and depth, and favored no type of music over another. This old set in an open-back cabinet, using paper cones for all speakers and a 15-inch woofer, would put today's $20,000 stereo outfits to shame. What goes on here?

-Gerald H. Miller, Rochester, Minn.

A. Your console was produced at a time when the standard for consumer audio gear was 5% THD. Yes, that amount of distortion was acceptable.

Of course, even then, equipment could be made to have much less distortion than 5%, but mass-market equipment often did measure out to that amount of degradation. So why did your old gear sound so good? Maybe it had to do with some of the recordings you played. In an effort to make poor equipment sound good, many recordings are made with a "presence" peak. This is a response peak in the range of 2 to 3 kHz. Such a peak sounds harsh through equipment which already has good presence. If some of your recordings have this peak, they won't sound right on a good system-especially once you have gotten used to smoother sound. I suppose, too, that the converse might be true, that your ears were trained to hear and enjoy a presence peak that either was created by some recordings or by peaks in the tweeters. Obviously, I can't know how you perceive sound.

It is difficult to find really bad equipment. When a person complains that he does not like the sound of his system, most of the time the problem is with the loudspeakers. Not that the speakers are bad, but that the particular listener just does not like them. So listen to other loudspeakers, using recordings with which you are very familiar. You should find at least one make and model speaker system which sounds good to you.

An interesting, but perhaps impossible, experiment would be for you to listen to that console again. It just could be that your perception of sound has become more acute and that you would no longer be satisfied with the old system's performance.

If, by chance, you still have any of the recordings you played on that console, listen to them again on your newer system. These recordings might even take on a character and definition you never heard before.

As for the fact that old consoles did not produce high electrical power output, well, it was a very expensive matter to produce amplifiers capable of high output power. Fortunately, when we only needed one speaker system, it could be a large one. These speakers could produce good low-frequency response and be efficient in terms of converting electrical power to acoustical power. Stereo brought a need for at least two loudspeaker systems, and space limitations meant that smaller systems had to be developed. If they were to produce solid bass, they needed lots of power. Solid-state electronics made high power a much less expensive proposition than it had been with tube gear.

Sadly, it is also possible that age has taken its toll on your hearing, which is not uncommon. If you had combat experience, the high noise level of artillery could have caused some damage.

Working in machine shops can also cause gradual destruction of the nerve in the inner ear.

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(Source: Audio magazine, Mar. 1989, JOSEPH GIOVANELLI)

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