Tape Guide (Q and A) (May 1975)

PLEASE GIMME MORE

Open Letter To a Tape Deck Manufacturer

Dear Sir:

I have been a happy user of one of your top-flight tape decks (open-reel) for nearly a year. While it has most of the features I could wish for, some important ones are lacking. Since the price of your deck is in the high hundreds of dollars, it doesn't seem unreasonable to ask you to please fill the lack. Besides, I'm sure we are both interested in progress.

First, I must thank you for what you have already given me. Your deck is a triumph of mechanical, electronic, electro-magnetic, and human engineering. Frequency response at 7 1/2 and 3 3/4 ips provides a virtually perfect replica of the original sound, and frequency response is very serviceable for many needs at 1 7/8 ips. With a signal-to-noise ratio in the vicinity of 70 dB, the silence is indeed golden.

Wow and flutter are imperceptible at any speed, and so is distortion at normal recording level. Tape handling is fast, accurate, and gentle. The deck is replete with features such as sound on-sound, echo, mono, pause control, solenoid operation, record warning light, optional tape lifters, self-locking reel hubs, etc. At the same time the deck is simple to operate and foolproof.

What more, then, could I ask? I ask that you enable me to cope with various brands and types of tapes, some old, some new, and some yet to appear. The variations in tape oxide formulations call for changes in bias, in treble boost during recording, and in the amount of audio current fed to the record head. Therefore, I ask you to include front panel controls which allow me to adjust (Although this letter is addressed by one user to one manufacturer, it should be taken in a general spirit, speaking for many users and intended for all who make high-quality tape decks for home use.) bias, treble boost in recording, and audio drive current.

You may legitimately object that these are not properly user controls; that there is too much danger the user will upset the delicately balanced operation of a high quality deck, which skillfully achieves an optimum compromise between the conflicting requirements for extended treble response, low distortion, and low noise; that a deck can give best performance with controls precisely set for a specific tape and accessible only to the competent person having the necessary knowledge, experience, and instruments.

Anticipating these objections, I would like to make the following specific requests.

1. Please give me a front-panel bias control, coupled with a switch that enables bias level to be read on the VU meter. Please designate a specific point on the VU meter, such as 50 on the lower scale, that corresponds to your recommended setting for the tape you recommend. This will let me vary the bias, yet return it accurately to its original level.

2. Please give me a front-panel control that lets me vary treble boost in recording, yet accurately return the boost to its original setting. I can think of at least two possibilities. The simpler would be a step control, which varies high frequency boost at, say, 15 kHz in steps of about 2 dB over an appropriate range. A more sophisticated approach would be as follows: provide a control that affords continuously variable treble boost; incorporate a high-frequency oscillator (say 10 to 15 kHz) and couple it with a switch so that the level of this test tone after treble boost can be read on the lower scale of the VU meter. Designate a specific point on the meter, such as 50 on the lower scale, which corresponds to your recommended setting for treble boost in recording.

3. Please give me a front-panel control that enables me to vary the amount of audio-drive current to the record head, yet accurately return it to the original setting. Again there are at least two possibilities. One is a step control that, for a given VU meter reading, varies the audio-drive current in steps of about 2 dB over an appropriate range. A more sophisticated approach, similar to that suggested for the treble-boost control, would be as follows: provide a control that varies the drive signal continuously without affecting the VU meter indication during normal operation; incorporate a mid-frequency oscillator (say 500 or 1,000 Hz) and couple this with a switch so that the level of the test tone can be read on the lower scale of the VU meter. Designate a specific point, such as 50 on the lower scale, which corresponds to your recommended setting of drive current. To illustrate, assume that the original setting of the audio-drive control causes the test tone to produce a reading of 50 on the lower scale of the VU meter. Now assume that I adjust the control to produce a reading of 60, which is about 2 dB higher. Thereafter, when recording, there would be 2 dB more drive signal supplied to the record head for a given reading of the VU meter.

To avert accidental disturbance of these three new controls and to discourage the consumer from fooling around with them, you might want to conceal them behind a hinged panel or recess them or make them operable only by screwdriver.

My earnest hope is that in the near future you will satisfy my requests for these front panel controls, though not necessarily in the exact manner I have suggested. Compared with the electro-mechanical marvels you have already accomplished, they should present no great technical problems. And, considering high quality tape decks as they already are, they would add little in the way of circuit complexity. When the day comes that my requests are met, not only will I be very thankful but, as should be no surprise to you, I will have a new list of requests. Such is progress.

-Sincerely, Herman Burstein

(Audio magazine, May 1975; Herman Burstein)

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