I am looking for a stereo system for use at first in the U.S. and later on overseas, where the AC frequency is different. What is involved in using a stereo system with both 50 and 60 Hz? Are there any components on the market suitable for both? If not, is the conversion of turntable and receiver to a new frequency a difficult procedure? Also, I like to listen to classical music at medium to low levels and wonder whether the loudness compensation networks built into some of the BIC speakers are more effective than the standard controls provided in receivers.
-P. R. Belden, Westmont, Ill.
For electronics there is usually little difference between a 50- and 60-Hz AC supply except that the power transformer may run a little hotter at the lower frequency. The situation should be similar for direct-drive turn tables and DC-drive tape decks, since these do not use the power-line frequency as a speed reference and many turntables come with strobe markings for both frequencies.
Units using synchronous or induction motors normally require that pulleys or gears be substituted when the power-line frequency is changed. Voltage is another matter, however. Unless the equipment you buy has pro vision for alternate connection of the power transformer, you could be in trouble. The best thing to do is tell your dealer of the problem when shopping.
Since proper loudness compensation depends on sound pressure levels and not electrical power levels, the efficiency of the speaker is a crucial consideration. Since BIC knows the efficiency of its speaker and can design accordingly, its compensation net work should have the inside track-unless the level at which your amplifier's loudness control takes effect is adjustable. (Sherwood and Yamaha appear to be the only companies still offering this option.) Then it's a standoff.
When I attempt to make a cassette tape recording on my Sony TC-152SD of an FM broadcast from my McIntosh MAC-1900 receiver, there is an instant hiss in the loud speakers, even when the recorder is set to record but is still being held in the pause stage. The hiss is also audible in playback.
This happens only in stereo. The hiss is not apparent in mono or when I'm recording discs. Neither Sony nor audio technicians have been able to locate the source of the trouble. Do you have any suggestions?
-C. Stanley Mahan, Vista, Calif.
Sorry, our crystal ball is out of order. Presumably those you have consulted have ruled out the obvious explanations: the inherently higher hiss levels of stereo (as opposed to mono) FM reception at moderate signal strengths, or intermodulation between the stereo subcarrier (38 kHz) or pilot (19 kHz) with the TC-152's bias -oscillator frequency.
Your reports have frequently noted the danger of using two pairs of 4-ohm speakers at the same time. My amplifier (Pioneer SA 9900) instructions say this too.
I have two AR-3, 4-ohm speakers. If I get two speakers that are rated at 8 ohms, will it be safe to use the four at the same time? I figure that, if I used the speaker pairs in different rooms and did not have all four on at once, it would be safe. But there is always the chance that someone would, by mistake, switch on all four. If that happens, is the dam age instant and terrible?
-T. M. Williams, Gettysburg, S.D.
Most amplifiers are safe with loads down to 4 ohms or slightly below and can therefore handle two pairs of 8 -ohm speakers or one of 4 -ohm speakers without trouble. Connecting an 8- and a 4-ohm speaker in parallel, as you suggest, brings the total load to 2.7 ohms; this is a definite no -no with most amps. The usual response of an amplifier to an excessive current demand (the result of too low a load impedance) is to activate its protection circuits and shut down, but if these circuits do not act quickly enough, damage to the amplifier may ensue. It seems to us that the best solution would be speaker switching via an external (double-pole, double-throw) switch that prevents driving both pairs at once.
My present setup consists of a Pioneer SX 838 receiver, a BIC 960 turntable with a Shure M-95ED cartridge, a Teac 2300 tape deck, a Teac outboard Dolby unit, a Soundcraftsmen equalizer, a Pioneer RG-1 Dynamic Range Enhancer, and a pair of Utah floor-standing speakers. I am considering the addition of an Audio Pulse Model One time -delay device. How many add-on units can I use without increasing the distortion level of my system or reducing the sound quality?
-Rudolph Johnson, Kendall Park, N.J.
You should see some of our systems! There is no reason why you cannot continue to be an insatiable gadget freak and still have clean sound; if you buy good quality gadgets and use them intelligently, your sound should continually improve. It's true that noise and distortion are cumulative for all units in the signal chain, though both generally are very low in the kind of outboard equipment you specify. And when most units of this type are switched out of the chain, they offer only passive connections (in theory totally distortion-free, though they may allow entry of minute quantities of noise) by which the signals are passed on to the other components. So, if all the add-ons are correctly adjusted for level, noise and distortion should not be a problem.
Why can't records be cut with the cutting stylus oriented just the way the playback stylus in a pivoted arm would be, thus eliminating the necessity for complicated tangent-tracking tone arms for undistorted play back?
-Carton Chen, Toledo, Ohio.
Pivoted cutting arms have been used in ex pensive home equipment, but the radial-tracking disc lathe offers vastly greater control over disc quality. In theory it would be possible to drive a cutting system in such a way as to "pre-distort" the groove to compensate for the tracing error to be expected with a typical pivoted playback arm, but the cost of the special technology presumably would seem entirely unjustifiable to the record companies that would have to pay for it. The distortion that such a system could correct is minute in comparison with that inherent in the disc-playing systems used by the vast majority of the record-buying public. And even if manufacturers were to be convinced that lateral tracking angle error is worth compensating for, tangent tracking still would be needed for comparable playback with the millions of discs already in existence.
Let's pressure them into solving the record-warp problem before attacking this one.
I recently purchased a Discwasher Zerostat and have found that it is tremendous for re moving static from my records. A friend of mine also has one, and he uses it for discharging other objects such as socks that cling together. I was wondering just how safe this is. The instructions state that the Zero stat should be used only on inanimate objects but give no other information about safety.
Also, I have heard that using it near tapes will cause partial erasure. Is there any truth to this?
-Thomas R. Jackson, Norman, Okla.
The last time we checked, our socks were inanimate, so we'd expect your friend to have escaped unscathed. The "driving force" in the Zerostat is the tiny arc in which a static charge, built up by operating the trigger, is released. It works rather like shuffling your feet across the carpet on a dry day and then touching a metal doorknob--though this can build up much higher static charges than the Zerostat can, according to the manufacturer.
The cautionary note was inserted into the instructions lest, with the "gun" in extreme proximity to the eye, the arc might somehow misdirect itself and cause damage--however minor-to the eye. Tests with a magnetometer held six inches from the Zerostat have proved negative; you might be able to achieve partial erasure by wrapping the tape around the device and firing it repeatedly, but we don't see why you would want to.
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(High Fidelity, Apr. 1977)
Also see:
Ortofon moving-coil phono-cartridge system (ad, Apr. 1977)
Aiwa Model AD-1250 stereo cassette deck (Equip Profile, Apr. 1977)
High Fidelity Pathfinders--The Men Who Made an Industry