Q. In comparing your report on the Sequerra FM tuner [January 1975] with that
on the Yamaha CT -7000 [March 1975] I get the impression that the Sequerra
is better, although the measurements don't seem to confirm this. Is it true?
-R. Baboushkin, Forest Hills, N.Y.
No. Both are extremely fine performers, and the Yamaha, in fact, has some refinements (notably the IF -bandwidth switch) that can be quite useful under certain conditions and that aren't included in the Sequerra. The Sequerra has an oscilloscope system that-if you include the optional RF-scan feature-is unique and utterly fascinating. As a result, it not only has unusual capabilities, but is, per haps, the most enjoyable to use of any tuner we've ever tested. The scope contributes only indirectly to performance, however; and on the basis of reception quality alone we feel that these two models represent performance seldom approached and never significantly bettered in FM equipment.
Q. I have a Sony TC-165 cassette deck that I now use with the Dolby circuitry in a Marantz 4270 receiver. What brand of chromium dioxide tape would be best suited to this combination? I have been using Ampex, Memorex, and Advent, but in making the Dolby adjustments for some of the Ampex cassettes the two sides of the cassette seem to require different settings. Is this possible?
-Larry Bronfman, Neshanic, N.J.
A. Most brands of chromium dioxide (including the three you mention) are so similar electro magnetically that they can be considered interchangeable in this respect. We can think of one exception: BASF, which seems to have less sensitivity than average and therefore may require that the Dolby controls be re -adjusted for good tracking. But the mechanical construction of the cassette can alter performance too. For example, if the pressure pad is slightly askew, it can produce better tape-to -head contact (and therefore higher output) on one side of the tape than the other. Something of this sort may be the explanation of your problem with some Ampex samples.
Q. The turntables article in the April issue states that the Rabco ST -4 has "simplified the means by which the arm is moved across the record [vis-a-vis the servo drive system in the SL -8], but only by adding complications else where in the design." I am a satisfied owner of a Rabco ST -4 and have been using it for approximately four years with great pleasure. Have I been living in a fool's paradise?
-Edward J. Sack, Brooklyn, N.Y.
A. Obviously not, if it has given you that much pleasure for four years-and we were pleased with it when we tested it (for the April 1971 issue). The design does require more bearings, more motion, and more positive drive (to turn the shaft on which the arm rides) than a conventional arm, and it has not been universally received with as much enthusiasm as you (and we) felt for it.
Since that article appeared, Harman-Kardon has corrected some information it gave us about both the old and the new Rabco models. It has discontinued the SL -8E servo arm (not the ST -4 turntable/arm ensemble, as stated in the article), and it calls the new ensemble the ST -7 (not the SL -7). At this writ ing we have seen only prototypes of the ST -7; but however exciting the new model may be when it appears, we'd urge you not to think of replacing a model you're delighted with just because somebody else isn't.
Q. I'm trying to choose between the Teac 2300S (open-reel deck) and the Dokorder 7100. Is the Teac worth the extra $100?
-Albert Pessot, Brooklyn, N.Y.
A. We haven't tested the 7100 specifically and therefore can give you only a generalized answer. In examining construction of the two lines we have found Teac decks to be exceptionally sturdy, the Dokorders only average in this respect. Dokorder, on the other hand, packs a surprising number of features and capabilities into its equipment of any given price class. Presumably you don't need any "extras" that the Dokorder may offer or you wouldn't be considering the Teac. In that case, and assuming that you plan to give your deck heavy use and want long-term reliability, the construction of the Teac probably will be worth the extra $100 to you.
Q. The DBX 117 Dynamic Range Enhancer [HF test reports, November 1972] is, I gather, a two-way noise-reduction system just like Dolby B. But can it also be used with pro grams that were not originally encoded with the DBX system? If not, what is the difference between using the DBX in playback alone and not using it at all, in terms of the sound coming from the speakers?
-Pongsak Srisa-an, Stillwater, Okla.
A. The DBX 117 is similar to Dolby B in that it can be used to compress the program during recording and then re-expand it during play back to reduce the audibility of noise picked up in the process. But it is not "just like" Dolby B, since it operates over the full frequency range, while Dolby B action is specifically tailored to the suppression of the noise in the high frequencies where it is most troublesome in tape recordings.
The DBX expander can be used in play back alone to increase the music's dynamic range. That is, it increases the difference in level between the loudest passages and the quiet ones, including any noise that is audible in the quiet passages. Set for a moderate amount of expansion, it will give the mu sic somewhat more impact and make the recording seem somewhat more noise -free; set for extreme expansion, it will make dynamic contrasts seem exaggerated and may produce some audible "pumping"--particularly if the noise levels in the recording are very high.
Q. Could you please tell me whether my Dual 1218 turntable equipped with a Grado FTR + 1 cartridge and a Marantz CD -400 demodulator is capable of playing CD-4 Quadradiscs? I've been told that the Dual's capacitance is too high. Listening tests certainly reveal a lack of separation with the present setup.
- Don Mullis, address unspecified.
A. We doubt that your problem is due to lead capacitance. We've used the older Duals (that is, the pre -"Q" models, whose leads were not designed for particularly low capacitance) successfully with regular CD-4 pickups, and Grado claims that its cartridge is uniquely in sensitive to this factor-and hence that it will provide good carrier recovery even with leads of relatively high capacitance. We have tested neither the cartridge nor the demodulator, however. If the separation sounds poor to you, it could be because of one or the other, or because you're expecting more obvious separation than is "built into" the recordings you're using in your listening tests. And since you do not complain of distortion (another result of poor carrier recovery), we suspect the recordings rather than the equipment.
Q. Is it always best to set the vertical tracking force of a tone arm to the lowest value possible? The Miracord 45 allows adjustment to as low as 1/2 gram. Will this result in good tracking?
-Walter Laning, Garden Grove, Calif.
A. To reiterate the oft-repeated rule: You should never set the tracking force lower than the minimum recommended by the pickup manufacturer. If, for example, the pickup spec calls for a tracking force of 1 to 2 grams, you might start at 2 grams and gradually reduce the setting until you encounter mistracking or audible distortion attributable to poor stylus-to-groove contact, then raise it slightly (perhaps by 1/4 gram). If you cannot get good tracking within the pickup's specified range, you have a problem: The pickup is a poor choice for the arm, you are trying to track excessively warped records, etc. A setting that is a little too low is worse (both sonically and in terms of record damage) than one that is a little too high. An extremely low minimum setting on the arm simply allows for a wider range of cartridges than an arm whose set tings start at, say, 1 gram; but just because the low settings are there is no reason you should attempt to use them.
Q. I recently purchased a Sony TC-161SD Dolby cassette deck, with which I am very pleased.
Could I use the Dolby circuitry, with some mi nor surgery, to receive Dolby FM broadcasts on my Dynaco FM-5?
-Neil K. Disney, Annapolis, Md.
A. We wouldn't advise it. The surgery will void your warranty and might compromise performance of the deck. And if a repairman should later try to service your altered deck following an unaltered service manual, it could be disastrous.
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(High Fidelity, Jul. 1975)
Also see:
Too Hot to Handle