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by Michael Riggs Patch in a Preamp? My system is built around an old Dynaco integrated amplifier. Over the years, its switches and controls have become noisy and intermittent, and this has led to thoughts of upgrading. A friend suggested that I could save money by buying a separate preamplifier and patching it into the Dynaco's power-amp section, which still performs well. Unfortunately, my amp has no preamp-out / power-amp-in jacks, so how would I hook in the new preamp? -Stuart Blair, Schenectady, N. Y. The success of the enterprise will depend on what's malfunctioning in the Dynaco and how willing you are to modify it internally to bypass offending parts though you may be able to get by with no modification. Set all switches and controls on the Dynaco to their neutral positions. Connect the preamp's main out puts to one of the integrated amp's high level inputs (TAPE, TUNER, AUX, etc.), and set the amp's selector switch to that in put. Leave the amp's volume control at a position that enables you to use the preamp's volume control over a convenient range of settings. From then on, connect all sources to the preamp and use its controls instead of the ones on the integrated amp. If you get intermittent level fluctuations in one or both channels, it may be necessary to give the Dynaco a VOLUME/BALANCE bypass surgically. Tracking Troubles The headshell on my Philips GA-312 turntable is tilted slightly to the left (viewed from the front). Unfortunately, the tonearm has no provision for correcting this error, which I think is causing mistracking. Would an alignment device such as the Dennesen Soundtracker help; If not, what would? -Frank Radano, Norwalk, Conn. The Soundtractor and other alignment protractors are for adjusting stylus over hang and offset angle so as to minimize distortion induced by lateral tracking angle errors; they will not help you correct the tilt you describe. Inadequate tracking force or a worn stylus are more likely causes of mistracking than your lateral tilt is, but this error will definitely cause reduced separation, so it is worth eliminating. Your best bet is to insert spacers between the cartridge's right hand mounting hole and the headshell to create a compensatory tilt. Thin plastic or metal washers stacked to the necessary depth around the mounting screw should do the job nicely; for fine adjustments, you could make paper washers of various thicknesses. Enough Power? I am contemplating the purchase of a pair of AR-9 loudspeakers and an SAE R-12 receiver rated at 120 watts per channel into 8 ohms. In your review of the AR-9 [October 1978], you note that it is some what low in overall efficiency and needs a "capable and hefty power amp" to elicit its best performance. Does the SA E fall in the "capable and hefty" category, or will I need more power? -James M. Arseneau, Elmendorf AFB, Ark. The R-12's power reserves are probably ample for your needs, especially if, as with most amps and receivers, it delivers more power into 4 ohms than into 8. A rating of 120 watts (20 3/4 dBW) per channel is comfortably high for most applications-at the edge of what used to be called the "super-power" range--and SAE's power specifications are usually conservative. Note, however, that we said "probably ample" (in this case there's a very high degree of probability), for there is no cut-and-dried answer to your question. The amount of power that you need depends on the size and liveness of your listening room, how loud you play your music, how tolerant you are of amplifier clipping, and the sensitivity of your speakers. Airports and FM I live a few miles from La Guardia Air port, and every time a plane passes over, the FM reception on my Technics SA-202 receiver is swamped by what sounds like voice transmissions from the airplane. My landlord won't let me put up an outdoor antenna, so I have been using a B.I.C. Beam Box, but it doesn't seem to help. What can I do to clear up my reception? -Howard D. Powders, New York, N. Y. Admitting right off that remote diagnosis of interference problems is a risky business, we suspect that the culprit is inadequate image rejection. Your tuner probably is picking up aircraft radio transmissions and transposing them down 21.4 MHz into the FM band, where they disrupt legitimate FM-broadcast signals. People who don't live near airports are rarely bothered by such "image" signals. The solution is to get a tuner with a higher image-rejection ratio-but exactly how much higher is hard to say. Technics specifies an image-rejection ratio of 55 dB for the SA-202, so we know you need more than that, and tuners and receivers are available (for a price) with ratings of more than 100 dB. Dubbing Dilemma My system now includes two cassette recorders connected to a Yamaha receiver. I would like to be able to add a new live vocal or instrumental part to an already recorded cassette. I could have done this with a Sony open-reel machine I used to have, but neither my cassette decks nor my receiver seem to have provision for this. Is there any way I can do this kind of dubbing with my present system? -Neil B. Downey, Reston, Va. There are two options. If one of your decks is giving you problems, you might want to replace it with a model that includes what usually is called mike/line mixing. You would then connect your microphones to that deck's mike inputs and connect the output of your other cassette deck, on which you would play back the previously recorded tape, to its line inputs. If your receiver has dubbing facilities, you can make the line-level connection through it. The next step would be to adjust the mike and line recording level controls for correct balance between the new and the old material and record them together onto a new cassette. Alternatively, you could buy a separate mixer and use the cassette decks you now have. This approach would also re quire separate microphone preamps or preamps built into the mixer. Mixers are available at many levels of price, complexity, and sophistication, so your choice would depend on your needs and your budget. For the greatest creative flexibility, this second option probably is the best way to go. -------- (High Fidelity, Jul. 1981) Also see:
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