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Poor Erasing Q. I purchased a TEAC 4010S tape deck in Singapore, and it plays beautifully with one exception. It only partially erases previously recorded material on a tape. What needs to be done? -Dick Prokopowich, Asheboro, N.C. A. Your difficulty seems due either to misalignment of the erase head (that is, the gap of the erase head doesn't span the same portion of the tape as do the other heads) or to insufficient oscillator current getting to the erase head. Possibly the erase head itself is defective. Too Much Recording Hiss Q. My problem lies in recording from records to tape. I seem to record with a large amount of hiss, which is quite annoying at times. I record just below the 0 dB level on the VU meters, but it seems that the hiss is not overcome at any particular recording level. If you can prescribe a method of recording which will alleviate some of this noise, I will be grateful. -Robert Sadowsky, Brooklyn, N.Y. A. The hiss of which you complain could be due to poor design of your tape machine, including failure to use low-noise components in the case of resistors and transistors. It might be due in part to magnetized heads, and this can be overcome by demagnetizing the heads. It might be due to a misadjusted record-level indicator, causing you to record at too low a level and therefore to reduce the signal-to-noise ratio. Switching to low noise, tape should help. If you are operating at 3 3/4 ips, you will probably get better results at 7 1/2 ips. Duplicating Q. I have a Revox A77 biased for low-noise tape, and a Tandberg 64X biased for regular tape. If I wish to duplicate a tape that has not been made on low-noise tape, am I better off going from the Revox to the Tandberg or vice versa? What apparent differences will show up when a tape is recorded on a machine not biased for low-noise tape, and played on a machine biased for low-noise tape? Can you use your preamp treble and bass controls to compensate for losses or gains in either treble or bass when dubbing? I have thought of biasing my Tandberg for low-noise tape, but I have a large library of tapes recorded on regular tape, and I dislike the idea of losing any playback quality. -Daniel S. Karsch, New York, N.Y. A. When shifting from regular to low-noise tape, the only required changes are those in recording (more bias, more signal to the record head, less treble boost). There are no changes in playback. Therefore in duplicating it would not matter whether the pre-recorded tape was made on regular or low-noise tape. What counts is the tape on which you wish to make the copy. If the copy is to be made on low-noise tape, use your Revox; use your Tandberg if the copy is to be on regular tape. If you plan to record on low noise tape from now on, there is no reason not to adjust your Tandberg for this kind of tape. It will still properly play all your tapes; and so will the Revox. With respect to using your tone controls to compensate for frequency deviations in duplication, this depends upon your audio preamplifier. Most such preamps provide a flat signal at the tape output; a few permit you to tailor the signal being fed into a tape recorder. If your preamp provides only a flat signal at the tape output (in other words, a signal taken before the tone controls), it would be necessary for you to modify the pre amp in order to provide a signal for the tape recorder following the tone controls. High Input Impedance Q. I have a Sony TC-355 purchased overseas and with European specifications. The major difference between this and the American version is its input impedance of 560 K ohms, compared with 100 K ohms for the U.S. model. My amplifier manual states that for the tape output the minimum recommended load resistance is 200 K ohms. Should I change the load resistance, and if so to what value? -M. C. Harrell, Timberville, Va. A. Inasmuch as the amplifier requires a minimum load resistance of 200,000 ohms, and since your tape recorder provides a load impedance above 200,000 ohms, there is no apparent advantage in changing the input load resistance of your tape recorder. (Audio magazine, Jun. 1972; Herman Burstein) = = = = |