--My present system consists of: Altec 848A speakers, a Dual 1009F turntable
with an ADC 10E Mk. II cartridge, and a Fisher X100B tubed amplifier.
The X100B is the only unit remaining from a previous system; it drives
the speakers well and never has needed servicing. Would the music I now hear
be further enhanced by replacing the X100B with a new transistorized high-power
amplifier ?
-Hilton Rodriguez, Perry Point, Md.
Transistors themselves are no guarantee of quality. And whether a new amplifier would be better or poorer than your X100B will depend solely on the relative characteristics of each amplifier and not on whether or not one incorporates solid-state devices.
--Why are frequency response figures--30 to 15,000 Hz ± so many dB, for instance-never published for speakers as they are for other components? Are speaker manufacturers afraid to publish these specs because most of the ratings would not come up to, say, amplifier specs in a comparable price range? Just describing how "good" a speaker is seems entirely inadequate to me.
-William Whitehead, Old Bridge, N. J.
You're right, of course, in assuming that speaker response generally won't be as smooth or as wide-range as that of an amplifier. But of all the components in an audio system, speakers are the most difficult to measure for response. What's more, there is no standard-or even widely accepted-method of measuring them. Finally, whatever method is used, the resultant speaker response curves can only indicate generally, rather than document precisely, the audible response to be expected from them because of several variables, of which room acoustics is the most apparent.
--I have purchased a Kenwood TK-140X receiver and two Pioneer CS-99 speakers. In addition to tone controls, the receiver has a loudness control and high and low filters. The speakers have three-position switches for both high and midrange frequencies. This seems a confusing duplication of functions. If I want to emphasize the highs in a particular recording, what would be the best way to do it?
-Ens. G. H. Anthes, FPO, San Francisco, Calif.
The speaker controls are intended only to match the speakers to the room in which you use them. Once you have them adjusted for what strikes you as the best tonal balance with average program material-which may require different settings on the two speakers--you should forget about the speaker controls. Use the filters only to reduce noise-surface noise on records or turntable rumble, for example. Use the tone controls to compensate for any inadequacies you may find in a particular recording or broadcast you are listening to or, as you suggest in your question, to emphasize a particular frequency range. Use the loudness control to restore a more natural-sounding balance when listening at low volume.
--I would like to know whether the overhang adjustment gauge supplied with the AR-XA turntable is accurate. I have read elsewhere that the tracking error is lowest when the arm is adjusted for 0.6-inch overhang. Is this correct? Also, is it true--as my local audio dealer tells me--that the damping can be defeated by removing the washer and foam rubber spring from the arm pivot?
-Michael J. Roddy, Baltimore, Md.
Optimum stylus overhang depends on the geometry of the arm in use and therefore can differ from one arm to another. An arm's overhang adjustment compensates for differing cartridge designs, usually by keeping the arm's effective length-technically the distance from its pivot to the stylus tip--constant even though the distance from stylus tip to mounting-screw holes can vary from cartridge to cartridge. The overhang specified for a given arm is a compromise setting intended to keep the pickup's axis as near tangent to the grooves as possible while the arm is pivoting across the record-or, putting it another way, to keep lateral-tracking-angle error to a minimum. As far as we can determine, the AR gauge is accurate for the AR turntable and arm. Removing the parts you mention from the arm will not defeat its damping but will degrade the arm's performance. For users who way. to eliminate the damping in the AR arm, AR will mail special instructions on request.
--I live on an 800-foot hill and there are two FM transmitters within two miles of the house. I can get about forty stations but have problems with overloading, causing the nearby stations to appear all over the tuning band. Cutting out the antenna eliminates the far-away stations. I'm using a Heath AJ-15 tuner. Can you recommend a better tuner for this problem?
-Thomas P. Johnson, M.D., San Diego, Calif.
The technical term for your sort of problem is "imaging," and you're correct in assuming that it comes from overloading of the input stage of your tuner by excessively powerful signals from nearby stations. The extremely broad dynamic range of FETs (Field-Effect Transistors), which your tuner uses, solves most problems of this sort.
That's why they're used in so much current equipment. Since your case is so extreme that even FETs won't solve it, we doubt that another tuner would do significantly better. One solution might be to order RF traps for the frequencies of the two strong stations.
Inserted into the antenna lead-in, the traps will reduce the offending signals without significantly reducing the strength of neighboring stations.
They're available from manufacturers of master antenna systems: Jerrold, for instance. But they are fairly expensive and may not solve your problem if enough signal from the two stations is leaking directly into the tuner and thus bypassing the antenna lead-in. In that case, extra tuner shielding--with or without the traps--would be the only cure. Incidentally, a 75-ohm coax lead-in system should be preferable to 300-ohm twin-lead under your circumstances because it will further reduce pickup of stray radiation.
--I am in the process of replacing a mono system with stereo equipment. My records, as you might expect, are primarily mono. I have been informed by a local stereo dealer that elliptical styli cannot be used to play mono recordings as the stylus tip won't follow the mono groove. Can you confirm or deny this?
-Robert N. Benneyan, Fond du Lac, Wisc.
Your dealer must be thinking of the converse of this matter: that is, a mono stylus can have difficulty in following a stereo groove. Tests conducted over a period of years demonstrate to our satisfaction that an elliptical stylus will not only play mono records but-because it will not ride in the groove precisely where the spherical mono stylus does--may actually improve the quality of the reproduced sound by avoiding the portion of the groove wall that had suffered wear in previous playings. The elliptical stylus, however, should be used in a well-balanced, low-mass tone arm-preferably one with antiskating provision.
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(High Fidelity)
Also see: Too Hot to Handle (April 1977)