Tweaking your Record-Player Page 9

If more than 1 out of 50 of your discs skips grooves at 2gm, you've got a problem that urgently demands further investigation. For example, a badly worn stylus can do this, and if that's what the problem is, you can be sure it is also shredding your precious records. (If your stylus is more than two years old, it is mandatory that you have it checked with a high-powered microscope. If your dealer isn't so equipped, send it back to the manufacturer for inspection.) There's also the possibility that your cartridge isn't as good as you think it is. This isn't so easy to check out, but reading Stereophile back issues may shed some light.

Tracking force should be set for the cleanest possible tracking of most of your discs, but probably no higher than 2gm. The limit is not because of record wear, but because the stylus will be retracted so much by then that you may not be able to zero-in its VTA. Which, of course, will have to be readjusted each time you change tracking force.

Azimuth tilt refinement
This section applies only to those tonearms which allow the azimuth tilt angle to be adjusted.

Since stereo separation in a cartridge is a cancellation phenomenon, it has a very sharp nulling point that demands higher azimuth-adjust accuracy than can be obtained visually, even with a mirror. Additionally, regardless of the care taken in placing the sensing assemblies in a cartridge, they rarely end up being positioned at exact right angles to one another. For these reasons, tilt adjustment is best optimized with an actual stereo signal source, as from a test disc.

Visual alignment will yield channel separation that is more than adequate to achieve wide, deep soundstaging, but this can nearly always be improved on, at least slightly, by channel matching. For this you will need a test disc, such as any of the CBS STR-series (available from Old Colony Sound Lab), which has a 400Hz tone recorded first in one channel and then the other, with silence "recorded" in the opposite channel. You can make the adjustment by ear, but it will be easier and more reliable if you use an oscilloscope or a sensitive AC voltmeter and a means for filtering-out both treble and bass. (If you own a stereo equalizer, no matter how cheap-and-dirty, you can use this as a filter by connecting both its channels in series, then setting the midrange controls at maximum and the upper- and lower-frequency controls at minimum.)

The tilt-trim procedure involves comparing left-to-right- and right-to-left-channel separation, and adjusting cartridge tilt until they are identical. (The reason this is not applicable to non-tiltable arms is because cartridge shimming does not allow the tiny increments of change necessary for optimization.)

A warning is in order here: If you find that the azimuth angle required to equalize the separation in both channels is severe, the relationship between the stylus and the groove will be severely asymmetrical. The cartridge is faulty in that the stylus and the coils are misaligned so that only one can be near optimum. Take the cartridge back to your dealer and exchange it for another.

Platter mats
When tracking disc modulations, a stylus induces a constant stream of vibrations into the disc. If these are allowed to set the disc itself into resonant vibration, they will cause sonic colorations and pronounced smearing of details, so the name of the game is to dissipate them as rapidly as possible. This is done in two ways: by clamping the disc as tightly as possible to the platter so it both vibrates as little as possible and when it does vibrate, the vibrations are efficiently coupled into the platter; and by absorbing the sound waves that the vibrations radiate toward the platter surface. A suitable platter mat may help to do both.

Nothing can equal a good vacuum holddown system for suppressing disc vibrations, so a vacuum system should never be augmented with an add-on mat. But in the absence of that, your choice of a platter mat can have a significant effect on the sound.

A platter mat will tend to sound the way it feels to the touch. A relatively hard, stiff material will reflect a lot of energy back to the disc, making the sound crisp and detailed or, if you don't like it, hard and analytical. A soft, rubbery mat will make the sound richer and warmer—that is, "more musical" if you like what it does, or "less lively" if you don't.

But do pay attention to VTA when you change mats. Different mats have different thicknesses, so changing them will change VTA. Obviously, the opposite is not the case; changing VTA will not affect the sound of a mat.

Stylus cleaning
Although this is generally considered an occasional maintenance procedure, it should be done prior to playing every disc side, in my opinion, particularly if the disc has never been wet-cleaned.

All vinyl mixes contain a so-called mold-release agent, a waxy substance that prevents the vinyl from adhering to its stamper, and small amounts of this remain on the surface of every new disc. A good laundering with a suitable wet-cleaning machine will remove a lot of it, but enough always remains that some will accumulate as a hard little glob on the stylus with each play. Usually, it will wipe off with a dry, stiff, fine, short-pile brush, such as the ones sold in audio stores for the purpose (always wipe toward you) (footnote 13), but it may sometimes be necessary to use a solvent.

Denatured alcohol is ideal, and a small container of it will usually come with the stylus cleaner. A word of caution, though: Moisten the cleaner pad with solvent, but never saturate it. Many pickups have a tubular cantilever, and if there is an opening in this at the stylus end, capillary suction will draw pooled solvent up into the armature, increasing its mass and, sometimes, even spreading out over the coils inside the cartridge. Also, some cartridges made prior to the 1980s used shellac as the cement for fastening the stylus and coils in place, and a succession of alcohol baths will dissolve this over time, with disastrous consequences.



Footnote 13: I use the green abrasive paper available from Linn dealers (which is excellent at removing the gummy deposits from the stylus tip) in conjunction with an occasional wet clean using an AudioQuest vibrating cleaner. Again, remember that the abrasive paper should always be dragged past the stylus away from the tonearm pivot if the cartridge generator is not to be damaged.—JA
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