Simulated Bidirectional Record Cleaning
Many record collectors who are serious about cleaning records suggest that cleaning a record bidirectionally may improve playback quality and lower surface noise. The results are questionable. Does bidirectional cleaning reduces the dirt and noise; or is it because the record was cleaned twice using this method? Only a high power microscope will reveal the condition of the grooves after cleaning a record.
excellent article on damaged, clean, and dirty vinyl records.
The theory is that when the vacuum cleaning mechanism (nozzle or wand type) sucks the cleaning fluid from the record, there is dust and dirt hiding behind the minute ridges and ripples of the groove. When the turntable platter moves in one direction the vacuum cleans the "leading edge" of the undulations but misses the debris behind the ridges.
Designing a machine that allows the turntable to move clockwise (as with a phono arm/cartridge) and then anti-clockwise is certainly possible, but makes the machine more costly, mechanically complicated, and requires more parts that can fail in the future. There is a "wand type" cleaning machine made in Germany, and availabable in North America, that costs over $3000 that can do this. A much simpler approach to simulated bidirectional cleaning is offered in the Loricraft design.
Loricraft now offers a record cleaning machine that has the ability to reverse the rotation direction of the turnable for customers that want this feature. It is the model PRC-4 Deluxe. The product is the same as the popular PRC-4, but with his added feature.
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The 3 position motor switch allows the turntable to move FORWARD (clockwise normal rotation) or REVERSE (anti-clockwise rotation) or OFF in the mid-position of the switch.
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On the standard machines:
The normal placement of the vacuum arm on the Loricraft is on the left side of the record (as you face the machine) so the nozzle is "against the groove" rotation. The arm is positioned at the edge of the paper record label and the drive motor moves the arm from the label to the outside rim of the record.
The Loricraft will also allow the arm to be placed on the right side of the record, like a playback tonearm, so the motor will move the vacuum arm from the outside rim to the spindle, "WITH the groove" rotation.
Now the big differences!
A machine that uses a plastic wand to clean the record has a long air slot on the bottom of the vacuum tube. Both sides of the air slot have a Velcro™ type (or velvet) material cemented to the tube. These strips are called "lips". The wand is perpendicular to the grooves* and will remove the cleaning fluid in a few rotations, cleaning all the grooves simultaneously. When the wand contacts the record the pump is under terrific load caused by trying to pull air through the thousands of fibers in the "lips." The air velocity is greatly reduced due to the high resistance of the fiber obstacles. Huge eddy currents of swirling air are produced as the air travels over the "land" and "groove" areas of the record surface due to the wide slot in the wand.
The Loricraft system uses a vacuum arm (similar to a phono tone arm) to clean the record locally instead of globally. The tiny orifice in the center of the vacuum nozzle cleans each groove separately. A nylon thread in the opening provides a soft spacer to hold the nozzle a few mils above the record surface. This spacing produces a huge vortex of airflow above the groove. This is called Bernoulli's law (or Bernoulli effect.) The "leading edge" of the mechanical sound pattern and the "lagging edge" are cleaned simultaneously as the air rushed through the "V" groove and straight up into the vacuum nozzle at high velocity.
The resultant cleaning action is as effective as a bidirectional cleaning without a complicated and expensive mechanism.
One suggestion to explain the action is that there is a horizontal flow to the cleaning liquid being drawn into the nozzle when the record is rotating; one side of the groove is dry and the other side is flooded. When you reverse the rotation direction this action is reversed. Whether this asymmetry would be beneficial or not, is hard to say.
One astute audiophile shared his system for cleaning records on the Loricraft which he claims is the best possible cleaning:
- With very dirty records apply SMART Potent record fluid to the record and place the vacuum arm on the right side of the record.
- When the arm reaches the record label spray SMART Regular record fluid on the record. Spread with the record cleaning brush until the entire surface is coated.
- Lift the vacuum arm over the spindle and allow the arm to continue its travel without turning the arm drive motor off.
- You have just cleaned the record twice in a single pass!
Another approach is to clean your record with this same method using your favorite cleaning solution during one half cycle and de-ionized (or distilled) water on the other half cycle to pick up any residual cleaning solution remaining on the record.
* Yes we know there is only one groove on each side of a record. It starts at the outside rim and ends at the inside "lead out" near the paper label. While most people refer to a visual cluster as "grooves", professionals call them "lines per inch of groove"