Since completing my Rega Planar 3 project I have reached the phase of “the tweak”. As many audiophile-types do, I enjoying many a great album with a slight distraction in the back of my mind….”what else could be changed in this setup?” One of those nuanced little tweaks is the Vertical Tracking Angle. Let’s take a quick look at the facts behind proper Rega VTA.
The Tonearm: The maximum up/down adjustment on a tonearm is about 0.5 inches (12mm). That being approximately 1 degree VTA adjustment.[Correction: if you do the math a 0.5inch variation on a 9 inch arm is about a 3° variation. You can work this out yourself once you remember that the sin() of an angle is the change in the y coordinate divided by the radius, so 0.5/9 ≈ 0.055 ≈ sin(3°)] (don’t worry, I don’t understand that stuff either!)
The Cartridge: Each model of cartridge has its own unique design which also determines the stylus VTA. Rega has accurately measured the VTA on at least one hundred different cartridge models. The lowest VTA we have measured was 24° (even though the manufacturer claimed 20°) and the highest was 36°. Most cartridges have a VTA of between 28° to 32°. The VTA of Rega cartridge is approximately 28°.
The Record: The VTA of a record cutting stylus is set to give the best continuous cut of the lacquer. Records are cut with a VTA which varies between 0° and 20°. On an individual record the VTA will vary by 7° or more, depending on the type of cutting head used, the depth of cut, the musical frequency and the lacquer springback. The VTA of the groove on every individual record varies by at least 7° over the record. Every record is cut under 20°.
Futility: We can see that cartridge VTA is normally around 10° higher than the record cutting angle. And the record cutting angle varies by around 7° whilst it is being played. THEREFORE A MAXIMUM ARM ADJUSTMENT OF ONLY 1° CAN BE SEEN TO BE COMPLETELY FUTILE. To accurately match cartridge VTA to the record cutting angle the back of the arm would need to be well below the record (impossible!) and the cartridge VTA would need to vary at least 7° whilst playing the record! However if you don’t want to take my word for it, you can always get the Rega-original space for the newer 3-point mount tonearms:
Advice for the Normal Guy: Most informed advice for the regular turntable aficionado is to keep the tonearm roughly parallel to the record surface. In fact, the VTA becomes more correct as the rear of the arm is lowered as much as possible, the limit being when the arm or cartridge touches the record.
What is the worst case? The most extreme situation is a record cutting angle of 0° and a cartridge VTA of 36°. The result is a VTA inaccuracy of 36°.
Question: Can there be any point in playing around with 1° of VTA?
VTA adjustment is actually a neurosis NOT a technical adjustment.
Alternative #1: If you alter the playing weight of a normal cartridge by 0.1 of a gram the stylus VTA will alter by around 1.5°.
Alternative #2: If the room temperature increases by 5° F, the stylus rubber suspension will soften and decrease the VTA by 1°.
“But when I alter the VTA I hear a difference”
Of course you do. Any variation or change to the very important joint between the arm and turntable will alter the sound quality. Try simply tightening or loosening the main arm fixing nut, the sound will change. Try tightening or loosening the cartridge fixing nuts, the sound will also change. Almost any change or adjustment to a turntable/arm/cartridge will alter the sound quality if one listens with an acute level of perception.
Final Advice: Hopefully this has explained a little bit of the VTA mystery and how it is of little or no significance. There are many other simple structural changes that are probably of more importance, such as fixing the cartridge rigidly to the arm and fixing the arm tightly to the turntable. Bottom line, for a Rega table you should only need to adjust VTA if:
a) The cartridge fitted is an unusual size and is significantly taller than the Rega cartridges.
b) You have a mat significantly thicker than the original.
If you are serious, but not quite obsessive Rega-user then your tonearm should be aligned as follows: The top of the arm should be parallel with the platter with a record on the platter. This can be done using paper with parallel lines drawn on it. Once that is done adjust VTF, antiskate and alignment. Once this has been done then you can assess the sound and decide if further adjustment is required. This is not meant to be a cure all, simply a sensible reference point to start. Happy aligning!