Vertical Tracking Angle (VTA) describes the angle between a line, from cantilever pivot to stylus contact area, and the record surface. While this angle is manufactured into the cartridge, VTA will require setting when installing the phono cartridge to a tonearm. On a pivoting tonearm, such as the Thorens TP16 in use below, a final VTA setting may be arrived at by raising or lowering the tonearm at it's base mounting. Raising the entire tonearm will increase VTA, lowering will decrease VTA. Conversely, raising or lowering the vertical position of the stylus as it rides the groove will have the same effect as raising or lowering at the pivot end. Different thickness records or platter mats can alter VTA.
Arriving at the correct VTA may or may not seem to be a simple matter. In a perfect world, where every record is perfectly flat and is cut on a machine that conforms to the same exact VTA standard, and every record is exactly the same thickness. VTA would only have to be set once. I don't know about your world, but in mine records come in varying thickness' and are often slightly warped. To make matters worse, some records have had their masters cut at a slightly different Vertical Tracking Angle.
Setting VTA on a Thorens TD160
This procedure makes the assumption that all other tonearm adjustments have been made previously. VTA should be in the ball park when making the other tonearm alignments. If VTA is been altered by a large amount, it could prove useful to double check your overhang setting with a protractor just to be certain that this has not been altered. Small amounts will be of no consequence. Another cautionary note; changing VTA by large amounts to accommodate taller platter mats will also require a similar height adjustment for the standard cue bar of the TP16 and TP11 tonearms. See photo #6 at bottom.
A practical approach, for those who wish to set VTA only once, is to choose the median thickness record with a median amount of warp and use this as your listening test mule for setting VTA by eye and ear. Initial setting will be to get the bottom edge of the arm tube closely parallel to the record surface. As seen in photos 1 and 2, with stylus resting stationary in the record groove, arm tube is the same 7/16 inches off the record surface measured at two points with some distance between them along the arm tube. This can be a starting point for the adjustments by ear. ( BTW, your distance does not have to be 7/16. This will vary according to cartridge height and mounting shims, etc. It just needs to be the same distance measured from two points.)
For adjustment by ear I like to sacrifice a favored album that is typical of the music most listened to. As noted above, this record will be of a median thickness from the record collection. I will listen to various tracks of this album repeatedly as adjustments are made. Naturally, this will induce accelerated wear into the record. This is one reason I have multiple copies of favorite albums. Adjustment increments can be precisely made using methods illustrated in photos 3, 4 and 5. When searching for the "ballpark" I will make incremental adjustments of .02 inches. When I think my sound is in the ballpark and needs a closer fine tuning, this increment is reduced to .005 inches. All this is determined in the stack-up of feeler gages shown below and a given setting can be repeated at will. Take notes of your feeler gage stack-up values that work and those that don't.
What am I listening for...? The fullest, most alive sound. In general, when VTA is too great (arm base too high) the sound will go hard and metallic, when too small (arm base too low) sound will go lifeless and lack detail.
A measured stack-up of feeler gages fills the gap between the arm board and the bottom of the anti-skate fixture at the tonearm base. One hand holds the gages while the other hand tightens the screw. There is a certain element of 'feel' involved in terms of a tight or loose fit. I want to feel a bit of drag on the stack-up of feeler gages as I push them into this gap.
Two allen set screws hold the tonearm in place. The first set screw is shown in photo 4. The next set screw is 90 degrees to the back. Size of allen wrench is 2mm. Remember to park the tonearm in the rest before your start this. Once the screws are loose, the entire tonearm may be raised or lowered. I prefer to hold onto the upper portion of the gimbal frame to lift and lower the tonearm. Place your stack-up of feeler gages in the gap and then lower the tonearm onto it. Caution; don't attempt to remove the tonearm or you may damage the fragile tonearm wires which are soldered to a terminal inside the box. There is no recommended torque value for the set screws so I use the small end of the wrench to tighten the screw (less leverage). This keeps me from over-tightening.
Here is the gap after setting. The actual surfaces that register this fit are narrow but give the most repeatable location for this adjustment on this tonearm.* I like to record my gap distances for a given turntable mat that I happen to be trying out. This way I can easily return the tonearm height to a previous setting.
*other tonearms may have a different, more suitable location for these measurements.
If you raise or lower the tonearm by very much, it will also be necessary to adjust the height of your cue bar. A single set screw holds it to the shaft. Release the set screw and slide the bar up or down. The bar should clear the arm tube when parked but hold the stylus above the record surface by a comfortable height margin. This height margin may be set according to your preference.