A Simple Recommendation for Anti-skate Setup:
My recommendation for simple anti-skate setup is to use the Frank Schroeder blank vinyl method. In this method the user adjusts the tonearm in all regards other than anti-skate. Then the stylus is set down near the leadout groove location on unrecorded space of a vinyl record. Anti-skate is then adjusted so that the armwand moves slowly inward toward the turntable spindle. If one does not have an unrecorded vinyl record disk, one can use the blank space between turns of the leadout groove. As an alternative, one can use the reflective side of a compact disk.
My research indicates that the Frank Schroeder blank vinyl method may under-compensate for skating. However it may be better to under-compensate than to overcompensate. Peter Leddererman of Soundsmith recommends the Frank Schroeder method of setting anti-skate. Peter has commented that with cartridges sent in for stylus replacement he sees more wear on the outer edges of stylii than on the inner edge. This indicates a tendency for anti-skate to be set too high.
Anti-skate Considerations
I have done a certain amount of investigation into anti-skate setup. This investigation is discussed below.
When I developed the Woody Tonearms I wanted a method of precisely setting up anti- skate. In pursuit of this method I developed a simple anti-skate measurement apparatus and system which I call the Pete Riggle Anti-skate Measurement System (PRAMS). This system is based on an analysis which uses stylus/vinyl drag coefficients reported years ago by investigators at Thorens. I sell the PRAMS system if you wish to buy one ($150 USD), but think it is a bridge too far for many audio hobbyists. For devout hobbyists the PRAMS might be the best way to set up anti-skate. The PRAMS system is similar to an anti-skate measurement system developed by Wally Malewicz, offered for sale by WAM Engineering.
For my Woody Tonearm manuals I have reverted to recommending the Frank Schroeder blank vinyl anti-skate setup method mentioned in the lead-in paragraph of this page.
My recommendation for simple anti-skate setup is to use the Frank Schroeder blank vinyl method. In this method the user adjusts the tonearm in all regards other than anti-skate. Then the stylus is set down near the leadout groove location on unrecorded space of a vinyl record. Anti-skate is then adjusted so that the armwand moves slowly inward toward the turntable spindle. If one does not have an unrecorded vinyl record disk, one can use the blank space between turns of the leadout groove. As an alternative, one can use the reflective side of a compact disk.
My research indicates that the Frank Schroeder blank vinyl method may under-compensate for skating. However it may be better to under-compensate than to overcompensate. Peter Leddererman of Soundsmith recommends the Frank Schroeder method of setting anti-skate. Peter has commented that with cartridges sent in for stylus replacement he sees more wear on the outer edges of stylii than on the inner edge. This indicates a tendency for anti-skate to be set too high.
Anti-skate Considerations
I have done a certain amount of investigation into anti-skate setup. This investigation is discussed below.
When I developed the Woody Tonearms I wanted a method of precisely setting up anti- skate. In pursuit of this method I developed a simple anti-skate measurement apparatus and system which I call the Pete Riggle Anti-skate Measurement System (PRAMS). This system is based on an analysis which uses stylus/vinyl drag coefficients reported years ago by investigators at Thorens. I sell the PRAMS system if you wish to buy one ($150 USD), but think it is a bridge too far for many audio hobbyists. For devout hobbyists the PRAMS might be the best way to set up anti-skate. The PRAMS system is similar to an anti-skate measurement system developed by Wally Malewicz, offered for sale by WAM Engineering.
For my Woody Tonearm manuals I have reverted to recommending the Frank Schroeder blank vinyl anti-skate setup method mentioned in the lead-in paragraph of this page.
More about Skating and Anti-skating:
What is tonearm skating?
If one lowers a pivoting tonearm to place the stylus on a blank vinyl disk rotating on a turntable, it may be seen that the armwand will swing inward toward the spindle of the turntable. This motion, called skating, occurs because friction between the stylus and vinyl creates a moment about the tonearm pivot. The skating tendency has the undesired effect of placing more stylus force on the inner face of a record groove than on the outer face.
Anti-skating mechanisms
Most modern pivoted tonearms have a so called anti-skating mechanism, which can be adjusted to counteract (to some extent) the imbalance between record groove wall forces.
Futility of Pursuit of Perfect Anti-skate Setup:
Skating force is approximately proportional to vertical tracking force, and increases with record groove modulation. Variation of skating force with the amplitude of record groove modulation makes it impossible to have a single anti-skating force that will be correct at all times.
Another thing to consider is that tonearm bearings have friction, some more than others. If tonearm bearings have excessive friction, the arm will not skate inward on blank vinyl. Further, unless internal tonearm wires are perfectly dressed near the pivot point, the wires will create some friction, usually minor. Friction works to confound the search for perfect anti-skate. Also, tonearm internal wires or external wire compliance loops have some torsional stiffness, which creates a torsional moment that depends on rotation of the arm wand, and causes the anti-skating force to increase a bit as the arm sweeps toward the leadout groove.
Suffice it to say that it is somewhat pointless to be too fastidious in the search for perfect anti-skate. Nonetheless, anti-skate can be important, especially with shorter tonearms.
What is tonearm skating?
If one lowers a pivoting tonearm to place the stylus on a blank vinyl disk rotating on a turntable, it may be seen that the armwand will swing inward toward the spindle of the turntable. This motion, called skating, occurs because friction between the stylus and vinyl creates a moment about the tonearm pivot. The skating tendency has the undesired effect of placing more stylus force on the inner face of a record groove than on the outer face.
Anti-skating mechanisms
Most modern pivoted tonearms have a so called anti-skating mechanism, which can be adjusted to counteract (to some extent) the imbalance between record groove wall forces.
Futility of Pursuit of Perfect Anti-skate Setup:
Skating force is approximately proportional to vertical tracking force, and increases with record groove modulation. Variation of skating force with the amplitude of record groove modulation makes it impossible to have a single anti-skating force that will be correct at all times.
Another thing to consider is that tonearm bearings have friction, some more than others. If tonearm bearings have excessive friction, the arm will not skate inward on blank vinyl. Further, unless internal tonearm wires are perfectly dressed near the pivot point, the wires will create some friction, usually minor. Friction works to confound the search for perfect anti-skate. Also, tonearm internal wires or external wire compliance loops have some torsional stiffness, which creates a torsional moment that depends on rotation of the arm wand, and causes the anti-skating force to increase a bit as the arm sweeps toward the leadout groove.
Suffice it to say that it is somewhat pointless to be too fastidious in the search for perfect anti-skate. Nonetheless, anti-skate can be important, especially with shorter tonearms.
PRAMS (Pete Riggle Anti-skate Measurement System)
The PRAMS is a system which allows more accurate setup of anti-skating than otherwise possible. You can read about the PRAMS in the section below. But first, how about some background?
The PRAMS, a Description:
The PRAMS is a measurement system offered by Pete Riggle Audio Engineering. The price is $99 USD. The system includes a measurement tool and information on how to use the tool to optimize anti-skating adjustment. The PRAMS tool consists of a wood gantry with a plumb bob string and a dangler string which loops around the finger lift of a tonearm. See the following images.
Caution: While there have been no reports of stylus damage using the PRAMS, the user must take responsibility for that possibility. PRAMS adjustments must be made with the armwand safely in its rest position.
The PRAMS is a system which allows more accurate setup of anti-skating than otherwise possible. You can read about the PRAMS in the section below. But first, how about some background?
The PRAMS, a Description:
The PRAMS is a measurement system offered by Pete Riggle Audio Engineering. The price is $99 USD. The system includes a measurement tool and information on how to use the tool to optimize anti-skating adjustment. The PRAMS tool consists of a wood gantry with a plumb bob string and a dangler string which loops around the finger lift of a tonearm. See the following images.
Caution: While there have been no reports of stylus damage using the PRAMS, the user must take responsibility for that possibility. PRAMS adjustments must be made with the armwand safely in its rest position.
Referring to the above image, the horizontal divergence of the two strings at a point 10 inches below their intersection provides a measure of the ratio of anti-skating force to tracking force. The measured ratio of anti-skate force to vertical tracking force is the horizontal divergence of the strings in inches divided by 10 inches (which is the length of the dangler string).
You could say that the PRAMS idea came to me out of the subconscious. When the idea arrived I attributed it to some work by early Thorens tonearm people on measurements of the ratio of stylus drag force to tracking force. Later I remembered reading something about a Wally’s Tools offering similar in concept to the PRAMS, which was executed in a prettier and more expensive way. The Wally's Tools device is called the Wally Skater.
I developed the PRAMS for use with my Woody Tonearms. Then I became concerned that if I included the PRAMS with the Woody Tonearms, and if someone wiped out the stylus of a $5000 cartridge while messing with the PRAMS, I would feel terrible. For a long time I backed away from the idea of promoting the PRAMS and set the whole idea on a back burner. Now though, I’ve added to the body of anti-skate theory and experiment, and have come to the conclusion that I need to offer the PRAMS as a product for those vinyl players who want to very carefully set up anti-skate or to investigate anti-skate on their own.
You could say that the PRAMS idea came to me out of the subconscious. When the idea arrived I attributed it to some work by early Thorens tonearm people on measurements of the ratio of stylus drag force to tracking force. Later I remembered reading something about a Wally’s Tools offering similar in concept to the PRAMS, which was executed in a prettier and more expensive way. The Wally's Tools device is called the Wally Skater.
I developed the PRAMS for use with my Woody Tonearms. Then I became concerned that if I included the PRAMS with the Woody Tonearms, and if someone wiped out the stylus of a $5000 cartridge while messing with the PRAMS, I would feel terrible. For a long time I backed away from the idea of promoting the PRAMS and set the whole idea on a back burner. Now though, I’ve added to the body of anti-skate theory and experiment, and have come to the conclusion that I need to offer the PRAMS as a product for those vinyl players who want to very carefully set up anti-skate or to investigate anti-skate on their own.
Anti-skate calculations and measurements:
I set a up antiskate for a Woody tonearm using the Frank Schroeder method. With antiskate set in this manner, I used my PRAMS (Pete Riggle Antiskate Measurement System) to determine the ratio of anti-skate force to tracking force, as measured by the deviation from vertical of a string from which the tonearm was dangling from the finger lift. I measured this deviation in the area near the lead-in groove and the area near the lead-out groove.
Then I made a graph (for various tonearm lengths) of the calculated amount of deviation (described in the above paragraph) that would be required to agree with a theory for correctly setting antiskating. I made the assumption that the stylus-in-groove drag coefficient (drag force divided by tracking force) is .25 for a lightly modulated record groove and .5 for a heavily modulated record groove. These stylus in groove drag coefficient values are from my memory of results of a study by Thorens researchers made many years ago. Unfortunately, I've searched for the study online, but cannot find it. Curves of the calculated string deviation required to balance lightly and heavily modulated grooves are plotted on the graph for various tonearm lengths.
Also, knowing that for a 45/45 groove, the pinch effect increases the drag by a factor equal to the square root of 2 (which is 1.414) as compared to blank vinyl (no groove), I added a curve to the graph for a stylus drag coefficient of .25/1.414 =.177, which I labeled as for blank vinyl (no groove). In truth the stylus drag coefficient for blank vinyl would be even lower than this, because the .25 stylus in groove drag coefficient of a lightly modulated groove will greater than for an unmodulated groove.
Here is the graph:
I set a up antiskate for a Woody tonearm using the Frank Schroeder method. With antiskate set in this manner, I used my PRAMS (Pete Riggle Antiskate Measurement System) to determine the ratio of anti-skate force to tracking force, as measured by the deviation from vertical of a string from which the tonearm was dangling from the finger lift. I measured this deviation in the area near the lead-in groove and the area near the lead-out groove.
Then I made a graph (for various tonearm lengths) of the calculated amount of deviation (described in the above paragraph) that would be required to agree with a theory for correctly setting antiskating. I made the assumption that the stylus-in-groove drag coefficient (drag force divided by tracking force) is .25 for a lightly modulated record groove and .5 for a heavily modulated record groove. These stylus in groove drag coefficient values are from my memory of results of a study by Thorens researchers made many years ago. Unfortunately, I've searched for the study online, but cannot find it. Curves of the calculated string deviation required to balance lightly and heavily modulated grooves are plotted on the graph for various tonearm lengths.
Also, knowing that for a 45/45 groove, the pinch effect increases the drag by a factor equal to the square root of 2 (which is 1.414) as compared to blank vinyl (no groove), I added a curve to the graph for a stylus drag coefficient of .25/1.414 =.177, which I labeled as for blank vinyl (no groove). In truth the stylus drag coefficient for blank vinyl would be even lower than this, because the .25 stylus in groove drag coefficient of a lightly modulated groove will greater than for an unmodulated groove.
Here is the graph:
The vertical axis gives the horizontal divergence of the PRAMS strings in inches. This divergence divided by 10 inches gives the ratio of anti-skate force to vertical tracking force. For example, if the divergence is 1 inch, the ratio of anti-skate force to vertical tracking force is .1.
The horizontal axis is tonearm effective length. Note that the curves on the graph decrease in value for longer tonearms. Anti-skate is more important for short arms than for long arms.
The upper curve shows calculated PRAMS string divergence to balance the skating effect of a heavily modulated groove.
The next curve down shows calculated PRAMS string divergence to balance the skating effect of an unmodulated (mute) groove. This curve has values that are 1/2 the values of the upper curve.
The bottom curve shows calculated PRAMS string divergence to balance the skating effect of blank vinyl. This curve has values that equal the unmodulated groove values multiplied by .707 (1/2 the square root of 2 ) or divided by 1.414 (the square root of 2).
It is useful to know that the required string divergence is proportional to the stylus/vinyl friction coefficient (drag force divided by vertical tracking force).
The graph shows PRAMS measurements for only one tonearm, a 12.7 inch effective length Woody SPU Tonearm. This tonearm was set up by the Frank Schroeder blank vinyl method discussed above. In this method, with the stylus resting on a rotating blank vinyl disk, the armwand drifts slowly inward at the part of the disk corresponding to end of play of a phonograph record.
Two PRAMS measurements were recorded. One of these was in the area near the start of play. The other was in the area near the end of play. On the basis of these results, it appears that Frank Schroeder’s version of the blank vinyl record method sets this particular arm up for a correction that would balance the skating force associated with a lightly modulated groove.
Because lightly modulated grooves are not a tracking challenge, it might make more sense to do a larger correction than for unmodulated groove friction. This can not be done with confidence without the PRAMS (or perhaps the Wally Skater).
In theory, if we set the PRAMS string divergence up for a value intermediate between the upper curve and the second curve down, we would be under-correcting anti-skate for the most heavily modulated grooves by the same amount we would be over-correcting for the unmodulated grooves. This might be a good choice for anti-skate setup.
It is recommended that the PRAMS results be plotted on the Figure 1 graph to put them midway between the curve for a heavily modulated groove and the curve for an unmodulated groove.
Provided below please find a compilation of PRAMS target anti-skate values, depending on the amount of stylus friction to be offset, and tonearm length:
Tonearm Length PRAMS string divergence values ( inches) to offset:
(inches) heavy modulation medium modulation zero modulation blank vinyl
9 2.24 1.68 1.12 .78
10 1.98 1.48 .99 .68
11 1.78 1.34 .89 .62
12 1.60 1.20 .80 .58
13 1.48 1.11 .74 .53
14 1.36 1.02 .68 .48
15 1.26 .94 .63 .44
16 1.18 .88 .59 .42
The Physics Behind the Prams:
Here is a quick peek into the physics of anti-skate:
It is an ancient empirical observation that drag force is proportional to weight of the object being dragged. The ratio of drag force to weight is called the friction coefficient. There are two friction coefficients. These are 1) static (or breakout) friction and 2) sliding friction. We are interested in sliding friction between the stylus and the record groove.
In the mid 20th century Thorens engineers made measurements showing the drag force for a heavily modulated groove to be about 1/2 the vertical tracking force, and drag force for an unmodulated groove to be about 1/4 the vertical tracking force. Relative to blank vinyl, because of a pinch effect, the groove itself increases drag by a factor equal to the square root of 2. Thus the stylus drag on blank vinyl equals unmodulated groove stylus drag divided by the square root of 2.
Given any tonearm alignment family tonearm and the effective length of the tonearm, one can calculate the ratio of anti-skate force to tracking force for a fully modulated groove, an unmodulated groove, and blank vinyl. The tonearm alignment family has little influence on the calculated results. My calculations are based on the Lofgren A (same as Baerwald) tonearm alignment family. Do not hesitate to use these curves for other tonearm alignments.
In giving advice on anti-skate adjustment, I thought (and others have suggested) have thought that it might be better to undercorrect than to overcorrect anti-skating. This would correspond to setting up for a PRAMS measurement corresponding to the drag of an unmodulated groove. One could certainly argue for basing the correction on a larger drag force, perhaps 3/8 of the tracking force, which would require greater divergence of the PRAMS dangler string from the PRAMS plumb string.
Blank Vinyl . . . Or Maybe a Discarded Compact Disk
If one sets up anti-skate using the blank vinyl method, and then repeats the test with a discarded compact disk, one will find that the drag characteristics of blank vinyl and the data side of a compact disk are identical. Therefore, don’t worry if you can’t find a blank vinyl for use with the blank vinyl method of anti-skate adjustment; simply use a discarded compact disk.
About the Variation of Measured Anti-skate Effect
One might ask why the anti-skate effect of the Woody SPU tonearm, as measured by the PRAMS method, is greater near inner groove than near the outer groove. The answer is twofold. First, the tonearm wire of the compliance loop has a torsional spring effect. Second, string bearings have a torsional spring effect. The torsional spring effect of the Woody Tonearm string bearing allows us to use the string bearing as the source of anti-skate torsion. To reduce the torsional spring effect of the Woody tonearm compliance loop I tried very compliant wire with vinyl insulation. This compliant wire did not sound good. Therefore I continued use of Teflon insulated wire, which sounds extremely good, but is a bit less compliant.
All tonearm wires have torsional stiffness; some more than others. The longer the length of the wire which has to be rotated, the less the torsional stiffness. This explains the large external compliance loop used by Woody and VPI Tonearms. The external compliance loop also eliminates wire friction sometimes encountered with internally routed wires. String bearings also eliminate friction. They are nearly frictionless.
Other Uses of the PRAMS
The PRAMS is useful for evaluation of arm wand rotational friction in the horizontal plane. An arm with low friction in the horizontal plane will swing like a pendulum when suspended from the PRAMS dangler string. Lower friction in the horizontal plane will result in a smaller final oscillation when the arm swings freely from the dangler string.
The PRAMS is also useful in identifying a bearing hangup in the horizontal plane. A bearing hangup in the horizontal plane will prevent arm wand rotation in response to a change in location of the top of the dangler string.
Final Thoughts
From the data acquired for the 12.7 inch Woody SPU Tonearm it appears that the Frank Schroeder version of the blank vinyl method for anti-skate adjustment yields anti-skating forces close to those which would balance the skating force for a lightly modulated groove.
One could argue that a mute groove does not benefit much from anti-skating correction, and that a larger correction might be advisable. Unfortunately, the blank vinyl method gives no measured way of upward adjustment of the anti-skating force.
For that reason, those interested in ultimate vinyl playback performance might benefit from use of the PRAMS.
When using the PRAMS, it is advisable to plot the data on the graph of Figure 1 to determine where the results lie between the correction for an unmodulated groove and a highly modulated groove.
The horizontal axis is tonearm effective length. Note that the curves on the graph decrease in value for longer tonearms. Anti-skate is more important for short arms than for long arms.
The upper curve shows calculated PRAMS string divergence to balance the skating effect of a heavily modulated groove.
The next curve down shows calculated PRAMS string divergence to balance the skating effect of an unmodulated (mute) groove. This curve has values that are 1/2 the values of the upper curve.
The bottom curve shows calculated PRAMS string divergence to balance the skating effect of blank vinyl. This curve has values that equal the unmodulated groove values multiplied by .707 (1/2 the square root of 2 ) or divided by 1.414 (the square root of 2).
It is useful to know that the required string divergence is proportional to the stylus/vinyl friction coefficient (drag force divided by vertical tracking force).
The graph shows PRAMS measurements for only one tonearm, a 12.7 inch effective length Woody SPU Tonearm. This tonearm was set up by the Frank Schroeder blank vinyl method discussed above. In this method, with the stylus resting on a rotating blank vinyl disk, the armwand drifts slowly inward at the part of the disk corresponding to end of play of a phonograph record.
Two PRAMS measurements were recorded. One of these was in the area near the start of play. The other was in the area near the end of play. On the basis of these results, it appears that Frank Schroeder’s version of the blank vinyl record method sets this particular arm up for a correction that would balance the skating force associated with a lightly modulated groove.
Because lightly modulated grooves are not a tracking challenge, it might make more sense to do a larger correction than for unmodulated groove friction. This can not be done with confidence without the PRAMS (or perhaps the Wally Skater).
In theory, if we set the PRAMS string divergence up for a value intermediate between the upper curve and the second curve down, we would be under-correcting anti-skate for the most heavily modulated grooves by the same amount we would be over-correcting for the unmodulated grooves. This might be a good choice for anti-skate setup.
It is recommended that the PRAMS results be plotted on the Figure 1 graph to put them midway between the curve for a heavily modulated groove and the curve for an unmodulated groove.
Provided below please find a compilation of PRAMS target anti-skate values, depending on the amount of stylus friction to be offset, and tonearm length:
Tonearm Length PRAMS string divergence values ( inches) to offset:
(inches) heavy modulation medium modulation zero modulation blank vinyl
9 2.24 1.68 1.12 .78
10 1.98 1.48 .99 .68
11 1.78 1.34 .89 .62
12 1.60 1.20 .80 .58
13 1.48 1.11 .74 .53
14 1.36 1.02 .68 .48
15 1.26 .94 .63 .44
16 1.18 .88 .59 .42
The Physics Behind the Prams:
Here is a quick peek into the physics of anti-skate:
It is an ancient empirical observation that drag force is proportional to weight of the object being dragged. The ratio of drag force to weight is called the friction coefficient. There are two friction coefficients. These are 1) static (or breakout) friction and 2) sliding friction. We are interested in sliding friction between the stylus and the record groove.
In the mid 20th century Thorens engineers made measurements showing the drag force for a heavily modulated groove to be about 1/2 the vertical tracking force, and drag force for an unmodulated groove to be about 1/4 the vertical tracking force. Relative to blank vinyl, because of a pinch effect, the groove itself increases drag by a factor equal to the square root of 2. Thus the stylus drag on blank vinyl equals unmodulated groove stylus drag divided by the square root of 2.
Given any tonearm alignment family tonearm and the effective length of the tonearm, one can calculate the ratio of anti-skate force to tracking force for a fully modulated groove, an unmodulated groove, and blank vinyl. The tonearm alignment family has little influence on the calculated results. My calculations are based on the Lofgren A (same as Baerwald) tonearm alignment family. Do not hesitate to use these curves for other tonearm alignments.
In giving advice on anti-skate adjustment, I thought (and others have suggested) have thought that it might be better to undercorrect than to overcorrect anti-skating. This would correspond to setting up for a PRAMS measurement corresponding to the drag of an unmodulated groove. One could certainly argue for basing the correction on a larger drag force, perhaps 3/8 of the tracking force, which would require greater divergence of the PRAMS dangler string from the PRAMS plumb string.
Blank Vinyl . . . Or Maybe a Discarded Compact Disk
If one sets up anti-skate using the blank vinyl method, and then repeats the test with a discarded compact disk, one will find that the drag characteristics of blank vinyl and the data side of a compact disk are identical. Therefore, don’t worry if you can’t find a blank vinyl for use with the blank vinyl method of anti-skate adjustment; simply use a discarded compact disk.
About the Variation of Measured Anti-skate Effect
One might ask why the anti-skate effect of the Woody SPU tonearm, as measured by the PRAMS method, is greater near inner groove than near the outer groove. The answer is twofold. First, the tonearm wire of the compliance loop has a torsional spring effect. Second, string bearings have a torsional spring effect. The torsional spring effect of the Woody Tonearm string bearing allows us to use the string bearing as the source of anti-skate torsion. To reduce the torsional spring effect of the Woody tonearm compliance loop I tried very compliant wire with vinyl insulation. This compliant wire did not sound good. Therefore I continued use of Teflon insulated wire, which sounds extremely good, but is a bit less compliant.
All tonearm wires have torsional stiffness; some more than others. The longer the length of the wire which has to be rotated, the less the torsional stiffness. This explains the large external compliance loop used by Woody and VPI Tonearms. The external compliance loop also eliminates wire friction sometimes encountered with internally routed wires. String bearings also eliminate friction. They are nearly frictionless.
Other Uses of the PRAMS
The PRAMS is useful for evaluation of arm wand rotational friction in the horizontal plane. An arm with low friction in the horizontal plane will swing like a pendulum when suspended from the PRAMS dangler string. Lower friction in the horizontal plane will result in a smaller final oscillation when the arm swings freely from the dangler string.
The PRAMS is also useful in identifying a bearing hangup in the horizontal plane. A bearing hangup in the horizontal plane will prevent arm wand rotation in response to a change in location of the top of the dangler string.
Final Thoughts
From the data acquired for the 12.7 inch Woody SPU Tonearm it appears that the Frank Schroeder version of the blank vinyl method for anti-skate adjustment yields anti-skating forces close to those which would balance the skating force for a lightly modulated groove.
One could argue that a mute groove does not benefit much from anti-skating correction, and that a larger correction might be advisable. Unfortunately, the blank vinyl method gives no measured way of upward adjustment of the anti-skating force.
For that reason, those interested in ultimate vinyl playback performance might benefit from use of the PRAMS.
When using the PRAMS, it is advisable to plot the data on the graph of Figure 1 to determine where the results lie between the correction for an unmodulated groove and a highly modulated groove.
A Case Study:
Recently customer David Torcoletti telephoned with an observation that he was experiencing distortion of a loud female voice in the inner grooves of an album. He suspected the problem might be with anti-skate setup. We talked about possible fixes, including changing from a Lofgren A (Baerwald) alignment to a Stevenson alignment (perfect alignment at the inner groove), and adjusting anti-skate. Here is David's feedback after solving the problem:
"Hi Pete, Thanks for thinking with me the other day. I tried a couple of things to rid myself of that inner groove distortion I was hearing. I did ask my wife to listen - and she heard it too.
So, I first worked with the anti-skating as we talked about. I did read your paper, and it made sense, as your verbal summary did when we talked. So, I went from allowing a slow drift towards the spindle, to actually having a slow drift towards the outer part of the record. I tried this with two different alignment schemes - first the Stevenson, and then Baerwald. With both methods, the inner groove distortion was just gone. It clearly was an issue of anti skating that caused the inner groove distortion. And I was doing it the way that some pretty famous people advocate! I think it is clear to me that you are thinking clearly about this, Pete.
The second test was which alignment method worked best for me, and it was definitely the Baerwald that was the winner. The Stevenson was a bit duller in the midrange, and had a bit more spittiness in the dreaded sibilance region.
So, I think that changing the anti skating, following your thinking, solved the inner groove distortion problem. All-around better sound, for me, was achieved using Baerwald rather than Stevenson alignment."
Thanks again, David"
Recently customer David Torcoletti telephoned with an observation that he was experiencing distortion of a loud female voice in the inner grooves of an album. He suspected the problem might be with anti-skate setup. We talked about possible fixes, including changing from a Lofgren A (Baerwald) alignment to a Stevenson alignment (perfect alignment at the inner groove), and adjusting anti-skate. Here is David's feedback after solving the problem:
"Hi Pete, Thanks for thinking with me the other day. I tried a couple of things to rid myself of that inner groove distortion I was hearing. I did ask my wife to listen - and she heard it too.
So, I first worked with the anti-skating as we talked about. I did read your paper, and it made sense, as your verbal summary did when we talked. So, I went from allowing a slow drift towards the spindle, to actually having a slow drift towards the outer part of the record. I tried this with two different alignment schemes - first the Stevenson, and then Baerwald. With both methods, the inner groove distortion was just gone. It clearly was an issue of anti skating that caused the inner groove distortion. And I was doing it the way that some pretty famous people advocate! I think it is clear to me that you are thinking clearly about this, Pete.
The second test was which alignment method worked best for me, and it was definitely the Baerwald that was the winner. The Stevenson was a bit duller in the midrange, and had a bit more spittiness in the dreaded sibilance region.
So, I think that changing the anti skating, following your thinking, solved the inner groove distortion problem. All-around better sound, for me, was achieved using Baerwald rather than Stevenson alignment."
Thanks again, David"
Pete Riggle Audio
2112 S. Olympia Street, Kennewick WA 99337, USA
shop phone: 509 582 4548 email: peteriggle@msn.com
VTAF™ Trademarked. U.S.Patent No. 7630288.
Website content Copyright © 2021 Pete Riggle Audio, All Rights Reserved.
2112 S. Olympia Street, Kennewick WA 99337, USA
shop phone: 509 582 4548 email: peteriggle@msn.com
VTAF™ Trademarked. U.S.Patent No. 7630288.
Website content Copyright © 2021 Pete Riggle Audio, All Rights Reserved.