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Stylus Rake Angle

I am trying to set up my new VPI 3D arm as close to perfection as I can. On the Analog Planet, Michael Fremer gives one opinion, however, a different opinion was voiced by Harry at VPI, and Peter at Soundmith. I've been discussing this with them....Fremer says that SRA should be adjusted even if the back end of the arm is WAY high up as needed, whereas Harry, and Peter said to start with the arm in a horizontal position and move it slightly up and down to find the sweet spot. Peter said that my cartridge (Benz LPS) and some others have an additional facet in the diamond so bringing the arm up in back would be exaggerating the proper SRA. When I wrote back to Fremer, he answered with an insistance that he was correct. Does anyone want to add to the confusion??
stringreen
don_c55
823 posts
 
Whatever your starting point, level or 92 degrees, the actual SRA arm height range is very, very small! Adjust "on the fly" is worthless, because you will pass over this very narrow peak with a quick adjustment. You must "zero in" over time, to find the optimal spot, and reset azimuth and VTF as you go. Note sonic changes throughout this process, as it is a learning experience.

On my VPI JMW 10 the final sweet spot "window" is plus or minus one index mark on the Micrometer head height tower. This is a range of +/- 3 10,000 of an inch!
Without a micrometer head on your arm, I doubt you will find this optimal SRA spot.

Once I find this "sweet spot point" after listening to many Lp's, over a few weeks or months (after break-in is complete), I do not change the height. 95% of my records are of "normal" thickness, so I do not readjust height for the 180 gm Lp's.

I find I get super playback quality on 80% of my Lp's with this one setting.

One must also take into account recording quality variation, as some Lp's just sound "off" regardless of SRA setting. The resolution of ones system must also be acknowledged for your personal results. Adjusting for each Lp is too "anal retentive" for me!
csontos
1,275 posts
 
What? It seems to me your process is far more tedious. Once you've set all other adjustments, it's simply a matter of tuning in the particular record. Similar to tuning a station on the radio. You can hear the sweet spot fade in and out as you tune forward and back. There is no better way. It may be anal if you care that much, but it's certainly not "retentive". If you have not tried this method, it will seriously enlighten you if you do. But you need a tone arm that allows it.
sarcher30
596 posts
 
Don_c55, I think what most people are adjusting for with fine VTA adjustment is actually proper overhang. Adjusting VTA will change overhang slightly. IME overhang adjustments make more difference than SRA adjustments. This is just a theory and I have no hard evidence to support it but it is my suspicion. Not to say SRA does not make a difference because it does. I just think fine VTA adjustment has more to do with dialing in overhang than it does with dialing in SRA.

Sean
csontos
1,275 posts
 
At those angles, the change in overhang would be on the molecular level.
sarcher30
596 posts
 
Csontos, I don't think so but you could say the same thing about SRA as well. What percentage of 1 degree of SRA is adjusted for with fine VTA adjustment?
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