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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
sarcher30
596 posts
 
Csontos, This is easy to test for yourself. Just check your overhang after you change SRA. I've done this many times and you might be surprised how much it moves. The only instance it wont change is if you started out with tail up and then changed to tail down the exact amount from level that you were with tail up. This is because at level your overhang will be the farthest. Going tail down or up from level will shorten your overhang.

I agree Raul. I think it is worth resetting overhang after changing in SRA. Especially if you moved it allot.
peterayer
1,382 posts
 
Using my MINT LP arc protractor, it is very clear that changes in VTA (SRA)
alter overhang. It is more severe at the outer edge than at the inner grooves
because of the trace of the arc. IOW, the variance away from the arc is
greatest at the beginning of the LP.

In my system, this is audible. The MINT is extremely precise, assuming that it
was ordered correctly with the right pivot to stylus distance, or effective
length.

Now the Mint glass thickness is different from the various LP thicknesses, and
thus overhang changes slightly with different LP thicknesses.

Regarding the timing of the note when adjusting VTA, I think Schroeder is
talking about the harmonics not arriving before or simultaneously to the
fundamental. IOW, the note's fundamental (frequency?) should be heard first,
followed by its harmonics with a natural sounding delay. This is pretty easy
to hear with a mandolin or harpsichord pluck. If the timing of that pluck is
off, the VTA is off. I think this is his and DougDeacon's point.
lewm
13,500 posts
 
Peter et al, If you hear an effect of VTA on timing, I don't doubt it. I just wonder why that would be so. I certainly believe that VTA adjustment makes a difference, and I do pay attention to it in a non-anal way. However, I never thought about it in the way stated or inferred by Frank Schroeder. If there is substance to it, it's interesting to me.
peterayer
1,382 posts
 
I think of it like this: If the fundamental is being obscured by the harmonics, the harmonics are arriving too early. I hear this when the arm is too low in the back. If the fundamental occurs unnaturally early, or there appears to be a minute lag before you hear the harmonics after the fundamental, then the arm is too high.

This is roughly how Doug described it to me and it corresponds to what I hear. I can see how this could be described as a tonal shift or emphasis between the high and low frequencies.
csontos
1,311 posts
 
This is exactly what my experience is. Let's say we're starting at 90 degrees. If you guys claim you will see a change in overhang from a minute SRA adjustment, Because that's all it takes to go from one side to the other, then it's an inherent fault of the system because of the vinyl. The only way this can be overcome is by incorporating an adjustment to raise and lower the platter itself. However, this still does not deal with the tooling issue. But I'm not so sure that this is relevant to playback.
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