I'd say it's pretty well infinite. But the change in overhang as a result is so exponentially minute as to be irrelevant once it's been set with VTA in the ballpark. |
Well, to be honest, I find that optimizing SRA yields a higher degree of improvement the closer to optimum the positions of the null points are. Not sure what the numbers are, but overhang is responsible for their correct location. |
John goron. I don't see why you should feel insulted. But I certainly have been. To suggest that those participating in this thread don't understand the terms borders on an insult to them as well. We all understand the terminology and what's clear is that you've been just playing semantics. |
Doug, your final assessment is spot on and is absolute since what proper timing sounds like at the stylus tip is exactly the same as what it sounds like on all the rest of the gear individually and is a perfect reference. Perfect because the same transitional changes will take place during adjustment no matter what the gear is and therefore represents an ideal model. |
Has the fact that both VTA and SRA measured angles change as soon as the stylus is loaded been mentioned? Also, this load changes with the depth of the groove causing more or less friction. The more cuts crammed onto the record the shallower the groove. Not only that, but the angle of the cutting stylus which is typically set up and adjusted by the particular technician at hand, varies from shop to shop,(even within the same shop), brand of machine, and specific cutting bit. The actual SRA issue is moot because of the variables. It's only valid for the sake of conversation. 'Around 92 degrees', or so. A tone-arm without adjustable VTA on the fly is imo, inferior. You've got to tune in every single record. |
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. |
At those angles, the change in overhang would be on the molecular level. |
Timing is referred to as a definition of transient performance as it relates to the stylus/groove contact point. The narrower the better, 'perpendicular to the apex'...or so. Hence, the 92 degree figure.
Start with a parallel arm and set overhang. I'm willing to wager that if you then set SRA on the fly, you will not find any measurable change in overhang. Granted, at or near that 90 degree standard. |
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. |
Good 'transient' performance is always easily distinguishable from poor transient performance. It really is the final goal and distinguishable difference we hear when successfully correcting set-up errors. It's not a matter of our ability to isolate first order harmonics when timing is right. It's a matter of the natural ability of our brain to recognize when it's not. It's when we hear the difference that we then recognize correct timing in comparison. |
Raul, My intention was not to present my point of view as fact, but just that, my point of view in a discussion. By all means, correct me if I'm wrong. I'm speaking from my owm personal experience. I don't have instruments to measure such tiny variations in adjustment. I'm a serious tweaker who can't leave good enough alone so I'm well aware of the importance of all of the factors involved. It's just that all things being equal, sra is the most convincing variable to improvement I have so far experienced in the last 30+ years. Once I settle on sra, re-doing overhang doesn't change the sound appreciably well enough for me to notice. Could be a matter of not having the ability to make such a small adjustment on my part. I make final sra adjustments with a sheet of paper or even finer with one side of a plastic record jacket trimmed and placed under the mat. Or should I say 'removed' as I start with a few there already. |
You answered your own question. |
Optimal SRA is an average based on the average 20 degree cutting angle standard, give or take. Temperature becomes moot as soon as changes in depth are introduced by modulation since that is accompanied by groove angle changes anyway. However as Atmasphere pointed out, average depth changes at the hands of the engineer and imperfect tooling set-up will certainly require a change in SRA. VTA refers to cutting angle. For all intents and purposes, VTA and SRA are virtually the same thing because it is impossible to perfectly maintain standardized specs. This is why the only way to match the two is by 'listening' and at best, listening on the fly. |
I'm still not convinced that SRA should match VTA(cutting stylus) necessarily. What shape is the cutting stylus vs. the many different playback styli? How many different cutting stylus shapes are there? |
Here's an interesting and somewhat revealing take on Micheal Fremer's TT set up technique.
http://m.youtube.com/watch?v=CJ7nAdITdk |
There actually is a standard cutting angle. It was changed from 15 degrees in the '60's, to 20 in the '70's. I think you've reiterated the pertinent points I've already made. However my conclusion is still that the best compromise is the ability to adjust SRA on the fly. That way the manufacturers and cutting engineers can go fly a kite:) |
John, have you read this article in it's entirety yourself? It corroborates every single point I've made without fail! I'm now wondering what your motive is in participating in this discussion. |
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You are mistaken. VTA has nothing to do with the angle of the cantilever. The angle of the stylus relative to the cantilever can vary wildly from one cart to another and therefore result in huge differences in cantilever/surface angles. VTA is set by the cutting stylus itself. Therefore there doesn't need to be a reference to VTA adjustment at all. It's done with as soon as the laquer is cut. The pertinent function to play back is SRA, the thing that follows. The fact that the cantilever angle changes with SRA adjustment is incidental. |
John, semantics aside, if you are correct, then why are we discussing SRA? If the cartridge manufacturers want to refer to SRA as VTA and vice-versa, so what? All they are doing is referencing a record manufacturing standard. There is no way VTA refers to cantilever/surface angle. I've owned many cartridges and I stand by my statement on that. My goodness, I've had cantilevers that are curved! |
But doesn't VTA become a moot point when matching SRA to whatever it is, by ear? VTA is static and fixed whether it's accurate or not. The angle of the stylus relative to the cantilever is not a fixed standard. I don't understand why you keep referring to the cantilever. If you insist that I refer to SRA as VTA, fine. It seems to be a matter of communication. Could you please explain to me the correlation between SRA and VTA? |
It's not clear that he understands the mechanical process of the cutting lathe. That could very well be a fault of mine. But what John doesn't seem to understand is that stylus/cantilever angle is not a fixed standard and cannot be used as a set up parameter by itself. As I've said, I've used cartridges with 'curved' cantilevers. My Dynavector Ruby has a 'faceted' cantilever. Cantilevers come in 'varying lengths'(think about that one for a moment). My London Decca doesn't even have a cantilever. Or at least not something resembling one as it is perfectly parallel to the surface of the record. Has anyone here seen cantilever specs being referred to for the purposes of adjustment or set up? If so , I'd sure like to see a copy of that.
I've never seen a cutting lathe either. If it does have a cantilever, then John has simply revealed an inherent design flaw in every cartridge cantilever that doesn't match either a standard length and stylus angle or that doesn't happen to match a particular cutting lathe. I personally don't think the arc of the cutting stylus is relevant just because of the motion of the medium or lacquer as it's being cut. The shape of the modulations are certainly not going to be that of a partial circle. Which affirms my position that I don't believe SRA needs to match VTA necessarily. It has to or 'may' have to match a particular 'angle', not an 'arc'. |
Google 'record groove modulation photo' |
I'm still wondering why, if slant angle varies not only from record to record but by the signal itself, by a cutter who's VTA is for all intents and purposes static, does cartridge VTA/SRA need to match VMA? Does it not stand to reason that in the same way variations are produced, the same information will be retrieved? Albeit once external influences such as adverse lacquer/cutter interactions are compensated for via SRA adjustment? Once adjusted, will the play back stylus not follow the same behavior as the cutting stylus. Same VTA constant. |
When I adjust SRA to where it sounds correct, how close is it to (average?) VMA? It sure sounds like the entire frequency spectrum is correct, not just parts of it. |
Thank you Kiddman. But my question is really an assertion or really an assumption that although the angles may not have to match, SRA still needs to be precise and exact irrespective of the stylus still making full contact with the groove within that 3 degree allowable tolerance. I'm suggesting that that 6 degree margin is actually far larger sonically than the math suggests. Where mathematically that exact point is, is anybody's guess and seems to me what this discussion is all about according to the op. |
...and hence the need to find it on the fly. |
