Stylus Rake Angle

Atmasphere:

Take it as a definition unique to the technology that 'groove depth' means how deep the groove is with no signal.

I understand that. It is the reference point. A silent groove has a fixed depth and smooth sides.

If the cutterhead were to rise and fall with respect to the lacquer surface, then we would see a varying groove depth

Clearly that is the case.

But when the cutting stylus records any signal other than a pure mono one it must move more and less deep into the lacquer, otherwise how can the signal be cut? That was what I was getting at and confused by your answer. I didn't mean the whole mechanism moved, solely the cutter itself.

It's an interesting subject. Maybe I should get my hands on a cutting lathe...

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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.

Doug and Raul, I've been experimenting some more with the VTA on my SME V-12. I don't know if my hearing is becoming more acute, or if I'm slowly learning more about what to listen for. It is now clear to me that my VTA has been too high for my thinner, mostly classical 150 gram LPs. The newer reissues at 180 grams sounds great but on careful listening to my older, thinner LPs, the harmonics do seem to arrive a bit too early, obscuring the fundamental.

Doug is correct that I reversed the description of the arm. So I lowered the arm about 1mm and this improved the relationship between harmonics and fundamentals, just as we discussed earlier up the thread. Interestingly, to Raul's point, dynamics also improved and this was quite noticeable. There is also a fuller, richer sound to massed strings and the midrange in general as well as more ambient cues and spatial information.

I listened first to 3 thinner 150 gram LPs: Vivaldi's Concerto for two Mandolins, a solo Mozart piano recording and the Sheffield Drum Track LP. In each case the lower VTA setting improved the sound and enjoyment of the music. But when I then listened to the thicker 180 gram reissues of Muddy Waters Folk Singer, Ella and Louise and Julie London, they lacked dynamics and sounded a bit dull. So I raised the VTA and everything sounded right again.

Yesterday, I heard Shostakavich's "Cello Concerto No. 1 in E-Flat, Opus 107" with Yo Yo Ma at the BSO from the fifth row center. Being about 20 feet from Mr. Ma's incredible cello playing was quite a treat and it gave me a real sense of the energy and sound of that instrument. With the sound fresh in my mind, I went home and wanted to immediately compare the sound of that cello to some of my recordings. Since I don't have that recording I played Dvorak' Cello Concerto and Brahm's Concerto for Violin and Cello. Sure enough, altering VTA by 1mm in the back of a 12" arm was clearly audible and effected how natural the recorded cello sounded, but it also improved the sound of the rest of the orchestra and the sound of the hall.

So, I just thought I would share my experience about listening to the effect of VTA/SRA changes and move for a bit away from the technical discussion of cutter heads and cartridges. I'm now a firm believer in the importance of proper VTA/SRA settings and the need to adjust, at least slightly for different thickness LPs. I never thought I would do this with my current arm. I don't want to change for every LP like some of you do, as it is too cumbersome. SME trades convenience/ease of adjustments for a very rigid/solid anchoring of the bearing tower in the arm board. I think I will simply change between two settings for thick or thin LPs by creating a metal shim for confirming the proper height. This will make changes fairly easy and repeatable and the music will sound better.

Peterayer and Stringreen,
Sorry to veer off on to record cutting.

To get back to the OP. The reason why there is an issue with regard to SRA and VTA is that they affect different things. An appreciation of what each term actually means helps to understand the issues. An appreciation of why cartridges have the geometry they do also helps. Reading the articles I linked to will be useful in doing this. Some might find them too technical, in which case, ignore the subject and set your arm up to sound as good as you can.

Csontas:
from your reply, it is clear that, if you have read the articles and are none the wiser, you fall into the last category above. Please don't insult me or question my motives.

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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.