Stylus Rake Angle

Dear Csontos: Yes, because transiente performance is main part of Dynamics in live music and recorded one.

As you said: " poor or good " transients, that's " all ".

R.

Yes, but "timing" per se is the job of the turntable. The turntable provides the "X-axis" for the music, which is time. Who could argue that correct time is not important? Not me.

Stringreen. I know what your problem is. It's the Vandersteens!

Mr. M.... what is the problem that is caused by the Vandersteens?

Chill out. Just a little audiophile humor on a subject with turntable tonearm/cartridge rake angle that a lot of people take WAY to seriously. Yes, I have a turntable. Had one for several decades and found a lot of other adjustments that are far more important than rake angle.

Dear Peterayer: ++++ " 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. " +++++

I respect your opinion as the Dougdeacon and FS but I always like to understand a subject analizing what is really happening around that subject before take other opinions as the " bible ".

I posted that maybe " timing " is not the right word but I don't have nothing against the word per se.

+++ " if the fundamental is obscured by the harmonics...." ++++

IMHO you have no precise evidence that that is what really happen because when the cartridge set up is not " perfect " and is off it then we can hear what you are saying because a wrong transient response on the bass but not because the " harmonics obscured the fundamental ".
All of us know that if we want more bright in the cartridge sound/performance we have to make a change to put higher the cartridge tail and for the bass the other way around.

Now, when we are listening our audio system fundamentals and its harmonics over the whole frequency range, of an LP score, comes one after the other in extremely fast way where you, Dougdeacon, FS, me or any one but a Mars bat can identify.

The only way to prove what you say could be to make a live tests:

using a musical instrument ( by a specific player: arp, piano, violin or whatever. ) make a live recording of one and only one note and try to identify fundamental and harmonics live against a D2D recording of that single note and with and with out a " perfect " cartridge set up.

Dynamics and what this envolve is IMHO what we have to look during a cartridge set up.

Regards and enjoy the music,
R.

Csontos and Peterayers hear exactly what I hear.

***
Lewm, sorry we haven't explained this in a way that helps you understand this as a timing issue. Thanks for hanging in there.

Of course you're right that the spinning platter controls the timing of the MUSIC. If a TT runs slow or fast, the pace and pitch of the music will be off. If TT speed varies, we hear pitch shifts.

With SRA we're talking about a timing on a much smaller scale: the *relative* timing of the component parts of a SINGLE NOTE. This kind of timing has nothing to do with pitch or rhythm. TT speed does not affect it, SRA changes alter the internal timing of each note even when TT speed is perfect. In fact, they're easier to hear on a TT that maintains highly accurate speed.

Peter wrote,

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

I think he got the arm positions reversed, but the effects he described are exactly what I hear.

As for a mechanism to explain this, I can only offer conjecture.

Fact: the cutting stylus had *some* specific SRA. This results in a unique cross-section for each and every complex set of groove modulations that make up what we call a "sound".

Assumption: to trace each cross-section exactly, the playback stylus must have the same SRA.

If the arm is too high at the pivot, the tip of the stylus will encounter each modulation before the the top of the stylus does, ie, too early. If the arm is too low at the pivot, the tip of the stylus will be slightly behind the top of the stylus, ie, too late. In either case, the stylus will "slur" across the modulation instead of encountering each part of it simultaneously.

If the playback stylus "slurs" across each modulation rather than tracing it *exactly* as cut, the aural effect is that harmonics arrive either too early or too late RELATIVE TO their fundamental.

I would not argue that this is necessarily what is occuring, but this is what it sounds like.

***
Raul mentioned dynamics. Optimal SRA provides optimal micro-dynamics. If the playback styles traces each modulation as cleanly as possible, cantilever excursions will match the path of the cutting head as closely as possible. To the extend the playback stylus "slurs" across modulations, cantilever excursions will be reduced and slurred in time, reducing dynamics.

I find this harder to hear than timing errors in fundamental vs. harmonics, but Paul finds it easier. With regard to SRA changes, I believe he and Raul hear similar things.

Dear Dougdeacon: I remember very clear when I was hosted at your place enjoying MUSIC and knowing both of you love for MUSIC and accurate ears ( my sincere regards for both of you. ).

++++ " I find this harder to hear than timing errors in fundamental vs. harmonics, but Paul finds it easier. " ++++

even that you are speculating on that " timing " I think that any one of us have their own way to to " kill the mouse ".

I'm accustom/trained to look for Dynamics at both frequency extremes looking for accuracy.
Dynamics is a word that involve almost everyhing in a reproduced sound: live or recorded, and through Dynamics evaluation in a recording transient response is critical as is critical each one overall knowledge level and audio system kind of resolution.

I think that all we know the importance to have the " precise " SRA set up.

I want to insist again thet OVERHANG is even more critical than SRA for a better quality performance. If we don't care about Overhang changes when VTA/SRA changes or VTF changes then where we leave the cartridge/tonearm accurate alignment where we invested on several protractors and choosed a specific alignment only to have a precise/accurate set up that we all always are looking for?!!!!!!

Regards and enjoy the music,
R.

At the end the subject is to be aware when the cartridge/tonearm overall set up is right or wrong and why.

R.

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.

Dear Csontos: I understand your point an opinions and I can tell you that's really tiresome to make overhang changes everytime but IMHO is necessary. Of course is up to each one of us do it or not: our each one privilege.

I really appreciated all your posts. Only under a friendly discussion we can improve our self.

regards and enjoy the music,
R.

Raul, when one slides a cartridge in the headshell 0.3mm to make a very slight change in overhang because the SRA has been adjusted, how does one achieve this tiny move without rotating the cartridge about its ZENITH angle? With some stylii profiles, proper ZENITH alignment matters a lot. Of course it changes over the length of the LP and is only truly tangent at the two null points.

And, if overhang changes, does this not also require a tiny change in ZENITH so that the stylus maintains proper alignment (true tangence) at the two null points?

I did compare the alignment results between the SME protractor and my custom MINT LP arc type protractor and found that the overhang was slightly different. I can't say which is more correct, but the MINT is more accurate and allows for more precise results. I did find the music sounded better also, though this may just be that "I like it" more with the MINT.

One issue with the MINT is that the thickness of the glass is not the same as every LP thickness, so overhang is only correct with LPs that happen to be the same thickness as the glass. Overhang for other thickness LPs will necessarily be different.

If, as you contend, that overhang is more critical than SRA, what do you think about all of the people who adjust VTA for each LP without also adjusting overhang? The people with whom I have spoken feel that proper SRA is more critical than perfect overhang, so they don't bother to adjust both with each LP. Could you imagine the time involved to do both for every LP?

I'm only asking these questions to learn more about the subject. I'm very curious about how each of these adjustments effects the others and really which is the most critical. I, for one, adjust my arm and cartridge to be the best compromise with a group of my favorite and most familiar LPs. I don't have the patience to adjust settings for different LPs.

Dear Raul, Perhaps I am mistaken but was there not a time when you expressed the opinion that small errors in overhang do not make much audible difference, may not even be "important"? I thought that was your position vis a vis that of Dertonearm et al, who was arguing the opposite. If my memory is accurate, what made you change your mind by 180 degrees?

Dear Lewm/Peter/all: Nothing changed on my mind about, overhang always is important. Things are that for many people overhang changes " makes " almost no diference on the quality performance and not because it does not makes a difference but because they are unaware of how the system sounds when overhang is off. It's not easy to be aware if you don't know what to look for: if you are not trained to do it.
In the other side in the very first time/moment that the cartridge stylus hit the LP grooves the overhang/VTA/SRA/VTF suffer minute changes due to the imperfect medium and maybe because of this I could said it has not " anal importance ".

This is something similar as the RIAA eq. deviation where I supported and support the critical importance on accuracy.
I say that a prety decent RIAA eq. frequency deviation of +,- 0.1 db is not enough and that a RIAA frequency deviation of: +,- 0.015 db is better and we can hear the difference IF we are trained to know what to look for during playback.

Now, all cartridge/tonearm alignment parameters are important and critical to achieve a top quality performance and we have to take care on each one if we want that the cartridge can shows us at its top performance.

In a pivoted tonearm the cartridge alignment start when we choose the the type of alignment: Baerwald, Löfgren B , Stevenson and the like.

Löfgren defined the geometry equations for a precise cartridge set up where we have mainly to know the overhang and offset angle ( between other parameters. ).

This is a sin-equanon the very first step for the cartridge can shows it at its best.
So IMHO overhang and offset angle ( for a choosed alignment geometry equations. ) must stay with out changes when other cartridge set up changes.

The different alignment equations is a trade offs " game " depending on what we want/prefer on distortions level between null points and outside null points at outer and inner LP grooves.

The alignment equations we choose optimize those distortions inside that choosed alignment in a way that any tyni deviation on the overhang and/or in offset angle cartridge set up produce a different kind of distortions to the ones choosed with different trade offs.

That we can hear or not the new distortions/trade offs does not invalidate the importance that on each alignment the name of the game is: accuracy that must stay that way always.

The target/main subject of any cartridge/tonearm geometry alignment is to do it as accurate as we can because we want optimized/lower distortions.
Tyni deviations from that " accuracy " increment in exponential way those distortions so we don't want to have this.

We all are very sensible to VTA/SRA changes and changes on Azymuth because we are aware of the differences on sound with these changes on cartridge set up and because we are accustom to do it and to hear the changes in performance when the overhang changes we are really unaware on how we detect it or how we listen it.

We have to learn trhough a training to be aware of it.

As I said, it's tiresoem/nightmare to change overhang each time we need it ( for VTA/SRA/VTF ) but we need to do it especially when we are doing cartridge comparisons or when we are fine tunning a cartridge.

Maybe some of you could remember that several times I insisted to have a proved and repetable evaluation/set up process that can permit to be aware of different kind of distortions and quality performance levels and know teh why's.

A easy way to be aware of overhang misalignment is to choose a well know LP tracks with bass range content and listen the system transiente response at different overhang values. You will be surprised on what you can hear down there those overhang changes.

Regards and enjoy the music,
R.

Doug and Csontos seem to have the way of it.

The cutting stylus on an LP cutterhead only does about 10 hours before it needs to be replaced. You'd think they were all exactly the same but after replacement you wind up resetting a lot of parameters on the cutterhead. Tiny little adjustments can have a huge effect on the groove you cut, so its anything but cut and dried. I find the talk about SRA a bit amusing as a result.

As the stylus wears, sometimes you have to make little adjustments, like the stylus temperature. Funny thing- it cuts a slightly different angle depending on the temperature. Some LPs don't have very much in the way of dynamics so you can change groove depth a bit to allow for more time on the LP, conversely if something has a lot of dynamics or out of phase bass, you might cut a little deeper. So groove depth affects stylus angle too.

Bottom line: don't get too upset about it. Its more important for the mastering engineer to cut a good groove than it is to get it exactly at 92 degrees. You are never going to be too far off either- the stylus won't cut right if its a few degrees off... trust me on this one- there are far more important things to worry about :)

I don't get this "slur" thing. The stylus is rigid/ inflexible and so whether the tip or farther up encounters the groove wall first, a deflection occurs. I'm not saying none of this makes a difference but if a guy who cuts lacquers for a living and a guy who builds some of the most coveted carts in the world says move along, there is nothing to see here, then maybe we should believe them.

On the subject of stylus overhang:
If the pivot to spindle distance is set exactly right, meaning +/-0.3mm of the recommended, because that is the best anyone can do, then it seems to me that small errors in overhang (say +/-1.0mm, but I would have to do the geometry before settling on that margin) can be tolerated.
Reason: None of the accepted tonearm geometries achieve more than two points on the arc of the stylus tip where there is tangency. The various algorithms differ only in the locations of these two points along the LP surface (and they also do differ in the amounts of tracking error at other points along the way, but I am not debating that here). A small error in overhang, assuming P2S is correct, will only move those two points of tangency by small distances in or out on the radius of the LP. So long as those two points remain on the playing surface, what is lost?

You answered your own question.

With regard to the distinction between SRA and VTA, there is also an equivalent distortion to Horizontal Tracking Error if the VTA is not that at which the record was cut. This Vertical Tracking Error is distinct from SRA and will influence tracking performance.

So with any given cartridge optimising SRA may mean VTA being compromised...

Atmasphere, you said:

As the stylus wears, sometimes you have to make little adjustments, like the stylus temperature. Funny thing- it cuts a slightly different angle depending on the temperature. Some LPs don't have very much in the way of dynamics so you can change groove depth a bit to allow for more time on the LP, conversely if something has a lot of dynamics or out of phase bass, you might cut a little deeper. So groove depth affects stylus angle too.

From what I understand, the cutter head angle may be a particular value, but the resulting profile on the record is different due to the springiness of the lacquer material which varies with temperature, such that the resulting optimum SRA is not that at which the record was cut. Variations in modulation mean that the cutter has to dig more or less deep, thus varying temperature and hence the profile, so that an optimum SRA at one point on the side may not be so at another. Would that be correct?

Lewm, you said:

A small error in overhang, assuming P2S is correct, will only move those two points of tangency by small distances in or out on the radius of the LP. So long as those two points remain on the playing surface, what is lost?

As you say, the important thing is the position of the two null points. Not because of their tangency, but because they define the distortion. As they become further apart, there is increasing distortion across the middle of the side. Closer together, the extremes are tracked with more distortion, particularly towards the centre. Small changes in null position make little difference.

However, that presupposes that the offset angle is set correctly which, rather than overhang or P2S, is , in my experience, the most difficult aspect of set up.

.

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.

What I would really like to see is a test record where each track of the same music be cut at different and documented SRA angles, plus a final track (of the same music) where the cutting SRA is constantly varied.

Then during playback and with our own SRA fixed, it should be interesting to try to hear whatever variations/distortions there may be. This will only serve to show what we should be listening for when playing back our regular records vis a vis our quest to set our SRA.

Dear John_gordon: It's unfortunate that with a pivoted tonearm a " right " set up cartridge is almost not posible at all. All the set up parameters are interrelated and any change on one of them affect the others and we have to reset it, tiresome.

The best we can do is to choose the best trade-offs and enjoy the MUSIC and when choosed try to stay inside those trade offs all the time because when we change the null points and accepted we are changed almost all: mainly distortion levels that means new trade offs.

The analog medium is full of imperfections and we have to deal with in the best way we can. Sometimes I think is an endless enterprise.

At the end each one of us have its own targets and MUSIC sound reproduction and each one trade offs choosed are related to achieve those targets.

Regards and enjoy the music,
R.

Dear Lewm: ++++ " then it seems to me that small errors in overhang (say +/-1.0mm, but I would have to do the geometry before settling on that margin) can be tolerated. " ++++

as I posted we have to choose our trade offs, this is each one privilege. For you 1.0mm could be tolerated and maybe for me even 1.5 mm too and as JG posted there will be an offset angle/linear ( and the like. )deviation too.

Imperfect world!

Regards and enjoy the music,
R.

Of course that we can take the attitude to don't care about at all and only listen. Nothing wrong with that.

R.

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.

Dear friends: IMHO speculations and theory is something that we have to prove.

Any one of you ( with Barwald or Löfgren B today cartridge/tonearm alignment. ) can make the next test:

simple make a change ( new set up ) to either of those alignments where you just need to make a change in overhang ( offset angle is negligible. Overhang less than 0.4mm. ) and listen carefully on both set ups with very good ( in deep ) know LP tracks at three LP surface positions: between null points, outer grooves ( out side null point. ) and inner grooves ( outside null point. ) .

You will now and understand why Löfgren calculated ( 50+ years ago. ) two alignment solutions: A ( Baerwald ) and B. Of course you can read his white papers somewhere in VE.

If you can try to find out tracks with high bass content ( more easy ) and listen the transient response on both set ups looking for differences and then share with us your experiences.

Regrads and enjoy the music,
R.

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

Raul

The analog medium is full of imperfections and we have to deal with in the best way we can. Sometimes I think is an endless enterprise.

At the end each one of us have its own targets and MUSIC sound reproduction and each one trade offs choosed are related to achieve those targets.

Yes, I agree all is compromise with regard to set up, especially with regard to SRA and VTA which are decided by the cartridge manufacturer. It is up to each listener to decide what is acceptable to them, and to be aware of why it is so.

Csontos

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.

The issue isn't that there is or isn't a standard (if recommending anything between 15 and 25 degrees for VTA constitutes a useful standard), but that it appears that the SRA parameter is variable depending on the mechanics of record cutting, and is at best an approximation of between 91 and 95 degrees, and can vary across a record. It also varies with downforce, and with offset, which in turn depends on chosen geometry and the accuracy with which it is set.

Until someone makes a headshell which allows variation of VTA/SRA without altering overhang and downforce, then those will be factors...

More info - old articles- here

.

John, What do you think is meant by the first sentence in that article you referenced?:

"Adjusting the cartridge for optimum SRA may alter the VTA away from optimum. Or vice versa."

I usually think of VTA as a useful surrogate for SRA, but I guess that a separate function of VTA, apart from its direct effect on SRA, would be to alter the angular relationships between magnets and coils, but that is a major function of VTF. The cantilever/magnets/coils are fixed in space except for the effect of VTF to re-position the cantilever, if too much or too little VTF is applied. Which takes me back to my question; what are they talking about?

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:)

From what I understand, the cutter head angle may be a particular value, but the resulting profile on the record is different due to the springiness of the lacquer material which varies with temperature, such that the resulting optimum SRA is not that at which the record was cut. Variations in modulation mean that the cutter has to dig more or less deep, thus varying temperature and hence the profile, so that an optimum SRA at one point on the side may not be so at another. Would that be correct?

No- but that is a common myth to which I subscribed before I started working with the cutting lathe. There really isn't 'springiness' in the lacquer surface. When modulation varies, the groove depth stays the same and the two can be set independently. The heated stylus cuts through the lacquer like butter if its set correctly - if not you get surface noise.

Csontos, I have been flying kites for some time :) seriously! But you are correct- if you can set SRA/VTA on the fly. LPs thicknesses vary as do the cutter angles. There is no other way to do it IMO. I don't think the thing you mentioned about standard cutting angles is correct though. What I have seen is that the cutter stylus needs a slight amount of rake (varies with each one as I said) and its really in the 1-4 degree range off of exactly perpendicular to the LP surface, so about 91-94 degrees. What we really don't know because no-one has really studied it is whether or not the best SRA position in playback is actually the same as the cutterhead was set to... I suspect that that varies with the individual cartridge.

I agree.

Atmasphere,
Surely the groove depth changes with signal? A right channel signal for example must cut into and out of the lacquer at 45 degrees. I can see that a heated cutting stylus will help the process, but then does that affect the final profile as the material cools?

Lewm,
The VTA is the angle from the cantilever pivot to the stylus tip relative to the record, which ideally should be the same angle as the equivalent angle a line from cutter pivot to the cutter stylus makes with the lacquer if there was no "give" in the material. Both can vary. Apparently there could be 10 degrees of a difference depending on the lathe.

But the cartridge is designed such that for an optimum downforce the generator is centred, and the resulting cantilever angle is the VTA. So the angle of the stylus relative to the cantilever is fixed and the two must vary together.

Now while the stylus might be set at 92 degrees, the cantilever may not be at the same angle as the the cutter. In which case there will be a distortion in the playback, similar to horizontal tracking error. Any adjustment to set VTA - the cantilever - to a particular angle will change the stylus rake as well, perhaps away from the average 92 degrees.

.

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.

Surely the groove depth changes with signal? A right channel signal for example must cut into and out of the lacquer at 45 degrees. I can see that a heated cutting stylus will help the process, but then does that affect the final profile as the material cools?

I used to hear about this thing called rebound associated with lacquers but yet to experience it. Yes, the groove wall is cut at a 45 degree angle, so if you were to cut an out-of-phase bass signal, the groove would indeed modulate up and down. Of course, the needle would not be able to track it, and such a signal fortunately does not exist in nature. If we encounter studio productions where out-of-phase information is a problem, we have a simple passive processor that takes care of it. So groove depth can be considered a constant.

Another way to look at this is if the cartridge body rises higher, that is a change in groove depth, if the needle simply traces a signal, the groove depth has not changed.

Atmasphere, Does azimuth vary from cutter to cutter and lathe to lathe? If so it would not surprise me.

Csontos, you said:

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.

You need to do your homework and think more on this.

Vertical Tracking Angle is a cartridge property. The clue is in the word "tracking".
The fact that it may not be the same as the equivalent angle used when the record was cut, as you mention but fail to realise its relevance, is what can lead to distortion in playback.

Atmasphere, you said:

Yes, the groove wall is cut at a 45 degree angle, so if you were to cut an out-of-phase bass signal, the groove would indeed modulate up and down. Of course, the needle would not be able to track it, and such a signal fortunately does not exist in nature. If we encounter studio productions where out-of-phase information is a problem, we have a simple passive processor that takes care of it. So groove depth can be considered a constant.

I wasn't talking about out of phase signals, but left or right signals. I can see that a mono signal varying only in amplitude, side to side, will maintain a constant groove depth which doesn't vary, but stereo?

I'm not trying to make a point but just trying to understand the process and its implications for playback, as coming from a mechanical engineering perspective, I am familiar with lathes and cutting tools, and the issues involved in machining different materials. That's why I'm interested in knowing more.

.

Sarcher30, it might, but if so it would be very very slight! If you look at any lathe you will see at once that they are built to be quite sturdy and machined to exact tolerances. Thus the cutterhead mount is exactly perpendicular to the platter surface; one of the better examples of how excellent machining really looks, such that the azimuth error cannot be measured. So in essence, I am saying 'no, azimuth does not vary from lathe to lathe'.

I wasn't talking about out of phase signals, but left or right signals. I can see that a mono signal varying only in amplitude, side to side, will maintain a constant groove depth which doesn't vary, but stereo?

I imagine my response was not entirely clear so I will try to restate in a less ambiguous way. There is no variation in groove depth due to signal. There is only signal modulation that varies, whether stereo or mono. It sounds to me like you are confusing the two- and I can see why.

Look at it this way- groove depth is something you can set on the cutterhead. Take it as a definition unique to the technology that 'groove depth' means how deep the groove is with no signal. The signal is a function of the electronics. Think of modulation in an radio signal and its the same idea- if you want to reproduce the signal, the groove depth is a constant, just as the frequency of the radio station is a constant. If you want to look at the groove as being variable depth according to the signal, you won't be able to reproduce it.

If the cutterhead were to rise and fall with respect to the lacquer surface, then we would see a varying groove depth. In theory, during playback the cartridge body is held in constant locus by the mass of the arm so that the cartridge can only respond by the motion of the needle in the groove, not anything else.

John, Thanks for the treatise. I agree with your definitions of the terms, but I cannot see the point of your statement:

"Now while the stylus might be set at 92 degrees, the cantilever may not be at the same angle as the the cutter."

The cartridge is a transducer whose optimal function depends upon a fixed spatial relationship between the magnets and coils, as one or the other vibrates. Once the LP is cut, why should the cantilever give a damn about the cutter angle? The stylus "cares" about that in terms of SRA. So I would think that you set VTA so as to obtain proper or optimal SRA, first of all to assure proper energy transfer between groove and stylus, and then it is VTF that mainly assures the proper spatial relations between the transducing parts of the cartridge. VTA is just a convenient surrogate for SRA. Probably this has become a discussion about semantics.

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!

Csontos,

If the cartridge manufacturers want to refer to SRA as VTA and vice-versa, so what?

They can call it what they wish, as can you, but the terms are distinct, and in adjusting every cartridge varying one varies the other.
VTA in a cartridge should be the same as the equivalent angle in a cutting lathe.
SRA should be the same as the cutting stylus angle.
My point is simply that optimising one does not automatically mean that the other is also optimised. This was the argument for using SRA rather than VTA to set up in the first place.

I used the cantilever angle as a easily understood approximation of VTA. The actual angle is that between a line drawn from the cantilever pivot point to the stylus tip and the record surface. For most cartridges this is close.

Lewm

Once the LP is cut, why should the cantilever give a damn about the cutter angle? The stylus "cares" about that in terms of SRA. So I would think that you set VTA so as to obtain proper or optimal SRA

The reason there is such a thing as VTA is that the stylus moves through an arc which is described by a radius the length of which is approximated by the cantilever and ostensibly at 20 degrees +/- 5, to the record surface. The reason for that is that the record was cut in a similar manner, the cutting stylus (while set at, say, 92 degrees to the lacquer surface), also describing an arc, as it is constrained within the cutting head. Variations in VTA cause distortions. They may be less of an issue than SRA but do exist.

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?

I think what John is trying to explain is that the arc of the stylus as it moves from side to side will be slightly different if the angle of the cantilever does not match that of the cutter. Irregardless of the SRA of the stylus/cutter.

I've never seen a LP cutting lathe up close. Does the cutter have a cantilever and suspension just like a cartridge?

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'.

I've found a1981 article in my "files" which explains things better than I've been able to, and uploaded it on to my blog:
Vertical Tracking Angle Explored - Keith Howard, Hifi Answers 1981

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Sorry - the article is from Practical HIFI not HIFI Answers - (from the days when there were too many hifi mags to keep track of...)

Csontos: I perhaps shouldn't have mentioned cantilevers per se, as opposed to the function of the cantilever. But have a read of the article mentioned.

John

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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.