VTF, VTA, SRA, and 92 degrees - question


I'm familiar with the logic that has been out there for a while about setting SRA at 92 degrees for what is considered the optimal styus position, based on a lot of analysis done by Elison and others. My question is, if VTF and VTA are set per cart maker's recommendations (let's discount Anti-skate for this discussion even though it would come into play), then wouldn't the SRA be automatically set optimally per the manufacturer's intention? Assume a cart that is built to the company's design parameters - no bent cantilever, no offset stylus etc.

Take a Benz cart for example. Many (if not all) of them specify a VTA of 20 degrees. So if VTF (and yes A-S) and arm height are set so that when all's said and done the VTA is 20 degrees, isn't that what it *should* be set at based on how Benz expects that cart to perform?

I ask because I set the SRA on my Benz to 92 degrees going by that camp, and when I checked the SRA it was at - guess what - about 22 degrees. That kind of suggests Benz expects the stylus to be at 90 degrees relative to the record. Isn't that how they've designed it? Don't I run the risk of having to compensate in other ways if the cart winds up exhibiting tracking problems at an SRA that does not support the specified VTA?
tonyptony
It really doesn’t matter if you pick 92 degree SRA or the manufacture’s recommended VTA, because they are both just “starting” points in which you fine tune and adjust by ear. No 2 cartridges of the same make and model are the same; therefore, the manufacture recommendations are deemed “average” settings.
VTA and SRA are basically the same, its just a matter of where you choose to measure. A better way of putting it may be they are 100 % related to each other.

I'd state that SRA is the most accurate measurement as it is where the interface to the vinyl is. What ever VTA ends up being with a SRA at 92' is just a matter of how accurate the stylus was adhered to the cantilever.

This measurement is of course to be taken at the right VTF as varying it will change the SRA.

Good Listening

Peter
VTA and SRA are basically the same, its just a matter of where you choose to measure.

I'm not sure about this, Peter. Based on what I'm seeing with my Benz, they have the stylus set up so that at the specified 20 degree VTA the SRA appears to be dead 90 degrees, not 92. Almost too exact to be a mistake. So is this what they really intended as the nominal staring point, I wonder?
I assume that you are using a digital microscope and overlaying the image with digital protractor to measure SRA. How are you measuring VTA?
"This measurement is of course to be taken at the right VTF as varying it will change the SRA." So will the thickness of the vinyl(ie: standard thin Columbia pressing vs 180 or 200 gram disc).
I assume that you are using a digital microscope and overlaying the image with digital protractor to measure SRA. How are you measuring VTA?

Yes to your assumption. VTA is being measured in a similar manner, except for that I am measuring the angle of the cantilever relative to the horizontal surface of the record.

Using Expressimoaudio's 0 degree precision VTA block to insure measurement are with respect to an angle corrected image. Using a Supereyes B008 digital scope.
I believe that the suggested 92' SRA angle is based upon that this is how most cutting lathes are set. SRA and VTA are completely aligned with each other, they change together. Again I'd state that the stylus to vinyl interface is the most important one as this is where the mechanical transfer happens.

On the other hand I don't loose sleep over the different thickness of the records I play, I set my SRA with a 180 GM record. Remember this is supposed to be fun not a chore, fretting about a different setting for each record is way beyond what I'd consider rational.

Good Listening

Peter
The difficulty with VTA is that it is the angle between the record, and a line joining the tip of the stylus with the fulcrum...wherever that is. It is not the same as the "cantilever angle"! It is usually about 2 degrees more than the cantilever angle, depending on the length of the cantilever and height of the diamond. It seems that no cartridge has the "gold standard" setup (VTA 20 and SRA 92), they all seem to be out, often by quite a large margin. So I'm not sure what to do about this. Mine sounds brilliant with the tone arm near horizontal, which gives a cantilever angle of 22 degrees and an SRA of about 95 degrees, to correct the angles I would have to drop the tonearm base by about 15mm, and I'm sure the mechanical problems associated would make things worse (on an 11 inch arm 1 degree change in SRA equates to over 5mm change in arm height!!). I think the jury is still out on this one, perhaps the best is to set by ear from horizontal. I suppose I'm as confused as most everyone else:)
Yes, you're right Peter. I guess my real concern is how much / whether a non optimal SRA can impact tracking ability. With everything set the way it is, I'm running a VTF of just under 2.1 grams for good tracking. That's a bit above the magic 1.9 grams that practically every bit on info I can find says is "correct" for the Benz Wood of my vintage. I'm not sure I understand what (if anything) the relationship is between SRA, tracking ability, and tracking force.
I'm with Michael Fremer on this one: Set the SRA at 92 degrees, or as close as you are able to get it, and leave it. With my tonearm I can only achieve 91...good enough for me. I then adjust VTF and azimuth optimally....recheck SRA...and I'm done. The difference in vinyl thickness will have no audible effect...it's too small a difference to throw off the SRA. If I recall correctly, Fremer stated a 4mm adjustment in tonearm height will change SRA by 1 degree.
Well, with all the measuring tools, calibrated blocks, and digital photos I have I think (!) I can get back to where I am now. I'm going to try again by starting with the cart at horizontal and see what happens from there.
Tony, can you hear any difference between 1 degree changes?
Dinster, you could try putting a 2mm shim on the back of the cartridge between the headshell and cart. This will angle the back of the cart down and get you much closer to 92 degrees. I have a little brass shim for this purpose and it works well. I have a cart that needs this shim in the front because I can't raise the back of the arm high enough without it.
I am sure some of you have noticed that different records seem to need a slightly different VTA. The reason for this is two-fold; first the LP is a different thickness. The second is the the cutter stylus on the cutterhead that cut the lacquer for the LP may have been set at a slightly different angle. This is why two LPs of the same thickness on the same label may still need to have two different settings.

The cutter stylus has the job of cutting the lacquer. To do this it is shaped a certain way, heated to a particular temperature, set to a particular angle (cutter height) and tracked at a certain pressure. What works on one day in the mastering lab may not work the second day as the lacquer can be different, even if only by temperature (they cut easier on warmer days for example). So the mastering engineer has to be constantly aware of the condition of the stylus and keeping test lacquers on on hand to get immediate feedback on the effectiveness of his settings.

So this may not be as exact a science as you all might be thinking- it is as much an art. The 92 degree value is an excellent approximation, just as is getting the front of the cartridge to be perfectly perpendicular to the LP surface. This is why it is helpful to be able to adjust the VTA on the fly, like you can do with the Triplanar tonearm.
One also must remember that as the record passes under the stylus and rides the slight (or excessive) warps, off centered spindle hole, etc., the VTA, the VTF, the Bias, etc....all the parameters are constantly changing. All we can do is get it "close".
can you hear any difference between 1 degree changes?

Well, I was as careful with my Denon 103R in experimenting and I heard a difference between 92 and 90 degress with that cart, which has a plain old spherical stylus. But I really didn't mean my original post to be centered only around the sound. The end of my original post was where my real concern is - whether there is any relationship between SRA, VTA, and the ability to track.
Dinster, you could try putting a 2mm shim on the back of the cartridge between the headshell and cart. This will angle the back of the cart down and get you much closer to 92 degrees. I have a little brass shim for this purpose and it works well. I have a cart that needs this shim in the front because I can't raise the back of the arm high enough without it.
Sarcher30 (System | Threads | Answers | This Thread)

Thanks for that suggestion, I actually investigated making a series of wedged shims in different angles for this purpose, thought there may be a market for them, can't remember now why I didn't go ahead. Think I might still give it a try!
I spent a good chunk of the afternoon realigning everything starting with setting the cart dead level. After tweaking and adjusting I think I can safely say that at least in my case it makes absolutely no difference in how the cart tracks, or the needed VTF and A-S. Both are practically identical to when I had the cart slightly tail up to get the 92 degree SRA. As to how it sounds, I think I like it a bit better tail up. It sounds clear and mellow (not soft), but I think I like that small extra bit of transient snap I was geting before.
Dear Tonyptony: +++++ " whether there is any relationship between SRA, VTA, and the ability to track. " +++++

yes, exist a relationship. Now, normally we are very near of the " perfect " VTA/SRA cartridge set-up, tiny deviations from that " perfect " parameter does not affect the tracking cartridge abilities but if we have a severe deviation then that could affect those cartridge abilities especialy on high velocity recorded grooves and in the inner part LP grooves.

Now, a difference of one grade inj SRA is audible and this depend on the audio system resolution and quality of the cartridge and quality of the other cartridge parameters set up.

About the difference in sounds becaus ethe thickness of the LP, example from 120 grs to 200 grs, we can hear the difference because of that and not only because the SRA change but because the overhang change.

Analog always is a compromise and many times that compromise comes from the very poor quality control that have all the LP manufacturers. Stringreen/Atmasphere posted the why's.

Regards and enjoy the music,
R.
^^ 'poor quality control'?? nah- certainly no worse than any other format. Most new LPs I see these days are really well done.
Dear Atmasphere: +++++ " are really well done.... " +++++

how is that? which are your references about because all that depends on that refrences/standards?

For me " well done " means: LP hole centered and no single warps.

For years now I usually bought no less than new 15 LPs each month, some times over 25 LPs and I never found out one/single LP that is " well done " builded.

Each one of us are paying over 30.00 ( even over 50.00 ) for each LP so for me " well done " must be really " well dne " not near " well done ".

IMHO the LP audio industry is taking our money in an irresponsable way and we are paying ( our culprit to follow doing. ) for a " crap " of products.

There are several threads in Agon and other forums where audiophiles/customers are and have severe complaints on that critical subject that throw out all our eforts in time and money to have a " perfect " tunned audio system that when the cartridge stylus hit the LP all those effort gone like " the wind ".

Good to know that you are the exception that confirms the rules about.

Regards and enjoy the music,
R.
Atmasphere
Most new LPs I see these days are really well done.

You must be joking. The quality of the great majority of today's records is absolutely abysmal. Finding a record that's flat on both sides is a rarity, as it finding one that has no surface noise. As I'm writing this I'm listening to Norah Jones "Feels Like Home" pressed at Kassem's QRP that retails for close to $40, and the record is both warped and has audible surface noise that's worse than on many of my records I bought used. Oh, and that's the replacement that Analogue Productions sent me. The original was much worse...

Sorry to get off-topic, but I just can't read such statements and stay silent.
QRP is doing some amazing work. We did a project through them recently and the final pressings were nearly as silent as the original lacquers (which is to say, so quiet as to rival digital recordings)!

It may be that the copy you got was warped, but that does not speak for all of them. IOW I was not joking. Warps have to do with heat during storage and shipping, not the process of making the LP. I buy a lot of LPs from indy labels, and it has been my experience that that they are usually excellent quality. But I live in Minnesota and that might make a difference with the warps.