Adjusting SRA using macro lens vs microscope

Glai,

You'll certainly see/learn something with the microscope. It should help you find a "close approximate starting point". Don_c55's statement that 80% of all LP's were cut at precisely 92 degrees is not consistent with my experience, but my collection extends from very early LP's from before 1955 to current releases, 4000 LP's on dozens of record labels. If a collection were limited to recent releases I'd agree with him.

Of course within reason it really doesn't much matter where you start. What matters is where you finish. :-)

Suggestions:
First, please start thinking about SRA, not VTA. They are two different things. What you'll be viewing with your microscope is SRA. The changes you'll hear as your listening skills advance will be primarily due to changes in SRA, only secondarily to changes in VTA.

Skipping over the correct SRA setting is very easy because the window is very small. This is especially true with modern line contact or micro-ridge stylus profiles. Until you become practiced it's helpful to hunt in very tiny increments, no more than 5 points on the TriPlanar's 100 point dial for example. Our recorded height settings on about 1000 LP's are to the nearest 1/2 point on that dial (1/200th of a turn). If you crank the dial around in big moves you'll skip right by and not know it, especially if you're not attuned to what to listen for.

P.S. With the TP or any threaded adjuster, don't forget to always approach the desired setting from below, which takes up the backlash in the threads. Otherwise you'll just have chaos.

What to listen for?
Frank Schroeder describes it as "the integration of fundamental and harmonics across the time domain". What????? Actually that's a perfect description. (FWIW, in less resolving setups you'll hear a shift in perceived frequency balance, but that's due to system-induced mud. Your system appears to be more resolving than that.)

Every note from a real, acoustic instrument is composed of a fundamental plus higher order harmonics. If the arm base is too high, you'll hear the higher frequency harmonics BEFORE the fundamental. The ring and hiss off a cymbal begin before the actual tap. (In that less resolving system it'll just sound "bright".) If the arm base is too low, you'll hear the fundamental followed by an unnatural time lag before the harmonics. (In that less resolving system it'll just sound bass-heavy.) When SRA is just right, the tap and the resulting harmonics will be tight and properly integrated in the TIME domain, as Frank said. (I heard all this before I heard Frank offer that description, but I can't think of a better or more succinct one.)

Remember, all this change happens in that very narrow adjustment window, 1/2 a turn of the TP's dial or less. If you're outside the window you may not hear anything at all from a height change. Work patiently.

As to particular records, forget any amplified instruments or anything with added reverb. Both of those totally screw up time domain information. Acoustic instruments, well and naturally recorded, are the best for building listening skills. Notes with clear leading transients are easier than sustained tones (adjusting SRA using a sustained organ or flute note is almost impossible). Vocals are possible to use if they contain lots of voiced fricatives and explosives (S's, T's, D's, K's, hard G's, etc.). No one can set SRA from "la-la-la".

It's pointless being more specific because different ears react differently, though they should lead to the same result.

Example:
I hear SRA changes best in higher pitched instruments with quick transients and a good decay. Plucked string instruments of any type, cymbal taps, etc. My partner hears SRA best in low frequency instruments. Despite this difference in what we're most sensitive to, we invariably agree on the best setting. Not knowing how your ears work (even you don't, yet!) I suggest focusing on different sounds until they "get" it.

Now get to work! :-)

Thanks Doug. That is a very good summation. I will listen for that tonight, though my SME V makes adjusting for this stuff a bit tedious.

Dear Dougdeacon: I know that what you said you were listening is what you in true were listening, no question about.

Where I don't know for sure where you are really " stand up " is if you heard what you heard because you are right on SRA for that track/groove recording or because you have the right azymuth or the right overhang or right in two of these parameters or what!.

As I posted, when we change SRA we have to adjust at least overhang and azymuth and I don't read that you made the overhang/azymuth changes everytime you change SRA. Maybe I'm missing something there but I can't understand how you compensate the other parameters when SRA is changes.

Doug, I'm assuming that you/we want that the cartridge set-up with that track in the recording be " perfect ".

In any decent audio system you could hear tiny overhang set up differences, as tiny as 0.1mm, your system is pretty good so you can and in the other side both of you I know have good ears.
How do you know that that tiny SRA changes are the one concept ( SRA ) that in specific made the difference and not the overhang or azymuth or some kind of distortion because some of those parameters ar out of target?

IMHO the first step to tonearm cartridge set-up is to choose a tonearm geometry set up: Baerwald, Löfgren, Bauer, Stevenson or what you like. Why choose any of these geometry tonearm/cartridge set up equations/calculators?

Because in any one of them we have different distortion level in different parts ( inner grooves, outer grooves, between null points, etc. ) of the whole recorded LP surface, so we choose due to that average distortions we want, we choose here our trade-offs.

First target is that the cartridge/tonearm set up be " perfect on three parameters: TT spindle center to tonearm pivot center distance, overhang and offset angle.
If you have a tiny error/difference in overhang or offset angle in the cartridge set up then your/our distortions targets changes and what we choose at the begin it is not any more achieved.

SRA changes not only change the SRA but made that other critical parameters change too so we have to reset these parameters for be again right on target.

All these considerations make that we can't speak that SRA was the " one "/culprit for the " new " sound, IMHO it is more complex than that.
This complexity IMHO too made the whole set up for each one recording a nightmare if we want to do it precise and near " perfect ".
I'm not against to do it with each recording but the analog alternative is so imperfect that we can't make it " perfect ".
In your case what happen if you decide to change your cartridge for other different? what happen with all the work that both of you take it with those 1,000 LPs where you writed in each one the SRA set up?

You need to test again all those 1,000 LPs with the new cartridge, not an easy task and for the second time!

I think that before we take this or the other or other one approach in the SRA subject we have to choose our targets/priorities and " build " around those targets with out changing it because the SRA or other parameter changes.

The ears are the tool that almost all are using to the cartridge set up but our each one knowledge on music makes a difference too as makes a differences to understand what is happening in our home audio system at each audio link.

Through the time ( listening time. ) we learn when our system performance is near " perfection " as you already know with your system.

My post is only trying to clarify the whole concept and what surounded the cartridge/tonearm/LP set up.

Btw, you posted:

+++++ " please start thinking about SRA, not VTA. They are two different things. What you'll be viewing with your microscope is SRA. The changes you'll hear as your listening skills advance will be primarily due to changes in SRA, only secondarily to changes in VTA. " +++++

Doug, everytime you change SRA you change VTA too and everytime you change VTA you change SRA too. Sure are different and the meaning is different but both are IMHO " primarily ". When people change VTA to improve his system quality performance the improvement comes because that VTA change changed the SRA.

Anyway, the important subject is to have trained ears to be " there ".

Regards and enjoy the music,
Raul.

Raul,

I see your point about the three parameters all being minutely affected when one changes his VTA setting. I also agree that the settings Doug wrote down for his VTA for each of those 1,000 LPs is useful information and saves him time when he plays one of those LPs. Those settings will be different with a different cartridge and probably with a different arm, especially one that does not have the same calibration or markings on it for repeatability. He will contend with that how he will.

However, I was at the listening session last weekend when we auditioned the Ortofon A90 and Doug adjusted VTA/SRA for each LP. I know what I heard and the results were much better after Doug did his adjustments. I learned a lot from his expertise. I don't really care if the improvements were in fact SRA related, overhang related or spindle distance related. That is for arm designers to worry about IMHO. His adjustments were easy to make given his experience, ears and the fantastic arm. And they were well worth the effort on a cartridge like the A90. We all make trade offs in this analog hobby, I agree with you. I don't plan go to the effort of changing cartridge alignment for each LP. The "effect" of changing the VTA/SRA setting is enough for me once a good average alignment is achieved and if the arm is capable of easy VTA adjustments.

@Doug,

Something like Dave Wilson's Razzmattaz V. 1 is a good record for setting VTA. A better Heliotrope ;)

Here's a link to another discussion with a good pic illustrating the utility of the USB Scope.

http://www.whatsbestforum.com/showthread.php?1570-Cartridge-Set-Up