Digital Microscope advice SRA

@folkfreak 

Thanks for the Rutherford audio link. That tool makes perfect sense.

An additional bit that can mess with things is that the cutter head's rake angle isn't a certainty!


A cutter stylus lasts about 10 hours of cutting. It has to be heated for best noise floor; as it wears it gets noisier and the temperature has to be adjusted but eventually it simply has to be changed out.


To do that the cutter head is removed from the lathe and the stylus is replaced. Then the head has to be set up again- to get the stylus to the proper position, depth, etc. Once that looks right, then test recordings can be made. Its right when the groove is completely silent. And by 'silent' I mean so quiet that literally the playback electronics are the noise floor.

At no point is there a measurement of the rake angle. The engineer is setting up for *lowest noise* and not anything else. Each stylus is a bit different, so after replacing one the engineer might have to do a bit of head scratching to get it right again. So that whole 92 degree thing is an approximation; its not cast in concrete and every LP is slightly different on this account.


IMO (I own a Scully lathe with a Westerex cutting system) this is a thing that isn't worth your worry. About the only thing that the microscope might be good for is making sure that the stylus is indeed on the end of the cantilever in the first place and that its not at a weird angle and so on- that you **will** be able to set it up in your arm.

Also...
just for fun I measured a few regular and 180 gram records and saw an average  thickness difference of around .6 mm in a range from 1mm to .25 mm.
On a 9” arm .6mm height difference  equals a change of .15 degrees (.12 degrees on a 12 inch arm) or about one turn on a VPI VTA on the fly arm.
Fifteen one hundredths of a degree? I’m amazed that makes a difference.

Others can debate the value and effectiveness, but to specifically answer your question about using a digital microscope, here’s a 5 min video by Mike Fremer who I consider a premier expert https://youtu.be/otysEyET6yE

You might also enjoy and learn from his one hour siminar on all aspects of turntable setup, including info on the microscope/SRA adjustment
https://www.youtube.com/watch?v=eQDa7suJn64&feature=share

Happy listening 

Dear @joes44: A few years a reviewer discovery the " black thread " with the use of a microscope to fix the rigth SRA ( I think MF. ).

Don't waist your time as he did and do, everytime he has a new cartridge, as several " audiophiles ".

During playback SRA/VTA is changing at almost each single groove in the LP due that the LP surface is not absolutely FLAT always exist micro and macro " waves ", additional the LPs comes with different tickness where always the SRA/VTA will be out of our original SRA/VTA set up.

Regards and enjoy the MUSIC NOT DISTORTIONS,
R.

I bought a digital microscope and tried this.

Far more trouble than it is worth. Better to start with the headshell parallel to the record and adjust by ear from there.

If you want to do this you will be able to see and get better focus resting the stylus on a CD instead of a record.

I agree with @lewm Even those who tout the microscope method agree it "might" get you into the ball park, but final setting is always by ear.

My own $.02:
Find a recording that people say is good for hearing the differences when you adjust SRA. Do a search here and elsewhere; there are a lot of suggestions out there. If you can't find one, take a record of a female singer and listen to it over and over 'till you know it very well. I have used Joni Mitchell's "Blue." Make sure it's something you like 'cause you'll be listening to it a lot.
Set your tone arm to absolutely level and listen to the recording a few times.
Read all you can about your cartridge and see if reviewers or users have a consensus suggesting tail up or down.
Change the angle in that direction a very small amount and listen to the whole record. You are listening for the voice and instruments to "pop' making them more 3 dimensional. Do that again and again in very small increments. If you do not hear improvement soon go back and stay at level.
If your reading does not come up with a tail up or down consensus. You may have to do this in both directions.
Ditch the microscope. IMO it is of little use with any cartridge, but especially for those with a sophisticated and non-symmetric shape

Judge it by ear. You will never be able to see anything like what you can hear. Classic case of misapplied technology.

Thanx folkfreak 1, I already have the smart stylus jig. Nice rig BTW.lewm, Did you ever hear the song "88 lines about 44 women" by the nails?Just whenever someone uses the word nihilist I think of that song.I'm actually not an Nth degree er. But I just thought since I have the equipment I'd give it a try. I was surprised as to how little my styli has worn. Nice to see that the stylus cleaner does the job it supposed to do. And I know, I know before I get frustrated,,, "Drop the screwdriver and back away from the Turntable!"

I have never tried using a digital scope myself.  I read comments by a couple of manufacturers of cartridges that there are problems with this approach.  For one thing, when the record is actually being played, the angle changes so the static measurement will be different from the supposedly correct angle during play.  

It makes more sense to start with a rough setting (the easier to accomplish setting of the tonearm/cartridge top parallel to the record surface, and then make small changes based on sonic preference.

Joe, Sorry to be such a nihilist, but yes, judge by ear.  While I agree with bimasta that it takes a big change in VTA to make much of a measurable change in SRA, I also observe that small changes in VTA, done by ear, have a subtle but satisfying effect on tonal balance, whether or not I am doing much to SRA.

The idea of measuring SRA using a digital microscope seems to be about as current as last year‘s high fashion. In recent weeks or months, there have been a few convincing posts by knowledgeable persons in the field suggesting that most of us would not know how to use the microscope to determine the true rake angle of the stylus, because it  requires an intimate understanding of the geometry of the stylus tip you are dealing with. And modern styli are very complex in shape.

It's not just the stylus shape that makes it difficult. The reality is that it takes a big change at the pivot-end to make an audible difference at the stylus end. I had VTA on-the-fly 30 years ago, I wanted that magic 'snap into focus' moment. But it took very large adjustments to hear any meaningful change. It was a VDH 1 stylus, with a very sharp edge — it should have been dramatic. I was so disappointed.

This puts it in perspective...

https://www.tnt-audio.com/sorgenti/vta_e.html

It can be done -- but is a PiTA and also can be next to impossible depending on your stylus profile

My detailed methodology is presented here
https://www.audioasylum.com/cgi/vt.mpl?f=vinyl&m=1084171&VT=T

Since then however I've moved on to two alternative options

1) Simply measure directly using a tool like this -- then fine tune by ear
http://www.rutherfordaudio.com/shop/default/brands/acoustical-systems/smartstylus.html

2) Or (best) use the AnalogMagik software and take the guesswork out -- but it will cost you!

So in other words; Don't get yer ******* in an uproar over minuscule amounts, Just judge it by ear?

 The idea of measuring SRA using a digital microscope seems to be about as current as last year‘s high fashion. In recent weeks or months, there have been a few convincing posts by knowledgeable persons in the field suggesting that most of us would not know how to use the microscope to determine the true rake angle of the stylus, because it  requires an intimate understanding of the geometry of the stylus tip you are dealing with. And modern styli are very complex in shape. Thus, it is difficult to know exactly how the contact points on the stylus tip are contacting the LP groove just by looking at it sideways via a common digital microscope. So you can search here and elsewhere in archives and probably find lots of information on this, and it may make you feel better to do so, But take it all with a grain of salt. For me, the realization that this process could not really be done with a high degree of certainty by someone like me made me feel really good, because I did not want to be bothered with it in the first place.