USB Microscope

[GP49]

Maybe I should share a few words of wisdom I got from Soundsmith: the correct industry specification for SRA is 2 deg - not 92 deg. We have all been misled by guru reviewer(s).

It will seem strange to read me in defense of Michael "The More It Costs The Better" Fremer.  In a recent article in Stereophile, he did give the 92° specification but it was clear to me that the angle was measured relative to the record surface behind the stylus tip; thus it was the same as 2° forward of the vertical.

[ianm0]

It will seem strange to read me in defense of Michael "The More It Costs The Better" Fremer.  In a recent article in Stereophile, he did give the 92° specification but it was clear to me that the angle was measured relative to the record surface behind the stylus tip; thus it was the same as 2° forward of the vertical.

Absolutely correct. Mr Fremer got me confused too. But allow me to quote Mr Ledermann: " When you mention the 92 degrees, I have no idea what you are referring to! The industry standard for SRA is 2 degrees – period." The agreed convention is to measure SRA from the vertical. How could Fremer get it that wrong?

Ian

[Diamondtone]

Ian, 92 deg = 2 deg forward of vertical (90deg) which means MF & Peter are both advocating the same
SRA, just measuring it at a different places.
BTW  your "perfect SRA" pic is showing way! shallower VTA than my SS line contact or my SS opt line contact
(or of online pics of same) How far away from parallel to the record is the cartridge?

[ianm0]

How far away from parallel to the record is the cartridge?

Do you mean the edge of the cartridge body? If yes, I can't give an exact answer as I no longer recall. But if you look at the photo closely, the "horizontal line" above the cantilever should be the lower edge of the body. The record surface is perpendicular to the yellow vertical line.

But I would only use the cartridge body as a very rough guide for setting VTA to quickly get me into the ball park. From there I vary arm height either way and listen for the difference - that was my pre-USB microscope days. The mic is a nice toy for me to confirm what I hear and to record the correct VTA for future quick settings.

[richard]

What's on my mind is the question of how to bring this home for practical music listening.

What VTA do we want to live with, assuming that we're actually listening to recordings that span a range of time? There's also the matter of SRA changing with the pressure on the cantilever. So, we get the "sweet spot" for one, then we have to get the "sweet spot" for the other. But I fear that we're into a new topic.

[willbewill]

What's on my mind is the question of how to bring this home for practical music listening.

What VTA do we want to live with, assuming that we're actually listening to recordings that span a range of time? There's also the matter of SRA changing with the pressure on the cantilever. So, we get the "sweet spot" for one, then we have to get the "sweet spot" for the other. But I fear that we're into a new topic.

and then there's warps...

[wer]

BTW, Werner,  that ruby cantilever and line contact stylus are from Soundsmith.

I tried to measure SRA in the photo below:               


Ignore the text "Perfect SRA". Actually it measures 3-4 deg instead of 2 deg. Need to adjust arm height to change SRA. But beware, tracking force must be re-adjusted with even slight change of arm height. 

Ian

Thank you Ian, but one more question (more a request for help):

If i understand correctly, the vertical line is perpendicular to the record surface? Fine, but how did you arrive at the other (left) line - i can't see any feature of stylus or cantilever that has anything in common with that line?
Please help me remove the cucumbers from my eyes 

[ianm0]

Thank you Ian, but one more question (more a request for help):

If i understand correctly, the vertical line is perpendicular to the record surface? Fine, but how did you arrive at the other (left) line ......

The explanation is clearly given in this link: http://www.audioasylum.com/audio/vinyl/messages/92/927670.html. Line joins outer "tip" with inner "tip". I've checked the photo with Mr Ledermann and he confirmed I was doing the right thing. Mind you, this is for Soundsmith's diamond only - I think. Not sure if your stylus resembles this or not.

Ian

[wer]

Thanks.
Most of my styli are humble conicals + 2 "standard cut" ellipticals, so i guess i will not be able to check the SRA this way 

[GP49]

An elliptical DOES have an oriented contact patch and although it may not be as critical as with a line-contact type, its SRA still should be optimized.

SRA matters very little with a spherical (you can rotate a sphere and it will still have the same contact patch), may as well optimize VTA instead. 

[ianm0]

Thanks.
... ellipticals, so i guess i will not be able to check the SRA this way 

For elliptical stylus, it is much easier to set SRA correctly. Looking from the front, the line of symmetry should be at 2 deg with the vertical. The cut of the diamond is symmetric about this line. Life a lot simpler vis-a-via line contact stylus.

Ian

[wer]

For elliptical stylus, it is much easier to set SRA correctly. Looking from the front, the line of symmetry should be at 2 deg with the vertical. The cut of the diamond is symmetric about this line.

You have lost me again, Ian. Looking from the front i thought that all you'd be able to see was the vertical alignment?

[ianm0]

You have lost me again, Ian. Looking from the front i thought that all you'd be able to see was the vertical alignment?

My apology for the confusion due to a typo in my earlier post. The SRA photo was taken from the side - not the front -  when the cartridge it was resting on the record surface.

[rocker65]

Hi All,
Has anyone tried taking a closeup photo with a digital camera set to macro and then enlarging the picture on a PC with someting like Photoshop or similar?
rocker65

[ianm0]

The photo below taken hand-held with Canon  EF100mm/f2.8L macro:



Could be sharper with a tripod.

Ian