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SRA adjustment using my USB digital scope


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Inspired by Fridays cartridge setup presentation by Mark & Michael during this year’s HiFi show here in Melbourne today I decided to check my SRA using a digital USB microscope I purchased some time ago.

After a bit of fumbling about I managed to get a semi decent shot of the styli and after checking the angle is was WAY off at approx 100 degrees to the surface of the disk. I had suspected it was not correct as looking through my 3x magnifying glass it appeared to be on to much of an angle but as I followed the recommended "arm parallel with the platter" I didn’t think much more of it.

That was until Friday where Michael Fremer stated he had seen many cartridges in the past that were way off and the only real way is to actually measure it. Assuming I have done everything correctly it appears mine falls into that category!

So I dropped the arm height as far as I could and re-measured. Still way off at around 98 degrees so I had to resort to shimming the back of the cart to drop the back of it a bit more so I modified a E-clip and inserted it between the cart and head shell. After another good hour of re-aligning everything I re-measured and it was now about 90 degrees so was in the ball park of the recommended 92 degrees. Raising the arm did the trick and it is now bang on at 92.3 degrees (using standard thickness LP)

BTW cartridge is a Ortofon Cadenza Red and the arm is a Audio Origami PU7.

Listening now and there certainly seems to be a massive improvement so this advice was definitely worth the price of admission as I could have continued my path of upgrades when a simple (relatively) adjustment was all it took....

Some pics before and after.

post-122789-0-59527000-1413684562_thumb.

post-122789-0-06042600-1413684593_thumb.

post-122789-0-33110100-1413684862_thumb.

post-122789-0-23669600-1413684923_thumb.

Edited by Tubularbells
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I have one of those, Doug.  Can I ask:

  1. what magnification were you using in those photos, and
  2. how did you get good focus?  That primitive stand has put me off trying to use it for VTA ... it seems to me to do a good job, the stand supporting the USB microscope needs to be based around a horizontal threaded rod that supports the microscope and can move it forwards, as you turn a wheel.

 

Nice pics, though.

 

 

Regards,

 

Andy

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This maybe a real basic question. What software did you use to measure the angle once you've taken the picture?

 

The DinoXcope program -which you load from the Dinolite Scope---calculates the Angle you scribe on the Screen and shows as below .

 

Willco

 

22_013_Final.jpg

Edited by Willco
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The DinoXcope program -which you load from the Dinolite Scope---calculates the Angle you scribe on the Screen and shows as below .

 

Willco

 

 

 

Hi, Des ... except that, shirley, the angle one is interested in (that should be ~92 deg) is from the perpendicular-through-the-stylus to the surface of the LP?  (Not the angle between the side of the stylus and the LP!  :confused:  )

 

 

Regards,

 

Andy

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I have one of those, Doug.  Can I ask:

  • what magnification were you using in those photos, and
  • how did you get good focus?  That primitive stand has put me off trying to use it for VTA ... it seems to me to do a good job, the stand supporting the USB microscope needs to be based around a horizontal threaded rod that supports the microscope and can move it forwards, as you turn a wheel.
 

Nice pics, though.

 

 

Regards,

 

Andy

Hey Andy,

In answer to your questions,

1) no idea what magnification it was on as the focus wheel changes optical magnification and the button on the side zooms in digitally ( which is what I used in my second final pic)

2)getting good focus requires patience as slight twists of the focus ring throws off the image however securing the base via a couple of rubber bands to my tripod helped enormously and it also helps to have additional lighting available.

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Hi, Des ... except that, shirley, the angle one is interested in (that should be ~92 deg) is from the perpendicular-through-the-stylus to the surface of the LP?  (Not the angle between the side of the stylus and the LP!  :confused:  )

 

 

Regards,

 

Andy

 

Yes A I agree---normally- but not with the one shown  above--it is the My Ortofon Replicant  Styli --and the measurement is taken from those parameters. Screen shot Pic here from the Valin/Andrew Jennings (Ab Sound)

 

Fremers Analog Planet version does not use a Replicant Sample.

 

Damn--I told you not to call me Shirley :P

 

Willco

 

Rep1.jpg

Edited by Willco
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Willco, nice shot, if a little from the top down. What did you take as the horizontal line for the measurement? If I recall correctly the Gyger stylus has a contact angle 15 degrees off the vertical reference, not sure about the Replicant though. By my guessing if you take horizontal to be the grooves, then the facet 39 will be close to desired angle?

On second look it seems as though the facet 39 is much bigger than I thought and it is what you measured.

 

post-130832-0-85899800-1413704558_thumb.

 

plagiarised from what's best forum, who plagiarised it from vinyl engine who.......

Edited by olderas
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Yoh Olderas, Yes this is not as cut and dried as it looks--in fact it can be hair removal material!--- re your note above I followed almost to the letter the Andre Jennings method without mention to the facet 39 spec --However  basically I got to a point  where I felt the sonic results was specific to my ears on well

 

known tried and true Lp's I used for testing--one's gotta draw the line somewhere in this crazy business!

 

The measurements I posted achieved that for me-- I felt the exercise merited the effort --the naysayers will certainly disagree,but hey it's not their arse in my listening chair :D

 

YVMV

 

Willco

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  • 5 months later...

Hi,

 

I had exactly same issue on my Pro-ject 6Perspex with 9CC Evoluton arm and Ortofon Cadenza Red combination. Tried also to lower arm but, it is not enough.Also on mine before placing shim, SRA was around 100deg a bit more actually.

I used old MicroSD-card as shim, weight is 0,26 grams. Later corrected VTF too. Now SRA settled around 92+ deg. Did listen and it sounded better on short test. But... Since I bought set as 2nd hand, stylus has been 3yrs already on wrong angle on previous owner.

I have had TT+cadenza about 1,5yrs with pretty low playing time.

 

Is it possible that previous owner has ruined stylus during those 3yrs (he had a lot of records and got feeling that he had really played that combo.) and now even with correct angle it will not give out it's best?

 

I do not know what is wrong, but Ortofon states tracking angle as 20deg, but I have no idea where to measure to achieve 20deg on some points. Seems like impossible task. i do not know what has happened to cartridge before my time, but for me geometry is totally wrong on that cartridge. Tonearm looks ok, fixed head shell look parallel to arm and not bent up-or downwards.

 

Any ideas or comments welcome. Also suggestion for new cartridge, in case present one is destroyed. :) 

 

-juha

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Yes the link to the one I purchased my original post comes complete with measurement software

Thanks mate link says item removed, brand ? Model?

Edited by hyper
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Hi,

 

at a moment I'm using this little sw for measurement: http://www.cthing.com/Meazure.asp

 

if compared to sw which comes with cheaper scope (Micro-Measure) in this one you can fine tune measuring point positions as on Micro-Measure you have to "hit target" at once. I placed order for hopefully better scope: http://www.ebay.com/itm/2MP-USB-Digital-Microscope-Video-webcam-Magnifier-Camera-Stand-Andonstar-Cam-/121292898829?pt=LH_DefaultDomain_0&hash=item1c3d9ec20d

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