Ortofon A90
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I am attaching the following photo for future reference for other JWM 10.5i owners, of how I calculated SRA - more precisely, side 'a', which represents the distance the arm has to be raised for a resulting 2 degree SRA (same as angle 'A' but rotated 90 degrees counter clockwise) - based on the effective length calculated earlier ('c'), and starting from a dead vertical of the stylus as best verified by the eye using a loupe...
I have the cartridge tracking at slightly over 2g, just barely within the recommended range, after initially setting it to 2.3g with 0 degrees SRA. I have experimented with adding an extra 0.264 weight on the headshell after setting SRA just for the heck of it, but there is no discernible difference in sound as stated by others, especially in the bass; it does track better with the Telarc 1812 LP but who cares. I'd rather go easy on the VTF and extend my records' life.
Great results.
I have the cartridge tracking at slightly over 2g, just barely within the recommended range, after initially setting it to 2.3g with 0 degrees SRA. I have experimented with adding an extra 0.264 weight on the headshell after setting SRA just for the heck of it, but there is no discernible difference in sound as stated by others, especially in the bass; it does track better with the Telarc 1812 LP but who cares. I'd rather go easy on the VTF and extend my records' life.
Great results.
Thanks for the memories, even if they're 40 years old
1. So for the present day math challenged, how many turns represents a change of 1 degree up or down?
2. Also keep in mind that cartridge mistracking is far more deleterious than a couple of tenths of a gram
OTOH, I do admit my eyebrows raise when I see the Clearaudios tracking at 2.8 gms.
Here's another interesting fact, which shows how good the VPI arms are... adjusting the tower a full turn results in precisely 1mm vertical distance offset.
OK picked this up on eBay today with a stand. Amazon had it for $240 w/o the stand.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=190542008488&ssPageName=STRK:MEWAX:IT
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=190542008488&ssPageName=STRK:MEWAX:IT
Nice; plz post some pictures when you get a chance. Although it's been replaced apparently by the 3011, it should still work well for this application.
Couldn't find the 3011 on Amazon
Scroll to bottom of page for another use for the 'scope
http://www.dak.com/reviews/3306story.cfm?Ref=G&PM=Brush&type=GCont&Srh=BrushC&gclid=CPXZy-qdpakCFUM65QodKXaQvw#quiz
Found this interesting discussion by Jon Risch on SRA on my computer.
http://www.audioasylum.com/audio/vinyl/messages/1240.html
http://www.audioasylum.com/audio/vinyl/messages/1240.html
I suggest bookmarking http://www.deadwaxcafe.com/vzone/cartalign.asp which I feel has a better definition of VTA, and definitely gets SRA's definition right.
Argh... I have ordered myself the Dino-Lite 3013T (offering continuously adjustable magnification) and a goose-neck stand; this is not the path I wanted to take, but the following on a'gon allegedly from Ortofon themselves has put a lot of doubts in my mind:
This is not what I saw with the loupe - the rear side of the stylus was dead vertical to the record surface when the arm was parallel to it and a VTF of 2.3g - if that's what they call "correct SRA" then that was not +2 degrees. So I need the microscope to see closer, measure, verify and/or adjust to the true vertical, then raise the arm by 9.67mm
I've already done this... as prescribed by Ortofon in the quote above (which was also my starting point), the sound is excellent but a little muddy and less focused. At its final position, there are no such issues. I suspect the quote above is the company line, so as not to turn off potential buyers with arms offering no VTA adjustment. Basically, there is no theoretical reason why my approach won't give the best results, IFF we agree add believe that the recommended VTF range can provide the best sound. The microscope will be used to re-set dead vertical, not final SRA - for that, I still believe in the power of math.
Of course, we all get swept up in this SRA/VTA conumdrum. Problem is that there was/is no standard angle used in mastering, esp in the early days of stereo. And then there's the problem of record thickness. I think the best thing is to set for an average record and readjust as needed for thinner/thicker or records with differening cutting VTA/SRA.
Absolutely true, in my view; I used a 180 gram record, and don't really care to re-adjust for thinner or thicker (too much work for very little gain)
Well I got a hold of a Dino-Lite 413 and tried to get the SRA dialed in. Wasn't easy getting a good shot of the stylus to if anyone has any suggestions please let me know.
Here's a shot of what I think is a dialed in SRA but please let me know if I'm wrong.... Thanks in advance.
Here's a shot of what I think is a dialed in SRA but please let me know if I'm wrong.... Thanks in advance.
Attachments
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A90 SRA - 2..jpg
I'll let you know when I get mine later this week
Did you use the ringstand/clamp to shoot? What was the problem in getting the shot? Focussing on the stylus/cantilver?
I'll let you know when I get mine later this week
Hi Myles....
I did purchase the stand but my biggest struggle was to get the microscope close enough to give me a large enough shot of the stylus. There's a clear plastic piece that prevents you to get any closer than what you see in my picture. I can zoom in digitally but then the picture starts to degrade. This particular shot was done with the A90 in the lead in groove and the microscope right up against the body....... Had to play with different lighting angles just to get this shot...... 5 hours later!
Sorry.... should have said ".... the microscope was against the edge of the record" not the body........
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