From Analog planet:
http://www.analogplanet.com/content/...rake-angle-sra
From Analog planet:
http://www.analogplanet.com/content/...rake-angle-sra
Thanks Myles for the link. I guess this will be the next analog investment I make. For those of you who already own microscopes and have set up your stylus optimally, please tell us about the differences you hear.
Ack's posted quite a lot on the subject. I bought mine a while back used on Ebay. Haven't really exploited it's capabilities but this article gives me more impetus to break it out again. But in the end, you still need to use your ears!Originally Posted by mep
It's really not a matter, directly, of what you hear since ultimately that always has to be tuned by ear. But what the USB microscope SRA setup does is to let/help you start at a known place, a 'center' of range so to speak, of 92 (+2 reference to perpendicular) degrees. Or if you prefer and your arm height adjustment has the range, you can start on the way low side at 90 degrees, which is easier to spot.
SRA on cartridges seems to vary widely, and on some it also varies with use (angle decreases with use), requiring both VTF and SRA touchups. There are times when things wander so far off that to be absolutely sure where you are range-wise, check and touch up as necessary with the scope.
--Bill
Nice article, thanks Myles. As posted before, get a 4xx series microscope for the higher resolution, which will definitely make your life easier - see the various A90 threads' pictures from Bill. I have no idea how Fremer got the last picture in his article, but I just don't believe it's with his Dino-Lite 313.
And Bill's right; I also feel 90 degrees is easier to spot, and that was the basis of my geometric calculations in other threads. What do we hear? Hi-hats, cymbals, high violin notes et al sound harsh, out of phase, distorted, if not set correctly; and images are not as clear as could be.
The next breakthrough in arms will be one where you select a fixed VFT, and then adjusting VTA/SRA automatically corrects VTF to your original setting.
Somewhat related, I always question the Shibata's ability to track well, considering its crooked elliptical contact area.
PS: Bill, I just started reading your manual (for others, Bill has given me a tough assignment to work on during my July 4th vacation :-))
Last edited by ack; 07-01-2012 at 06:16 AM.
System link WBF
You know what I think would be the next breakthrough? All cartridge manufacturers would standardize the tip to mounting screw distance so tone arm manufacturers could drill a single pair of holes in the headshell thus optimizing contact and eliminating alignment error!
Great article, I ordered a USB microscope. For the amount of magnification required there's no way I was ever able to set it by anything other than ear before.
Deepak
It's an AD413T. I also picked up a 400-470x version (also Dino-Lite) but so far its optics aren't quite good enough for that power. I still have more testing on that one to do.
The problem is that some arms (like my ET2) don't have as much SRA range as others. So if I use 90 degrees as a starting point, I don't have enough positive range to get where I need to be. So I try to measure as accurately as possible to 92 degrees on the scope and then set the middle of my SRA range there.And Bill's right; I also feel 90 degrees is easier to spot, and that was the basis of my geometric calculations in other threads. What do we hear? Hi-hats, cymbals, high violin notes et al sound harsh, out of phase, distorted, if not set correctly; and images are not as clear as could be.
One thing to remember when looking at that stylus angle, is that as the record moves, the stylus is pulled forward and SRA decreases. That is often considerably different than just setting the stylus on the record. I try to use a record of average thickness with a lead-in groove that starts clear at the outer edge, but inside of any beading of the vinyl. I have the platter 'stopped' with rubber shims. Place the stylus in a groove at the outer edge, get a focus on it, then slowly force the platter clockwise. You'll see the stylus move forward and shell drop. The lowest and most forward point is where the stylus typically rides during play. Try to get the platter in a spot to mimic that position before doing your calcs. Otherwise you'll be way off.
That is just a matter of using spring controlled downward force for VTF adjustment, instead of weight/balance controlled. Some arms/wands are designed that way from the start.The next breakthrough in arms will be one where you select a fixed VFT, and then adjusting VTA/SRA automatically corrects VTF to your original setting.
Do you mean because the traditional Shibata's contact area is at a different angle than the shank of the stylus? I've wondered about that too, but I think that regardless of the shank position, if the contact angle is at the correct VTA relative to the shank pivot point that it would work the same as a conventional stylus. You'd just have a hard time using visuals to start the setup.Somewhat related, I always question the Shibata's ability to track well, considering its crooked elliptical contact area.
Is it done yet??PS: Bill, I just started reading your manual (for others, Bill has given me a tough assignment to work on during my July 4th vacation :-))
--Bill
Indeed so! And a realistic VTA, VTF and SRA position. I'm convinced that some cartridge/stylus designer/manufacturers don't seem to know as much as they should about cutting head and groove geometry.
--Bill
You took the words out of my mouth.
System link WBF
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