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In Reply to: RE: PICS! WE WANT PICS! posted by Muzikmike on August 17, 2012 at 13:36:43
Hey Mike,
Do you like mirrored protractors? I have a WallyTractor, but I've never been able to get a good alignment with it. All the reflections confuse me too much. Perhaps if the mirror was on the surface instead of underneath a plexiglass window, it might be easier for me to use. So far, I really prefer non-mirrored protractors a lot better. What do you think?
Best regards,
John Elison
Follow Ups:
I've got a mirror "protractor" with the primary side silvered. Works good. At least it did with with the arm I was using at the time.
From what I've read and researched, there are as many ways to set up a table / cart as there are people writing about how to set up a table / cart. And most of the techniques seem logical and would probably work.
I'm assuming you have an arc protractor.
Many people don't realize it, but you can use your arc protractor to align any tonearm regardless of length. You just won't be able to use the arc to set overhang, but you can still use it as an ordinary two-point protractor if you like your protractor's specific alignment null-points. For example, if you have an arc protractor with alignment null-points of 66-mm and 120.9-mm, those alignment grids are perfectly valid for any tonearm besides the one for which the arc is intended.
Best regards,
John Elison
Overhang was a bit mysterious to me at first. My cart specified, 12mm, but tonearm states a different overhang, and different alignment methods call for yet different numbers.
In the end, there is only one correct overhang for any two points. It was using a simple two-point protractor that helped me get this.
I should have never started out with the db.
Anyway, having the arc on the protractor really does help.
> My cart specified, 12mm, but tonearm states a different overhang
That's interesting. What kind of cartridge do you have?
The funny thing is that overhang has absolutely nothing to do with the cartridge and everything to do with a specific tonearm alignment geometry. Therefore, if a cartridge manufacturer states a specific overhang for his cartridge irrespective of a tonearm, he obviously knows little to nothing about tonearm alignment geometry.
Best regards,
John Elison
I've been very pleased with Conrad Hoffman's free turntable arc template generator. It's quick and easy. Just plug in your mounting distance (spindle to pivot), pick your std for inner & outer groove radii (IEC here), alignment scheme, and print. You can also print strobes. I've printed several for a few of my tables for Lofgren A (Baerwald) and Stevenson alignment schemes. Most recently, I printed one for my recommissioned Nott Horizon (spindle to pivot 222mm, not the 209mm in screenshot).Jim
"If less is more, just think how much more more would be!" - Frasier Crane.
-----------------------------
Russco Studio Pro B/Syntec S220/Empire 2000E/3-Technics SL1210mkII/ADC XLMII-Yam C-70 pre-Yam M-4 amp-KLH 6 spkrs-Outlaw sub
Edits: 08/18/12 08/18/12 08/18/12
Well that's the thing no one says explicitly. Learning to ignore information that is irrelevant is harder than it should be sometimes. The cart is an AT150 MLX. It comes with a little plastic bit for the purpose of hitting the proposed overhang.
I realized pretty quickly there was no way to get a good alignment using that figure. If I remember, this was before vinyl engine had figures posted for the specific alignment methods.
Thus my use of a simple protractor with no overhang arc, which was a good experience.
Sota also doesn't publish a lot of data on their tables, so being confident of certain measurements has taken me some time comparing different approaches.
I've owned several Audio Technica cartridges over the years and I guess I've never read their instructions. I just pulled out the box from my old OC9ML/II and you are absolutely right about the overhang instructions. They specify 15-mm overhang for my OC9ML/II and the little plastic thing used to carry the cartridge in its box has a cutout that is supposed to be placed against the platter spindle and there is a scale on the plastic with a mark at 15-mm.
The reason for this is probably because most Japanese tonearms specify 15-mm overhang. In fact, Rega even specifies 15-mm overhang. I have no idea why this is the case, but I suspect that very few tonearm manufacturers know much if anything about tonearm alignment geometry. There are countless Japanese tonearms having slightly different lengths, yet they all specify 15-mm overhang. I'm surprised the instructions with your Audio Tehcnica cartridge specifies a 12-mm overhang. Anyway, I certainly learned something surprising today.
Best regards,
John Elison
Won't the arc be shallower with longer arms, the null points farther apart? (Currently listening to Scheherazade an OC9ML (1) on a JMW-12, at least between movements.)
Yes, the arc will be shallower, but the null-points will be the same. Therefore, you can disregard the arc and use the mirrored protractor like a simple two-point protractor. If you need an accurate arc, you can download Conrad Hoffman's Custom Arc Template Generator and print your own custom arc protractor for setting overhang. Then you can use your mirrored protractor for setting offset angle. This way, if you have several tonearms, you need only buy one expensive mirrored arc protractor.
Best regards,
John Elison
Well, it's sounding pretty good, printed at 1200 dpi on some cheap office paper—aligned on a humid afternoon. Found some overhang data for Löfrgen A. I had been thinking Löfrgen B was a decent solution. This is better though.
Also figured out you can put a string on a washer, put that over the spindle, and the string will hang, centered, very nicely in the groove at the hub center of the RB 301 arm. Perfect way to make as sure as possible you have the protractor lined up from the go.
Nothing fancy.
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