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Vinyl Asylum: You can, you just enter the inner groove radius and the outer groove radius by B.K. Welcome Licorice Pizza (LP) lovers! Setup guides and Vinyl FAQ. |
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In Reply to: Jelco alignment null points... posted by tketcham on January 22, 2010 at 08:16:32:
If you go to the link below, Steve Clarke has uploaded an Excel file which gives the relationship between tonearm parameters, null radii and inner and outer groove radii.
I made this file sometime around 2002.
Back then, everyone seemed to calculate tonearm parameters based on inner and outer groove radii. I was trying to get the idea across that it makes much more sense to calculate arm parameters based on null radii, because these five properties (effective length, mounting distance, offset angle, inner and outer null radius) are geometrically linked. The inner and outer groove radii are not directly linked to the tonearm parameters - there is only an indirect link.
Just enter the arm parameters, and it will automatically calculate the null radii and the inner and outer groove radii for which the distortion is equal.
The answer for the Jelco SA-750D is to enter 214mm for spindle to pivot distance, 53.773mm and 138.453mm for the groove radii and select Loefgren A, and the template generator will produce the protractor that you want.
BK
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Topic - An open apology to AbeCollins - VynylTap 16:58:47 01/19/10 ( 36)
- Cool. I feel better about it now. (nt) - VynylTap 13:51:02 01/20/10 ( 0)
RE: An open apology to AbeCollins - AudioDoctor 09:27:06 01/20/10 ( 0)
Thank you but no apology necessary... - AbeCollins 08:32:44 01/20/10 ( 0)
You're both doing a service to the asylum IMO - tubesforever 23:41:42 01/19/10 ( 0)
The exchange was of value... - Ivan303 21:22:15 01/19/10 ( 0)
I'm not Abe but I play one on TV... - tketcham 19:31:03 01/19/10 ( 30)
- "And remember..... - JimK 05:57:44 01/20/10 ( 0)
Me neither, and I don't. - hesson11 19:40:25 01/19/10 ( 28)
- I'd love to finally resolve the debate too - it seems simple enough, but I need some help... - VynylTap 13:49:35 01/20/10 ( 27)
- OK...I'll take a stab at it.... - blake 18:43:44 01/20/10 ( 24)
- Thanks for the post! - VynylTap 19:38:51 01/20/10 ( 23)
- "It hadn't occured to me that the drawing may be wrong" - cactuscowboy@bresnan.net 10:01:04 01/21/10 ( 1)
- RE: "It hadn't occured to me that the drawing may be wrong" - blake 10:09:37 01/21/10 ( 0)
- Jelco's alignment strategy... - tketcham 08:43:32 01/21/10 ( 20)
- It's a lot more simple than that. - B.K. 11:46:35 01/21/10 ( 19)
- Not sure I'd call it simple... - tketcham 13:15:27 01/21/10 ( 18)
- What still has not been proven to my satisfaction... - Ivan303 19:52:07 01/21/10 ( 17)
- Jelco alignment null points... - tketcham 08:16:32 01/22/10 ( 5)
- You can, you just enter the inner groove radius and the outer groove radius - B.K. 01/22/10 10:38:29 01/22/10 ( 4)
- That's it!... - tketcham 11:49:45 01/22/10 ( 0)
- 2 quick questions for you... - blake 11:33:48 01/22/10 ( 2)
- RE: 2 quick questions for you... - B.K. 13:25:06 01/22/10 ( 1)
- I don't think that there is much difference between one alignment system and another - dean man jim 17:24:23 01/22/10 ( 0)
- There is no onus on anyone to prove anything to your satisfaction here. - B.K. 02:33:48 01/22/10 ( 10)
- Wasn't talking about you, necessarily... - Ivan303 07:41:52 01/22/10 ( 9)
- RE: Wasn't talking about you, necessarily... - blake 08:04:05 01/22/10 ( 8)
- RE: Wasn't talking about you, necessarily... - Ivan303 09:13:27 01/22/10 ( 7)
- The effective length... - blake 09:34:32 01/22/10 ( 6)
- IF the effective length AND overhang are allowed to vary... - Ivan303 09:48:40 01/22/10 ( 5)
- RE: IF the effective length AND overhang are allowed to vary... - tketcham 12:06:29 01/22/10 ( 2)
- Makes sense... - blake 14:22:54 01/22/10 ( 1)
- SME protractor... - tketcham 19:46:25 01/22/10 ( 0)
- RE: SME protractor... - blake 21:06:38 01/22/10 ( 0)
- Good question... - tketcham 21:27:26 01/22/10 ( 0)
- RE: Good question... - blake 21:56:05 01/22/10 ( 0)
- Another good question... - tketcham 22:24:56 01/22/10 ( 0)
- SME tonearms and null radii. - B.K. 00:31:13 01/23/10 ( 0)
- And another, for B.K. - tketcham 21:47:15 01/22/10 ( 0)
- I don't know... - blake 11:42:50 01/22/10 ( 0)
- SA-750D Mounting Template - Ivan303 10:15:47 01/22/10 ( 0)
I really don't know but.... - AbeCollins 15:06:55 01/20/10 ( 1)
- Yes - several, in fact. - VynylTap 15:39:03 01/20/10 ( 0)