Pivotal Tonearm Alignment Equations...
74.130.29.193 |
||
| Posted on May 27, 2015 at 05:30:09 | ||
|
Posts: 23900
Location: Central Kentucky Joined: December 20, 2000 Contributor Since: January 29, 2004 |
I received an email through the Asylum from someone named James, but there was no return email address. James had a question about the following tonearm alignment equations, but I have no way of contacting him. The following equations are pretty straight forward and apply to pivotal tonearms with fixed offset alignments. The null-points are radial measurements from the center of the record to each null-point. I always use millimeters and degrees for my units of measurement. Hey James, if you want additional information please send me your email address or else post your questions to the Vinyl Asylum forum. Best regards, 
|
|
| RE: Pivotal Tonearm Alignment Equations..., posted on May 28, 2015 at 12:42:47 | |
|
Posts: 23900
Location: Central Kentucky Joined: December 20, 2000 Contributor Since: January 29, 2004 |
Offset angle is a function of the sum of the null points divided by effective length. Therefore, the null-points can be changed without affecting offset angle as long as they add up to the same number, assuming effective length is fixed. In reality, the only parameter that is truly fixed on most tonearms is mounting distance. The vast majority of tonearms have slotted headshells so that effective length can be changed slightly and this also allows offset angle to be altered a few degrees in either direction by twisting the cartridge slightly before tightening the cartridge bolts. One thing everyone should know about offset angle is its definition. Brian Kearns stated it very eloquently in his Treatise on Cartridge Alignment, which can be found in the Vinyl FAQ: Offset angle (theta): The angle between a projection of the cantilever on the record surface, and a line which passes through the centre of the tonearm pivot and the stylus tip. This shows that offset angle is not the angle the headshell makes with the arm tube. It also shows that offset angle will change slightly by simply moving the cartridge fore and aft in the headshell slots without changing its alignment in the headshell. Therefore, simply moving the cartridge fore and aft in the headshell not only changes effective length, but it changes offset angle slightly, too.
|
| RE: Pivotal Tonearm Alignment Equations..., posted on May 28, 2015 at 18:31:50 | |
|
Posts: 605
Location: NYC Joined: February 17, 2001 |
Thanks! I understand it now.
|
