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I am trying to set up a Micro Seiki MA 505 (actually a 505X but the specs in the copy of the manual I have appear to be the same as the specs for the 505 noted on the Vinyl Engine).The Vinyl Engine has the null points for this arm at 58.4 and 117.9 using an effective length of 237, pivot to spindle of 222, offset of 21.833 degrees (and o/h of 15).
The Baerwald calculation (thanks John!) suggests 66 and 120.89 and slightly different numbers for o/h, o/s, p-s.
My existing armboard is actually fixed to the turntable base and being made out of a 25lb chunk of solid brass, it's going to be difficult to move the pivot-spindle distance (which appears to be exactly 222) until I can get a new armboard made.
Using John's spreadsheet would suggest that optimum alignment is not what the manufacturer originally suggested. The 237/222/15/21.833 set of numbers has RMS distortion numbers which are twice as high.
Follow Ups:
Hadcock was adamant about using their null points.. even though they were quite different.
Here's a link to Wally's instructions that may provide additional general insight. Note his comments in the beginning re: Baerwald and Loefgren re: overhang.
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Jim Ricketts
tmh audio
I would suggest moving the cartridge forward in the headshell and turning it inward slightly so you can use Baerwald's alignment of 66-mm and 121-mm. The new values would be:Effective Length = 239.3-mm
Mounting Distance = 222-mm
Overhang = 17.3-mm
Offset = 23.0-degreesRMS Distortion = 0.41%
If you can achieve the desired results, you might not need a new armboard.
If it is impossible to slide your cartridge far enough forward in the headshell to achieve this alignment, I would recommend sliding it as far forward as possible and aligning to the inner null-point of 66-mm only. This should provide acceptable results until you get a new armboard.
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