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How critical is alignment error??

I would appreciate advice regarding the following issue.

A tech recently installed a new tone arm on my old turntable base. The new arm has a spindle to pivot (S-P) distance of 222 MM. Upon return of the TT with the new arm, I noticed that the S-P distance was about 5 MM short, say 217 MM. I own a protractor and checked alignment. As I suspected, the cartridge overhang was about 3-4 MM over the sweet spot indicated on the protractor. BTW, I was able to move the cartridge back in the arm shell towards the pivot point, but even with the maximum adjustment, as stated, I was still off 3-4 MM.

My question is how much distortion will this error introduce in the playback? Ordinarily, I would ship the TT right back to the tech for adjustment, but I am reluctant to do so because of the possibility of damage from shipment. Further, I suspect that the fix will entail cutting out a part of the undercarriage in order to accomodate the larger arm and I suspect the tech will argue. The old arm had a S-P distance of 215 MM. If the error is signifant, I will have to reconsider what may next steps will be.

Thanks for your advice.
bifwynne

Showing 3 responses by bifwynne

bifwynne OP
2,206 posts
 
Elizabeth: Any comments about the question raised in my original post, i.e., how much distortion will the overhang error introduce in the playback?

BTW, I did not bargain shop for the work, and yes, it was stipulated that he was to do the work in a "workmanlike" manner, which means, the right way. As far as drilling holes, I found instructions on the web which explained how to install the arm in question on my TT and sent it to him. And yes, the installation instructions contemplated drilling out part of the undercarriage to make room for the larger arm.
bifwynne OP
2,206 posts
 
Thanks guys for the advice and tips. I will recheck the S-P distance again and work the numbers on the Vinyl Engine. Assuming I can adjust the cartridge in the head shell to achieve the correct effective length, how do I adjust the offset angle.

However, I'm still confused. As I mentiond above, I have an aluminum Dennesen protractor which automatically tells you what the effective length and offset angle should be once you adjust the device by measuring the actual S-P distance. As I also mentioned, I need to shorten the effective length by about 3-4 mm, but the headshell won't take the adjustment.

Just "thinking outloud" here, I could work the problem backwards. That is, if I know the effective length and S-P distance, then the only other variable is the offset angle. So, as I asked above, how do I adjust the offset angle??? Does V-E have a compass??
bifwynne OP
2,206 posts
 
Thanks Tom. I double checked my measurements and checked V-E as well. I can't move the cartridge back far enough in the head shell to achieve optimum geometry. It's back to the tech for me. I'll take Audiofeil's advice and take some pictures.

The real problem is the hassles of packing and shipping. I may take another direction and try to make the fix myself. If I do, I'll report back and let everyone know how I made out.

Thanks to everyone else for the great advice!
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