Like I said, "without the ability to correct the figures for the error." Where is that option provided, on the Vinyl Engine website(the only one you mentioned)? Maybe I missed it.
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.
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.
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- 16 posts total
You can approximate unknown or non-standard parameters by using a separate alignment calculator to come up with the unknown parameters. For example, if we assume that the design geometry of the original tonearm was for Lofgren A/Baerwald then the parameters are as follows... Effective length: 232.8mm Overhang: 17.8mm Pivot-to-spindle: 215.0mm Offset angle: 23.7 degrees And the design geometry of the new tonearm is as follows... Effective length: 239.3mm Overhang: 17.3mm Pivot-to-spindle: 222.0mm Offset angle: 23.0 degrees Then the current setup (based on Bifwynne's estimate of pivot-to-spindle distance) should have a geometry as follows... Effective length: 234.7mm Overhange: 17.7mm Pivot-to-spindle: 217.0mm Offset angle: 23.5 degrees However, Bifwynne states that the overhang is about 3-5mm too long so, using the lower value, the overhang is now 20.7mm and effective length becomes 237.7mm. (What's missing is which alignment protractor geometry is being used to estimate incorrect overhang.) Compared to the "correct" alignment parameters the current setup doesn't look very promising, as shown in the chart and graph from VinylEngine VinylEngine Tonearm Alignment Comparator Regards, Tom |
Dear Bifwynne: The other thing you can make is to change the effective tonearm length. Due that you know the precise/accurate S-P distance then your " new " set up patameters will be for overhang: 17.665 mm with an offset angle: 23.46°. This is using Löfgren A ( IEC ) but you can use the same Löfgren A with DIN standard and then the parameters will be for overhang: 16.68mm with an offset angle: 22.95°. With both set up you could have a good set up. Use the one that permit your tonearm headshell slots. If you can't make either set up then you have to re-drill that arm mount base to the right position. Regards and enjoy the music, Raul. |
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?? |
- 16 posts total