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Re: Tracking Alignment Adaptor for the Exhibition Soundbox
Posted: Mon Jan 20, 2020 8:36 pm
by audioengr
emgcr wrote:The man who originally worked out optimal tracking in the nineteen-twenties was Percy Wilson. His findings, together with those of his co-author G W Webb, are incorporated into their definitive 1929 publication "Modern gramophones and electrical reproducers". We are extremely fortunate that this extremely valuable knowledge can now be viewed at nil cost on the internet. Page 121 initiates the discussion of tone-arms from the three viewpoints---geometrical, acoustical and mechanical :
https://archive.org/details/ModernGramo ... /page/n141
This analysis assumes that the arc of the needle goes through the turntable spindle. This is not necessary. If it ends below the spindle, one can get zero offset across the entire record.
Re: Tracking Alignment Adaptor for the Exhibition Soundbox
Posted: Tue Jan 21, 2020 3:36 am
by Marco Gilardetti
audioengr wrote:If it ends below the spindle, one can get zero offset across the entire record.
Both the
offset angle and the
linear offset are
constants of the geometry of a tonearm. Whichever tonearm can be built with zero offset angle and zero linear offset, completely disregarding its position in relation to the spindle. Also, being geometric constants of the tonearm, in any case they never vary across the record.
Re: Tracking Alignment Adaptor for the Exhibition Soundbox
Posted: Tue Jan 21, 2020 5:35 am
by emgcr
audioengr wrote:emgcr wrote:The man who originally worked out optimal tracking in the nineteen-twenties was Percy Wilson. His findings, together with those of his co-author G W Webb, are incorporated into their definitive 1929 publication "Modern gramophones and electrical reproducers". We are extremely fortunate that this extremely valuable knowledge can now be viewed at nil cost on the internet. Page 121 initiates the discussion of tone-arms from the three viewpoints---geometrical, acoustical and mechanical :
https://archive.org/details/ModernGramo ... /page/n141
This analysis assumes that the arc of the needle goes through the turntable spindle. This is not necessary. If it ends below the spindle, one can get zero offset across the entire record.
Table 1 on page 128 shows the length by which the needle point must
exceed the spindle centre ie the necessary
"overlap" of the needle point in relation to the spindle centre to achieve minimum (and only
sometimes zero) tracking error. Wilson advised EMG on their publication of "The book of the fibre needle" where he helpfully complied two schedules---
"Table of best overlaps"---as shown in a previous thread in December 2013 here on the TMF :
viewtopic.php?f=11&t=15253&hilit=questi ... nior+motor
Re: Tracking Alignment Adaptor for the Exhibition Soundbox
Posted: Tue Jan 21, 2020 12:48 pm
by audioengr
Marco Gilardetti wrote:audioengr wrote:If it ends below the spindle, one can get zero offset across the entire record.
Both the
offset angle and the
linear offset are
constants of the geometry of a tonearm. Whichever tonearm can be built with zero offset angle and zero linear offset, completely disregarding its position in relation to the spindle. Also, being geometric constants of the tonearm, in any case they never vary across the record.
I don't understand the relevance. I am talking about the arc of the tone arm not passing through the spindle.
Re: Tracking Alignment Adaptor for the Exhibition Soundbox
Posted: Tue Jan 21, 2020 12:50 pm
by audioengr
emgcr wrote:audioengr wrote:emgcr wrote:The man who originally worked out optimal tracking in the nineteen-twenties was Percy Wilson. His findings, together with those of his co-author G W Webb, are incorporated into their definitive 1929 publication "Modern gramophones and electrical reproducers". We are extremely fortunate that this extremely valuable knowledge can now be viewed at nil cost on the internet. Page 121 initiates the discussion of tone-arms from the three viewpoints---geometrical, acoustical and mechanical :
https://archive.org/details/ModernGramo ... /page/n141
This analysis assumes that the arc of the needle goes through the turntable spindle. This is not necessary. If it ends below the spindle, one can get zero offset across the entire record.
Table 1 on page 128 shows the length by which the needle point must
exceed the spindle centre ie the necessary
"overlap" of the needle point in relation to the spindle centre to achieve minimum (and only
sometimes zero) tracking error. Wilson advised EMG on their publication of "The book of the fibre needle" where he helpfully complied two schedules---
"Table of best overlaps"---as shown in a previous thread in December 2013 here on the TMF :
viewtopic.php?f=11&t=15253&hilit=questi ... nior+motor
Got it. I understand that table now. Thanks.
BTW, now that I have the bustle installed, my original Exhibition reproducer sounds amazing. Still fine-tuning my Victor 4A.
Re: Tracking Alignment Adaptor for the Exhibition Soundbox
Posted: Wed Jan 22, 2020 3:05 am
by Marco Gilardetti
audioengr wrote:I don't understand the relevance. I am talking about the arc of the tone arm not passing through the spindle.
The relevance is that what you have written in the post that I have quoted is wrong.
Wether the arc is passing through the spindle or not, it is absolutely irrelevant. As already written (please don't have me go through it a third time) the offset angle and the linear offset are geometrical constants of the tonearm design
by definition, and they will never change, wherever the tonearm is placed and whichever its arc across the record will be.
Re: Tracking Alignment Adaptor for the Exhibition Soundbox
Posted: Fri Jan 31, 2020 9:17 pm
by cheryla
great work