Hello Dertonarm,
I would be very interested to hear what you have to say about using the Uni-Protractor with tonearms that do not allow the cartridge to be moved backwards and forwards in the headshell, like the Schroder and the SME V, IV etc.This question was raised by T. Mackris but has not answered yet, I think.
Surely with arms like these the crucial thing is to determine the effective length as accurately as possible and then set the appropriate pivot-to-spindle distance, again as accurately as possible.
The producer of the Mint Protractor is of course aware of this problem, and asks that, when ordering a protractor for a given cartridge with non-standard cantilever length (distance between stylus tip and mounting holes), customers should either indicate the cartridge manufacturer's specification of the stylus tip to mounting hole length or, failing that, provide a close-up photograph of their catridge viewed against a measure.
The problem here is clear enough: since the point of a dedicated protractor like the Mint is to provide a highly accurate alignment template for a given effective length, the whole enterprise is compomised if the effective length cannot be determined accurately to start with - and the photograph technique is by its very nature approximate.
It was this consideration that stopped me from ordering a Mint for my SME V & Benz combination.
Can the Uni-Protractor (or any add-on that you have in the pipeline) help with this problem?
My approach so far has been to measure the effective length, using the trammel that comes with the Feickert Protractor. This is simple enough: first choose a point on the template disk and rotate it until the stylus drops exactly on this point. Lift the stylus and block the turntable so that no movement is possible. Then place the spindle hole of the Feickert trammel over the point (so that the latter is in the middle of the hole), and then measure the distance to the centrepoint of the arm pivot (easier if you have removed the 'bridge' on your SME). Read off the effective length, and then use Conrad Hoffman's template generator (or similar)to make a template for precisely that effective length.
Of course there are several points in this where inaccuracy can creep in: (i) in trying to ensure that point on the disk is exactly in the middle of the spindle hole in the trammel base; (ii) in judging that the vertical pointer is exactly over the centre of the arm pivot; (iii) in reading off the measurement from the scale on the trammel.
Despite these possible sources of inaccuracy, this method has given me by far the best alignment so far.
Sorry for boring everyone with this detailed description, but my question is: can the Uni-Protractor - maybe via some sort of add-on - provide a way of eliminating the approximation inherent in the above system?
This is a genuine question, not a covert plug for anybody else's protractor.
Best regards, and congratulations on what you have created.
Peter
I would be very interested to hear what you have to say about using the Uni-Protractor with tonearms that do not allow the cartridge to be moved backwards and forwards in the headshell, like the Schroder and the SME V, IV etc.This question was raised by T. Mackris but has not answered yet, I think.
Surely with arms like these the crucial thing is to determine the effective length as accurately as possible and then set the appropriate pivot-to-spindle distance, again as accurately as possible.
The producer of the Mint Protractor is of course aware of this problem, and asks that, when ordering a protractor for a given cartridge with non-standard cantilever length (distance between stylus tip and mounting holes), customers should either indicate the cartridge manufacturer's specification of the stylus tip to mounting hole length or, failing that, provide a close-up photograph of their catridge viewed against a measure.
The problem here is clear enough: since the point of a dedicated protractor like the Mint is to provide a highly accurate alignment template for a given effective length, the whole enterprise is compomised if the effective length cannot be determined accurately to start with - and the photograph technique is by its very nature approximate.
It was this consideration that stopped me from ordering a Mint for my SME V & Benz combination.
Can the Uni-Protractor (or any add-on that you have in the pipeline) help with this problem?
My approach so far has been to measure the effective length, using the trammel that comes with the Feickert Protractor. This is simple enough: first choose a point on the template disk and rotate it until the stylus drops exactly on this point. Lift the stylus and block the turntable so that no movement is possible. Then place the spindle hole of the Feickert trammel over the point (so that the latter is in the middle of the hole), and then measure the distance to the centrepoint of the arm pivot (easier if you have removed the 'bridge' on your SME). Read off the effective length, and then use Conrad Hoffman's template generator (or similar)to make a template for precisely that effective length.
Of course there are several points in this where inaccuracy can creep in: (i) in trying to ensure that point on the disk is exactly in the middle of the spindle hole in the trammel base; (ii) in judging that the vertical pointer is exactly over the centre of the arm pivot; (iii) in reading off the measurement from the scale on the trammel.
Despite these possible sources of inaccuracy, this method has given me by far the best alignment so far.
Sorry for boring everyone with this detailed description, but my question is: can the Uni-Protractor - maybe via some sort of add-on - provide a way of eliminating the approximation inherent in the above system?
This is a genuine question, not a covert plug for anybody else's protractor.
Best regards, and congratulations on what you have created.
Peter