multiple motors...
can be a godsend.
If the platter is light in mass, then multiple motors can provide the Inertia required to keep a light mass moving smoothly. Voyd and AudioNote are two that come to mind (the Voyd became the AudioNote "reference" TT.
An assumption is made of course, that the motors are well isolated from the platter and bearing and the transmission of vibes is minimal. I've seen TT's (on the Internet only) that use a single motor and 2 additional (idler" pulleys apparently trying to do the same thing.
As old Aengus said, if multiple motors are used it can help to offset some of the torque (lateral) to the stylus cantilever.
can be a godsend.
If the platter is light in mass, then multiple motors can provide the Inertia required to keep a light mass moving smoothly. Voyd and AudioNote are two that come to mind (the Voyd became the AudioNote "reference" TT.
An assumption is made of course, that the motors are well isolated from the platter and bearing and the transmission of vibes is minimal. I've seen TT's (on the Internet only) that use a single motor and 2 additional (idler" pulleys apparently trying to do the same thing.
As old Aengus said, if multiple motors are used it can help to offset some of the torque (lateral) to the stylus cantilever.
The advantage of two (or more) motors is that, effectively, the apparent rotational mass of the platter is increased and belt tension on the main bearing is equalised (depending on specific implementation. It may also be that cogging effects are disguised (not eliminated). However, there are also a number of potential issues.
1/ There is now twice as much motor noise to contend with.
2/ There is twice as much electrical noise to deal with.
3/ To work ideally both motors must rotate at exactly the correct speed and both drive pulley must be exactly the same size..
4/ The tension of the belt will be even more pronounced in line with the drive pulleys compared to an angle of ninety degree offset and this may have a significant impact upon the dynamic of the suspension (if one is used).
5/ If a DC motor is used the problems relating to operating near the lower limit of its operating speed (poor speed/torque tracking) may be reduced but the problem is really being disguised rather than eliminated.
1/ There is now twice as much motor noise to contend with.
2/ There is twice as much electrical noise to deal with.
3/ To work ideally both motors must rotate at exactly the correct speed and both drive pulley must be exactly the same size..
4/ The tension of the belt will be even more pronounced in line with the drive pulleys compared to an angle of ninety degree offset and this may have a significant impact upon the dynamic of the suspension (if one is used).
5/ If a DC motor is used the problems relating to operating near the lower limit of its operating speed (poor speed/torque tracking) may be reduced but the problem is really being disguised rather than eliminated.
binspaul:
I believe that the position is a huge factor in designing a turntable. I had a discussion with "Seb" of vinylengine, and although we agreed to some extend, we are not in complete agreement.
If the 7 o'clock position puts the motor in-line with the tonearm ( taking the headshell offset into consideration), then the lateral torque on the stylus cantilever can be reduced significantly. Something like a minimum of 48% and a maximum of 84%, depending on where on the record the stylus is.
This may also have more of an advantage if using a suspended table, such as the trio of Scottish turntables (Ariston, Heybrook and Linn). The Funk firm sells kits to do this very thing.
YNWOAN : yes the potential for additional noise is there, but if properly implemented, then not an issue regarding noise (both electrical and mechanical)
An alternative is to use a very large platter, a huge motor, or perhaps an idler pulley or two.
stew
I believe that the position is a huge factor in designing a turntable. I had a discussion with "Seb" of vinylengine, and although we agreed to some extend, we are not in complete agreement.
If the 7 o'clock position puts the motor in-line with the tonearm ( taking the headshell offset into consideration), then the lateral torque on the stylus cantilever can be reduced significantly. Something like a minimum of 48% and a maximum of 84%, depending on where on the record the stylus is.
This may also have more of an advantage if using a suspended table, such as the trio of Scottish turntables (Ariston, Heybrook and Linn). The Funk firm sells kits to do this very thing.
YNWOAN : yes the potential for additional noise is there, but if properly implemented, then not an issue regarding noise (both electrical and mechanical)
An alternative is to use a very large platter, a huge motor, or perhaps an idler pulley or two.
stew
nicoch46...true,
but your Nottingham has a very good bearing and is not a suspended deck as some are (without the motor being suspended with the platter and the tonearm). It is much less likely to suffer from a lateral deflection because it uses a Brute Force method...simply rigidly mointed main bearing, motor and tonear. In this case simpler really is better '
'
Jeff: well one thing that you could check is the amount of antiskating required... it should be greatly reduced...
stew
but your Nottingham has a very good bearing and is not a suspended deck as some are (without the motor being suspended with the platter and the tonearm). It is much less likely to suffer from a lateral deflection because it uses a Brute Force method...simply rigidly mointed main bearing, motor and tonear. In this case simpler really is better '
'Jeff: well one thing that you could check is the amount of antiskating required... it should be greatly reduced...
stew
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