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VPI Classic tweak

So I ordered a spare belt for my Classic One to have as a spare and when I got it I looked at the table and thought...Hmm why not try 2 belts? After a little research I did find a post on another forum from Mike at VPI who stated that a second belt should open things up a little bit and it did. A little bit more focus and imaging is what I observed. I found no discernible difference in platter speed. At 26 bucks it's a relatively cheap tweak plus the platter looks pretty cool with 2 belts.
mjm1124
captain_winters
133 posts
 
I believe the position on the platter is irrelevant, the platter is machined to the same diameter up and down its sides. I believe the pulley is machined intentionally with a larger diameter on each groove progressively to accommodate those enthusiasts without a SDS. This is the only way they have to compensate for AC frequency differences, which is how speed is determined on an AC motor.
actusreus
733 posts
 
It totally makes sense, if true, and would perfectly explain the speed difference among different pulley positions. However, I'm still unclear why using two belts would not result in a net speed that could be adjusted by the SDS since both belts would be subject to the same forces with each rotation.
captain_winters
133 posts
 
The belts will be binding, one belt will try and turn the platter faster in each rotation than the other. Therefore one will have to slip. The belt with the most torque will probably win. Hard for me to visualize how this could be an improvement in sound.
brf
1,715 posts
 
Use a micrometer and measure the various pulley positions.
kbell
31 posts
 
I used to have a Scout turntable for which I bought a straight, non variable speed pulley, which was close to the diameter of the 33rpm portion of the stock Scout pulley. With the SDS I could adjust for correct speed and also switch between 33 and 45 rpm. I was also able to use multiple belts without the potential problem of varying belt speed rotation.
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