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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
 
Don't see how that can be done on classic series pulleys. Every pulley position is a different diameter, to allow for speed adjustment for variable AC frequencies. Multiple belts will each be at a different speed.
actusreus
733 posts
 
The pulley has three possible positions for each speed so it is certainly possible to put two belts on the top and bottom groove respectively.

This is interesting and I'm tempted to try it myself. Out of curiosity, those who have the SDS, do you use the the 33 or 45 diameter? Either one is possible since the SDS will adjust the speed so I'm wondering which diameter would offer the best speed stability. The 45 being thicker would grab more of the belt; the 33 being thinner less of the belt and more of the platter. Any thoughts?
captain_winters
133 posts
 
interesting to see what speed you will end up with, since the belts will be fighting each other, with my AC frequency and I don't have a SDS I run at the top groove for 33, it is the closest using freickert android app and the test disc.
actusreus
733 posts
 
You mean since different pulley positions render slightly different speeds without the SDS? With the SDS this should be a non-issue; I just wonder about the physics of pulley thickness and how it affects the speed and ultimately the sound.
captain_winters
133 posts
 
No different with the SDS, different pulley positions are different diameters and will yield different speeds. You can verify it with the friekert app and test disc. The different pulley positions are for those that don't have the SDS to get as close as they can to 33 or 45 since without the SDS you have no control over AC frequency. With the SDS you don't need all the different pulley diameters since you can control AC frequency and optimize any of then for perfect speed. Adding another belt at different pulley diameter just upsets that balance.
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