Rigid or elastic belt for turntable?

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Which is better? A flat butyl rubber belt is used commonly, even in premium turntables. Some DIY constructions use dental floss, others mylar tape (VCR tape) with good results. A while ago I constructed a turntable with an inverted bearing and marble platter, driven by a 500 RPM Papst motor. I experimented with a very soft rubber string, but it had unbearable wow. Then I replaced the string with a piece of silk yarn, and the wow has gone.
I concluded that the soft rubber belt is filtering the motor speed fluctuation. However the platter may have worse speed variation due to variable friction of the bearing, since the platter is detached from the motor, so that the motor will not straighten the fluctuations.
Any thoughts, exeriences?
 
Personally I'm in the direct drive or idler wheel camp and feel that a rubber belt is the worst connection between platter and motor. There are several movements in a turntable/tonearm/cartridge system and trying to detach one from another leads to each part of the system doing it's own thing in regards to vibrations and fluctuations instead of vibrating and fluctuating together as a system.
I am aware that this a very basic description.
In your case with a very heavy platter: use the least elastic coupling you can find. Maybe even a V-shaped drived belt, the stuff that's used in machinery or a step further a tooth belt.
 

PRR

Member
Joined 2003
Paid Member
You are towing a car.

Bungee-cord: the stretchy cord bounces against the mass. Wow-wow-wow--

Solid hard steel rod: no bounce, but every jerk or twitch is transmitted full force.

It does seem to be a good place to spring-isolate the motor from the platter. But like any spring-mass problem, the spring, mass, and *damping* must balance out.

Twisted yarn has some spring, and internal friction and damping.

Mylar has little spring but may have slip, which self-damps jerks.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.