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Rega red silicone belt

YNWOAN said:
I'm afraid that is an oversimplification and belt tension does definitely alter speed - easily checked with an accurate strobe.
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I can empirically confirm this , after moding my PT Anni , i could get it to go a 33.3 , but I couldn't get the speed to stop fluctuating , eventually somewhat embarrassingly I traced the problem to belt tension because I used a new pulley .

£25 from o/l , bloody rip off but only one I can find to fit the maxon motor.
 
Sue Pertwee-Tyr said:
Curious as to how that could happen. Surely turntable speed is a function only of motor speed and the ratio of the diameters of the motor and platter pulleys. Belt tension, or any other property of the belt (apart, possibly from a lack of friction), shouldn't affect any of these, should it?

I'm just wondering if this is a generally accepted phenomenon, and if so, what the explanation is because, on the face of it, it's no more likely than mains cables making a difference, and we know what short shrift they get, on here.
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It's the belt tension that causes it, if the belt it too tight or to grippy then the deck runs too fast.
 
YNWOAN said:
I'm afraid that is an oversimplification and belt tension does definitely alter speed - easily checked with an accurate strobe.
Click to expand...

What actually matters is the thickness and elasticity of the belt. Effectively the turntable is not being driven from the surface of the pulley and inner platter, but from a point inside the thickness of the belt. This paper by Basis Audio explains it well. I have to say it was a surprise to me initially, but it does make sense and also explains why it is worth going to the effort of precisely grinding drive belts so that have uniform thickness.
 
Max will be along in a minute to say that "rubber is rubber is rubber"
 
thebiglebowski said:
Max will be along in a minute to say that "rubber is rubber is rubber"
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Surely that should be 'belts is belts' innit?

Actually, thanks to all who replied to my post. I realise now that my point about the important things being motor speed and pulley ratios only works in the ideal situation of an inelastic belt, so belt tension and elasticity could change the effective length of the belt and thereby bugger up the effective ratios of the pulleys.
 
Sue Pertwee-Tyr said:
Surely that should be 'belts is belts' innit?

Actually, thanks to all who replied to my post. I realise now that my point about the important things being motor speed and pulley ratios only works in the ideal situation of an inelastic belt, so belt tension and elasticity could change the effective length of the belt and thereby bugger up the effective ratios of the pulleys.
Click to expand...

Yep, as I found out when I purchased a third party white belt and the deck ran way too fast!
 
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