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Why Use Aluminum for a TT Platter?

Mass I am told is a good thing when it comes to TT platters. Lloyd Walker for one extolls it's virtues and as a rule some of the better turntables like to brag about their big ..Platters. Why then would aluminum, known for it's light weight (low density) turn up as frequently as it does as a platter material. I know it is easily machined but isn't there anything better and much denser.
mechans
dan_ed
2,451 posts
 
Let me restate that. ;-) The mass is not there for inertia.

That flywheel affect that folks like to think about when high mass platters are mentioned with belt drives would only matter when the platter is accelerating or decelerating. Once the platter is up to speed the mass would make any sudden changes in platter speed near impossible.

This is also why so many DD tables have light-weight platters. The motor on a DD is designed to directly manipulate the platter in order to correct speed. The platter is supposed to have it's acceleration constantly manipulated.
chayro
1,801 posts
 
02-09-11: Wntrmute2 wrote:
"Belt drives...in terms of speed accuracy, are clearly inferior to properly implemented direct drive tables."
Humm, proof, evidence to back this up?
-----

I was going to ask this as well, until I realized who the author was. Although I must ask - who's making a properly implemented dd nowdays? I recall people liking the Goldmund DD.
viridian's avatar
viridian
4,184 posts
 
Has2be, I wasn't speaking about Michell at all, simply about the chemical composition of Delrin. It was also chemical and spelling education as well. Miss that part?
peterayer
1,373 posts
 
I think the key to an aluminum TT platter is to properly damp the aluminum to reduce resonance. This is often done within the platter and/or on top of the platter as in the case of SME. Mass does matter depending on the drive system and what problem the designer is attempting to solve.

Regarding the whole belt vs. DD discussion here, I agree with Dan ed, though this is far too complex a topic to discuss on this thread and I think we should stay away from gross generalizations regarding TT drive systems. It's how its implemented that counts.
atmasphere's avatar
atmasphere
7,068 posts
 
Aluminum is used for several reasons. The first is that it is non-magnetic. This keeps it from messing with the cartridge. Aluminum is also relatively cheap, as it is one of the most abundant metals. Its also easy to machine.

An aluminum platter should be damped in some fashion for best results. If this is done it will keep up with any other material with no worries.
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