Benefits of wooden platters !?

[Rotsch]

I've seen several of this wooden platters, the last time...
Mostly made of MDF.
Are there any advantages/disadvantages !?

Just curious...... 

[richard]

I had a new one pass through during the 80s. I was briefly a Rotel dealer (brief meaning one shipment) and I'd ordered a turntable like this. As was usually the case then, Rotel was a Japanese company manufacturing in Taiwan. The TT was a clever British design.

The idea is that the fiberboard platter will be stiff and inert, not very prone to resonance or vibration in general. In other words, having the same properties that make it so good for loudspeaker cabinets.

The machine's deck was well-conceived. It was a sandwich of metal-fiberboard-metal: something like that, with lots of screws holding the layers together in an asymmetrical pattern. I thought that the machine sounded good.

Maybe someone who made a double-platter Lenco with two identical platters will give you his platterless Lenco and then you can put a wood disk on it. Come to think of it, since I have two Lencos with bad platters, hmmmm. Thank you for asking, dude!

[OsteSpiser]

I think I remember a low-tier Rega  - or a NAD copy - with an MDF platter rather than the then-current Rega glass platter.
It is of course a lower-cost material, but my main concern would be that it is *too* dead ... but with a careful choice of mat?

-kristian 

[blademage]

MDF platters are:
easy / cheap to produce
have different (not better) resonance frequencies
are just another material, like acryl, zinc, alu, glass, copper, fibreglass, ...

On my Pro-Ject 1 (nearly twenty years ago) I had a a platter with an inner ring of alu (for the belt), outer area of MDF and a glass platter on top. I don't know if it was any better, anyway it didn't survive (seperated) transport on my rear seats. The metal ring broke out and I had no chance to repair it.

[Rotsch]

MDF platters are:
easy / cheap to produce
have different (not better) resonance frequencies
are just another material, like acryl, zinc, alu, glass, copper, fibreglass, ...

On my Pro-Ject 1 (nearly twenty years ago) I had a a platter with an inner ring of alu (for the belt), outer area of MDF and a glass platter on top. I don't know if it was any better, anyway it didn't survive (seperated) transport on my rear seats. The metal ring broke out and I had no chance to repair it.

THAT...sound like a reso-killer to me !!!  

Another question....
IF...one would make a platter from...uuummmh...maybe oak or other hardwood...
What's about the resonances.... methinks that MDF is somewhat of DEAD !!
I'm just askin....cause i've really no idea how this kind of material (wood) will "react"
as a platter.... unlike as multiple screwed material for a plinth !!?  *IYKWIM* !?
It'll have definitely a greater impact for the sound ......
Any experiences.....??

  

[sashasdad]

  Sounds like an interesting question to me......But I would be a little concerned about a solid disc of hardwood
warping , you have heat from the motor underneath....& of course the dreaded central heating !!

  David

[ZM1080]

MDF platters are:
easy / cheap to produce
have different (not better) resonance frequencies
are just another material, like acryl, zinc, alu, glass, copper, fibreglass, ...

...

couldn't agree more.

Natural wood would be disastrous. I spoke to a friend last week who's father was planing some 150 year old oak for another project (not audio related). My friend said that the piece of oak had warped after planing, and after 150 years!!

Any material used for platter duties must be totally inert, not change over time and be machinable within very fine limits. This rules out most things, including mdf.

[rfgumby]

Wood is like metal- if you machine off any material you change the surface tension.   It's quite surprising in metal when you work it, but it's even more of a problem with naturally random structure like woods.  MDF will hold dimension rather well, but is a bit of a wild card with environmental moisture.

[wer]

The Acoustical 3100 has some sort of a pressed fibreboard platter (guess it was made a while before MDF appeared on the scene?) , and does a good job.

[richard]

I recall something about MDF outgassing nasty stuff. I'm thinking about formaldehyde. It's possible that different types of fiberboard are made with different types of filler/adhesive/whatever. Maybe they have to pass national health standards (do we have any standards for this at all in the USA ?)?.

Formaldehyde? Maybe I'm thinking of the smell of a fabric store. What's the difference between cotton platters and wool platters? The Linn Baaa.

[Rotsch]

I recall something about MDF outgassing nasty stuff. I'm thinking about formaldehyde. It's possible that different types of fiberboard are made with different types of filler/adhesive/whatever. Maybe they have to pass national health standards (do we have any standards for this at all in the USA ?)?.

I think....Formalde....is just a content of chipboard....
I dunno exactly....
But this F.....has been proscribed several years ago..... here in Europe !
If i'm not mistaken !? 

[jervill]

The Pro-ject 1.3 I had, had an MDF platter.  Other Pro-ject and Rega entry level decks have mdf platters.  I used my mdf platter (30mm) on top of my original for the stack platters.  I found it very good in this arrangement coupled to the metal with 3M spray to stop it slipping. If it wasn't for the fact that I dropped and dented it, I would've been happy to carry on like that.  It's colouration agreed with me enough that I did seek out a quote for having a platter to stack machined out of a 25mm piece to sit flush on top.  Around £100-150+(if I remember correctly) with my own CAD for a one off.  Price range depends on the machine setting up requirements for prototypes.  I can buy two replacement platters or 2ndhand Pro-ject or Regas for the platters at that price!  So I've kept the drawing and am on the permanent look-out for panzerholz off-cut or something (Delrin, nearly but wanted to research more in the end.) in the rough dimension of a platter to have machined...

 As the main platter for an idler, I have grave reservations...

Although they absorb moisture and expand, they can be sealed. There are different grades including water resistant varieties that'd dull carbide tools.  (Also has a denser hdf (high) cousin as well.). There are concerns of formaldehyde emission, EU made ones have emission levels considered insignificant.  Bear in mind that formaldehyde is being naturally released by other wood based products as well and are considered a pollutant and a (suspected) carcinogen. There are mdf types that have formaldehyde free binders for even lower emission. The dust from working on mdf are considered hazardous.    Was reading up last year before I put a sander to my prototype speaker cabs

[Brumm]

But this F.....has been proscribed several years ago..... here in Europe !
If i'm not mistaken !? 

Yes, except for the noses of doctors-to be, they have to spend hundreds of hours stooping over their formaldehyde-conserved test objects!
Ask Jean, he told me he liked it very much... maybe some kind of drug?   

Afaik, the cancer percentage among doctors is not significantly higher than in the rest of the population.

Greetings, Hansrudolf

[sukram]

I think it is possible to build a platter out of massive wood by choosing a slow and straight grown tree and take a so called rift sawn plank to build the platter. The wood should also be carefully seasoned and air dried. At best store the wood for a few weeks in the same room where the lenco is used. To take care of the wood movement I would make the platter out of triangular segments,like pieces of a round cake, and glue it together.
If one weights every piece it should be possible to avoid an out of balance platter, but it can also be balanced like a metal platter.
For preventing warping of the platter it could either be rotated after every day if the surface is raw or painted with shellac.

Markus

[pde2000]

hey hansrudolf;  our medical schools don't do dissections anymore.  the one I went to in 1987 (royal free hospital) was very modern so we had surgical fellowship students doing most of the cutting for us and we shared a dozen bodies between us plus the specimens kept in the fridge and the buckets of brains/spinal cords.  the bodies we kept for the year were indeed formaldehyde preserved, and smelled a bit like over-ripe stilton cheese, but the fridge had very sweet smelling tissues which were kept with glycerol solutions (so the muscles remains red coloured and supple).  my school friend went to another school (st georges hospital) where he had a body to himself, in his team of 4 first years, for the whole year.  he 'borrowed' my dissection kit as the royal free provided everything, including a half skeleton to borrow.  dissecting was one of my hobbies as a child.

one wood product that has phenol formaldehyde copolymer holding it together is OSB (oriented strand board).  this stuff is manufactured under high temperature and pressure and is immune to moisture penetration and is dead cheap.  the factory in inverness (caber?) makes a floor board that is planed so the surface is smooth and very pretty so could make some nice plinth or platter material.  damping is much higher than ply too.  most osb gets seen as shuttering on building sites.  its easily recognised because the wafers of wood are quite large, like potato chips.  when doing a study tour I was shown around the caber factory and the lab had samples kept in water baths to simulate weathering.  the manager was very proud of the oldest sample which had the equivalent of over a hundred years of exposure and was still intact if a little ugly.