Aluminium/ steel platter mats

[Pharos]

I would have thought that any extra weight from mats was very low compared with the mas of the platter.

[Boussven]

Sometimes, I have the feeling I'm talking to myself on this forum ;-) Did anyone heard of the "special material" POM used for record weights? What is it, and is it any good?

[JohnG]

POM when referencing the Web, is described as the shortened name for the thermoplastic Polyoxymethylene or Acetal.
I have always referred to it as Delrin, it is available in a few forms, depending on the role it is to be used in. POM is not as resistant to wear as PEEK, so PEEK is the upgrade material sometimes put forward to be used in the bearing housing when adding weight to a Platter assembly.
If a Bearing housing has a secure bottom seal that the Spindle Point Loads, and is robust enough that additional weight won't apply a stress to it that could dislodge it, then the platter could receive extra weight without concern.
If the spindle point load is coming into contact with a unknown material,or a known material where the condition of the material is a unknown, then any added weight could increase the rate of wear, that will be seen as detrimental or amplify the unwanted effects of a excessive abrasion on the spindles contact surface, due to an increased surface area being in use, this effect can be seen to be having a detrimental effect.
I recently have had a good look at a particular TT's Bearing Housing Base Bottom Seal, and my view is that, the material the spindle point loads, is not resistant to wear as is POM or PEEK, and it would be best left to have as little additional weight added as possible, as this would be keeping it protected from any further accelerated wear, that could be caused by the adding of weight.
The other risk is in a case like the one above, is that any changes to the properties of material in the chain, can effect the sonic signature of the device, and the new attenuation/ Sound Quality being perceived by the listener might not be as attractive to them, so the idea of keeping a material as close to the original condition, would be the most attractive if the SQ of the device as originally heard, was the Deal Clincher when buying.

[mbic]

I use a Ringmat/MRA system on my 401. No record weight of course. The sound is full of life.
The tonearm must have height adjustment.

[Boussven]

No record weight of course.

I see lots of record weights on Garrards 301/401, is this not advisable, and if so, why?

[Boussven]

POM when referencing the Web, is described as the shortened name for the thermoplastic Polyoxymethylene or Acetal.
I have always referred to it as Delrin, it is available in a few forms, depending on the role it is to be used in. POM is not as resistant to wear as PEEK, so PEEK is the upgrade material sometimes put forward to be used in the bearing housing when adding weight to a Platter assembly.
If a Bearing housing has a secure bottom seal that the Spindle Point Loads, and is robust enough that additional weight won't apply a stress to it that could dislodge it, then the platter could receive extra weight without concern.
If the spindle point load is coming into contact with a unknown material,or a known material where the condition of the material is a unknown, then any added weight could increase the rate of wear, that will be seen as detrimental or amplify the unwanted effects of a excessive abrasion on the spindles contact surface, due to an increased surface area being in use, this effect can be seen to be having a detrimental effect.
I recently have had a good look at a particular TT's Bearing Housing Base Bottom Seal, and my view is that, the material the spindle point loads, is not resistant to wear as is POM or PEEK, and it would be best left to have as little additional weight added as possible, as this would be keeping it protected from any further accelerated wear, that could be caused by the adding of weight.
The other risk is in a case like the one above, is that any changes to the properties of material in the chain, can effect the sonic signature of the device, and the new attenuation/ Sound Quality being perceived by the listener might not be as attractive to them, so the idea of keeping a material as close to the original condition, would be the most attractive if the SQ of the device as originally heard, was the Deal Clincher when buying.

Thanks for sharing this information

[mbic]

Before I switched to a Ringmat, which was a number of years ago, I used a Michell clamp, which isn’t a weight.
The only plus point was, that it flattened a warped disc. There was very little difference in the sound, if any.
My dealer at the time who sold and serviced 401’s said only use a weight if the turntable has been designed with the use of a clamp or weight.
Bear in mind when the 401 was in production, record weights etc was not part of the design. A platter matt was part of the design, so it does make sense to experiment here.
I said in a previous post that I use the MRA version of the Ringmat, this consist of a thin rubber matt and two spacers, this damps the 401’s aluminium platter, the Ringmat sits on the top.
I think the correct platter matt achieves more than a clamp or weight.

[karma67]

Has anyone used an acromat?

[mikeyb]

Has anyone used an acromat?

I use a 5mm one on top of my Mike New platter as its needed to get my arm level as the platter sits very low. Sound wise I've no complaints.

[karma67]

Cheers, I will have one to try soon, the theory behind it is interesting.