Quiz about B55 mat design

[casta diva]

Hello everyone, I have a question that I haven't been able to find an answer to for quite some time.

My mat has three concentric circles whose thickness decreases with the radius. So, the outer one is 1.9mm high, the middle one is 1.2mm, and the smallest one is 0.8mm. The aluminum plate in the center is 0.4mm lower than the lowest circle.
 
Why?

thanks for the answer, or at least for a little mental gymnastics !

[willbewill]

Well the outer supports 12", middle 10" & inner 7" records, and I'd hesitate a guess that the different heights (diminishing toward the centre) allows each record to be fully supported at its edge and also allows for any thickening of the record towards its centre.

[casta diva]

yes, that's what I thought too, but what about the lack of support for the LP plate and that over the largest part of the surface? using a clamp or weights is out of the question, the LP is bent visibly with the naked eye...

But that's not all the trouble. The platter has the same problem. If it is deformed, then it was done perfectly because it spins idealy centered in 3D...?
A modification with a new platter and bearing is definitely needed.

[willbewill]

Clamps weren't a thing back then

[pde2000]

Supporting the record minimally, with the edge gripped by the rubber, does have advantages and sounds very good.  The spindle is also quite fat and most records fit rather tightly (acting like a clamp).

[casta diva]

I have nothing to do with physics and natural sciences professionally, so I'm confused: if the hifi world has accepted clamps and weights, if Sota makes complicated systems for holding the record while playing, if damping is important in many contexts, including stopping the vibrations of the record, how am I to understand that minimal contact between the record and the platter is desirable?
How do I combine opposing systems, holding firmly the record to the platter and minimal contact with the platter; one is very good, but the other is also very good?
I would like to apply knowledge exactly, although it seems to me that the market is full of opposing but equally valid (?) opinions and solutions.

[wenig watt]

I have nothing to do with physics and natural sciences professionally, so I'm confused: if the hifi world has accepted clamps and weights, if Sota makes complicated systems for holding the record while playing, if damping is important in many contexts, including stopping the vibrations of the record, how am I to understand that minimal contact between the record and the platter is desirable?
How do I combine opposing systems, holding firmly the record to the platter and minimal contact with the platter; one is very good, but the other is also very good?
I would like to apply knowledge exactly, although it seems to me that the market is full of opposing but equally valid (?) opinions and solutions.

 
welcome in the market of storytelling! Look at flying objects, I always find it amazing all the things that fly.

With best regards

Arndt

[willbewill]

There isn't one correct way and you can get to the same result by applying different methods - believe me I think I've tried them all. Mats/clamps/weights etc can be a good way of voicing/tuning your system.

[pde2000]

If playing pristine records I prefer minimal contact for most pleasing sound. Old discs with lots of wear are better on a soft felt mat as this lowers the noise.

It takes enough effort to play records already that extra faff like clamps can ruin the fun.

A lot of hifi is hair shirt iykwim

[casta diva]

Thanks for the welcome!

I keep being amazed by the same rubbish again and again and ... I can't understand why, for example, blind tests of hifi equipment are pure sacrilege and a curse?! 

[stratokaster83]

Thanks for the welcome!

I keep being amazed by the same rubbish again and again and ... I can't understand why, for example, blind tests of hifi equipment are pure sacrilege and a curse?!  

Because it hurts sales of cables, cable risers and other audiophile jewellery

[casta diva]

 

[wenig watt]

I have been to the High End in Munich every year for the last 10 years. Originally because a good acquaintance who is now a friend invited me.
At that time he worked as a developer of tube circuits for other companies. I couldn't imagine how many bad sounding systems were presented there.
But sometimes it sounds excellent, which indicates that someone with a lot of knowhow is getting the best out of the assembled components. It's often not the most expensive or the "best", and sometimes it's something you wouldn't expect, like speakers without cabinets, or without woofer, or amplifiers without power, or turntables from 70 years ago....
I've seen almost everything under records and couldn't make a general statement about what doesn't work at all.

With best regards

Arndt

[simon]

... I couldn't imagine how many bad sounding systems were presented there.
But sometimes it sounds excellent, which indicates that someone with a lot of knowhow
is getting the best out of the assembled components. It's often not the most expensive...

Arndt

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