Turntable platter-LP impedance match

ack

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My understanding is that is precisely what it provides. If I didn't have vacuum hold down on my TT it is the one I would try.

I hear you, but I don't think foam - in any form - offers the right impedance
 

spiritofmusic

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Ack, my Trans Fi Audio Salvation direct rim drive tt uses an Al platter.

But bonded onto the platter are multiple small Delrin cones that in effect the lp sits on. Delrin is pretty close to vinyl as a material to be used, and indeed softer (meaning no damage to the lp as it rests on the cones).

I'm sure this has a major bearing on the sound of my vinyl playback compared to when previously the lp sat directly on the metal platter.
 

ack

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Thanks Marc, I believe Delrin is an option on the TechDas as well?!? I am seeing more and more such mechanical impedance solutions gravitate toward some sort of vinyl, and at least based on what I hear during my experiments, it feels like it's the right direction for optimal coupling to the platter... Strictly speaking, we are talking about thermoplastics like delrin, Isodamp or typical vinyl.
 
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Mike Lavigne

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Thanks Marc, I believe Delrin is an option on the TechDas as well?!? I am seeing more and more such mechanical impedance solutions gravitate toward some sort of vinyl, and at least based on what I hear during my experiments, it feels like it's the right direction for optimal coupling to the platter... Strictly speaking, we are talking about thermoplastics like delrin, Isodamp or typical vinyl.

why not make the platter out of the right material to begin with?

as I mentioned earlier, this was the general idea behind the NVS platter. a sympathetic composite to vinyl for ideal performance.
 

morricab

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I hear you, but I don't think foam - in any form - offers the right impedance

Foam is a lossy material by nature, which makes it naturally good for damping. This is not a soft foam but very rigid hard foam made probably from polyurethane or vinyl. Air bubbles will create greater loss than a solid material.
 

ack

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why not make the platter out of the right material to begin with?

as I mentioned earlier, this was the general idea behind the NVS platter. a sympathetic composite to vinyl for ideal performance.

Excellent question. I don't know the answer, but I very strongly suspect that: a) the platter needs to add mass and inertia - which the impedance-matching material won't to the same degree; b) the impedance-matching material may be too soft and pliable to make a platter in the first place; c) the designer may actually want the platter to be sympathetic to some vibrations and add "color" and excitement.

In other words, I see the platter as addressing totally different things than the platter-to-LP impedance matcher, and ideally, they are designed together, as in some of the tables we have discussed herein so far. I don't believe that slapping on a 'mat' to reduce noise is what we should be solely after, but a true impedance-matching solution. For example, what I have devised so far enables me to tap hard on the LP with my finger, cartridge in the grooves, and get very little acoustic feedback. Contrast this to having nothing between the LP and the platter, or a leather mat, and then, contrast again with what you'd get out of the TechDas or the Basis: no acoustic feedback. Therefore, although soft materials do reduce noise etc, a true mechanical impedance-matching interface would stand to be superior. How that's done I don't know, but I am making progress. This is why I continue refusing to call this interface a 'mat', which to me refers to something pedestrian and unscientific. After all, I don't think it's accidental that I keep reading of mats attenuating bass and treble, which is not what this interface should do; it should simply reduce vibrations to the highest possible degree, affecting nothing else.
 
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PeterA

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why not make the platter out of the right material to begin with?

as I mentioned earlier, this was the general idea behind the NVS platter. a sympathetic composite to vinyl for ideal performance.

Being a direct drive design, the NVS may not need the platter mass that the better belt drive designs require for speed consistency. Mike, isn't the NVS platter built up in layers of different material? How heavy is the platter?
 

PeterA

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Ack, my Trans Fi Audio Salvation direct rim drive tt uses an Al platter.

But bonded onto the platter are multiple small Delrin cones that in effect the lp sits on. Delrin is pretty close to vinyl as a material to be used, and indeed softer (meaning no damage to the lp as it rests on the cones).

I'm sure this has a major bearing on the sound of my vinyl playback compared to when previously the lp sat directly on the metal platter.

Marc, were these Delrin cones retrofitted to your previous metal platter? How many cones are there, and how did the sound change with the addition of the cones?

Also, I sometimes find vinyl-like surfaces can be somewhat slippery when contacting each other. With such little surface contact between the LP and cones, is there an issue with slippage between the cones and your LP? If so, do you use a clamp or weight?
 

spiritofmusic

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Peter, the sound is very different.
A slight metallic edge now replaced w no identifiable colouration.
My tt breaks a few rules in having lps sit on the cones w no clamp or weight. Haven't seen a record slip yet.
 

Folsom

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I think this topic is senseless because there's no real reason to impedance match, or tune impedances. Why? Why would you do that? Do you WANT to transfer energy between the two?

Most important factor of an LP on a TT platter: LP should not slip in any way what so ever. The LP should be able to move the platter if pressure is applied to it in a horizontal motion.

Second important factor: Whatever is below the LP should not reflect sound back up. If you listen close you can hear the music playing off the stylus.

Third & Fourth equally important factors: Does it negate as much noise as possible through whatever means, that could come up through it? And can it keep speed through it's design, weight, or shape?



What part does impedance play in any of that with matching to an LP? If anything the impedance should be enough to stop noise coming through it. The stylus needs to read the groves, not interactions between the LP and the platter.
 

ack

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In my opening post, I mentioned a few turntable manufacturers.

Here's the language from SOTA http://www.sotaturntables.com/engineering.htm

The top layer of the platter is an acrylic material, impedance-matched to the vinyl record. A special damping material isolates the mat from the platter, a one-piece cast aluminum frame integrated with a variety of special damping materials.

Here's the language from AMG http://www.musicalsurroundings.com/product/ces-2016-new-products-and-concepts/

AMG Viella V12 turntable with optional 2-tone platter
A special version of AMG’s Viella V12 with white top emphasizes that the massive aluminum platter has a PVC mat inlaid, bonded, and machined for mechanical impedance matching with the vinyl LP.

and it goes on and on...
 

Folsom

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So it is just marketing language to say they don't have a (highly) reflective surface for the LP to ride on... That is all that means.
 

PeterA

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So it is just marketing language to say they don't have a (highly) reflective surface for the LP to ride on... That is all that means.

Folsom, do you think it is better to have a highly reflective surface for the LP to ride on? Interestingly, my friend, and others, prefer a copper platter top to the rubber mat on the Technics SP10 Mk 3s. The TechDAS has a few options. I wonder which is the most popular. It probably has a lot to do with how noisy the platter is and whether or not it transmits much of the bearing or drive train noise to the vinyl. There is also noise from the stylus tracing the grooves which must travel through the vinyl and onto the platter. Whether or not this gets reflected back may also be an issue. I wonder if the thickness of the vinyl matters.
 

DaveyF

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Folsom, do you think it is better to have a highly reflective surface for the LP to ride on? Interestingly, my friend, and others, prefer a copper platter top to the rubber mat on the Technics SP10 Mk 3s. The TechDAS has a few options. I wonder which is the most popular. It probably has a lot to do with how noisy the platter is and whether or not it transmits much of the bearing or drive train noise to the vinyl. There is also noise from the stylus tracing the grooves which must travel through the vinyl and onto the platter. Whether or not this gets reflected back may also be an issue. I wonder if the thickness of the vinyl matters.

Peter, IMO, it all matters.However, IME, the biggest differences can be had with upgrading the tonearm wire and even more importantly, the phono cabling. Much larger differences to be had than changing the platter mat..or interface between the record and the turntable.
 

microstrip

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So it is just marketing language to say they don't have a (highly) reflective surface for the LP to ride on... That is all that means.

+1. Exactly.

Acoustic impedance is a very complex subject - much more complicated than electrical impedance - but sounds great in marketing and pseudo-technical literature.
 

Folsom

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Folsom, do you think it is better to have a highly reflective surface for the LP to ride on? Interestingly, my friend, and others, prefer a copper platter top to the rubber mat on the Technics SP10 Mk 3s. The TechDAS has a few options. I wonder which is the most popular. It probably has a lot to do with how noisy the platter is and whether or not it transmits much of the bearing or drive train noise to the vinyl. There is also noise from the stylus tracing the grooves which must travel through the vinyl and onto the platter. Whether or not this gets reflected back may also be an issue. I wonder if the thickness of the vinyl matters.

I think it's subjective preference. I don't prefer reflective, but I think a lot of stereos probably simply sound better with them. There's no way around the fact that it's very hard to get gear designed with different approaches to sound right together, so if something makes it sound better to the ear go with it. But know that ultimately you may be limited and unable to upgrade certain parts due to tuning.

The music playing at the tip is what gets reflected. Music from the speakers may, but it isn't playing directly into the surface, in the same way. If the music from the speakers was putting much pressure on the vinyl, then I suspect a harder (heavier, really) surface would be wise to make the vinyl couple with it and drop the vibration frequencies down to undetectable levels. So far though I haven't particularly liked weights. Maybe a combo with an outer ring weight would work for me.

In general I haven't liked the sound of weights. When you look at the vinyl it isn't unusual to see them, or clamps, cause the vinyl to flex a little. When the vinyl gets this flex it becomes rigid and able to transfer more vibration energy because it damps less the more solid it gets. At the center of the LP the coupling is better, so it may be nice but the outer tracks seem to suffer from what I can tell.

If you're going to couple the LP, I think you should go with the heaviest platter possible. Hopefully that also means it transmits little to no noise into the platter or the frequencies drop through the heaviness into too low too matter. Also if the platter is exposed outside of a plinth, it makes a lot of sense to me for it to be very heavy so that it isn't as susceptible to acoustical energy.
 

jeff1225

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Folsom, do you think it is better to have a highly reflective surface for the LP to ride on? Interestingly, my friend, and others, prefer a copper platter top to the rubber mat on the Technics SP10 Mk 3s. The TechDAS has a few options. I wonder which is the most popular. It probably has a lot to do with how noisy the platter is and whether or not it transmits much of the bearing or drive train noise to the vinyl. There is also noise from the stylus tracing the grooves which must travel through the vinyl and onto the platter. Whether or not this gets reflected back may also be an issue. I wonder if the thickness of the vinyl matters.

Peter,
I think you hit the nail on the head. There is no prefect mat that works on all turntables, it's dependent on the turntable platter materials and the design of the turntable itself.
 

mountainjoe

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If this latter part is true, then that may lead us to wonder if a single mat or weight design can have a net positive effect across all TTs or if designs will need to be specific to particular TT architectures or implementations?

In my instance it's pretty clear to me that it's very easy to negatively affect the transient performance in particular, with any damping material or device added to the base design...

Cheers, Joe

Peter,
I think you hit the nail on the head. There is no prefect mat that works on all turntables, it's dependent on the turntable platter materials and the design of the turntable itself.

Full circle :cool:
 

ack

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Peter,
I think you hit the nail on the head. There is no prefect mat that works on all turntables, it's dependent on the turntable platter materials and the design of the turntable itself.

I would totally agree with that as well, and is why I admire those 'tables designed with such an interface built-in - if nothing else, for the effort someone made to try to address this. In my case, I am attempting to build it myself, because VPI hasn't thought about addressing it.
 

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