So what about the plinth?

[tromba]

I believe it. Mass isn't the only way to make a turntable quiet. You really have to know what you're doing to get a light 'table working at a high level like they do. Lots of time spent with expensive instrumentation checking to see how the latest scheme actually works...

That said, mass is probably the only way I can make one quiet!! This is a fascinating thread. Based on a comment here, I went to Lenco Heaven and asked about using the mushrooms or bolting down the table to the plinth. That's an interesting read also although you might have to be a member to see the pictures.

 

[Bigerik]

I believe it. Mass isn't the only way to make a turntable quiet.

You really have to know what you're doing to get a light 'table working at a high level like they do. Lots of time spent with expensive instrumentation checking to see how the latest scheme actually works...

I'm glad someone here gets it! More then gets it, actually. Rega gets slagged regularly around here due to their lack of weight. All you need is one open minded listen to know that those folks work really hard at getting their designs right.

 

[SteveA]

I'm glad someone here gets it! More then gets it, actually. Rega gets slagged regularly around here due to their lack of weight. All you need is one open minded listen to know that those folks work really hard at getting their designs right.

Because 'make it bigger' achieves more reliable results more quickly than 'make it smarter' for the average home enthusiast working in their garage.

I lucked out using CLD and combining different materials when I built my rack but doubt I could achieve the same results a second time if I tried to build a light weight plinth. I simply dont know enough or have the resources to model it then build and test multiple itterations.

Steve

 

[myu701]

I saw a Technics SL-1200 (or 1600, can't recall exactly) in action. You could slam your fist down on the table where it was situated and the record wouldn't skip. The shock absorbing platter foundation really did the trick. It's no wonder why these TT's are so popular in clubs where dancing sends shockwaves through everything attached to the floor.

The massive plinth route certainly can do the job, but at the sacrifice of adding tremendous weight. But there's no complicated shock absorbing mechanism involved.

What if you're dealing with a TT featuring a stock plinth and you want to improve the vibration isolation? Certainly some feet designed for this purpose will help, but it looks like applying some damping material to the underside of the plinth is the more effective thing to do. What are some viable materials that one can apply? I've seen photos of people applying a putty, like plasticine, but it makes me wonder how much of a mess it would leave behind if you later decided to remove it.

 

[Stacker45]

I'm glad someone here gets it! More then gets it, actually. Rega gets slagged regularly around here due to their lack of weight. All you need is one open minded listen to know that those folks work really hard at getting their designs right.

I'm sure that Rega works really hard on their arms, and probably on their platters too, on their motors? maybe, but since were talking about plints here, i hope you don't think that they had to work very hard to come up with a piece of MDF and three unajustable rubber feet.

 

[Bigerik]

I'm sure that Rega works really hard on their arms, and probably on their platters too, on their motors? maybe, but since were talking about plints here, i hope you don't think that they had to work very hard to come up with a piece of MDF and three unajustable rubber feet.

I most certainly think so. The whole unit is designed to work as one very well thought out whole. And it works very well.

 

[kach22i]

....soapstone

One of my local shops wants $65 SF, rep said all the affordable domestic stuff was used up years ago (used to be cheep), and now ships out of Brazil. Some of it had white veins in it, other a green glass like veins. The older stuff I remember was rather boring and monolithic looking, and perhaps more dull and porous (less dense too?).

On the whole plinth verse platter weight debate, I suspect a very heavy platter combined with a light weigh plinth is less desirable than a lighter platter with a heavier plinth.

You don't want the platter throwing the plinth around the room, do you?

There might be a ratio or perfect desirable balance for the two elements. If I said platter/plinth of 33/66 weight distribution how far off would I be?

An important thing to remember is that mass in movement, even a balanced rotational movement will have more potential force than a larger stationary mass. Think of rifling a bullet for instance. More destruction if that bullet mass is spinning, even more so is it's wobbling as it spins like a Sig 40.

 

[waterjetguy]

One of my local shops wants $65 SF, rep said all the affordable domestic stuff was used up years ago (used to be cheep), and now ships out of Brazil. Some of it had white veins in it, other a green glass like veins. The older stuff I remember was rather boring and monolithic looking, and perhaps more dull and porous (less dense too?).

On the whole plinth verse platter weight debate, I suspect a very heavy platter combined with a light weigh plinth is less desirable than a lighter platter with a heavier plinth.

You don't want the platter throwing the plinth around the room, do you?

There might be a ratio or perfect desirable balance for the two elements. If I said platter/plinth of 33/66 weight distribution how far off would I be?

An important thing to remember is that mass in movement, even a balanced rotational movement will have more potential force than a larger stationary mass. Think of rifling a bullet for instance. More destruction if that bullet mass is spinning, even more so is it's wobbling as it spins like a Sig 40.

Keep in mind that the mass is there to minimize the amplitude of any transmitted vibration. If anything is to be made massive, you'd want it to be the plinth, since it's the foundation of the whole mess. The platter depends on it as well as the tonearm/armboard for dead quiet support.

I don't see any reason to seek a particular ratio of the masses of the plinth vs platter. The bullet analogy has no bearing here. The platter should have no motion at all except to spin at a constant speed around its center, which should also be its center of mass. If the platter ass'y is in good dynamic balance, then it will exert zero force on the plinth while rotating, outside of the downward force of its weight.

If the platter is out of balance, then it will apply a forcing function to the plinth that repeats every 1.8 sec(running at 33 1/3 rpm), which will be proprtional to the amount of mass that is out of balance. Obviously, that is not desirable.

 

[waterjetguy]

I'm sure that Rega works really hard on their arms, and probably on their platters too, on their motors? maybe, but since were talking about plints here, i hope you don't think that they had to work very hard to come up with a piece of MDF and three unajustable rubber feet.

It may have taken a lot of work to figure out how thick the MDF should be, and where the feet should go to keep everything quiet. I'll bet it was a good deal more complicated than just drawing up something that looked nice and making it out of the most readily available size of MDF at Home Depot.

 

[mfrench]

One of my local shops wants $65 SF, rep said all the affordable domestic stuff was used up years ago (used to be cheep), and now ships out of Brazil. Some of it had white veins in it, other a green glass like veins. The older stuff I remember was rather boring and monolithic looking, and perhaps more dull and porous (less dense too?).

On the whole plinth verse platter weight debate, I suspect a very heavy platter combined with a light weigh plinth is less desirable than a lighter platter with a heavier plinth.

You don't want the platter throwing the plinth around the room, do you?

There might be a ratio or perfect desirable balance for the two elements. If I said platter/plinth of 33/66 weight distribution how far off would I be?

An important thing to remember is that mass in movement, even a balanced rotational movement will have more potential force than a larger stationary mass. Think of rifling a bullet for instance. More destruction if that bullet mass is spinning, even more so is it's wobbling as it spins like a Sig 40.

I've built two from soapstone. Both pieces were apprx., 4'x4' (one was solid 4'x4', and the other was a large piece of about 2'x2', and two other remnants that amounted to a 4'x4' quantity). I paid $75 for one, and $90 for another one. The more expensive of them (solid) came from a private party that was selling their excess from having a countertop renovation. The less expensive piece(s) came from a countertop builder who had lots of rem pieces in his backyard.

 

[myu701]

Sorry, I only later realized that the conversation is quite a bit above where my concern lies. Didn't mean to intrude...

 

[Stacker45]

It may have taken a lot of work to figure out how thick the MDF should be, and where the feet should go to keep everything quiet. I'll bet it was a good deal more complicated than just drawing up something that looked nice and making it out of the most readily available size of MDF at Home Depot.

I should hope so, but i'm just looking at the obvious here, i mean the engineers who desing high end TTs can't all be making them very heavy just for the fun of it, surely they know their stuff just as much as Roy Gandy.

I believe that most entry level TT's plinths are made of MDF, because it's cheaper to built and to ship, and it does a reasonable job at dissipating vibrations, but i still think that it's a cost cutting measure, otherwise the high end TTs would use it as well.

 

[SteveA]

...... but i still think that it's a cost cutting measure, otherwise the high end TTs would use it as well.

No they wouldn't because they are selling their tts for big $ and big $ customers don't like to see cheap materials in what they buy, irrespective of how well it does the job. I am sure many high end manufacturers would choose to use a lesser performing material if it looked and/or was more expensive and they could put enough spin on it to justify how importent that choice was.

Steve

 

[Bigerik]

I should hope so, but i'm just looking at the obvious here, i mean the engineers who desing high end TTs can't all be making them very heavy just for the fun of it, surely they know their stuff just as much as Roy Gandy.

I believe that most entry level TT's plinths are made of MDF, because it's cheaper to built and to ship, and it does a reasonable job at dissipating vibrations, but i still think that it's a cost cutting measure, otherwise the high end TTs would use it as well.

Like everyone else, they build to a price point. But cheaper materials certainly don't mean it wasn't well engineered. The incredibly success Rega has had over the last 30 years attests to that.

 

[marc mc]

The P-9 is $5000. The RB 1000 accounts for $2000 of the total price.

I am a huge Rega fan, Roy kept the vinyl fires burning when most TT manufacturers went belly up. He has a clear vision of lightweight TT's that simply dissipate energy from within and from without. And they do a very good job of it.

The question at hand however is not simply about plinth weight but it has to include applications in different conditions. There is many ways to design a TT or speakers or whatever and there is good and bad examples of both. Regas only sound slightly better when placed on massive stands or sandboxes and Lenco's sound poor in lightweight plinths. So it's more about application than anything else.

With that said I use Reference Lenco L75's. One weighs 80 and the other around 100lbs.

Marc mc

 

[gusten]

As I see it it really is of little importance if the TT is leight or heavy. It would be obvious that how little the TT is effecting the sound is the quality of the total design. I mean the expression 'if everything is being equal' never really can be applied.

The matter is different if we have a certain TT and want it to be improved.
gusten

 

[tromba]

With that said I use Reference Lenco L75's. One weighs 80 and the other around 100lbs.

I don't know much about Lencos, but would think that's not stock!! I googled that model and found lots of pictures, but they don't look THAT heavy!! Do you have pictures of yours?

 

[tromba]

In an earlier post I asked about using or leaving off the rubber mushrooms -- someone mentioned that many Lenco users have gotten better results screwing the top plate directly to the plinth. I went over to LencoHeaven and asked that question, and while the topic took a turn to Lenco, here's that thread. At least one TD-124 user fastens it directly to the plinth.

My advice for TD 124 : a solid heavy plinth with direct coupling the top plate with the plinth. No rubber mushrooms.
The TD 124 is an hybrid belt / idler and is loosing dynamics compared to a full idler like Lenco, Garrard or EMT, so less compliance in the best for gaining dynamics.
I use a slate plinth and the top plate is directly coupled to the plinth. The arm board is also slate.

 

[tromba]

Sorry, I only later realized that the conversation is quite a bit above where my concern lies. Didn't mean to intrude...

Doesn't seem like an intrusion to me (the OP). In asking about the plinth, feet certainly enter into that. We've touched on sound/vibration insulation, TT design, etc. -- all the parts that help construct a well designed system.

 

[gusten]

In an earlier post I asked about using or leaving off the rubber mushrooms -- someone mentioned that many Lenco users have gotten better results screwing the top plate directly to the plinth. I went over to LencoHeaven and asked that question, and while the topic took a turn to Lenco, here's that thread. At least one TD-124 user fastens it directly to the plinth.

The use of 'dynamics' seems a bit odd to me, the question is if using the rubber mushroons is creating some resonance that is not wanted IMO.
gusten