Light Weight Turntable Plinths

[RDM]

There seems to be a few turntable manufacturers currently dabbling in light weight, minimalist plinth designs, in contrast to the more traditional designs.

If stiffness and damping are more important for a plinth than mass, does mass actually add anything, apart from better stability against external forces?

Here is my attempt at this concept, which is still yet to be tested. Extruded polystyrene and bamboo ply sandwich, with pine and paulownia sides, and a simple veneer.  Simple to make, very stiff, well damped, and weighs in under 2kg.

 

[crtexcnndrm99]

Super lightweight! I’m planning to imitate the Loricraft lightweight approach for the Lenco - shares the use of sorbothane spheres I see : D

 

interested to here more impressions, it looks great 

[aussievintage]

17 minutes ago, RDM said:

There seems to be a few turntable manufacturers currently dabbling in light weight, minimalist plinth designs, in contrast to the more traditional designs.

If stiffness and damping are more important for a plinth than mass, does mass actually add anything, apart from better stability against external forces?

Here is my attempt at this concept, which is still yet to be tested. Extruded polystyrene and bamboo ply sandwich, with pine and paulownia sides, and a simple veneer.  Simple to make, very stiff, well damped, and weighs in under 2kg.

 

 

Nice looking plinth.

 

But as for the theory, I am sure it isn't the light weight that is the parameter actively making it work in these modern plinths.  It's the exotic materials and construction that work to make it sound good, and the ability to make it lightweight is a plus for the consumer, not the sound.     However added  mass could further improve things as it acts in a different way.  So, I would think you could combine the skeletal foam filled sandwich design by coupling any remaining vibrations to a massive sound/vibration sink.

Edited July 24, 2020 by aussievintage

[markielinhart]

That’s a very nice piece of work. As a once-was picture framer I’ve been toying with idea of having ‘picture frame’ plinth made up. There are some oversized mouldings available - 60mm in depth - made from some solid timber species and in a variety of finishes including some nice coloured timbers and black of course. They could be perfect for a drop-in toplate such as the one in your photograph. Watch this space...

[RDM]

I’ve also got another idea on the go for the Lenco. A 3D printed plinth chassis which could then be clad in something a little more visually pleasing, and the voids filled with a dampening/stiffening material of choice (epoxy resin, concrete, sand, etc). I have already modelled the design, but it will be a while before I get around to getting it printed. I’ve separated it into four parts so they’re small enough to be printed on a domestic 3D printer and then glued together.

 

 

[John0001]

The theory behind super-low mass plinths is to stop the storing and then discharge of energy. ie virtually no mass equals almost no stored energy to muddy the sound. So high-rigidity and low mass should (if done right) be the ideal approach as there is no energy sink problem.

I'll be interested in the OPs impressions on the sound of the very interesting and ingenious design! 

[aussievintage]

4 minutes ago, John0001 said:

The theory behind super-low mass plinths is to stop the storing and then discharge of energy. ie virtually no mass equals almost no stored energy to muddy the sound. So high-rigidity and low mass should (if done right) be the ideal approach as there is no energy sink problem.

 

High mass constrained layer plinths work a little differently though don't they?  They don't store the energy, they dissipate it by trapping it in the layers and reflecting it through the material until it is dissipated as heat.

Edited July 24, 2020 by aussievintage

[audiofeline]

1 hour ago, John0001 said:

The theory behind super-low mass plinths is to stop the storing and then discharge of energy. ie virtually no mass equals almost no stored energy to muddy the sound. So high-rigidity and low mass should (if done right) be the ideal approach as there is no energy sink problem...

I agree with this.  However, it's also depends on the ability of the material to be able to dissipate the energy.  I've read that while granite plinths are very high mass and look superb, the dense volcanic internal structure allows the energy to bounce around inside so it's not dissipated.  In comparison, stone plinths from slate dissipate the energy much better due to the layered construction of the stone. 

 

Which brings me to bamboo, a material that's become available in relatively recent years and is highly regarded for audio use.  It appears that bamboo is able to dissipate energy very well (in comparison to other wood) and is very rigid.  So it is feasible that you need less of it to do the same job as other wood.  Hence, there is the potential for a lightweight bamboo plinth to be very good.  I look forward to the experimenters making the comparison between a light bamboo and high-mass plinths, so we can move from the theory to an evidence-based approach.

 

[Juzbear]

40 minutes ago, audiofeline said:

I agree with this.  However, it's also depends on the ability of the material to be able to dissipate the energy.  I've read that while granite plinths are very high mass and look superb, the dense volcanic internal structure allows the energy to bounce around inside so it's not dissipated.  In comparison, stone plinths from slate dissipate the energy much better due to the layered construction of the stone. 

 

Which brings me to bamboo, a material that's become available in relatively recent years and is highly regarded for audio use.  It appears that bamboo is able to dissipate energy very well (in comparison to other wood) and is very rigid.  So it is feasible that you need less of it to do the same job as other wood.  Hence, there is the potential for a lightweight bamboo plinth to be very good.  I look forward to the experimenters making the comparison between a light bamboo and high-mass plinths, so we can move from the theory to an evidence-based approach.

 

There is a plinth made of bamboo for the LP12 which looks great and they tell us sounds great. CNC machined from one big piece of bamboo ply, I think. Unfortunately it is too expensive for me to justify!

http://www.booplinth.com

 

Justin

 

[aussievintage]

2 hours ago, audiofeline said:

the dense volcanic internal structure allows the energy to bounce around inside so it's not dissipated.

I don't like stone plinths.  The idea is to make the energy bounce around in a layer of material that absorbs it, until it's gone.  Layers of varying density wood are good at this.

[stevoz]

5 hours ago, RDM said:

There seems to be a few turntable manufacturers currently dabbling in light weight, minimalist plinth designs, in contrast to the more traditional designs.

If stiffness and damping are more important for a plinth than mass, does mass actually add anything, apart from better stability against external forces?

Here is my attempt at this concept, which is still yet to be tested. Extruded polystyrene and bamboo ply sandwich, with pine and paulownia sides, and a simple veneer.  Simple to make, very stiff, well damped, and weighs in under 2kg.

 

Looks great....but does it sound good? That's why we're here....

[RDM]

25 minutes ago, stevoz said:

Looks great....but does it sound good? That's why we're here....

I know, I know. I prioritised the building of the plinth over getting the Lenco running again, which probably wasn’t the smartest move. I will get there eventually though. 

[Full Range]

Built a skeletal plinth a few years ago 

Used two different timbers to counteract resonance - the main timber used is called Crows Ash 

 

This plinth would be the 4th or 5th plinth build since the early 70s when I purchased the Garrard 401 

And so far it’s the best sounding plinth build so far and still in use to this day.

 

Full build details here

https://www.stereo.net.au/forums/topic/82084-garrard-401-rebuild-for-the-22nd-century/
 

 

Here are some photos for you

[cafe latte]

On 25/07/2020 at 8:48 AM, RDM said:

There seems to be a few turntable manufacturers currently dabbling in light weight, minimalist plinth designs, in contrast to the more traditional designs.

If stiffness and damping are more important for a plinth than mass, does mass actually add anything, apart from better stability against external forces?

Here is my attempt at this concept, which is still yet to be tested. Extruded polystyrene and bamboo ply sandwich, with pine and paulownia sides, and a simple veneer.  Simple to make, very stiff, well damped, and weighs in under 2kg.

 

Ok a few things..

Before I talk about the plinth itself in the picture you plinth is also the cupboard. Your feet are wood and I hope sorbothane?You need to isolate the plinth form the shelf it sits on in your case the plinth is sitting on a sound box. For isolation, think Sorbothane not spikes as they couple the plinth more to what it sits on.

Now plinth design, there are two ways to approach plinth design, one is mass and the other way is damping or you can go both. Mass works as it takes more energy to get a massy plinth so start to vibrate in the first place. To give a simple example closing a wooden door on a room which has loud music even if the door has an air seal you still hear the music quite a bit. Now if we brick up the door the volume reduces much more, Why? Simple the door which is lighter vibrates much more from the music in the room than the brick due to less mass so more noise is heard with the door example.

We can have a stiff well damped light plinth ie made with material with good damping properties and use constrained damping techniques, but heavier will always win as these same constrained damping techniques can be used with massive plinths which take far far more energy to start moving regardless of damping material used.

Chris  

Edited July 25, 2020 by cafe latte

[Cardiiiii]

I really admire people who can do this kind of DIY. I promise I’m not jealous at all.