Garrard 301 plinth design

[Tony L]

Seeing as I sent a large cheque off yesterday to a total stranger for a largely unseen Garrard 301 I guess I better start thinking about plinth design. I know there are others here in a similar position, so a fresh thread on such things might be A Good Thing.

My requirements are simple – I want a two arm plinth with my Hadcock 242SE at the side and a SME 3009/II at the back. That’s pretty much as far as my thinking has got.

Reading around it looks like a successful Garrard plinth is very different in concept to a successful Lenco plinth. The Lencos like very complex tightly fitting ultra-high mass constrained layer damping plinths. This makes sense as they have a comparatively flimsy / resonant pressed steel top-plate assembly which needs supporting / coupling. The complexity and expense of a good Lenco plinth is the reason my L70 project is on hold for a while (well that and the fact I couldn’t come up with an arm layout I really liked for a ‘main system’ deck). The Garrards are different as they have a very solid casting, they need to be thought about in an entirely different way. The Japanese know a lot about 301s and I found this quote from 6 Moons interesting:

Originally Posted by 6 Moons

The Japanese actually have a theory regarding Garrard 301s. It says that one should consider the modulations that occur at the interface of record and needle as miniature "explosions". Everything possible should be done to preserve the transmission of that explosive event all the way through the table. You definitely don't want to do anything in the plinth that could damp those "explosions". Simply put, damping Garrards is a curse that guarantees bad sound.

Currently I’m leaning towards one of two ideas, a) going the Lorricraft route of a decoupled top-plinth, or b) trying to figure out how a Shindo plinth works and getting one made.

The Lorricraft is logically very similar to a Roksan Xerxes in concept in that it is a wooden panel resting on rubber decoupling, I believe Lorricraft use proper wood where Roksan famously used MDF shit that was simply not up to the job (yes, I’m an ex-Xerxes owner!). It would be easy to build a Lorricraft clone in stages, i.e. first build the top plate and run it as a ‘skeletal’ plinth, then build the ‘box’. Lorricraft use squash balls as decoupling, but I never liked racket sports at all, skateboarding was my thing. It occurred to me that skateboard truck bushings might be ideal for this purpose – they are smaller than squash balls and similarly available in many different compliances, but being cylinders they could be far easier to deal with. Logically there is no reason why a decoupled plinth like the Lorricraft should be based on a ‘box’, one could just as easily have a solid laminate plinth with decoupled top section, i.e. what would look like a small gap from the outside.

The Shindo is mysterious – I’ve never seen a picture of one with the deck removed, but I suspect that it is similar to the Martin Bastin plinth, i.e. a tight fitting solid laminate plinth. I’d love to learn more about these as they look very cool indeed. I know the Basin plinth supports / couples the main bearing from beneath, not sure about the Shindo. This actually interests me more than the decoupled plinth, I just need to figure out how it works.

Oh, my plinth will not contain any MDF as I detest the stuff! It will be natural wood, marine ply, slate or some combination thereof.

Tony.

[clivem2]

I tried mdf and birch ply CLD (medium mass) and skeletal, decoupling and all sorts. Slatedeck trashed the lot. Totally. Game over.
http://www.slatedeck.com for info (I'm sure you've seen this already).

[Markus S]

A certain ex-member here reports great success with his slate plinth for some funny old Japanese turntable. Came very reasonably priced, too, apparently.

[Patrick Dixon]

From what I've read, the Shindo plinth might be constructed something like this:



(which are made by a guy in Ireland IIRC)

but the Shindo one is made of hardwood blocks rather than birch ply. I read some speculation that Shindo wouldn't be able to charge the price if it was ply rather than solid wood, so that, rather than 'sound' reasons, might be why they use it.

I too have heard that slate is the way to go, and I'm planning on talking to a Kitchen Worktop supplier to see if I can get something at an affordable cost.

[Tony L]

That's a Neil Hollow plinth! It's an option I'm seriously considering. Slate is an option too, but I'll need to see what's available locally and at what price (Slatedeck seem very expensive). Let us know how you get on at the kitchen worktop supplier. I guess a gravestone maker might be able to do the job too.

Tony.

[MarkS]

Do the 301 plinth theories apply to the 401?

[andy831]

As far as I am aware the design principles would be identical and applicable to both tables as both have a similar cast chassis.

[GaryT]

I've been looking at a slatedeck plinth for the 401 I've just bought, and according to their site, not all slate is the same. The stuff they use is superior because it is quarried from a different site to other slate. Can anyone verify this i.e. compared a plinth made from 'superior' to one made from 'inferior' slate?
On a slightly different note, does anyone know how the Neil Hollow plinths compare both sound & cost wise? Given the choice, all things being equal, I think I'd prefer a wooden job as I think they look better (once stained, varnished etc). The single Slatedeck 401 plinth comes out at about £550, so is the Neil Hollow type in this ballpark?
Gary

Originally Posted by Tony L

That's a Neil Hollow plinth! It's an option I'm seriously considering. Slate is an option too, but I'll need to see what's available locally and at what price (Slatedeck seem very expensive). Let us know how you get on at the kitchen worktop supplier. I guess a gravestone maker might be able to do the job too.

Tony.

[martin clark]

The stuff they use is superior because it is quarried from a different site to other slate

Slate is a metamorphic rock (from clay) and does differ wildly, depending on where it is sourced from - from something not much harder than talc, to something approximating a decent sandstone.

It's also widely available in large lumps at not-horrific prices. Bet you could buy a slab cut and honed to a finished top-plate size quite cheaply - and with not much more than a masonry drill and a little patience, do your own cutout.

[timothygurney]

Tony,

You have seen my plinth design in its finished state, yes made from the left over naturals of wood formed into that ugly product called "MDF".

I previously made a solid plinth design from "real plywood"; layers of 10mm crossed. I managed to get a tight fit around the 301 installed then listened and now use it a support in my workshop .

Sounded a tad "dead" compared to the plinth I had it fitted to : simple slab of MDF mounted to bed legs!!! But "waf" got me to think and work and the end result that you have seen : http://www.flickr.com/photos/2466806...n/photostream/

The Shindo design is very simple like everything in life I guess, just hard work at a high cost!! Shindo builds his plinth from laminated cherry wood.
They are glued with hide glue, crossing the grain each layer letting glue set between each layer. Hes fits each layer "very very" close to the deck...This can raise issues in regards to heat of the motor.

One other issue to seriously consider : The length of the arm. Shindo only goes for 12inch () and bans the use to 9inch (). Note that the arm on a sindo in fixed to a "solid' base that itself is inserted into the plinth, like a sepaerate mass isolated from the plinth (is that clear )

The theory is that solid plinths with 9inch are a "no no". Somebody here can explain that I guess.

Cheers
Tim

[Tony L]

Originally Posted by timothygurney

You have seen my plinth design in its finished state, yes made from the left over naturals of wood formed into that ugly product called "MDF".

I think you have done a beautiful job with your plinth, it looks great. I am however personally biased against MDF, I just think it's an inherently shite material - I bought a Mk1 Xerxes when it came out and there now isn't a flat surface in it (a friend has it), I've got a QS Ref table too, and again that ain't square in the slightest either (unlike the Xerxes it still works though). It's just not a material I'd waste any effort with - you put weight on it and it bends over time, plus it's soft, soggy and generally toxic stuff, it has no beauty itself, all you can do is to paint it (as you have done, very, very well). I want the material on display - I plan to use either real wood, marine ply (exposed so one sees the construction) or slate. I haven't decided which (or which combination thereof), I don't feel I have enough knowledge yet.

In a way I'd like to go back to first principles and ask: What does a successful Garrard plinth actually do? If we start from the premise that slate is good, Lorricraft is good, Shindo is good, Bastin is good, then what do these different approaches actually have in common? How do the differences between them effect the sound? In what way exactly do they sound different, i.e. what are their sonic traits?

I'm curious about solid wood too, the sort of thing one would craft a electric bass guitar body out of. I assume nice thick solid wood is expensive, but how much compared to say slate? What would it sound like? What about a chunky vertical laminate like say a through-neck bass (e.g. this)?

Lots to think about... my aim is to build my 'final' deck so I want to get it right.

Tony.

[Patrick Dixon]

I get the impression that solid wood is not good - layers is good. All the successful plinths seem to use either inherently layered material or decoupled layers. It seems to be a question of mass to damp, and layers to scatter vibration. There also seem to be a variety of ways of arm mounting.

[cds]

Did anyone see this?

http://www.vinylengine.com/phpBB2/vi...r=asc&start=34

its interesting to see the the methodology.

In the end it seems that there are several material approaches to a plinth and
the variables of materials, construction, tonearms/cartridges will make this
a never ending discussion on forums for quite some time.


regards


cds

[Tony L]

Originally Posted by Patrick Dixon

I get the impression that solid wood is not good - layers is good. All the successful plinths seem to use either inherently layered material or decoupled layers. It seems to be a question of mass to damp, and layers to scatter vibration.

Yes, I'm forming a similar view after much reading. The mistake I initially made was to misunderstand what slate actually is, I always viewed it as a hard solid material, not a naturally layered structure. I'm still afraid it might be a bit fragile / brittle, but I guess if it will stand up to typical kitchen worktop abuse it should be ok. The downside is the aesthetics as I'm not a huge fan of 'skeletal' plinths, but perhaps something like a 20 or 30 mm slate layer coupled / decoupled on top of a marine ply base would be an answer.

Tony.

[timothygurney]

Tony,

From my personal observations its seems that there are some basics; if we look at the really high end TT's then they all share common characteristics:

Motor is isolated : http://www.soundscapehifi.com/tw-acustic-raven-ac.htm[/url]
Arm is on isolated support like the 6moons project you refer to
Bearing is as isolated as possible from these two (not to mention the quality of the bearing)

Achieving all three of the above seems to be a challenging objective within reasonable budget considerations. Linn gave it the LP12 is an example; isolated motor with little mass and high quality bearings, lacked the isolation of the bearing/arm; maybe the reason why this area has had upgrades, including recent one?

Having said this our cherished Garrards don’t seem good companions for these challenges; “simple” motor fixed in a rudimentary way to the deck driving the platter with a rubber idling wheel….fixation bolts of the deck reaching out and getting very close to the base of the tone arm (when using 9inch)…

Listeners swear an oath that the “ultimate” Garrard is the Shindo and even that its one of the best TT in this universe. Now I just don’t know if that is true nor do I know what part of reality drives such comments. But if we give credit to them then what has Shindo done?

My take:

He has fitted a heavier, finely balanced platter. I will bet two things 1) the heavier platter will reduce any vibrations coming from the motor 2) The inner side of the platter (where the idler has contact) will be smoother than the original Garrard. If you observe the inner side of the platter on your 301 then you will notice it is not “super finely machined” I bet the shindo platter is polished in that area!

Also he has got the arm far away with the 12inch and mounted that on an independent tone arm support isolated from the plinth and last but not least a heavy not so rigid tone arm, this will also isolate the cartridge from ant adverse vibrations in the plinth.

So what part does the material of the plinth play ? I really don’t think it plays that bigger part. Some claim that the natural wood will act like an instrument, that solid plinths are ultimate, and so on….

But my next project for my 301 will be a solid plinth with all the above attributes. It will be plywood veneered (yes I can also do that ) with a 12inch arm…

Tony, you want to build your definitive TT..I and probably many of us here wish you good luck in that endeavour!

Tim