Plinth Design for Garrard 301/401

[soulforged]

Was trawling through Audio Circle when I came accross this page from Promitheus Audio where Nick's showing his design for a Plinth for Garrard 301/401.

Since there were no direct links to the page, thought I'd post it here in case someone is interested - Garrard Plinth

Has anybody made/interested in making a similar one???

On another note...does anybody know if Promitheus Audio/Nick is still active???

 

[stevieboy]

Soulforged,

It seems to be a standard constrained layered plinth but open and placed on feet. Kuruvilla has made one for his garrard, Arj has made one for his Lenco.

Regards

 

[jls001]

For the 301, there is a very detailed layer-by-layer cutout here (scroll to bottom of page). For Lenco L75, one can get the cutout from one of the moderators of Lenco Heaven for non-commercial, personal use (username ropie). But I haven't come across something similar for the 401. If anyone has it for the 401, please share for increasing the overall general knowledge and well-being of the forum .

 

[kuruvilajacob]

If you can get a good carpenter , they can make plinth for any models . Though it is a time consuming , you could really pack the plinth to the full using marine plywood just giving enough space for the moving parts. I think that is the right approach for modifying plinth for Garrards and Lencos or for any other heavy idler wheels. I think Dual 1229 can also be a good deck for modification.
kuruvilajacob

 

[Gerry_the_Merry]

Kuruvilla Jacob, cant agree more with you. My carpenter is ready to take the cut out of the current 18mm motor board for my 301, and replicate it in a more robust 30mm hardwood. He also says (here I am inspired by Cyber Vinay) that just by visual inspection he can cut out another 30mm layer quite easily, which also covers the bottom for dust protection. Is a two layer hardwood the best? I am sure the gurus worldwide will scoff at it, but what the heck...we have seen slate discussed, CLD, baltic birch with hide glue, Shindo's hardwood formula. No one formula is the universal proven best. I am not going to potter around with drawings. But I will get there...

 

[stevieboy]

Gerry the merry,

Kuruvilajacob used plywood layers. Hardwood will not be as good at dissipating vibration.

Regards

 

[Gerry_the_Merry]

Steve, that is the theory anyway. But I heard at cybetvinay's place. 2 layer hardwood plinth. Perfect vibration free sound.

 

[stevieboy]

Hi gerry the merry,

Am sure it will work but how much better or worse compared to a ply layer is the question. Lot of people like slate. Kuruvilajacob himself tried a stone plinth and found differences. Worth try hardwood and ply since it's a simple cut one layer. I myself intend making a regular ply single layer to see how much better my birch ply plinth is or if theres no difference. Of course if you're sold on hardwood then cool.

Regards

 

[Gerry_the_Merry]

Steve, single layer ply in a box is my current config. In theory it is fine, since one school believes that a simple box plinth preserves liveliness (I think so too). However I find that the top plate lacks rigidity, and there is hence no assurance that the motor hangs perfectly vertically (I wont hard bind it to the plinth a la Jean Nantais) as it is supposed to. I even considered the idea of a 30mm aluminium top plate inside the box, it is much more massy but also messy, and impractical. In any case, this is a journey, with hopefully many enjoyable milestones. Anyway the overall sensitivity of the system to changes includes equally influential like arm, cart, speaker placement, room treatment, sundry isolation efforts etc.

 

[stevieboy]

Would have been interesting to hear your notes on the difference in sound. However your current ply seems to be 18mm and you're going in for a 30mm hardwood which in one way tilts the scales in favor of the hardwood. 18mm seems to be on the leaner side. Generally most people who do a single ply do it around the loricraft single ply thickness which is around 25mm.

Do post pics of your new plinth when ready.

Regards

 

[jls001]

GTM: have you zeroed in on any specific wood?

I'd second stevieboy's suggestion to go with something thicker, 25 mm (= 1 inch) on the bare minimum, 30 or 40 mm would be nicer and give much better (and much needed) mass loading. If you're going with wood, a second "storey" below the plinth layer may be a good thing, especially with some arrangement to effectively drain off the vibration from the motor-carrying layer to this lower layer.

 

[Gerry_the_Merry]

I am planning on 40 to 50mm single board thickness. Dont want to do more than this for the present as too much wood will be lost. For now, will keep it in the same box, with some isolation underneath. A single thick wooden layer may still carry some vibrations. It will make my task tougher in controlling, but will drive me to a better isolation solution.

Later, perhaps next year, I may ditch the box, and add another similar thickness layer underneath the first wooden layer. It will have a smaller cutout, and I will use part of the cutout to seal from bottom, as I am obsessed with dust. Lets me do it in stages.

Wood will be Nagpur / CP Teak. Who has anyway tried all these variations? Cant lay my hands on Shindo type Cherrywood. I am not that obsessed anyway on striking gold at first strike itself.

Currently I can just lift off the motor board, but if I put 50mm wood (or at least 40mm), it will be heavy, and then I will have to drill 2 holes each big enough to let in two fingers to hook and lift along with the machine from inside the box. And a hole for the 45RPM adaptor (it looks too cute). There will be no other complications. The whole thing can be done in 24 hours. Perhaps next month sometime.

 

[jls001]

Currently I can just lift off the motor board, but if I put 50mm wood (or at least 40mm), it will be heavy, and then I will have to drill 2 holes each big enough to let in two fingers to hook and lift along with the machine from inside the box. And a hole for the 45RPM adaptor (it looks too cute). There will be no other complications. The whole thing can be done in 24 hours. Perhaps next month sometime.

Please make sure that your design gives enough room for the RCA adapters below the SMEs. We don't want to go about performing surgical mods on the poor adaptor. Again.

 

[jls001]

Cant lay my hands on Shindo type Cherrywood.

In India, Cherry is grown in Kashmir. So you might get lucky if you know someone from that corner of the country. Or you could try your luck at some of the wood markets like the ones in Amboli in SV Road (Andheri West) or Oshiwara furniture market (SV Road, Jogeshwari West). Another candidate could be aged teak wood taken off old furnitures and household fittings.

 

[kuruvilajacob]

Sorry I had missed out on this thread.It is widely accepted that marine ply or birch ply is found to deaden the vibrations caused by the motor. Yes, as mentioned by Stevie, I tried stone and it completely failed it's purpose . Hard wood like teak will not have the deadening effect of ply in my opinion to the same extent as plywood. Maybe with better isolation, it may be possible to deaden the unwanted vibrations from coming to the top even by using hardwood. There will certainly be different effect for different wood used and it will be difficult to predict which will be the best. But plywood is a proven material. Regarding the thickness, I think the thicker plinth could give the deck more stability and isolated arm can certainly make a difference.
kuruvilajacob

 

[jenson]

is there a thread where there is some form of conceptualization on as to what does shindo, loricraft or other did in theory? what actually causes the rumble? how does a certain plinth deaden it in theory.

i read an analogy about comparing it with a car, as to how an engine is placed and how the interiors are sound proofed to block any sound from engine.

 

[jls001]

is there a thread where there is some form of conceptualization on as to what does shindo, loricraft or other did in theory? what actually causes the rumble? how does a certain plinth deaden it in theory.

i read an analogy about comparing it with a car, as to how an engine is placed and how the interiors are sound proofed to block any sound from engine.

At the basic level, all these plinths for old, torquey idler drives follow the same principle - drain off the bad vibes from the motor into the plinth so that the least amount of that unwanted vibration reaches the cartridge-tonearm assembly.

Is some plinth material better than another? Perhaps some materials are more equal than others. And a combination/composite of different materials may produce a better damping than the individual materials. A case of 1+1>2.

The mass loading brigade believes in draining off the vibration through heavy mass (where the vibration gets dissipated into harmless heat).

I think Loricraft's principle is quite different in that they drain off the vibration using some rubber balls.

The rumble is caused by the operation of the motor.

 

[kuruvilajacob]

I use squash balls to suspend the Garrard 301 similar to the Lorricraft method on one of my decks. Initially, I felt that deck sounded not as warm as my other 301 which was not suspended. But now I realized that the suspended deck gives a better three dimensional sound stage after changing the cart to DL-103 and also making some minor adjustments to the suspensions while the non-suspended deck is warmer. (I use a Shure 95 ed cart for this deck). In short, every deck will sound different as no two decks can ever be same .
kuruvilajacob

 

[G401fan]

The Garrard motors are suspended by 6 springs which provide excellent isolation from the rest of the chassis. The only transmission of energy is through the motor spindle(especially if it has play), via the idler wheel on to the platter, where it could be exacerbated by a centre spindle bearing that is poorly lubricated, and/or damaged through previous use resulting in play in its movement. A thick rubber mat (original) reduces ringing in the platter. Its all a matter of execution, or rather, how well maintained the Garrard you bought was originally kept by its previous owner.

The rumble issue is overstated, in my opinion. Don't second guess the designer is applicable for almost all audio products, but we still love to tweak. The Garrard manual recommends a ply board and ply works wonderfully well in soaking up any residual resonances, as the entire assembly is a piece of heavy metal. Mass loaded plinths look great, but there are as many stories out there about excess mass leading to deadening of the sound as there are about light plinths doing the opposite. So, if one's got the time and energy, one can always experiment and build multiple plinths, but it won't fix a Garrard that was not looked after well in the past. Me, I've used 18mm marine ply on a teak wood box plinth, and am quite satisfied with the results. YMMV.

 

[Gerry_the_Merry]

Please make sure that your design gives enough room for the RCA adapters below the SMEs. We don't want to go about performing surgical mods on the poor adaptor. Again.

Unlike the Linn, the depth of the current 301 box is 4 inches, so this problem will not occur. But man, that Linn surgery has given me incredible headaches.

In India, Cherry is grown in Kashmir. So you might get lucky if you know someone from that corner of the country. Or you could try your luck at some of the wood markets like the ones in Amboli in SV Road (Andheri West) or Oshiwara furniture market (SV Road, Jogeshwari West). Another candidate could be aged teak wood taken off old furnitures and household fittings.

No idea of the sonic improvement different types of hardwood will bring. Am far from having that level of obsession. A mere shift from slightly sagging 18mm ply to 30-40mm hardwood (regular teak) will do for now. That would result in a solid, stable combination worthy of a serious cartridge upgrade. That is the limited objective (for now).

Mass loaded plinths look great, but there are as many stories out there about excess mass leading to deadening of the sound as there are about light plinths doing the opposite.

Completely agree. Would hate to conduct a huge plinth building exercise only to discover I have frittered away what was good about the current one.