Technics sl-1200 mk1 suspension board and isolation upgrade - diyAudio
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Old 15th July 2011, 07:28 PM   #1
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Default Technics sl-1200 mk1 suspension board and isolation upgrade

Hi, I have already been helped by thorstenL on how to generally isolate my table. I just want to continue the conversation in a new thread and will update my results and pictures in this thread so it will also be a reference later for other people.


This is what thorsten told me:

Quote:
Originally Posted by ThorstenL View Post
The Suspension board is really simple.

Buy a rubberwood butcher block of suitable size, or if you can find a marble or granite cutting board. basically anything that is not very resonant when knocked, important is that is non0resonant and stiff and heavy. If you cannot find really heavy stuff mass load it with whatever you can find over at the sports store.

Then buy something that is air-filled.

At the Apothekary you can find doughnut shaped blow up cushions meant for people that broke their tailbone, these can hold a lot of weight, but may be embarrassing/expensive to get. However three of them, limply inflated make a swell air suspension. You may have to occasioanlly re-adjust the pressure.

At the sports shop you can find squash balls, yellow dod is the right kind, you need enough to not "squash" them by more than a third with whatever is on top, I'd say one ball for every 1kG appx... Balls roll, so you need to find some round rings made from wood or plastic (check home stores or toy stores) that you can put under the balls to stop them from doing that rolling thing.

There are also magnetic floater thingies, but they are epensive.

In germany string suspension is popular, you can google it.

I have used in quite a few shapes and guises, I normally use steel HaiFish (Shark) fishing line from the rod and tackle shop (can be a good source for lead shot, incidentally)...

So many methods.

I would suggest to start with the isolation platform.


.

Last edited by murphythecat8; 15th July 2011 at 07:38 PM.
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Old 15th July 2011, 07:58 PM   #2
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Quote:
Originally Posted by ThorstenL View Post
The metal chassis has a lot of cavities that can be filled be filled in, using car body sealant (asphalt based) stinks for a few weeks (so leave it to set in the shed), but is very good, you can add ball bearing balls or similar to increase the mass.
I don't have a camera, but I will open and take pictures whenever I can, because I don't understand where to put the car body sealant and where not to put it. But just so I understand, the heavier the base of my turntable, the better?

Also, when you say take a butcher block and squash balls, you mean that the butcher block will go under the plastic chassis filled with car body sealant?

Jason
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Old 15th July 2011, 08:25 PM   #3
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Quote:
Originally Posted by murphythecat8 View Post
I don't have a camera, but I will open and take pictures whenever I can, because I don't understand where to put the car body sealant and where not to put it. But just so I understand, the heavier the base of my turntable, the better?
I would use SR500/1000 anti vibration compound. Cleans up with water, no nasty solvents flashing off.

jeff
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Old 15th July 2011, 09:18 PM   #4
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I second Murphy's donut ring idea, many years ago a comparison was made between all different media that are used to support turntables and CD transports. I think it was in stereophile or sound and vision. They compared granite slab, formed concrete, spring, elastomeric, rubber, sand filled and air cushion. Of course they reviewed products that were all manufactured by different companies for the specific purpose.
IIRC they came to the conclusion that a produt called earthquake platforms were found to be the best at isolating both airbourne and mechanically transmitted vibrations. This product was of the air suspension type.
They then went on to explain that most air suspension isolators would do a better job @ this and stated that the common hemrrhoid ring ( I think which they tested as well) would do the job admirably.
I then came up with the idea to use those 3/4" neodymium supermagnets laid within the bottom and four sides of a shalllow box 22"*22"* 1 1/2" , as well as on the lightweight platform sitting under my transport so that each box magnet had a corresponding platform magnet of the same polarity: north to north. I used glued-on Velcro on the backs of the magnets for repositioning until I got the platform floating centered... Voila
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Old 16th July 2011, 01:36 AM   #5
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Quote:
Originally Posted by ThorstenL View Post
The Suspension board is really simple.

Buy a rubberwood butcher block of suitable size, or if you can find a marble or granite cutting board. basically anything that is not very resonant when knocked, important is that is non0resonant and stiff and heavy. If you cannot find really heavy stuff mass load it with whatever you can find over at the sports store.

Then buy something that is air-filled.

At the Apothekary you can find doughnut shaped blow up cushions meant for people that broke their tailbone, these can hold a lot of weight, but may be embarrassing/expensive to get. However three of them, limply inflated make a swell air suspension. You may have to occasioanlly re-adjust the pressure.

At the sports shop you can find squash balls, yellow dod is the right kind, you need enough to not "squash" them by more than a third with whatever is on top, I'd say one ball for every 1kG appx... Balls roll, so you need to find some round rings made from wood or plastic (check home stores or toy stores) that you can put under the balls to stop them from doing that rolling thing.
I'm not sure if I understand correctly. Their is the suspension board I need to do with a butcher block that I'll stick to my table case filled with something heavy inside AND I get something air filled like squash balls to put under the butcher block, or it's one or the other (suspension or air)?
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Old 16th July 2011, 07:32 AM   #6
Previously: Kuei Yang Wang
 
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Hi,

Quote:
Originally Posted by murphythecat8 View Post
This is what thorsten told me:
Just to clarify a few things.

First, if you take the 1200 or 1210 apart, you end up with a rubbery plastic lower part and a cast metal top part.

The cast metal top part has many areas that are hollow and are not filled with the plastic base when attached.

You can see this a little in this crossection:

Click the image to open in full size.

And in this picture of a partially disassembled table:

Click the image to open in full size.

There are also voids in the area under the platter.

It is these areas that I propose filling with a mixture of Lead or Steel shot (or if you cannot find these, use small M3 Nuts or any such) and some semi-solid filler, carefully of course, making sure you do not foul any part of the mechanism.

Car body sealant is what I have used a number of times, as it is cheap and easy to get, the smell dissipates after a while, during which one keeps the chassis in the shed... Other options are of course welcome and I am not insisting on using foul smelling chemicals, it is important that the filler will adhere to metal and can set semi-solid.

I have done this style of mod over the years to a wide range of Japanese DD Tables, from a cheap plastic Sansui to Kenwood KD-500 and (yes) Technics SL1200.

For the suspension, what is needed is a board or block of a material that is heavy, rigid and reasonably well damped AND available.

So-called Butcher Block cutting boards are a good choice. They are often made from so-called rubber wood, which hard, dense and well damped. They look like this:

Click the image to open in full size.

You need to find a large size one, to be a bit larger than the Technics table.

In principle a granite slab like a gravestone (now don't go rob cemetries, try the local stone mason for leftovers and "dents & damages") are also good choices. Ideally we want as much mass as possible, constraints are size, the ability of the HiFi or other furniture present to support the weight and ultimately the static loading limit of the floor.

My last turntable with stand all together came to nearly 200Kg when fully assembled and floated on steeel fishing line "string suspension". Pictures here here:

My (Thorsten) system through the years

The doughnuts from the Apothecary are a good choice to make our butcher block levitate, otherwise string suspension would be my recommendation, but it is more involved, but even the yellow dot squash balls work very well...

Here is an isolation box with small size inner tubes (wheel barrow maybe) that illustrates how to use air filled doughnuts, the top plate is obviously taken off in this picture...

Click the image to open in full size.

It seems that the squash ball with something to stop it from rolling away is now also commercial:

Click the image to open in full size.

Pictures of a commercial string suspension system can be found here:

SSC Base CLASSIC Beech

The principle and execution should be clear from it, my variation was not to use poly rope but steel.

In my experience String or "air-doughnut" are best, but squash balls run close.

In many ways it is more question of putting what you can find locally both easy and cheap to make it do the job you need it to do.

Ciao T
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Old 16th July 2011, 04:46 PM   #7
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Thanks, but I'm not sure if I understand everything correctly. I have a couple of question:

-The stock plastic case will go away and will be replaced by the butcherblock? I then screw the butcher block to the metal top part?

- between the cast metal top part and the butcher block, thats where I put the squash balls and make the air suspension?

Also, the sl-1200 mk2 and mk1 isn't the same internally. I have open it up yesterday (I'll post pictures tonight). I have the sl-1200 mk1 just so you know thorsten.

cheers and thanks

Jason

Last edited by murphythecat8; 16th July 2011 at 04:49 PM.
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Old 16th July 2011, 06:18 PM   #8
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Hi,

Quote:
Originally Posted by murphythecat8 View Post
Thanks, but I'm not sure if I understand everything correctly. I have a couple of question:

-The stock plastic case will go away and will be replaced by the butcherblock? I then screw the butcher block to the metal top part?
No, the turntable is more or less original (except mods) and is placed on top of the buthcher block.

Quote:
Originally Posted by murphythecat8 View Post
- between the cast metal top part and the butcher block, thats where I put the squash balls and make the air suspension?
No, whatever suspendion you choose is below the butcher block,

In essence the suspension elements are placed on your rack (or whatever furniture you use).

The butcher block, or marble pastry cutting bord, or gravestone shaving or whatever you can readily find that is the right size, heavy and solidis placed on top of the suspesnsion element.

The combination strongly resists the transmission of mechanical vibrations to the top of the butcher block.

So putting anything on top there isolates it from mechanical vibrations.

While the benefits are debated for (say) pre-amplifiers or CD-Players, in case of a purely mechanical system such as a turntable they are undebated...

Quote:
Originally Posted by murphythecat8 View Post
Also, the sl-1200 mk2 and mk1 isn't the same internally. I have open it up yesterday (I'll post pictures tonight). I have the sl-1200 mk1 just so you know thorsten.
They are quite similar in principle, the details are just details...

Ciao T
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Old 16th July 2011, 06:39 PM   #9
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okay, so what do I do with the plastic case? I filled it with body car sealant as well?

Also, you say that I need to use about how much squash balls? They do need to be placed at regular distance from each other under the butcher block?

Do I just put the table on top of the butcherblock or do I screw the butcher block to the table?

Last edited by murphythecat8; 16th July 2011 at 06:43 PM.
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Old 16th July 2011, 06:42 PM   #10
Previously: Kuei Yang Wang
 
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Hi,

Quote:
Originally Posted by murphythecat8 View Post
okay, so what do I do with the plastic case? I filled it with body car sealant as well?
Rather not. The plastic probably will not like the solvents in the filler.

BTW, no need to absolutely car body sealant, it is really smelly until set. You can try the alternatives suggested here.

Once you treated the cast metal part simply re-fit the plastic.

Ciao T
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