Technics SL1200 plinth damping

[mulane]

Clive, your experiences are very interesting - will have to have a play with some o-rings (in the nicest sense). I have just gone to some trouble making an aluminium arm board so was somewhat dismayed to hear the timber ones sounded better to you - oh well. Did you try an o-ring under the arm post mounting 'ring' or flange as well?

[Clive]

Clive, your experiences are very interesting - will have to have a play with some o-rings (in the nicest sense). I have just gone to some trouble making an aluminium arm board so was somewhat dismayed to hear the timber ones sounded better to you - oh well. Did you try an o-ring under the arm post mounting 'ring' or flange as well?

Don't be dismayed. Results will vary quite significantly according to turntable / plinth. You could find wood is too dead and you need metal. I did try o-rings all over the place, again results will vary by arm/deck. Some arms will need o-rings under the mounting pillar, others will need to be rigid (ie unipiviots). There are no rules about what's optimal for a specific deck.

[mulane]

I thought I'd post a few pics of the damping layer and the gaps, and the bare aluminium top plate. I think I will damp at least some of the top plate with another material (in the flat corners for example) but may keep some of the original damping layer cut into sections and glued on, perhaps where the shapes are very complex.

Not sure what other material I'll use on the top plate - might be perspex or SDS damping sheets or home made SDS-type sheets. The visco-elastic polymer sheets used in constrained layer damping are available from 3M, and they even have their own aluminium damping sheets. Food for thought.

I am not in a hurry as I have another deck to play actual music, so I dont forget why I am doing this. Will keep you updated with how I go.

[mulane]

Tonight I removed the two damping layers from the working turntable and placed the turntable on four springs. I did this to see if removing the Technics damping was a step in the right direction sound wise. I played "Bird on a Wire" by Jennifer Warnes and with the first few notes my ears immediately pricked up. Well I am impressed! The sound seems to "breathe" better and I can more easily hear into the mix. I guess this means it seems more three dimensional and the soundstage seems deeper. Dare I say the deck sounds more like my belt drive in a good way. There seems to be a bit of bloom or resonnance in the bass which is not unpleasant and the bass goes deep. Hopefully damping the top plate with Isodamp or SDS will fix this.

I could be imagining all this but I have no desire to put the damping back and this is a good sign. When I find my camera USB cable I will put a few pix up - it looks a bit like a Gyrodeck now!

[Ammonite Audio]

I tried this, placing the naked deck onto three Stillpoints and was initially shocked and impressed by the sheer verve and searing detail; however it soon became apparent that the whole affair lacked sonic weight, so I reluctantly replaced the damping layer and rubber base. I do think that a massy wooden plinth might work, one way or another, but I am not the one to try it (my woodworking skills are not up to that sort of job).

[mulane]

The spring suspension gives it weight. I have transmission line speakers and there is no lack of weight. It is nicely balanced. I know some people like massy wooden plinths but I'm leaning towards damped aluminium now, at least I'd like to try to stay with the std plinth top and see if I can get that sounding good. If that doesnt work I might try a laminated plinth a la Froggyspit but with aluminium.

[mulane]

Here are a few pics. It's all very makeshift and done with whatever I had at hand: some coffee jar lids to hold the springs screwed to existing screw holes and the std feet under the springs. I will try fixing the springs to the corners but this will need some dowel cut to give the springs enough height.

[mulane]

I was looking at the platter the other day in my hand and tapping it to make it ring. I realised that alot of the ringing is actually comming from the magnet assembly screwed to the underside of the platter. This is quite a big chunk of metal hanging there undamped.

So I unscrewed the assembly and put lines of blu-tack all over it, both sides. I also put a thin 3mm chord of blu-tack on the bottom edge of the magnet. I had to flatten it quite a bit so it wouldnt foul anything when I put it back on the turntable.

How did it sound with the magnet damped? Well it was hard to pick and quite subtle but I think the bass was a little clearer and less resonnant-it went as deep but was a bit more lifelike. But it was hard to pick so I'll have to keep listening. Steve Winwood's "The Morning Side" off the "Roll With It" LP sounded absolutely magnificent! Anyone know this track? I would be interested if others can hear a difference with this mod.

I'm really loving my naked Techy-I think it sounds brilliant!

I will try using some 3M damping foil on the magnet instead of the blu-tack and see if that changes anything, and am making (slow) progress with the plinth too. (no I dont think I am going mad and yes I am still seeing people and getting out a bit ).

[mulane]

I've been busy applying 3M damping foil 2552 to the top of the platter and offcuts to the magnet assembly and underside of the platter under the magnet. The foil is a layer of 5mil viscoelastic polymer constrained by a thin layer of al foil. Havent had time yet to hear the results or compare it to the std platter but will do so in a day or two. I'm hoping the platter with al foil tape will be a cost-effective alternative to the SDS plattermat.

(the hands in one of the pics dont belong to me but to my gracious assistant)

[mulane]

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