TECHNICS SP-10MKII turntable – Pt 3 new plinth construction

Plinth concept for this SP-10: (see also Technics SP-10MkII turntable – Pt 2)

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3D complete 140119 a

CNC router-cutting plywood  for the new plinth:

Assembled plywood layers:

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Special metal sub-ring ‘buried’ within the plinth, 4 x M5-tapped for fixing down the L-07D tonearm:

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Test-layout for 12′ and 10″ tonearms:

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Sanding the glue-laminated plywood plinth:

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SP-10 test installation into the plinth (white ‘blonded’ fonish):

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(The L-07D tonearm requires a small top cut-out to accommodate its arm-height turn-wheel.)

SP-10 chassis installed (note the 2 additonal wood-screws to ensure rotational rigidity).

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6mm thick, laser-cut Stainless Steel baseplate (9.5kg):

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‘Mag-lev’ support footers (10kg load capacity x 4):

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Footer housings for mag-lev supports:

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Finished SP-10 turntable (shown below alongside the Trans-Fi Salvation rim-drive turntable). Tonearms initially installed are:

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The sound :

(Using Transfiguration Temper W and Koetsu Rosewood Signature cartridges, Fidelity Research FRT-4 moving coil transformer, Lounge Audio LCR Gold phono stage.)

First impressions – I was not surprised to hear excellent image focus & low frequency ‘solidity.  However, I must admit that I did not expect to hear such an excellent overall reproduction with ‘transparent’ soundstaging with greater ‘depth’ & also ‘width’ perception. Also excellent resolution, high frequency ‘presence’, macro and micro dynamics.

With the Koetsu on board (loaded ~140 ohms via the FRT-4) bass power is much improved (compared to the Transfiguration Temper W), with a more ‘expansive’, less ‘clean-edged’ but larger ‘sound ‘picture’.

Noise Sink‘:

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(Underside view of bottom plate ‘Noise Sink’ bolt.)

This is an idea adopted on some other Technic SP-10 turntables – using a threaded rod to connect a heavy metal bottom mass to the SP-10’s motor bearing above.

In our case, the 9.5kg bottom plate was threaded for a M12 x 1.25mm fine-thread Stainless Steel Hex Bolt with ‘jam nut’,  This can be screwed upward to contact the  motor bearing ‘thrust-plate’ underside and then jam-locked in place – arguably allowing the bottom plate mass to absorb any bearing or motor noise and also adding vertical support to the Direct Drive motor.

On audition, with the ‘Noise Sink’ bolt connected, the reproduced sound is more ‘taut’, less dynamically ‘open’ and a little constrained and ‘boring’. Without the Noise Sink, there is more ambient detail, more ‘air’, more ‘delicacy and ‘bloom’ to the sound.

Your preferences may differ, but this effect is not to my liking and seems to me to be similar to the sound when employing a record-clamp.

 

(First test-run with the Transfiguration Temper W cartridge and standard Technics platter mat.)

Reso-Mat:

I recommend using the Trans-Fi Reso-Mat.  It happens to be the same 5mm thickness as the stock SP-10 rubber mat, but provides a much more open and transparent sound, with excellent tonal bandwidth and dynamics.  No real drawbacks, to my ear, noticeable so far.

 

12 thoughts on “TECHNICS SP-10MKII turntable – Pt 3 new plinth construction

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  5. Hi Owen

    I’m also using an SP10 mk2, but mine is in a heavy plinth. I’m really intrigued with the additional 2 screws you mention to improve rotational stability. Mine doesn’t have these extra holes – did you drill and countersink the chassis to do this?

    Cheers

    Andy

    • Hi Andy,
      Thanks for stopping by.
      Extra screws – my feeling at the time was that the 5 stock hold-down screws would be rather long (unless you countersink & shorten them) & the the TT chassis would not be held rotationally rigid, from an structural standpoint. I can’t be sure (as I implemented a few mods at installation), but my feeling is that, as long as your hold-down screws are firm & your plinth interface/surface allows sufficient frictional ‘grip’, then this mod may have only a minimal effect. However, by all means do it, if you can.

      Yes, the 2 screws need to be c’sunk flush in the groove bottom under the platter rim – I have arrowed a pic above.

      However, a significant improvement that I can recommend, is to remove the plastic ring for the mechanical brake. This black plastic guide forms a plastic interface between the motor hold-down screws & the TT chassis, creating a ‘soft’ interface & preventing truly rigid motor (rotational) stability. The motor can now be tightened down rigidly.

      I will post a Pt.4 update showing this, soon..
      With the brake (strap) removed, the platter still stops rapidly, in around 1.5 rotations – as you can see in this video – https://www.youtube.com/watch?v=kz3ftSSIkys

      Sonically, I heard more finely-drawn, sharper-edged sounds, cleaner harmonic decay, less ‘blurring’. Seemingly more HF extension, finer detail in the strings for example, subtley ‘wider’ tonal shadings.

      PS. The mag-lev feet, do not work so well under this TT & plinth. Unfortunately, I think, these do not compliment rotational rigidity that seems to be a key requirement of this TT.

      Cheers, Owe

      • Hi Owen

        Thanks so much for the speedy response and the great info! I’m looking forward to learning more about the brake strap modification- that sounds very interesting.

        My table is firmly bolted to the plinth so I should be in good shape from that point of view.

        I love reading the posts on your site – I’m learning a lot!

        Cheers

        Andy

      • Hi Owen

        I have an SME 312s with a my sonic lab GL cartridge, my other one is a Decca super gold. Phono stage is a Herron VTPH 2a into a Wyetech Opal linestage. Amps are the first version of the VTL MB450 monoblocks and speakers are Soundlab M1 electrostats.

        I mostly listen to 20th century classical (Stravinsky, Prokofiev and similar). For jazz I like just about anything on Pablo records plus old Duke Ellington, Charlie Mingus and similar. Also delta blues – right now Fred McDowell is my favorite.

        Cheers

        Andy

    • Hi Andy – great.
      That indicates to me that you should have no difficulty discerning these improvements.
      Will try to post a Pt.4 update soon.

      My London Decca Super Gold has finally been reinstalled, after 2 trips to John Wright for repair, Decapod fitting & some troubleshooting. More anon.
      Cheers, Owen

      • Hi Owen

        Thx for the post – I’ll check out the mod in the near future. I’m just finishing a couple of projects before I get to the brake –
        I’ve just recapped my VTL monoblocks, so I need to let them settle back in before I make more changes. I also need to do the wiring on a pair of Hashimoto HM7 SUTs that’s nearing completion.

        I’m also very interested in your wot linestage – did you try the 76 tube yet?

        Cheers

        Andy

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