Terminator tonearm – new arm mount

We all know that the small things matter in hi-fi.  Especially at the front end of the audio system – eg. the pickup cartridge and tonearm.

The Trans-Fi Terminator tonearm is constructed with a 6mm aluminium ‘L’ Mounting Plate.  It’s machined shape and necessary slotted holes, no doubt reduce its structural and torsional rigidity.

Would there be energy loss?

In my real job, I think a lot about structural  and construction matters, so I’ve been wondering for a while about this tonearm support.

I’ve been thinking that it could be beneficial to provide as much support surface as possible underneath the Terminator’s Mounting Plate.

The whole tonearm assembly is typically fixed onto the turntable on a tonearm ‘board’ or on a column/pillar.  The standard mounting column is a Delrin (acetal) or sometimes an acrylic round pillar, 36mm diameter – however it does not support the entire bottom surface of the Mounting Plate.

Does this matter?

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Terminator mounting plate

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Delrin pillar (on a Trans-Fi Salvation turntable).

Below is the Trans-Fi Salvation turntable outline showing the experimental new Arm Mount base (shaded), to fit the Salvation’s curved slate plinth below and the irregular shape of the terminator Mounting Plate on top.

Salvation-2

 

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The Salvation Turntable’s slate plinth.

Armblock 2b

This was the initial concept for the new Arm Mount base.

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The final engineering model – shown inverted and attached to a ‘fixture’ base ready for CNC milling.

My instinctive preference was to make this new Arm Mount base from hardwood.  However it is more practical to make accurate prototypes first in aluminium, when using a CNC mill in an engineering workshop.

I was fortunate to have access to some engineering assistance:

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Raw aluminium material for the fixture base and for the new Arm Mount base.

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Initial facing of the aluminium.

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Firstly, the ‘fixture’ base is machined, complete with fixing bolt holes and a datum hole for the irregular shaped Arm Mount part.

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2 x M6 threaded holes for the tonearm mounting screws and an M8 counter-bore recessed hole for bolt-fixing through the turntable slate plinth.

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Because of the complex final shape, a Ruby probe is used to reference positioning from the datum hole.

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The finished part (inverted), with smooth contoured ‘shoulder’ to support the tonearm base.

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Bead-blasting surface treatment was done as an experiment.

However, this part is quite heavy (430gm) and I was concerned about the added eccentric loading on the Salvation’s magnetic-levitation feet.  So we decided to return to the workshop to remove some metal from the underside of the block.

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After the ‘pocketing’ operation.

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(Final weight 350gms.)

OLYMPUS DIGITAL CAMERA

New Arm Mount and the original Delrin Arm Pillar (both 45mm height).

OLYMPUS DIGITAL CAMERA

Main mounting bolt – new M8 stainless steel hex socket bolt with original Trans-Fi spacing washer.

OLYMPUS DIGITAL CAMERA

New Arm Mount base installed on the Salvation turntable.

OLYMPUS DIGITAL CAMERA

Mounting Plate fixing – 2 x M6 stainless steel hex socket screws.

The sound:

I really was unsure if all this work would have any effect on the sound of an air-bearing / pivot-point bearing tonearm. (Note, nylon pivot-points were installed last September.)

However, I was shocked.  Such was the dramatic impact, that my first thought was to change the material to wood instead of aluminium.

This is a significant change.  Sound jumps out of the loudspeakers and initially seems to be more ‘forward’.

On 105dB/W horn speakers, this is confronting.  I immediately tape-marked the floor & moved my listening chair backwards.

Then, you notice stronger deep bass.  Substantially increased bass ‘punch’ and impact.  More power and energy throughout, more ‘attack’ – eg. pizzicatos & ‘plucks’, but especially bass frequencies.

There is a ‘fatter’ tone and ‘body’ to instruments and voice, more orchestral ‘density’.  Orchestral power and dynamic range is at an increased level. (I became concerned about the loudspeaker drivers!)

More energy seems to be preserved or generated from the grooves.

The upper range also, seems more ‘brilliant’, more detailed, there is more ‘sustain’ and decay.

I am noticing more front-to-back separation, depth and a larger scale ‘sound picture’.

After adjusting to the initial surprise, I am now liking the sound – a lot.  The listening chair has returned to it’s normal position.

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18 thoughts on “Terminator tonearm – new arm mount

  1. Having owned the same tt/arm for three years or so I commend you in your pursuit. Being about ready to add some tweaks myself I wonder if you have run this by Vic as to making this available.

    • Hi tomturnerdds – thanks for looking in & I trust you are enjoying the Salvation + Terminator combo. Happy to advise with anything – if I can.

      I haven’t yet had a chance to discuss this one with Vic but will do so soon.
      With the CNC machining, the hard computer work is done so multiple copies can be executed relatively easily. However, this part is quite complex & my engineer advises that a small batch of 2 or 3 would be most efficient.
      Cheers, Owen

  2. I have a different kind of plinth and I made my arm base of brass, it´s 7 cm tall and 9 cm wide and very heavy. Nails the sound. Highly recommended up-grade. Cheers, Hente

  3. Owen,
    I have used the Transfi arm for about 5 years and Salvation TT for about 3 years and have enjoyed emmensely. I have added all Vic’s upgrades, mag bearing and feet and nylon points. I am also interested in your mounting base. I have an earlier version of the arm that has a square base instead of the cut out around the platter. I do not think it will make a difference but worth mentioning. I also live in the US
    Thanks
    Steve Gunther

  4. I too would be interested and I also live in the US. I have a TransFi arm sitting around waiting to be installed on a project.

  5. Hi Owen,
    just read your article and would be interested in getting one to fit my TransFi arm fitted to a Notts Analogue spacedeck. Great work.
    Cheers
    Mark.

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