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?
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.
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:
Because of the complex final shape, a Ruby probe is used to reference positioning from the datum hole.
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.
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.
Update 5 Oct 2018:
We have developed a new, shorter, 27mm height arm mount, for Terminator tonearms installed on non-Trans Fi Salvation turntables.
These are straight-sided but again ‘pocketed’ underneath to minimise weight for suspended turntables (approximately 213 grams) and bead-blast finished.