How to set plinth, tonearm and cartridge in a turntable

17.04.2015..
Brinkmann Spyder
Brinkmann Spyder

Plinth, tonearm, cartridge…Keep well in mind that when we set all these elements, our aim is the result of several targets, sometimes conflicting.

 

In fact, we should have a tonearm capable of “holding” the cartridge in the groove and, at the same time, capable of following with the utmost agility the concentric spiral towards the center of the record, opposing the minimum obstacle to this movement.

It will have to put the cartridge in the optimal condition of tracking. That means having the smaller error possible in the tangency angle of the tracking. That also means having a cartridge mounted on a pivoted tonearm that has the smaller skating force towards the center of the record. Then we need an opposite force via an antiskating mechanism that, in any case and a posteriori, will always be an imprecise system of correction.

Contemporaneously, the tonearm should have a reduced inertial moment since the records are not perfect. They have undulations and inaccurate centering of the hole.

This would require the shortest arm possible and, consequently, the error of tangency will increase. Besides, the undulation of the record, if present, would become dangerously capable of making the cartridge leaving the groove.

 

The plinth or the entire turntable should put the tonearm in the condition of exploiting its characteristics at best so to avoid vanishing the qualities.

On one hand, the plinth-tonearm system is asked to “extract”, as quickly as possible, the vibrations made by the cantilever and insisting on the tonearm. The plinth should also act in the same way with respect to the vibrations made by the motor and insulate this last one from the external frequencies.

The last required element is a perfectly regular, constant and noiseless revolution.

 

Considering that some of these requirements are in opposition to others, the designer often has to choose what the lesser evil seems. This is why we can find turntables whit different philosophies.

 

More recently, the designers have been considering mandatory in the turntable system – plinth and motor platter – a resonance that places itself at the lowest frequencies possible: that is far from the audible spectrum.

 

For years many solutions have been found, effective or less effective, to solve the problems affecting tonearms and plinths.

 

For years many objects have been made that, although very good also in the measurements, were exceptionable when connected to a Hi-Fi home system.

 

At some point, someone has started to see the overall problem and no more the single element: the turntable as a whole of table-plinth-tonearm-cartridge. Like Goldmund with their Reference turntable placed on a table at a certain height - or “lowness”- and rigidity, totally matched to the floor via spikes.

The turntable itself was high mass with a high mass platter – at that time, nowadays it would be considered as midhigh mass – with an adjustable suspended subchassis although semi-rigid, placed on a chassis on spikes and belt driven. Its spinning was controlled by a quartz system and set, like the tonearm, through an external mechanism integrated in the table…

 

The tonearm was a unipivot of medium mass and length, whose plinth was a motor-powered carriage with a linear movement and the cartridge was a Clearaudio made on Goldmund specifications.

 

Goldmund’s philosophy for their top product was the research of the maximum extraction speed of the vibrations produced. A 2 hertz RF –Resonance Frequency – was guaranteed.

These solutions were initially applied on the top systems and, later on cheaper turntables

 

On the other hand, the Versa Dynamics, for their top model, proposed to “isolate” completely the cartridge and the record from the outer world through an air suspension and a reduction of the tonearm length. The same thing, but in different way, had already made Southern with the Triquartz arm –matched to the perfect planarity of the record, always belt driven and with RF around 1,5 hertz. Here the dynamics was intended as range of the inertial speed of the tonearm, while in Goldmund’s was as a match.

 

The following new or mixed philosophies brought new ideas and took into account the other’s concepts that considered the system turntable as a whole.

 

The latest objects, like ad example the Caliburn Continuum, indicate new ideas like the battery supply of the motor, the mix of magnetic/air suspension to avoid stressing the shaft, together with a dual unipivot tonearm made of new materials that are very light and very rigid at the same time.

 

The new Pierre Lurné and/or Wilson Benesch have made researches on the shapes and the material for the arm casting, to be always matched to the choices made for the plinths. Or the new Rega turntables. In sum, the turntables that have no more problems of RF so that are capable of given a true flat response in the audible audio spectrum are the majority.

 

In any case, they are objects to be used with caution to extract their best.

.

Ad example, the Rega has to be placed on a shelf and NOT on a table.

 

After this premise, let’s talk about the setting.

 

The first thing is choosing the support: for the rigid plinth a shelf is better, for the others is not a big deal. Then we have to center the bubble. Same thing for the turntable. If it is floating, the springs have to be set in order to get a perfect vertical movement of the platter without lateral oscillations.

 

Setting of the tonearm:

 

1.         Assembling of the cartridge following the code of the colors: red and green= right channel, white and blue= left channel. If there are no codes on the back of the cartridge just remember that the left channel is engraved so to simplify and you can see it while it reads on the “internal side” of the groove and, therefore, towards the shaft. Usually – except maybe just Denon – the red pin is upward towards the shaft and the green pin is downward. The white pin is upward towards the outside and the blue pin downward. I suggest using a pair of tweezers to insert the Litz wires of the tonearm onto the pins. Do not use the testers on the cartridges, especially if MC.

2.         Setting of the weight or VTF - Vertical Tracking Force: to avoid any damages –except in rare cases like SME IV or V – I suggest using the nonmagnetic gauge.

3.         Setting of VTA - Vertical Tracking Angle: put the arm casting acting on the height of the arm.

4.         Setting of the overhang and error control on the null points: if you do have a specific template jig of the tonearm, or if you us a universal one, knowing the values, with a cardboard and some graph paper you can reproduce it easily.

5.         Exact setting of the weight.

6.         Setting of the VTL: lateral inclination, the cartridge seen from the front has to be vertical. Necessary with unipivot arms or with rolling headshells if not perfectly fixed.

7.         Setting of the antiskating.

 

For all these setting, it would be advisable having:

  • Test record
  • Glass record for the antiskating, together with a record with one instrument/voice perfectly central and a test record with the dedicated track.
  • Gauge for the weight and test record to verify the result
  • A 10 cm pencil lead, adhesive tape, 1 rectangle of graph paper (15 cm x 6 cm) stuck on a rigid cardboard to set easily the alignment in the null points, VTL and VTA

If later you want to set the VTA higher or lower with respect to the horizontality, remember to control all the passages, otherwise.

  • you will change the alignment of the null points
  • you will change the VTF
  • you will change the VTL

Now the tonearm is ok. Check again if the Litz wires do not touch the record during the tracking, that the lift of the tonearm is at the right height…and start listening!

 

Tonearm Goldmund T3, platter Goldmund Studio, plinth Goldmund Reference
Tonearm Goldmund T3, platter Goldmund Studio, plinth Goldmund Reference
Versa Dynamics Model One, simplified version of the 2.0<br />(it does not lift the platter on an air cushion and does not suck the record on the platter)
Versa Dynamics Model One, simplified version of the 2.0
(it does not lift the platter on an air cushion and does not suck the record on the platter)
Caliburn Continuum
Caliburn Continuum
by Massimo Riserbo
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