A matter of gravity: the relationship between the cartridge and tonearm

There’s no great mystery about cartridges and tonearms: the former ‘reads’ the information in the spiral groove of the record, while the latter makes sure it’s in the right position to do so accurately. Well, sort of…

It’s a misapprehension that the tonearm places the cartridge in the right place. In fact, what determines the cartridge’s position is the tiniest part of the whole system – the stylus in the groove. All the tonearm has to do is support the cartridge and move as freely as possible in response to the moving groove and yet be absolutely ‘still’ relative to the signal pressed into the groove. Sounds easy, right? 

So what qualities does the arm need? Well, it needs to be rigid so that the energy passed from the record to the stylus isn’t wasted in flexing the arm, however minute. 

At the same time, it needs to be sufficiently low in mass for the stylus tip to move and position the arm as effortlessly as possible. And on top of these, its mass in conjunction with the cartridge mass and dynamic compliance should ensure a resonance of between 8-12 Hz. That’s because it falls between the frequency of record warp and the lowest notes recorded. This in turn will allow the full range of the music to be captured by the stylus. 

However, without a proper bearing design, this will all be for nothing!

Bearing design for tonearms has been the cause of much debate for many years with different designers espousing their own ‘gospel’. 

While it might seem a good idea to have stiff bearings on the tonearm pivot, with no slack, that can also impede the action of the cartridge when it comes to moving the arm. The problem is called stiction which is a sort of friction relating to starting movement. Conversely, an arm that has very ‘loose’ bearings will probably have noisy bearings and not be able to hold the arm consistently in place relative to the groove. Both detract from the signal your record player should deliver to your amplifier. Rather than preach we’ll let our designs speak for themselves in a demonstration. 

Suffice it to say we like silent bearings with virtually no stiction. After all, it’s the cartridge driving the arm, and telling the arm where it needs it to be – not vice versa.  Only with that and the mass of the tonearm correctly matched to the compliance of the cartridge suspension, can the stylus quite literally tell the tonearm where to go.

And where does the gravity come in?  Gravity assists in keeping the bearings in place and providing the downward force that keeps the stylus in the groove.

Get the tracking force and cartridge alignment right and the stylus will sit at the correct angle in the groove, and more importantly, it stays securely in place even when playing the most dramatic pieces of music.

Watch Vertere’s founder, Touraj Moghaddam, show you how this works in the below video.