Counterweight Position and Low Centre of Gravity
A common idea that should be questioned is whether a tonearm counterweight should be positioned as close as possible to the yoke for best performance. This minimises inertia and thus reduces “see / saw” effects over record warps. A variation of this theme is that low slinging the weight drops the centre of gravity and thus stabilises the arm, reducing bearing chatter and vibrational rocking etc. We will address these two concepts in turn as the principles involved are entirely different.
Frequently you find that observations on the performance of particular arms, make folk jump to conclusions that miss the real causes of the performance changes perceived. Although the theory of decreasing the inertia of the counterweight seems very plausible, there is another more proven explanation. It gives peace of mind to realise that when the counterweight is positioned at the end of the stub on an Origin Live arm, you are NOT losing performance.
The notion that counterweight position affects performance has much more to do with vibration and lack of structural rigidity than inertia effects - in other words on some arms it pays to keep the counterweight close to the yoke as it decreases resonance effects from counterweight “waggle”. On these arms the counterweight causes an increasing vibrational whiplash effect as it gets further from the pivot. Origin Live have gone over and over this with their arms and established conclusively that the counterweight position hardly affects performance at all on a properly designed arm. The idea that inertia is an enemy is also based on pure ideology - the fact is that without inertia the stylus could not read the record groove at all! Some systems add weight at the headshell to INCREASE inertia as it is proven to be beneficial up to a point. 12 inch arms have much higher inertia than 9 inch ones but nobody seems to bat an eyelid!
Calculations show that an 8 gram increase in cartridge weight will increase inertia 4 times more than having your counterweight position at the rear end of your arm stub.
COUNTERWEIGHT LOW CENTRE OF GRAVITY
Another case of observations drawing questionable conclusions is the case of low slung counterweights. Low centre of gravity IS important for unipivot arms but dual pivots and gimbal arms do not “sway about” and listening tests prove that all other things being equal, it makes no audible difference to sling the weight low. As previously outlined, any beneficial observations are usually down to resonance effects on certain arms but not Origin Live arms.
Many low slung weights use varying methods of clamping themselves to the rear stub. This alone is very influential on the sound but the mistaken assumption is made that the difference is due to low slinging
We have probably experimented with counterweight materials and attachment more than anyone. Avondale Audio was the first company to modify Rega counterweights and they sub-contracted us to produce them, since then this has become almost a bandwagon of inferior copycat ideas.