Comparing technical performance
Tonearms appear quite similar, but in fact nothing could be further from the truth. There are various schools of thought on how to tackle the design challenges presented. The most popular theory is that energy is best absorbed by damping, so there are manufacturers who go to great lengths to “prove” superior performance by using instruments to measure and compare resonant frequencies.
The big problem with this approach is that it’s only one aspect of a complex picture. Technical measurements have proved time and again to have their limitations. Suffice to say, there are many well known examples in Audio history from CDs low distortion figures, to speakers with perfect frequency response that sound terrible.
The fact is that excessive damping is often applied to solve problems which should not exist. Heavily damped arms may measure fantastically but sound dull and lifeless. They also tend to compress and kill the delicate decay of notes – this is sometimes mistaken for “control” or an “analytical” sound.
Questions to ask about measurement data
We noticed that accelerometer tests (which measure arm movement frequency) conducted on tonearms which gave “better” technical figures did not always give better results in subjective listening tests. So what is going on? To oversimplify a complex subject is always dangerous and it should be pointed out that the interpretation of accelerometer data ignores four very important aspects:
a) Actual deflection and angular rotation of the tonearm in vibration – This measurement is in our view more important than resonant frequency figures. In other words the size of movement is more important than the frequency it’s moving at. For example if the movement was infintesimaly small the frequency would be completely irrelevant. In an effort to increase stiffness some tonearm manufacturers have used very large diameter tubes. These may be stiff for very low frequencies but they will suffer from vibration ripple within the very thin walls of the tube.
b) The ” recovery speed” (the speed to get back to correct position) – e.g a good long bow, recovers very quickly to it’s original shape when firing an arrow, but a soft wood bow is slow and ineffective because it is more damped. As a rule, the higher the damping, the slower the recovery. You actually need the correct balance of both high speed recovery and damping which is why we test exhaustively to achieve this.
c) The speed of energy transmission and the locations at which damping or energy loss occurs is not measured. These factors introduce timing issues and energy reflections.
d) The measurements given are usually in only one axis which leaves 5 other movements totally unmeasured. Unfortunately one axis measurements do not necessarily indicate what the rest are like.
The Founder of Origin Live is a fully qualified chartered engineer with experience of complex structural analysis. It was his conclusion that current models for tonearm behavior are oversimplified to the extent of being plain misleading. One example of this is how compliance formulas which are supposed to match cartridges to the effective mass of tonearms bear so little relation to practical outcomes. This matters because you need an accurate theoretical model to determine best tonearm design.