Originally posted by julian2002
tones,
from what i understand a potentiometer works by having a runner follow round some sort of conductive track thereby varying resistance. if vibration makes its way to this part of the pot then you are going to get very small changes in volume level made worse by the fact that this is going on twice for stereo and you may even have a balance pot to contend with too. these variations in volume and balance may not be immediately audiable as such but they *may* have an effect on the sound produced.
this was my train of thought when i wrote what i wrote, please feel free to kick it apart.
cheers
julian
Julian, I can understand that something in the signal path may affect the signal, but to suggest that something NOT in the signal path has a noticeable effect is, well, to use Technobear's splendid description, absolutely barking. If the pot vibrates, the pot vibrates - the fact that a knob happens to be fitted to it is not going to change that one iota. The vibration is inherent in the system and it will not be absorbed or diminished by changing the material of the knob. It's like saying that you can stop a clock pendulum swinging by making the weight of a energy-absorbing material. You are in fact expecting the suspension of one of the most fundamental laws of physics, namely that energy cannot be created or destroyed, only changed in form. Here we apparently have energy disappearing into thin air. Next Nobel Physics prize coming up for these guys!
It seems to me that, if this problem did exist in reality, as opposed to in the heads of the money-grabbing individuals who thought this one up, the logical thing would be to make the knobs as light as possible, for example, by using aluminium, magnesium or beryllium - most certainly NOT beech, which is quite a heavy wood.
P.S. Just occurs to me that your argument is based also on one of hi-fi's most enduring fallacies, namely that uniform, linear change all the way down to zero is possible. But this simply isn't so. As Tom says:
"Given the degree of friction in most potentiometers, and the inertia of the whole mechanism, and the microscopically small magnetic fields surrounding the conductive elements, I'd say that these knobs will be bought by, well, knobs."
And that's the point - systems are
not frictionless such that minute vibrations will unsettle them. Tiny currents will not overcome the resistance inherent in even the best conductors and therefore will have no effect. There is a background level below which is simply isn't possible to go, courtesy of the nature of materials themselves. In addition, the components themselves have flaws, even the best constructed of them, meaning that, again, there will be a level of performance that they simply cannot exceed. The con artists are basically asking you to assume that normal physical limitations can miraculously be overcome. I eagerly await the day of frictionless, inertialess components and room temperature superconducting materials, but we'll wait for a while longer, I fear.
