Dear Raul,
Your question regarding the choice of arm(wand) material is valid and I'll see if I can address the issue to your satisfaction.
Low frequency reproduction is quite strongly linked to the quality of the rendition of upper harmonics. This is why adding a "supertweeter" often improves the perceived bass quality of a speaker. A tonearm(wand) that exhibits pronounced high frequency resonances(a "metallic" sound when tapped) will emphasize(read: exaggerate) the leading egde of the note, followed by some, more or less well damped, ringing. The ringing obscures fine detail and decay and corrupts the harmonic envelope of a sound(of an instrument), the exaggerated upper harmonics content of the low note might be perceived as "better attack". But, when a double bass player lets go of(fingertip releasing) the string instead of plucking it, the resulting sound is quite soft, dominated by the resonating body of the instrument(sometimes difficult to locate in space). Most arms can't capture that bloom realistically. Much more in demand seems to be the kind of "funky" bass that I hear at show demos left and right..
Over the years many audiophiles have gotten used to an exaggeration of upper harmonics, resonant arms(platters, too), bad amplifiers(often solid state, sorry) and cartridges with high frequency resonance peaks as low as 12kHz(!) being some of the contributors.
And sometimes this little added "spark" might just be what is needed to compensate for a poorly designed(weak) turntable drive system or the WRONG step up transformer(veiling the original signal), creating an overall quite pleasant, nevertheless inaccurate, and ultimately dissatisfying facsimile of real music played by real people(or the event as recorded by the engineer). We have all witnessed others mistaking MORE highs for MORE detail.
So, should I design my arms to match well with severly flawed components? Certainly not.
It is not this "HiFi sound" I'm trying to adhere to, but rather produce a component with as little a sonic fingerprint as possible(there'll always be SOME signature, if only because no perfectly neutral wiring exists), one that allows the listener to differentiate between "soft" and "tight" bass, one that keeps not just the sound of A violin, but the sound of any violin reproduced as distinct and recognisable as that recording engineer managed to capture it.
I have built tonearms for more than 25years and tried ANYTHING that you could possibly(lets say reasonably) use as a material for the various elements of a tonearm. Initially I did use metal(sandwiches) and carbon fiber as armwand materials(and, upon request, still do!), but when comparing the properties of some woods to the more "traditional" materials like aluminum, steel, ceramic tubing or carbon fiber, I found those woods to be superior in many respects. For a mass produceable arm wood is a poor choice. Too many variables to compensate for, possibly inconsistent supplies, etc... But you can use the differences between various woods to your advantage, see my comments on maintaining outer dimensions while having a wide choice of eff. masses on this forum and elsewhere.
You mentioned the wooden Grace arm. Let's just say you'll never see one of my arms with a Teak armwand(but Teak was and is easy to come by in decent quantity and quality).
BTW, Ebony is not a particularly hard wood. Snakewood, Grenadill, Acacia, Horizontalwood are much harder(to name but a few). If I were to use the different woods without any treatment(this doesn't refer to a coat of wax...), each would indeed have an identifiable sonic character. But I do saturate the armwands with a variety of oils, some remaining liquid, others solidifying over a period of three to six weeks, until they all exhibit the same internal damping properties. This is rather important as the cartridge tracking a signal will "send" spurious energy down the armwand, which in this design needs to be dealt with(damped) in the arm(wand) and bearing as there is practically no energy transmitted via the bearing to the armboard to be dissipated there(the conventional way of doing it).
Reducing the internal damping or using, say carbon fiber for an armwand, will yield a sound closer to "conventional"(no disrespect intended) arms, with the benefit of near zero bearing friction(more importantly, zero "stiction"). The added sense of "zing" at the cost of a natural, non-mechanical character might be prefered by some people, all reasonable inquiries will be executed...(and so will be all unreasonable inquirers, - just kidding ;-)
Now, lastly the issue of bass "authority" or power. An example: At the last thorough comparison with a Triplanar arm, the consensus was, among other things, that the Reference arm had more authority below 80Hz and lower bass extension too(not that the Triplanar was flabby sounding, on the contrary!). Now put the Triplanar onto a different deck and the situation might be different. That's because most other arms do not only depend upon the mounting board for dissipation of energy, they also pick up energy and relay it to the cartridge. Put your turntable in the adjacent room(I know it is impractical...) and you'll see(äh, hear) what a fabulous microphone it was, sitting so close to your speakers(or in their soundfield). A SME V on a Linn LP12 has terribly illdefined and bloated bass, the same arm on an SME 20 or a Sota Millenium is capable of excellent bass performance.
My arms are far less dependent upon the mounting surface, which was one of the design goals from the start. But, as there is no possible mechanical incompability, there is also no chance for that lucky case of perfect synergy....:-).
It's late over here and I'd better hit the sack. Feel free to comment or dig deeper.
Cheerio,
Frank
