Schroeder Reference Arm

Lewm,
I'm not advocating setting azimuth by ear as necessarily the best method over any other one, but one thing I've noticed is that using only one frequency (1kHz, or another one) to measure crosstalk isn't terribly reliable. When I managed to establish a good balance at 1kHz, I measured that it was not right at other frequencies. Obviously, a musical signal is extremely complex because of the number of acoustic waves occurring at any given time, but also because of the way they interact with each other (addition, subtraction), to stay with just the frequency domain. I wonder if one could make a recording where, instead of just single frequencies, there would be "blocks" of stacked up sine waves in various groupings across the spectrum... But even that might not be realistic enough to parallel the complexity of musical signals.
Joel

The question of tonearm/cartridge resonance is a very complex one, as seems clear from some of the posts here.
What is referred to as "damping" usually refers to the combined action of two of the basic parameters that allow to identify the acoustical properties of a given material: internal friction (tan ∂, loss tangent) and elastic modulus. Density is often included in this equation, but in my experiments and measurements, it seems to be less relevant than the other two parameters, in the particular application of a tonearm tube (as opposed to, say, a sound board).
But there is actually more to this than just the properties of the material--the shaping of the tube is critical, and not just whether it's tapered or cylindrical. With wood, in particular, the orientation of the rings, and other such considerations need to be taken in consideration, together with the properties of the "raw" material. It's an amazing field of investigation and, to a large extent, not easily subjected to simple measurements--unless perhaps if you combine together a very large pile of data...
I'll be happy to talk more about all this at the RMAF, and I too am looking forward to the session.
Joel Durand

Doug,
You're very right about the process--with one addition, perhaps a very personal one: I love accidents, mistakes and wrong turns. In musical composition (which many people don't see as rigorous, but actually is, just as much as scientific explorations, in different ways) as well as in tonearm making, I've often come to theoretical understanding after empirical discoveries resulting from unreasoned decisions (what if? oops! what did I just do? etc...).
Hypotheses sometimes get proven by testing, but more often than not, they just serve as jumping boards to jog the brain into action, to bring oneself into places one hadn't thought about.
If you get a better result than before, you try to reproduce the outcome again and start generalizing... until you find a new reason to move on and discard the theory you just established.
This is fun.
Joel

Raul,
You are right about trying to minimize the factors between tonearms. However, I agree with Paul about the important fact that using a wire that is not offered to customers would be a serious problem in any type of evaluation. Nobody would know what the "real" tonearm would sound like.
I don't think Frank and I use the same type of cable.
Another aspect of this is that, to a certain extent, the tonearm is "tuned" with the cable I'm using. If I used another wire, I might have to modify other things to get to the sound I want. In that sense, the cable is as important in the global sound result as, say, the wood I use for the armwand, or the material I use for the counterweights, and so on. Any change anywhere modifies the delicate balance between the elements. It can bring the whole thing to a higher level, of course--I'm not implying that I currently have the perfect recipe--and when that is the case, I adopt the change.
Joel

Thanks Mike for your offer to bring your A90 for Frank! Very nice of you.

I'm happy to settle on the A90 for this session, so I'll bring mine. If we indeed do a first set up before switching to the A90, I'll use Thom's VX-1S.

Cheers,
Joel