This thread runs the risk of rehashing everything we've talked about over the past few years. With that in mind, I encourage the original poster to use the search facility on both this forum, Audio Asylum, DIY Hi-fi, etc.
For the purpose of this thread however, let's start with some simple stuff - a few guiding principles in audio component design. With that in mind (and in no particular order) here is Mackris' incomplete list of design axioms. Feel free to add others:
1. Designing any audio component is all about engineering and the art of compromise
2. You need keep the sound of real music in your consciousness, and if you play an instrument or are involved in its production or recording, you will be guided in profound ways
3. Measurements are a key starting point to any component aspiring to greatness, but they are ONLY a STARTING POINT (see #2)
4. If you attempt to optimize one design parameter at the expense of all others, you will fail miserably (see #1)
5. If you start to compare your component against other components, you will fail miserably (see #2).
There are all too many audiophiles who obsess about parameters, measurements, and numbers. Re-read #1 & #3 and get over it.
A bit of tough love ... a metaphor:
Imagine the music "lover" who approaches his music appreciation the way many tortured audiophiles do - in a decompositional manner. One day, he begins reading about tuning methods (just, well tempered, Pythagorean, equal tempered, etc.) It dawns on him that all fixed interval instruments (fretted instruments, keyboards, African thumb pianos, etc.) are inherently flawed. From that point onward, he refuses to listen to any of these instruments.
Does this remind you of anyone? Let the healing begin ...
Tonearm length is an attribute that raises its ugly head every few months. If you search this and other forums, you'll find posts by Frank Schroeder and Bob Graham on this topic. They can both address this better than I can. This is, after all, their own specialized part of this audio world and both have argued that a shorter arm better balances all parameters (see#1).
As far as Frank is concerned, he'll make any arm length your heart desires, but his personal arms are (in general) 9" arms.
Let's assume you set out to design a long tonearm, because you consider minimizing tracing distortion to be of paramount importance. Let's further assume that you want the arm to be compatible with a range of commonly available cartridges (Benz, Ortofon, Dynavector, Lyra, etc.). This means that you'll need to keep the effective mass down to the 10-12 gram range.
How do you accomplish this? Thinner walls in the arm tube (as compared with a 9" design)? Thinner, lightweight headshell (as compared with a 9" design)? Remember, that effective mass is an inertial moment, so weight at the headshell side of the arm has a greater influence on your effective mass.
How to you keep this lightened arm from rattling like a bucket of bolts when your Mahler 9th starts rocking and rolling? Things to think about ...
The bottom line is, that there is no easy answer to this. Both Frank S, and Bob G. consider that all parameters can best be balanced in a shorter (9") tonearm.
Now, if you want to design a dreadnought to run with a low compliance cartridge, you may not face as many compromises. You get my drift. There is no simple answer.
Those of you who were fortunate enough to see/hear the world debut of the Durand Talea tonearm in my room at this year's Audiofest will note that we have yet another great arm that centers around the 10" length (266mm, or 10.47" to be precise).
Joel did not set out to design a mid-length arm any more (I'm sure) than Herb Papier did with the Tri-Planar. As a matter of fact, Joel's earliest efforts were on the long side of 12".
Now ... don't go out and quote me as saying that 10" is the ideal length because I love both the Durand (266mm) and Tri-Planar (250mm). The point here, is that their material exploration and design process brought them to these lengths. I know this in the case of Joel, and strongly suspect it in the case of Herb Papier and the Tri-Planar.
Bob Graham and Frank Schroeder landed more in the 9" camp. The point is that all 4 of these arms are great tonearms. There are some great 12" tonearms as well but to ascribe any of these arms' greatness to their length would be drawing an erroneous conclusion.
Cheers,
Thom @ Galibier
