What makes a good tonearm?


I'm entering the world of decent analog and believe I understand why the turntable design is critical (e.g., vibration isolation, balance and speed stability) but am scratching my head a little about tonearms. What makes a good tonearm good and a great tonearm great? The resulting sound is always the key, but what design characteristics contribute to that sound? Tonearms are a big investment and can be tough to change later so I'd like to understand more about them before I buy anything. Thanks in advance.
ozfly
Buscis2, I have been looking at the Origin Live Silver, which is a heavily modified RB250 and favored by some Analog gurus here on the 'Gon. But, if some great used package deal comes along with a nicer arm, I'd certainly consider that too. Still looking. Thanks.
Ozfly, You've been doing your homework haven't you? I own an Origin Silver, full mods, including slotted armtube/revised bearings.

For what's it's worth, I'll give you my spin?.....

My present arm of choice is, and has been, a modified RB900. Some interesting notes:

One step in the Origin upgrade includes glass beading and shot peening the armtube. These procesees actually alter (increase) the armtube surface hardness and surface texture. The surface hardness then becomes almost equivalent to the surface hardness of the "FACTORY" RB900 armtube. Get it?
(Origin won't tell you this but...) this process alters the resonance frequency of the armtube and actually INDUCES ringing in an more audible frequency range.

Their solution? Cut a slot in the armtube. It absolutely works. In fact it reduces the actual ringing to a lesser degree of magnitude than the standard RB900 arm. It also alters ANY resonances to a more desirable area of the frequency spectrum. Also, the arm is now hand assembled using the same "abec" spec'd bearings used in the "FACTORY" RB900. Get it?

Sound good right? It is. To an extent.

Throughout this whole concept, we MUST keep in mind that the coatings applied to the outside of the factory armtubes is not just "Krylon" or "RustOleum" spray paint. These coatings are specially formulated to provide very specific finish mil thicknesses, surface hardnesses, and vibration DAMPENING characteristics. Application procedures, fluid application viscosities, and deposition thicknesses are held to extremely close tolerances.

This is REGA'S way of doing things. As you can see, these are two different approaches to ultimately achieving similar results.

Kinda.

The info I just provided you is the fact. Now I'll provide you the opinion part. Personally? I feel that the Origin, although wonderfully detailed, open, airy, and all those other stupid adjectives, don't sound like music. After the mods? The weight disappeared. To Me? It sounds "clinical/critical". I hear the music being dissected, not played.

Some people may like that sound. Not me. I really enjoy the music that the RB900 makes. The 900 has been rewired w/ Cardas Litz, an adjustable Heavyweight and VTA. That's it.

It allows a Fender Precision to sound like a Fender Precision. Not an Alembic. Double 30" bass drums, sound like 30"s, not 26"s. A cathedral pipe organ has BALLS and tends not to sound "compressed". The 900 arm fools you into thinking it's not there. The Origin is audible, present, pronounced.

Please don't misread this. You will be very hard pressed to find a tonearm in the sub $2-$3000 price point that has all of the wonderful qualities of the Origin sound. But, that's just the point. The origin HAS a sound. It HAS a sonic signature. I don't want to hear ANY of my components. I also would have to question why a company modifies a tonearm (RB250/300) to closely replicate the specs of an already EXISTING (RB900) tonearm. Is it because that (EXISTING) tonearm is being used as the standard? Is it the benchmark? The pinnacle? Hmmm.

IMHO. Food for thought.

Regards, ED

Ozfly,
The OL Silver is a great arm for the money, especially if modded with Twl's HIFI Mod. Not quite world class of course, but hugely impresive for the money. It mates well with some extraordinarily good cartridges like Shelters and Koetsu's. (The Shelters are also extraordinary performers for the money, as everyone on this thread probably knows.)

There are two articles worth reading on the Basis website. Good info if you can translate dorky engineering-speak. The Basis Vector is one of the three or four best pivoting arms in the world by all reports, as it should be for 3x the cost of a Silver.

http://www.basisaudio.com
Thanks all. Right now, I'm seriously considering an Origin Live Resolution table with an RB-900 arm. I'd welcome feedback as to whether that will provide sufficient lower end punch for my taste. I've not decided on this nor have I decided on a cartridge. Some lower end Clearaudio systems are also available for a decent price (Evolution, Tangent with a Virtuoso Wood ii) as well an an Audiomeca rig (Romance, Romeo arm, Lyra Lydian). Any feedback would be welcome. Thanks again for the great advice so far.
What do the Resolution + RB900 go for? I could offer some of my usual opinionated recommendations if I knew that. I'm guessing there are tables that will be considerably punchier.