What does a tonearm contribute to the sound of a turntable?


Curious about how a tonearm affects a turntable sound. I guess it's the piece of the turntable I know the least about and feel the least connection with. how does a really good tonearm affect the sound or not affect the sound? And what about the tonearm does the affecting?
128x128simao
@fsonicsmith Cool. Thanks for the clarification. Another thing I've often wondered is how good the tiny wires connecting the cartridge to the tonearm are. With all the fuss and expense about IC's and speaker cables, are these overlooked?
There is really not that much mystery involved with tonearm wire. The same concept applies-basic tonearm wire is fine with basic gear and as you go up the chain, the quality of the tonearm wire makes a subtle difference and improvement. Btw, "tiny" is endemic to tonearm wire due to the very low level signal. All that said, I am a true believer in FireWire AG, a wire that is manufactured in Germany by  Stereo-Lux Musikanlagen. Something has to account for the amazingly transparent sound I am getting with my Reed arms and Reed uses this wire. It is incredibly pliable as opposed to being stiff, with a very soft clear rubber-like insulator. The clips are unusually nicely machined, they just exude quality from end to end. 
The wire is probably fine, but Reed tonearms have a lot more going for them besides good wire.  Otherwise, we could all buy FireWire and use it to re-wire some el cheapo tonearm.  (Another owner of a Reed tonearm with cryo-treated FireWire here.)
lewm7,760 posts04-28-2020 5:00pmThe wire is probably fine, but Reed tonearms have a lot more going for them besides good wire. Otherwise, we could all buy FireWire and use it to re-wire some el cheapo tonearm. (Another owner of a Reed tonearm with cryo-treated FireWire here.)
I could not agree more. 
I have a Sumiko Premier MMT on an Oracle Alexandria MK3 (the black one for those who are unfamiliar.) I love the table; but it's a PIA to change tonearms and there are only so many that can be applied without buying new suspension springs from Oracle. $$$$$

The MMT is the better of the two arms I've had on it; the other being an Audioquest PT6, both manufactured by Jelco.

I have not been able to disabuse myself of wondering if another tonearm on the same table with the same cartridges would be a cost effective upgrade, even though I am pushing 68 and my hearing is pretty much tuned into a comfort zone. My favorite cartridges are in this order at this time: Audio Technica AT33/PTG/2, Hana SL, Denon DL-301 II, and SHURE V15 with a Jico SAS stylus.

Does anyone have a strong recommendation for a tonearm that would offer a significant improvement in SQ (I value detail and spatial imaging; but not at the cost of true-to-life experience, not 'warmer' than live) at a reasonable cost; maybe 2 to 3 times that of an MMT? It would ideally be close to the same weight to balance the suspension, and the same pivot to spindle distance (or close; I have a spare armboard) to make it practical.

I am NOT trying to Shanghai the OP's thread. I think any replies would be of interest to all involved. 
"Maybe the proper question is what does a turntable contribute to the sound of a tone arm?"

Yup, that sounds about right.