10 Inch Tonearms

lewm, my thought was that the tonearm length is important depending on the cartridge build, including a mono cartridge (i.e. SPU) but I may have been confusing information. Most likely confusing length for weight. I was also thinking that a more expensive arm would most likely render better results but that seems minimal with a mono cartridge? I believe I’m going to have to buy a used arm over a new one so it’s good to know what to consider ahead of time. Always appreciate your input.

goofyfoot, I suspect that the SPU mono cartridge will be a low compliant cart (stiif cantilever suspension) so it will need a high mass tonearm to get the best out of it. If you put a low compliant cart in a light weight arm the stiff suspension will tend to wiggle the end of the arm around during the low frequency bass notes. Since the arm is moving as well as the cantilever, the out put on the bass notes will be both low and muddled. The stylus/cantilever riding in that stiff suspension needs some mass to push against as it's swinging side to side, on the light arm it's pushing the end of the arm as well.  This is why it's important to match arm and cartridge.
That Audio Technica arm I purchased above is a high mass arm, it will mate very well to a Denon DL-103 cart because they are very low in compliance.
As far as the cable, I usually use the cable if it's still in good shape. Audio Technica built quality components.
I'm sure somebody will tell me I need to spend hundreds on a new cable or I need to rewire it so there are no connections from cartridge to RCA connectors but I really don't think I'm leaving much on the table. I work with industrial electronic controls, some of the signals are very low and we don't seem to have issues with it.

BillWojo

Since a mono signal is entirely encoded in lateral motion of the stylus, one would think that maybe lateral compliance of the cartridge (not vertical) and inertial mass in the horizontal plane of the tonearm might be critical factors. Azimuth setting would just be for perpendicular physical orientation of the stylus; there is no such thing as crosstalk. Anti-skate is also less critical.

lewm, if you're going to add a tonearm to a modified Thorens TD160 for a Hana MC Mono, what arms would you consider? 

I would use one of the 5-6 tonearms I already own that are not already in use. Or if I needed extra length I’d buy a good one used, but only if the TT required the longer tonearm, not merely to enhance performance.