why do some turntables have multiple tonearms?


i have seen some turntables that have 2 (or more) tonearms. what is the purpose for having more than one tonearm mounted on a turntable? what does it allow you to do that you can't do on a tonearm that has one tonearm?
paperw8
well, normally you use different cartridges for 50ties and 60ties music and again different for the after 7ties pressings....(SPU MONO65, SPU MONO25, SPU GE and SPU Silver Meister) and of course the EMT TSD 15.....FUN!
The older I get, the more I appreciate mono recordings. Having two tonearms allows for dedicated stereo and mono setups at the ready. It makes things that much easier.
- One for Stereo Cartridge, the other one for Mono
- one for this color, the other one for that color of cartridge
- one for Cartridge without, the other one for cartridge with body
- first one was not expensive enough, the other one is
- one 9" Arm and a 12" Arm
or the second one, because you don't trust the set up from the other one
or ... :-)
The battle cry of the militant audiophile: 2 ARMS! 2 ARMS!!! I tried it myself 30 years ago with a Micro Seki DDX 1000 but found that I used one to the exclusion of the others. Haven't tried it since and most of the reviewers I trust seem to rely on the single arm approach but there are certainly advantages to multiple arms; ask an octopus. Seriously, I am currently setting up a second table with a removable headshell arm so I can change cartridges fairly easily but I'm not sure how much I will use it. But since my phono stages have two separate inputs it seems a pity not to use them.
To me it is about the kind of music one is listen to. I use
Triplanar/ Benz Ruby 3s for vocals and the Reed 2A /Phase
Tech P-3G for piano music and symphonys. There are no perfect carts nor tonearms. So one should use what is best
in the given circumstances depending on the owned combos.

Regards,