One turntable with two arms, or two turntables with one each - which would you prefer?

He looked at this PBN GrooveMaster

I talked to Peter at PBN, he will make a second tonearm board and metal cap for it.

Denon DP-80 Spinner, build your own 2 arm plinth

Garrard 401 in 2 arm deck

https://www.canuckaudiomart.com/details/649859226-rgtt-ferrari-gt401/

Luxman Two Arms, PD444

I just helped a friend acquire and set up one of these

Garrard 301 with custom 2 arm plinth

Technics Base B500 also allows quick change arms, the 250 S arm has removable headshell, the ___? is straight

In Use, things evolve: 

I have a lot of Jazz LP's, many Mono LP's. There is nothing as easy as having a Mono cartridge ready (mounted, aligned, azimuth/overhang/vta/tracking/anti-skate) all set to go, play some Oscar Peterson Stereo, up comes a mono LP, switch arms, select arm C on the SUT, change the Mode on the preamp to Mono (or just a single speaker), then back to arm A or B for Stereo.

Original Idea: I had 2 arms, mono in the back. I was selling LP's, giving them a farewell listen. I realized I was wearing out my MC Stylus when I could have been using a MM with a replaceable stylus. That's when I added the 3rd arm, left side backwards for Mono, rear for MM or MC (mine and friends cartridges we listen to); right long arm favorite MC, fixed.

I went to 1 TT with 3 arms, I don’t have room for two TT’s, and 1 SUT with 3 inputs to 1 Phono Stage, and PASS for MM thru the SUT to that favorite MM Phono Stage.

I’m gonna assume two arms means you will get into MC cartridge. And 1 arm could be fixed cartridge, but the second should be removable headshell so a variety of cartridges, i.e. MONO, MM, Elliptical. Advanced Stylus could be acquired over time.

MC Low Output means a SUT to get up to MM signal strength.

SUT with PASS for MM.

SUT with two selectable inputs; out of SUT to single Phono Stage.

.......................

My Fidelity Research FRT-4 SUT has 3 selectable inputs, PASS, and 4 optional x-factors/impedances

this one is over-priced, but shows it’s features, they often show up for around $700.

Entre ET-100 has 3 inputs, PASS, and 3 optional x-factors/impedances, usually cost a bit less that the FRT-4.

Note: FRT-4 has internally connected output cable with old simple connectors

Entre ET-100, rca jacks: you can use your own output cable, better connectors, I may modify my FRT-4 one day.

Acoustic Solid Round, 2 arms

https://reverb.com/item/39706894-acoustic-solid-solid-round-dual-tonearm-turntable?gspk=SGlmaXNoYXJrLVJldmVyYg%3D%3D&utm_campaign=Hifishark-Reverb&utm_medium=affiliate&utm_source=partnerstack-legacy

This 7 layer JVC Victor CL-P2 Plinth is what I have.

https://yahoo.aleado.com/lot?auctionID=c1062117063#enlargeimg

Two Removable Arm-boards, normally 2 arms.

It fits JVC Spinners: TT61, 71, 81, 101 (don’t go there). I chose TT81.

Three Arms:

1. rear 9" Removable headshell, various cartridges, MM, MC, ellip, shibata, ML ...; Arm has VTA on the fly for easy cartridge height changes.

2. right side can be long (mine is 12.5"), best MC cartridge, fixed..

3. Then I found a compact Mission arm with a short counterweight section and ’squeezed’ it in, for MONO ready to go.

https://www.vinylengine.com/library/mission/774lc.shtml

the mission arm is made by Jelco, there is a Jelco matching model, and you do not need the mounting plate, just mount the round base ring, 3 screws.

ClearAudio has several models for two arms

Micro Seiki DQX-1000 Fits 3 Arms

VPI,

Several Big Ones allow 2 arms

AND, they have a UniPivot Arm, you can have several cartridges mounted to spare arms, simply switch them

wmorrow

I've seen Steve at VAS change his beloved Uni-Pivot arms on his VPI. It seems easy, until ....

change arm: pull out mini-din connector from the VPI junction box: that mini-din connector now dangling from delicate tonearm wires. Simply lift arm up, put down in safe location. 

Pick up spare arm from safe location, with alternate cartridge pre-mounted, pre-aligned. Place on the arm base spike, plug in it's mini-din connector.

NOW, cartridge body height might be different, reset VTA as you mentioned. Cartridge weight likely different, it's recommended tracking force probably different, and thus anti-skate should be re-adjusted.

VPI arms used to skip anti-skate, they said "put a twist in the wire" from tonearm to junction box (oh that's precise), then they started making aftermarket anti-skate devices, VPI now offers them

I have changed arms on my friend's Technics B500 base, no delicate wires involved.

Changing a headshell with pre-aligned cartridge, then the same VTA/Tracking Force/Anti-Skate is needed. 

Second or 3rd arms, very carefully aligned, ready to go is much preferred if alternate cartridges are used.

A true Mono cartridge DOES make a difference, slight or a lot, varies

I wouldn’t go near the delicate TT101 (I chose the TT81), however, Halcro, member here did, went thru all to achieve perfection, then proved that the DD motor was able to maintain perfect speed when 1/2/3 arms were simultaneously playing.

I went with the conventional vintage JVC Victor Plinth, he made custom and separate pods for his 3 arms. And, dust cover??? one of the reasons I stayed with the JVC design.

best groove

I nearly bought the hard to find JVC Victor CL-P3 Three arm-board plinth.

Luckily, the seller showed a ruler in the photos, and I realized: in order to get a 3rd removable arm board on the left, and not be too wide overall, they moved the main arm board on the right side closer to the TT by cutting the arm board into a curved shape.

Luckily I realized, my 12.5" long arm will not fit. My CL-P2 plinth main armboard is further away, allows my longer spindle to pivot length needed. I’m not sure what the longest arm a CL-P3 fits.

Victor's 7082 long arm is actually only 270 s/p and 12mm overhang: total effective length 282mm (11-1/8")

my blackbird needs 304mm s/p plus 13mm overhang: 317mm effective length (12.5")