Hello I would like to connect my voyager xl and Slim Phatty and produce two voices, it is possible because I have never seen a youtube video with voyager XL Poly Chain. and how do I connect it to, is the patch pannel also controllable
I believe you can only poly chain voyager with other voyagers.
Phattys chain with phattys.
but it comes , it is in my manual
I believe the Moog poly chaining is a MIDI based protocol. Each synth gets assigned a specific number in a sequence (max number of synths in the chain). Then after an "all notes off MIDI event’', each synth will play it’s subsequent “MIDI note on event”.
As long as all synths use this protocol you can poly chain them together. However, each note will sound different based on it’s assigned synth, unless they all are all the same type of synth programmed to the same patch. So, Slim Phatty’s and Little Phatty’s play together well, as well as any set of keyboardless synths, like the Minituar played from a master controller. But a Yoyager and and a non-Voyager are going to sound a bit odd, unless you’re chording the same number of notes as your poly chain length. It’ll be weird, but what isn’t in analog? 
I could be wrong, and somebody from Moog can chime in if they have the time, but I specifically asked a tech from Moog about this
when I bought my XL.
They told me that I could control Slim phattys with my voyager as a midi controller, but that my Voyager would only Poly-Chain with other Voyagers or RMEs.
This has been covered in other threads as well, that the poly chain implementation of the voyager with other voyagers is not ideal, but I have not had the chance to try it.
If anyone has that ability I would love to see a video of even a two-voice voyager set up.
I did a 3 voice with a Voyager XL, Sub37, Slim Phatty. Worked fine.
Voyager- MIDI KEY ORDER, Maximum Keys(PolyMax), Active Key(Poly #)
Sub37-Poly Number, Poly Max
Little&Slim- POLY(#) of(##)
You will find some quirks using mixed systems, as far as not every single panel control sent from #1 will will have the expected result in the others in the chain. Which is to be expected since they are a combination of CC’s and Sysex and every Moog would have to have a copy of all other Moog’s Firmware and know what type was being used for each Poly # and would therefore have to have HUGE memory in each. It’s not seamless unison of controls like using 3 Slim, 3 Voyagers… that share identical firmware. So be aware and check the effect that #1 is causing.
Someone gave you the wrong info if they said you cannot mix sytems, the Voyager XL manual says…
“You can use any combination of Voyager/Little Phatty/Slim Phatty synths to create a polyphonic synth stack. For information on config- using an LP or SP to function in a polyphonic arrangement, consult the User’s Manual for those instruments.”
I don’t think the patch panel causes any midi to be sent but you can of course use each of the 3 Mults for sharing a given CV out to 3 seperate Moog’s CV IN. Which offers many possibilities for sharing the patch panel functions among the other units in the polychain. LFO2 Has some midi functions see the manual addendum for details. http://www.moogmusic.com/sites/default/files/xl_man_add__lfo2_midi.pdf
Other Fun Options..
You can use the PatchMorpher iPad app to make the Voyager play 3 notes at once.
You could even bypass the polychain entirely and use the XL patch panel to send CV using the MULTS to control the other Moogs or any analog with CV in.Don’t forget about your KBD Outputs on the Patch Panel. Although that would be Mono by CV since the Voyager can only send Poly my midi control. Check out the Future Retro Mondovox for lots of complex options to play up to 16 Mono synths Polyphonically .