hello i have an external percussion synth , with a mono output signal . I have connected the synth output to the input A in the OT but i hear the sound in left speaker. Is there any way to make the input A mono to hear in both speakers or i need some split mono cable? Sorry my english .
You have to use a Thru machine for that 
Check the A-1 section of the manual, THRU Machines. Set the input on the THRU main page to whatever input the synth is connected to !
thanks a lot hahehehe
Or make or buy a cable with a mono jack on one end that splits to two mono jacks.
The advantage is you save a track. But the advantage of Shoki’s suggestion is you then get to use effects on your synth.