How do I connect a rack mount effects processor to a Peavey 8600D mixer?

SOURCE: how do i connect the cables between peavey vocal

if you mean effects loop try graphic out to ultraverb input and output to power amp in. this will effect all channels of the xr500c

SOURCE: can i connect the pv 112 to the pv 118 subwoofer

Generally speaking you should only send low frequencies to subs. The highs, while lower in power than the lows, will over time harm the voice coils. The ideal way to do this is to use an external crossover netween the main output and the amp input with the higher range going to a general set of speakers. Send the lows through the second channel of the amp and then to the subs.

In short, while not recommended, yes you can hook them up in parallel.

Dan

SOURCE: i have the peavey xr

That's easily done. Simply connect the left(or right) output of your mixer to one of the channels on the peavey. Use any line input. Since the peavey is a mono system, there's no need sending a stereo mix to it.

SOURCE: I have a peavey 8600 powered mixer. If i run

If you run the speakers FROM the main you should have BOTH the effects and the EQ invilved with your signal.