first system i ever bought, still using it- a lorex 4 camera system with 4 b+w cameras and audio built in to the cams. video and audio is carried by same wire{bnc connection} to the monitor. i bought this a couple of years ago because they are 2 way audio, and it gave me the chance to yell at my kids when i saw them doing something stupid in the yard.they hate it, i love it. now i'm in the market for a dvr and i want to use these cameras as well as a few others i will be purchasing. the 4 lorex cams are actually pretty decent and suit my needs. will i get audio on my dvr from the cams this way, or will i have to get separate mics for the cams and plug into audio inputs on the dvr? i know i'll lose 2 way audio with the dvr. that much i know. another scenario. if i output from the monitor to the dvr, leave the monitor in quad screen, will the dvr start to record on motion detect from the monitor output? sorry for being long winded, was just looking for a way to keep the 2 way audio on a few of the cams. thanks in advance for any replies.

You can but depends when system it is exactly. We will need more info such as a model number to look it up.

I have taken a system before which got power from its own monitor and had audio and video, and it ended up having to splice a whole bunch of wire together to a 15 VDC Power Supply, also had to splice together a whole bunch of ground for both the audio and the video. The audio was not used though, but as it is there you could also grab that, it would be a single wire, the ground for it would come from the power supply (maybe, depends on the system, dont take my word for that as I dont want you to fry something!).

Its been along time so I cant remember exactly how I did the wires, and I would never do it again (would make the client buy new products as it is a hassle and unprofessional) but it can be done.

You can get cheap mics though, cheap regular CCTV cameras would be much better than the type that gets power from the monitor also so I would also suggest chucking the old ones away and using new ones.