lV line levels, same chase, opposite signal directions, ok?

vibrations1951 · Post by **vibrations1951** » Mon Mar 17, 2008 9:25 pm

I'm trying to lay out my cable chases in pvc conduit under my planned isolated slabs. It gets pretty tight when I get to the contol room coming in from an iso booth, medium sized live room and a medium sized rhythm room. Total sudio space is about 1200 square feet (34'x40') using John's corner control room design.

I want to run mics separately in their own chases. AC lines come in from the top so no prob there. I plan to put Fold back speaker lines to all rooms with emt/metal conduit from the ceilings as well as some metal chases under the slabs. My line levels to the control room from keys, guit amps etc. will be going in one direction and my separate headphone feeds (likely amped from the control room to the tracking rooms) will be going in the other. It would save a lot of incoming ground space at the patchbay if I could put both line level type cables in the same chase but I have heard conflicting advice. Probably because we are talking live show snakes verses studio levels and quality, but i don't know????

Can I do this or should I make lines to the tracking rooms lower voltage signals and separate musician controled amps/mixes in each live room (not my preference, guess I'm a control freak of sorts but I want to know what they are hearing)?

Would this be a better solution for a single chase for all lines (both directions in one chase) or just go additional chases and completely isolate differing line level directions and voltages?

Additionally, I want to do it all so would video lines as well as digital/optical lines be figured in with separate chases or can they share the line level chase or chases if extra needed for flow direction thing???

Any suggestions would be helpful because I need a pro level set up and have very little studio pro level experience. I need to do it right the first time. thanks so much in advance.

Speedskater · Post by **Speedskater** » Mon Mar 17, 2008 11:22 pm

Don't know about the level question.
But direction doesn't matter.
From the audio signals prospective, the cables are so short that the the signal voltage is the same at both ends of the cable.
It only takes 100 nano-seconds for the signal to get from end to end.
Thats about zero for audio.

On second thought you might split it:
a) Mic level
b) Line level, digital & video
c) Speaker & head phone

vibrations1951 · Post by **vibrations1951** » Tue Mar 18, 2008 7:01 am

Thanks for responding Speedskater.

I'm not sure I get the speed of signal thing.
So you don't think direction differences in line feeds going opposite directions would be a problem even if they are both constant at the same time? No crossover?
[/quote]But direction doesn't matter.

On second thought you might split it:
a) Mic level
b) Line level, digital & video
c) Speaker & head phone

I see here you split them up and I get that but it doesn't really help my problem because speaker lines are above and I would like to feed from below for headphone feeds if possible. I'll have to think that over a bit.

Any further thoughts of yours or others would be greatly appreciated. Thanks again, jp

Speedskater · Post by **Speedskater** » Tue Mar 18, 2008 11:43 am

Lets do it another way.
Any audio signal uses two wires, like a speaker. At any instant the signal on one wire is going one way and on the second wire it goes the other way. So from outside the cable, the signal doesn't have a direction. To the rest of the world one conductor cancels the other.

I don't think it will make any difference, if you run headphones in the same trough as line level.

vibrations1951 · Post by **vibrations1951** » Tue Mar 18, 2008 11:58 am

Ah ha! Yes of course!

That all makes sense to me now. I can get so caught up on things but I see your point very clearly now. I think you are absolutely correct! I can save myself lots of problems (and conduit/dollars!) many thanks Speedskater! jp

Speedskater · Post by **Speedskater** » Wed Mar 19, 2008 12:51 am

What type of video are you sending? (RF, Composite, Component )
What video cable do you plain to use?

vibrations1951 · Post by **vibrations1951** » Wed Mar 19, 2008 11:43 am

Over my head now! I have little knowledge right now of the video stuff. My son is into cinematography and some artist friends as well. I'm trying to be ready for any case scenarios without knowing what the needs will be with video. Can you say cart before the horse?? Any thoughts??

Speedskater · Post by **Speedskater** » Fri Mar 21, 2008 8:17 am

Puzzling out the video needs might be good. The future is HDMI, but right now HDMI has lots of problems, connectors break (and are not replaceable) and newer video rates place higher demands on long cables. The connectors are large and sooner or later the cables will need to be replaced.

vibrations1951 · Post by **vibrations1951** » Fri Mar 21, 2008 9:45 am

Good advice. In checking this out I've found that the length of run for this cable,(type A 19 lines) or B (29 lines), should not be more than 15' or signal degradation occurs. This leads me to believe that i should provide these somewhat shorter runs with their own chase and bundle the other lines as follows:

Chase 1- MICS, DI
Chase 2- line levels
Chase 3- amped HP
Chase 4- HDMI/video/cat5

Speaker, speaker sends, ac are all set and separate in my plans.

Perhaps this could work as well???

Chase 1- MICS, DI
Chase 2- line level, amped HP
Chase 3- HDMI/video/cat5

I may be splitting hairs but i don't want to chance it either.

what do ya think?