Hi,
I have a gig in the open air. The PA is being supplied by a DJ but his mixer is off stage (40ft trailer). Now I need two runs from the main outs of my mixer to the DJ's mixer.
I have shed loads of twin coax, i.e. two shielded cables in the same insulated PVC outer insulator. The two conductors are shielded by braid and the braids are touching along the length o fthe cable. So my query is can I use this balanced via XLRs or would I lose a lot of the interference rejection that you get from a shielded twisted pair audio (mic) cable?
I have a gig in the open air. The PA is being supplied by a DJ but his mixer is off stage (40ft trailer). Now I need two runs from the main outs of my mixer to the DJ's mixer.
I have shed loads of twin coax, i.e. two shielded cables in the same insulated PVC outer insulator. The two conductors are shielded by braid and the braids are touching along the length o fthe cable. So my query is can I use this balanced via XLRs or would I lose a lot of the interference rejection that you get from a shielded twisted pair audio (mic) cable?
Most of the interference rejection comes from the balanced impedance a good balanced source and balanced receiver have. The braids are pretty much transparent for HF junk, but they help with mains hum.
The very best option would be two wires tightly twisted so they remain in very close approximation for balanced rejection, and then an overall braid against hum.
And make sure the source and receiver are properly impedance balanced, otherwise it's all for nothing.
Jan
The very best option would be two wires tightly twisted so they remain in very close approximation for balanced rejection, and then an overall braid against hum.
And make sure the source and receiver are properly impedance balanced, otherwise it's all for nothing.
Jan
Does you mixer have balanced XLR or TRS outputs?
What mixer is he providing?
The ideal situation would be XLR out from your mixer to balanced line inputs on his mixer but it's pretty rare to find that on a DJ mixer and you definitely do not want to connect to the mic inputs... those are notoriously poor quality on DJ consoles... even on those expensive Pioneer versions. So the second best option is to use whatever line output and line input that is available on either end with a device like the ART DTI inserted between them to isolate both systems, this will eliminate the possibility of a ground loop and any noise that may be induced in the wires. I use one of these any time I encounter this situation, in your case if your mixer has balanced outputs the DTI should be placed right next to the providers mixer, long XLR cables connect from your mixer to the DTI and short unbalanced cables connect from the DTI to the providers mixer.
What mixer is he providing?
The ideal situation would be XLR out from your mixer to balanced line inputs on his mixer but it's pretty rare to find that on a DJ mixer and you definitely do not want to connect to the mic inputs... those are notoriously poor quality on DJ consoles... even on those expensive Pioneer versions. So the second best option is to use whatever line output and line input that is available on either end with a device like the ART DTI inserted between them to isolate both systems, this will eliminate the possibility of a ground loop and any noise that may be induced in the wires. I use one of these any time I encounter this situation, in your case if your mixer has balanced outputs the DTI should be placed right next to the providers mixer, long XLR cables connect from your mixer to the DTI and short unbalanced cables connect from the DTI to the providers mixer.
I used Bt telephone cable. Four core twisted pairs on a 250mtr roll.
Never had any issues running very long cables but find an RF link the best way.
Never had any issues running very long cables but find an RF link the best way.
Just get a pair of transformers to use at line level. Do the bal to unbal right there at the DJ mixer inputs. The $65 1:1 Hammonds with the Mu metal shields are good enough for hi-fi, you can get cheaper Triads that work ok as long as you drive from a LOW Z source. You can make up a little adapter box with the proper jacks. Tools like that are always good to have on hand on the sound business.
The device I provided a link to above is exactly what you suggested.. a dual transformer isolater packaged will the 3 most common types of audio connectors... RCA, XLR, TRS.
I should have said that the Mixer is a Soundcraft Ui16 so balanced O/P on both XLR and TRS jack. There will be a 1-1 isolation transformer at the DJ mixer end with short unbalanced cables to the DJ mixer.
Well that is not a "DJ mixer" it's a live sound mixer with lots of high quality input channels so no problem there. If your mixer has XLR or TRS outputs you could likely directly connect them with no issues, but a xfmr isolator is never a bad idea.
I don't like the idea of using DIY cables for this.. safer to use a know commodity. If the provider has the above equipment chances are he will also provide a pair of long cables to connect your rig to the system.
I don't like the idea of using DIY cables for this.. safer to use a know commodity. If the provider has the above equipment chances are he will also provide a pair of long cables to connect your rig to the system.
The Ui16 is my mixer. The DJ has a DJ mixer and only has unbalanced line inputs.
However he does have 10K power amps and JBL/EV cabs to go with them,
However he does have 10K power amps and JBL/EV cabs to go with them,
Well OK then. Definitely pickup one of the ART boxes I suggested and keep the unbalanced cables as short as practically possible, and try to keep the signal levels on that feed at around 0dBu(-18db FS), the Dj mixer won't have anywhere near as much signal headroom as your Soundcraft.
For 40 ft (12m) runs I wouldn't be concerned about interference unless the cables run near heavy Amperage power cables. I have a twin balanced cable roll with 150ft (~50m) which I use sometimes in weddings connected to unbalanced mixer or DJ consoles boot outputs to feed powered speakers in another room or garden. Use good quality RCA cables or use XLR / Jack to RCA cables but made with balanced mic cable. I would however try to power all from the same outlet to minimize ground loops. The goal is to inject Voltage in them and that means faders high and masters just loud enough.