I entered the world of church sound guy and video streamer a few months ago (I got drafted but wanted to help). I 'm a volunteer. I have an IT background and built an FM receiver from scratch a long time ago but have much to learn about mixers, streaming, and more,
Roughly 150 people attend. Rural, no rock band, lots of hard wood and sheet rock surfaces, overhead HVAC, etc. The sound booth is at the back of the church. Microphones and speakers are about 75' of away as the wiring goes.
Someone in earlier days switched from wired microphones to wireless microphones and left a bundle of XLR cables in place. That bundle contains 20+ individual cables; one of which is still used for one remaining wired mic. In this bundle are also four cables that connect to powered speakers (two stage monitors and two wall mounted speakers).
All of the cables that are not used are not connected to anything at either end. They float. Should I be grounding these unused cables at one end? If so, suggestions for an easy and/or inexpensive way to do this? There is no way to pull out these cables from the bundle without a lot of (painful maybe) work.
Thank you.
John
Roughly 150 people attend. Rural, no rock band, lots of hard wood and sheet rock surfaces, overhead HVAC, etc. The sound booth is at the back of the church. Microphones and speakers are about 75' of away as the wiring goes.
Someone in earlier days switched from wired microphones to wireless microphones and left a bundle of XLR cables in place. That bundle contains 20+ individual cables; one of which is still used for one remaining wired mic. In this bundle are also four cables that connect to powered speakers (two stage monitors and two wall mounted speakers).
All of the cables that are not used are not connected to anything at either end. They float. Should I be grounding these unused cables at one end? If so, suggestions for an easy and/or inexpensive way to do this? There is no way to pull out these cables from the bundle without a lot of (painful maybe) work.
Thank you.
John
Is there a specific problem you are trying to address? Normally the cables in use will be adequately shielded and being balanced should not be susceptible to hum and buzz pick up.
I have been chasing hum problems with the wall mounted speakers. With the Yamaha MGP24X mixer powered off, Yamaha DXR15 wall mounted speakers powered on, and Harbinger APS15 stage monitors powered on we hear hum from the wall mounted speakers but the stage monitors are quiet.
The wall mounted speakers are powered from different outlets than the stage monitors. The wall mounted speakers get turned on / off by switches like those in a house.
I have tested outlet wiring with an outlet tester and everything checked out fine. It is my understanding that power for the wall mounted speakers and stage monitors come from different breaker boxes.
If I power the wall mounted speakers temporarily off the same power as the monitor speakers - no hum. Due to physical layout it is not possible to get power to the wall mounted speakers using the same power source as the monitors.
Seems like ground loops or poor AC power wiring are the possible causes? I didn't know about floating cabling and wanted to know what to think about what we know and hear.
Make sure both ends are actually wired correctly and are actually balanced. (No unbalanced connection at the source or speaker?) An electrician should probably check out the AC wiring to the wall speakers. Line bridging transformers that isolate the mixer from the speakers are a possible fix. WE115C "repeater coils" still show up at hamfests for cheap money and are excellent broadcast quality line to line transformers and will pass 20 - 20kHz signals IME. (I have a few)
How hands on are you? Able to check internal wiring, etc?
How hands on are you? Able to check internal wiring, etc?
Not afraid to get my hands dirty, learn, solder, tune for smoke, work on 110, etc. I have never tested an XLR cable, though. That will be more "fun" to do given the connectors are 75 feet apart. DVM probes usually don't reach that far!
If an XLR cable has hot and cold wires switched or one wire is broken how does that manifest itself to the listener? Or does it?
Edit:
Just discovered "XLR Sniffer/Sender Microphone"... 🙂
Try to connect the monitors and the wall speakers ("FOH") the other way around. As if the monitors were the FOH and vice versa. What happens then? If the hum remains in the Yamaha's, it's there. If the hum appears in Harbingers, it is in the wiring and/or mixer.
To test for continuity, at one end short together pins 2 and 3. At the other end measure the resistance between 2 and 3.
If you get a low ohms value, there is continuity. Also check 1/3 and 1/2 in the same way.