Seriously weird sound system

soundtech193746

Active Member
Hello!

As I've previously posted, we are upgrading a junior high's audio system. This is great although, we are having seriously weird sound issues. We have a fixed install (TOP: 2 Sennheiser Wireless Mics, Crestron Touch Panel, Assisted Hearing, CD, Bluray, DSP, Monitor amps.

The issue i think we're having is with the DSP. Anytime I close the rack up/lock it, the DSP gets weird hissing sounds going in to the input indicator lights on the dsp. Also, the BluRay will only play the video but audio will randomly come through. (I forgot to mention that the BluRay is on a distributed network for the projector in back of AUD.)

Anyone know what's going on? The DSP is the BSS Audio Soundweb London BLU-100 12x8 Signal Processor
 
Are the mic antennas in the rack?

Is this a pro install, or an internal project?

Lots of other questions, but I’m sure someone here can get this sorted out with a few more details
 
Gonna need more information, probably photos, to diagnose this more. Front of the rack, back of the rack, inside of the rack door, close-ups on the wire terminations at the BSS, amps, and other devices.

My gut instinct is that if the rack door is metallic, you either have a grounding or an RF problem. If it's a grounding problem, it could be a safety ground issue on your rack or power cabling, or a signal ground issue on your audio cabling.

I would double check that the rack door is grounded and that the equipment rack is grounded. Assuming this is a metallic wall or floor rack, you should have a dedicated equipment grounding conductor, probably a single green wire, that's tied into the back of the rack. Then from the main rack to the front door should be a short jumper wire to electrically bond the door to the rack frame.

If your assistive listening system has a local antenna, you want to make sure it's outside of the rack. If it's a local antenna and you close the door on it, that could be causing some of your issues.

Few questions:
  • Is it a couple inputs or all of the inputs on the BSS that light up?
  • If you turn the ALS transmitter off, does the problem go away when you close the door?
  • How is the Blu-Ray on a "distributed network"? Does it use long HDMI cables, or does it use HDMI extenders? Does it use HDMI over Ethernet extenders that connect to a traditional network switch?
  • How is the audio for the Blu-Ray player hooked into the sound system? Is there a pair of wires coming off of the Blu-Ray or an HDMI extender into the BSS, or is there a pair of wires coming into the BSS that's plugged into the audio out connector of the projector?
  • Have you visually inspected the wires at the BSS and at the projector and "jiggled the handle" to see if that affects the problem in any way? It sounds like maybe a wire isn't fully terminated or possibly a wire is shorted.
 
Are the mic antennas in the rack?

Is this a pro install, or an internal project?

Lots of other questions, but I’m sure someone here can get this sorted out with a few more details

This was a pro install. What details you need? I can provide you them
 
Gonna need more information, probably photos, to diagnose this more. Front of the rack, back of the rack, inside of the rack door, close-ups on the wire terminations at the BSS, amps, and other devices.

My gut instinct is that if the rack door is metallic, you either have a grounding or an RF problem. If it's a grounding problem, it could be a safety ground issue on your rack or power cabling, or a signal ground issue on your audio cabling.

I would double check that the rack door is grounded and that the equipment rack is grounded. Assuming this is a metallic wall or floor rack, you should have a dedicated equipment grounding conductor, probably a single green wire, that's tied into the back of the rack. Then from the main rack to the front door should be a short jumper wire to electrically bond the door to the rack frame.

If your assistive listening system has a local antenna, you want to make sure it's outside of the rack. If it's a local antenna and you close the door on it, that could be causing some of your issues.

Few questions:
  • Is it a couple inputs or all of the inputs on the BSS that light up?
  • If you turn the ALS transmitter off, does the problem go away when you close the door?
  • How is the Blu-Ray on a "distributed network"? Does it use long HDMI cables, or does it use HDMI extenders? Does it use HDMI over Ethernet extenders that connect to a traditional network switch?
  • How is the audio for the Blu-Ray player hooked into the sound system? Is there a pair of wires coming off of the Blu-Ray or an HDMI extender into the BSS, or is there a pair of wires coming into the BSS that's plugged into the audio out connector of the projector?
  • Have you visually inspected the wires at the BSS and at the projector and "jiggled the handle" to see if that affects the problem in any way? It sounds like maybe a wire isn't fully terminated or possibly a wire is shorted.

It is only a couple inputs.
I never tried turning off the ALS transmitter but will try that tonight
Since signal degradation would occur with how long the run is, there is an unbranded "Distributed Network System" installed in to the rack that interfaces with the DSP (BSS) and projector. But I would gess that it is "HDMI Over Ethernet". I will provide pictures tonight.
It comes out of the Blu-ray into the bss directly because you have to select BluRay on the touch panel.
Yes, sometimes if I just push on the front of the BSS it will push signal then stop. Sounds like wires aren't terminated. I will check them out when I can find keys that work for it cause it seems like my rack door key doesn't work in it, maybe I have to jiggle it a little bit to get it to open.

To answer your question about rack materials, it is a Middle Atlantic metallic rack. The wall it is mounted on is brick.

:)

Thank you!
 
Hello!

As I've previously posted, we are upgrading a junior high's audio system. This is great although, we are having seriously weird sound issues. We have a fixed install (TOP: 2 Sennheiser Wireless Mics, Crestron Touch Panel, Assisted Hearing, CD, Bluray, DSP, Monitor amps.

The issue i think we're having is with the DSP. Anytime I close the rack up/lock it, the DSP gets weird hissing sounds going in to the input indicator lights on the dsp. Also, the BluRay will only play the video but audio will randomly come through. (I forgot to mention that the BluRay is on a distributed network for the projector in back of AUD.)

Anyone know what's going on? The DSP is the BSS Audio Soundweb London BLU-100 12x8 Signal Processor

Which input meters show a signal when the hissing sound happens? All of them? The unit has 12 available inputs and it sounds like you have 6 inputs in use - 2 wireless mics, L/R from CD and L/R from DVD so if all 12 meters show signal I'd have the installer back out to see why (maybe a physical input has been assigned to all 12 processing inputs, or the unit needs warranty service/replacement) or there's an RF or grounding issue as @MNicolai suggests.

That you mention in a followup that if you push on the DSP face plate the noise will abate should be sufficient to get the installer back out...
 
Which input meters show a signal when the hissing sound happens? All of them? The unit has 12 available inputs and it sounds like you have 6 inputs in use - 2 wireless mics, L/R from CD and L/R from DVD so if all 12 meters show signal I'd have the installer back out to see why (maybe a physical input has been assigned to all 12 processing inputs, or the unit needs warranty service/replacement) or there's an RF or grounding issue as @MNicolai suggests.

That you mention in a followup that if you push on the DSP face plate the noise will abate should be sufficient to get the installer back out...

working on getting the installer back out here... It seems that unplugging the whole thing then plugins it back in has fixed it for the time being, however, it still has issues that will be repaired soon.
 
When you say that bluray audio will randomly come through - do you mean that it depends on the disc or scene playing or that it is intermittent within one thing playing?
 
When you say that bluray audio will randomly come through - do you mean that it depends on the disc or scene playing or that it is intermittent within one thing playing?

It’s intermittent. Doesn’t matter on the scene. We tried multiple discs too
 
The DVD input is probably gated and the threshold is set too high. Gating turns off the input when it doesn't sense audio exceeding the threshold.

DVD audio levels are all over the map. Cutting in and out is what would happen if the installer made adjustments by playing a hotter than average disc. It would be better to test with a disc that has low very audio levels. Better yet, a disc with 400 Hz test tone at -60 dBFS. That tone would be faint, but should still open the gate.
 
The DVD input is probably gated and the threshold is set too high. Gating turns off the input when it doesn't sense audio exceeding the threshold.

DVD audio levels are all over the map. Cutting in and out is what would happen if the installer made adjustments by playing a hotter than average disc. It would be better to test with a disc that has low very audio levels. Better yet, a disc with 400 Hz test tone at -60 dBFS. That tone would be faint, but should still open the gate.

The only thing is that it used to work
 
So what changed? Did it happen after a show or after some kind of "different" event?

Either somebody messed with settings or physically damaged the London, or you had a statistically unlikely electronic failure.
 
So what changed? Did it happen after a show or after some kind of "different" event?

Either somebody messed with settings or physically damaged the London, or you had a statistically unlikely electronic failure.

After a group rented out the space it hasn’t worked since
 
{lights pipe, puts on "Hemlock Stone's" deerstalker hat}

"I think we're on to something..."
 

Users who are viewing this thread

Back