Hello, everybody. Hoping to tap your knowledge.
My church has a combination of some rather old technology, and some very nice, modern stuff, specifically a DSB-based mixer. Everything is working just fine, except .. ..
We have a very annoying occasional POP through the speakers. We've had this for a long time, since the "new" system was installed. The DSP manufacturer has heard the problem, but doesn't think it's in his system.
I've replaced the amp on the speakers with no change, so I'm pretty sure it's not that.
I've run the system with all inputs disconnected at the DSP, and we still get the pops, so I'm pretty sure it's not the mics, wireless receivers or cabling. As far as I can tell, all that's left is the DSP or power-line.
We can send the DSP in for repair, but I expect to simply get it back with a "no problem found" if we do that.
Is there a reasonably easy way to monitor the power line for spikes? If we can do that, perhaps we can find what's causing it.
thanks
My church has a combination of some rather old technology, and some very nice, modern stuff, specifically a DSB-based mixer. Everything is working just fine, except .. ..
We have a very annoying occasional POP through the speakers. We've had this for a long time, since the "new" system was installed. The DSP manufacturer has heard the problem, but doesn't think it's in his system.
I've replaced the amp on the speakers with no change, so I'm pretty sure it's not that.
I've run the system with all inputs disconnected at the DSP, and we still get the pops, so I'm pretty sure it's not the mics, wireless receivers or cabling. As far as I can tell, all that's left is the DSP or power-line.
We can send the DSP in for repair, but I expect to simply get it back with a "no problem found" if we do that.
Is there a reasonably easy way to monitor the power line for spikes? If we can do that, perhaps we can find what's causing it.
thanks
Disconnect the mixer from the amps and make sure that the pop goes away.
The other thought if the amps are exonerated might be to plug the mixer and supporting hardware to a good EMI power filter.
The other thought if the amps are exonerated might be to plug the mixer and supporting hardware to a good EMI power filter.
I thought replacing the amp with one that's been doing service at home for 20 years without a single pop pretty much eliminated the amp as a problem, but thanks for the advice. We can certainly try it Sunday after service.
jay
jay
Turn on just the amp. Wait a bit then the DSP. Then the mixer. Be freaking sure that all units are firmly plugged in. An incandescent lamp is a great power line drop out indicator.
Normal cause of pops in church systems is first that a wireless mic receiver is on without a matching transmitter. Second is a phantom power mic with loose connections. Third is a boundary mic that got hit with spray cleaner on the capsule. So if you pulled all the mic lines you have ruled out all the common problems.
Another quick check is what the mixer meter shows when you get the noise.
Normal cause of pops in church systems is first that a wireless mic receiver is on without a matching transmitter. Second is a phantom power mic with loose connections. Third is a boundary mic that got hit with spray cleaner on the capsule. So if you pulled all the mic lines you have ruled out all the common problems.
Another quick check is what the mixer meter shows when you get the noise.
The mixer is part of the DSP. There's no meter on it unless I connect up my laptop, then it's a slow thing. . .
Yes, we will try with the DSP off. I may need to rent a power line logger, too, or just get a line conditioner and give that a try.
Yes, we will try with the DSP off. I may need to rent a power line logger, too, or just get a line conditioner and give that a try.
Just try to get pa to sort out your church popsystem, preferably on a saturday night. It will probably sound awesome and glitchfree early sunday morning. In the unlikelyhood it doesn't, look for alternative farther. Anywho....DSP does that.
Yes, we can hear the system coming on and turning off, and the pops are unrelated to that. One of our first thoughts, actually. Thanks!
jay
jay
One of the reasons why I suggested making sure first that the power amp regardless of which one is installed is not picking up emc from HVAC or something else nearby.
Kevin, we'll try it. There's nothing electronic nearby the PA system, it's hidden under the choir loft in a very nice cubby. I'll have more testing done Sunday after service. We can test with the DSP off, and that'll tell us something. I have a powerline filter we may try, too.
One of our members suggested that the fire station across the street might be causing RF interference, but I'd expect more pops and some correlation with them roaring out.
One of our members suggested that the fire station across the street might be causing RF interference, but I'd expect more pops and some correlation with them roaring out.
How many inputs on the mixer? Is it a digital mixer or analog with a DSP processor. Also what make and model is the mixer?
Um, 3 wireless mics, 3 wired mics, a line pair. I think that's it. It's a digital mixer/dsp processor. It's a Biamp Nexia CS system: Biamp Professional Audio Systems - Nexia CS
Put the unit on a ups. If the problem persists ask to exchange the unit for a new one. Biamp is a reputable manufacturer and should do that.
Power amplifiers may pick up rf but I have never heard random impulse noise.
Power amplifiers may pick up rf but I have never heard random impulse noise.
A nearby FM transmitter being keyed can create plops even when the modulation is not heard. Radio hams, CB etc?
The original post said occasional pops. Now with several thousand sound system installs under my belt I have never encountered the issue with transmitters causing an occasional noise.
FM transmitters used for two way communication by either amateur radio, commercial or life safety services would be of modest power, rarely used on Sunday morning and most importantly be a series of modulations.
FM transmitters do not demodulate if the receiver bandwidth is flat. Any tilt and there will be AM components. Not the usual case for interference.
Now a digital system including a signal delay could have a bad memory bit that would cause a step impulse when that location is addressed and the information is not the default data.
I am surprised to hear that where you are amateur radio is rarely used on Sunday morning. 'Modest power' could be 50W, which is enough to have an effect. As a typical audio system can't demodulate FM, and a good FM transmitter will have little AM, the only effect will be a DC shift caused by AM detection of the RF carrier. This could sound exactly like a plop - it would depend on the accidental detector and the rise time of the carrier.simon7000 said:
Again unless the receiver's bandwidth is flat there will be what is called slope demodulation. So you would even demodulate FM.
50 watts even across the street from the church in unlikely to affect the gear in question.
50 watts even across the street from the church in unlikely to affect the gear in question.
The sounds in question are sharp "pop" sounds, of varying intensity. Not what I would characterize as a "plop". To me, it sounds more like a static discharge. I'm going to run the system tomorrow after service without the DSP, just the amps live. Also going to try my line filter if I can find it.
Thanks for all the inputs, I really appreciate it.
jay
Thanks for all the inputs, I really appreciate it.
jay
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