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Author Topic: microphones combined incorrectly  (Read 2918 times)

Gary Fitzpatrick

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microphones combined incorrectly
« on: November 03, 2012, 04:10:25 PM »

I have started doing some maintenance work on the installed PA system in my local church. This particular system was installed before I started working for the church so I had nothing to do with the installation. This is a fairly basic system, turn on and let go, completely operatorless system.

The system is based around a BSS London BLU-16 DSP. There are a total of 14 microphone points around the church, which are wired into 8 inputs on the Soundweb. The original installer has wired two microphones into one input a number of times. Normally this is not a problem, as during a normal service only 4 microphone points are used.

During a recent service, I plugged in an extra microphone (Sennheiser e835, same as the normal microphone), and a strange anomaly occurred. When the switch was flicked on the first microphone it would not work, however when the switch was flicked on the second microphone, both mics worked normally. I am guessing that the two points in use during this service were wired back to the same input on the BLU unit. Is there any way to stop this happening? Or is a proper microphone combiner unit the only solution?
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Mac Kerr

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Re: microphones combined incorrectly
« Reply #1 on: November 03, 2012, 04:52:37 PM »

I have started doing some maintenance work on the installed PA system in my local church. This particular system was installed before I started working for the church so I had nothing to do with the installation. This is a fairly basic system, turn on and let go, completely operatorless system.

The system is based around a BSS London BLU-16 DSP. There are a total of 14 microphone points around the church, which are wired into 8 inputs on the Soundweb. The original installer has wired two microphones into one input a number of times. Normally this is not a problem, as during a normal service only 4 microphone points are used.

During a recent service, I plugged in an extra microphone (Sennheiser e835, same as the normal microphone), and a strange anomaly occurred. When the switch was flicked on the first microphone it would not work, however when the switch was flicked on the second microphone, both mics worked normally. I am guessing that the two points in use during this service were wired back to the same input on the BLU unit. Is there any way to stop this happening? Or is a proper microphone combiner unit the only solution?

Use mics without switches. The switch is shorting the line when it is in the off position. This will happen through a transformer combiner as well.

The best solution is to map out which inlet jacks are combined at the Soundweb inputs and don't use both jacks on one input. Somewhere there should be 8 unique inputs.

Mac
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David Sturzenbecher

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Re: microphones combined incorrectly
« Reply #2 on: November 04, 2012, 10:04:31 AM »

I have started doing some maintenance work on the installed PA system in my local church. This particular system was installed before I started working for the church so I had nothing to do with the installation. This is a fairly basic system, turn on and let go, completely operatorless system.

The system is based around a BSS London BLU-16 DSP. There are a total of 14 microphone points around the church, which are wired into 8 inputs on the Soundweb. The original installer has wired two microphones into one input a number of times. Normally this is not a problem, as during a normal service only 4 microphone points are used.

During a recent service, I plugged in an extra microphone (Sennheiser e835, same as the normal microphone), and a strange anomaly occurred. When the switch was flicked on the first microphone it would not work, however when the switch was flicked on the second microphone, both mics worked normally. I am guessing that the two points in use during this service were wired back to the same input on the BLU unit. Is there any way to stop this happening? Or is a proper microphone combiner unit the only solution?

Are you able to identify where these mic lines are "paralleled"?  If it is at the input to the processor you have some more (not free) options.

How many outputs are you using on the BLU-16, if 4 or less, an input card can be added/swapped out, this would allow for 12 mic inputs at one time.

A patch bay/panel could provide you will the flexibility to use any jacks at the same time as long as your total is 8 inputs (with your current processor I/O).

If these jacks are paralleled at the input plate location your best bet is to simply map out the inputs as already described.
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Gary Fitzpatrick

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Re: microphones combined incorrectly
« Reply #3 on: November 05, 2012, 07:21:51 AM »

Are you able to identify where these mic lines are "paralleled"?  If it is at the input to the processor you have some more (not free) options.

How many outputs are you using on the BLU-16, if 4 or less, an input card can be added/swapped out, this would allow for 12 mic inputs at one time.

A patch bay/panel could provide you will the flexibility to use any jacks at the same time as long as your total is 8 inputs (with your current processor I/O).

If these jacks are paralleled at the input plate location your best bet is to simply map out the inputs as already described.

Thankfully they are paralleled at the DSP...the tie lines all come into the back of the control cabinet seperatly so I have some flexibility. My biggest problem to making changes at the present moment in time is that the original installer has password protected the DSP, and so far does not seem too keen to let out the password for me to gain access.
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Brad Weber

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Re: microphones combined incorrectly
« Reply #4 on: November 05, 2012, 11:10:38 AM »

My biggest problem to making changes at the present moment in time is that the original installer has password protected the DSP, and so far does not seem too keen to let out the password for me to gain access.
Are they in any way still responsible for the system through a system warranty, service contract or similar?  That is often the dilemma, the Owner has padi for the system and should be able to do what they want with it but if there is any related responsibility by another party then that needs to be considered, especially in regard to the terms that were agreed to when that responsibility was assumed.
 
A less obvious factor is that the installer may end up being associated with the results of any modification even if they had nothing to do with them.  I once had a pastor threaten to "make sure I never worked in another church" because of problems that turned out to be the results of changes some unknown party, or at least none that would admit to it, had made to the system wiring and processing.  Ironically, when I was later with another firm we were hired to get the system to work properly, all we did was pull out the original drawings and programming and return everything to the original state and the same person was apparently very happy with us.  So if they were asked the original company got bad feedback due to something that others did while the second company got good reviews for simply returning the system back to the original conditions.  That's an example of why I am always wary of feedback provided by others without also knowing the full story.
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Re: microphones combined incorrectly
« Reply #4 on: November 05, 2012, 11:10:38 AM »


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