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Author Topic: Whirlwind splitter help!!!  (Read 2992 times)

Chuck Fudge

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Whirlwind splitter help!!!
« on: January 25, 2013, 12:36:07 pm »

we have a 40 in/16 out split that I have been fighting with for 7 years.  Previously this unit has been at whirlwind....they replaced the 3 MASS 4 connectors; 1 trunk out, 2 iso out.  The original MASS connectors failed from some sort of organic growth that caused shorting when 48v was applied. 

Still things have not been perfect, and the issues where hard to track.  So to help diagnose I purchased a new MASS trunk cable for house connect, and a new MASS fan out for monitor.  The FOH trunk wires to a AVID stage rack/Venue system.

Today we connect the MASS fan out to monitor console.  NO CONNECTION TO HOUSE...just the fan out to monitor from splitter ISO out..  I notice a buzz in channel two, but all other channels seem to be quiet.  The ground lift switch on the split cleans up channel two.   OK...I think there must be a broken solder point/ground issue somewhere.  THIS IS WERE IT GETS WEIRD.  I can actually tap the splitter metal casing and hear it through channels of the console.  I can speak into the mic jacks on the splitter and hear it through channels of the console.
This is with a few channels gained up and faders at -0-.  No mics....nothing plugged into the splitter.  Its like the whole splitter has become a crown PZM mic!!!!!   No 48v on...no connection to house....just splitter and monitor fan out.

Monitor console set up is MIDAS Sienna, mix 1 output to Crown 5000hd,  VUE a-12.

If anyone has any ideas...please help.  I could make a short phone movie and email if that would help.  

My concern....when we build a show through the split.....more bad shit will happen.
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Greg_Cameron

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Re: Whirlwind splitter help!!!
« Reply #1 on: January 25, 2013, 12:54:35 pm »

Try banging on the blue Belkin cable itself at different points to see if that noise is coming through. I wonder if maybe the shield inside are shorting together and getting microphonic on you.
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Geoff Doane

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Re: Whirlwind splitter help!!!
« Reply #2 on: January 25, 2013, 01:49:07 pm »

It sounds like the splitter, and possibly the cable, is just microphonic.  This happens with foil shielded cables because they don't have fillers in between the conductors.  Fillers keep the distance between the conductors constant when the wire is moved.  Because of the capacitance between the conductors, if they move, you get the same effect as a condenser microphone (in Europe, they call them "capacitor" microphones, or at least they used to).  Foil shielded wire doesn't normally have fillers because it's not usually moved once it's installed.

The effect is worse than it would be normally because you don't have a microphone terminating the end of the mic line.  I'll bet you dollars to donuts (which are just about on par these days) that plugging a mic in the input will make the effect disappear.  Use a condenser mic, but leave the phantom off, that way they mic will terminate the line but not make any noise of its own.  An in-line XLR barrel pad would work too.  Phantom won't pass through the ISO output anyway.

The buzz on channel two is likely because it had no ground on the splitter side of the transformer.  Connecting the ground stopped the shield from just floating in the air.  If you actually lifted the ground and the buzz went away, then something else is going on.  Generally speaking: buzz = no ground; hum = too many grounds.

FWIW, I've gone through the same problem with the MASS inserts.  I used several NOS W3 panel connectors in a project, and less than a year later they were unusable with phantom power.  I wound up replacing them with some even older Cannon parts that have been OK, so far.  Seems like Whirlwind had a bad batch about 15 years ago.
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Chuck Fudge

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Re: Whirlwind splitter help!!!
« Reply #3 on: January 25, 2013, 04:26:03 pm »

It is microphonic.   The fan out does the same thing in the dog house.....producing noise when moved around..   I have never come across this...and you are right.....I'm sure that it will go away when terminated.  I have had some many issues with this system....first being the bad MASS connectors produced around 1996.  Our whole inventory had the same date tag.

to insure we will not have additional problems....we are going to pull out a bunch of mics and W1/boxes and connect.  Then test.
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Chuck Fudge

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Re: Whirlwind splitter help!!!
« Reply #4 on: January 28, 2013, 03:39:04 pm »

All is well.  Once connected to microphone sources the microphonic tendencies went away.  Our channel two issue ended up being a bad punch on the MASS 4 punch block on our house input panel.

The explanation regarding the microphonic issue makes sense.....never experienced this first hand.


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Al Keltz

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Re: Whirlwind splitter help!!!
« Reply #5 on: January 28, 2013, 04:03:19 pm »

We get this call fairly often, even with simpler Medusa snakes. Because of the open source, your snake can get microphonic and be a pretty good "antenna" when unterminated.

Glad it worked out.

- Al
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Chuck Fudge

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Re: Whirlwind splitter help!!!
« Reply #6 on: January 29, 2013, 10:56:00 am »

We get this call fairly often, even with simpler Medusa snakes. Because of the open source, your snake can get microphonic and be a pretty good "antenna" when unterminated.

Glad it worked out.

- Al

Thanks for the assurance.

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ProSoundWeb Community

Re: Whirlwind splitter help!!!
« Reply #6 on: January 29, 2013, 10:56:00 am »


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