Balanced output provided for webcast connections

Conversations around originating a webcast for conference, including cameras and mixers.
rogerscr
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Balanced output provided for webcast connections

Postby rogerscr » Tue Apr 09, 2013 10:35 am

I am in the process of setting up our Webcast system and have been doing some test runs and have come to realization that the 'webcast output' provided in the satellite closet is balanced line level, not the unbalanced line level PCs (including the Webcast Communicator) are designed for. This leads to hot audio that distorts if you don't make adjustments. For more info on unbalanced vs balanced see Wikipedia. For now I have gone into the audio properties in the Webcast Communicator and turned the input level down to ~20% and that seems to be working. I fear this solution is limiting our sound quality and dynamic range but won't know for sure until our first webcast.

It seems odd to me that this hasn't been taken into account by CHQ when designing the new digital sound systems with audio and video outputs for recording. At one of my old building the audio DA had gain controls on each output so I was able to turn it down to improve our VCR and DVD record quality. The audio DA we have now doesn't have this feature. I have found devices like this one http://www.rdlnet.com/product.php?page=504 that are designed for this purpose but this one is a bit spendy and I would have to cut the leads for the binding post input. There are cheaper units but they all take XLR input. I hope CHQ realizes this issue and will fix it for future installs.

I am looking to make our setup simple for use so I am trying to avoid a mixing board that needs to be setup and taken down. Having the mixing board in the closet while the camera is in the chapel is also difficult. I would think putting in a converter should remove the need for continual monitoring. I have noticed the new digital sound system seem to do some normalizing of the mic audio on their own so the output should need little control. Has anyone tried such a balanced to unbalanced converter (purchased or built)? Is it a hands off solution like I hope? Maybe CHQ can add one of these to the standard equipment list for a simple solution.

russellhltn
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Re: Balanced output provided for webcast connections

Postby russellhltn » Tue Apr 09, 2013 11:21 am

Is the problem really balanced vs unbalanced or is it "pro level" vs "consumer level"? I suspect it's the latter. I've got some short RCA cables that are attenuators that fixed that problem for me back when the satellite receivers cranked out "pro level" and caused problems with our "consumer" VCRs.

As for the mixer, I'll bet you'll end up with one anyway. The house system typically doesn't do that good a job capturing the organ and choir. So you'll likely need additional mics and feed them into a mixer to have a better sounding broadcast during the musical numbers.

I see a number of users are using remotely controlled cameras. It has the advantage of having a smaller "foot print" in the chapel then a manned camera would have. That solves the problem of having controls in different places.
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rogerscr
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Re: Balanced output provided for webcast connections

Postby rogerscr » Tue Apr 09, 2013 11:39 am

Pro = Balanced
Consumer = Unbalanced
So really it is 2 names for the same thing. The Wikipedia article goes into it more.

We got a single mounted camera as well but I am working hard to avoid being stuck in the 'recording booth' in the library, I would prefer to be in the chapel. The audio quality may not be perfect for musical numbers but I am hoping a few extra mics (for those conferences when we have them) will suffice. We have a regional choir that performs out of our building so they may choose to use a mixer but I really don't want to be in the booth if I can avoid it.

PS For the camera I am looking at connecting the serial camera connection to the Webcast Communicator and use VNC to remote control the camera control software from the chapel.

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johnshaw
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Re: Balanced output provided for webcast connections

Postby johnshaw » Tue Apr 09, 2013 12:01 pm

Couple of notes on the New Design of Chapels (The 9-phase building that is the norm these days outside of the Mormon Corridor) - Tech closet is tuned perfectly for the webcast, a Video post is right there as well as a 'mic-level' input. There is an IR repeater into the tech closet that controls the mounted PTZ camera mounted in the chapel.

The video switch allows for multiple inputs (I've played a video from a computer and a video from a dvd over the webcast) - it still feels like A/B switching, but should do for even the most technically weak stakes to webcast to other meetinghouses fairly easily.

It does not have a design that works 'out-of-the-box' for multiple cameras, I was able to get them to run me some conduit for a 2nd camera (had to intervene during the build phase), but have not felt the need to mount one as we use the current mounted one with a separate camera (we bring the feed back to the closet through an 'output' in the cultural hall)
“A long habit of not thinking a thing wrong, gives it a superficial appearance of being right, and raises at first a formidable outcry in defense of custom.”
― Thomas Paine, Common Sense

russellhltn
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Re: Balanced output provided for webcast connections

Postby russellhltn » Tue Apr 09, 2013 12:39 pm

rogerscr wrote:Pro = Balanced
Consumer = Unbalanced
So really it is 2 names for the same thing. The Wikipedia article goes into it more.


That's a gross oversimplification. Balanced vs. Unbalanced is a reference to "ground". The level is "what is 0 VU audio". The Nominal levels part covers this. Plugging a "Pro" device into a consumer device means your feeding a 1.737V signal into something that's expecting a 0.447V signal.

Balanced is usually "pro", but you can have (and I have seen) "Pro" levels on a unbalanced. That's why I'm saying it's NOT the same thing. Any adaption needs to deal with both aspects of the problem.

On top of that is the issue of impedance (600 ohms vs 10K ohms). But you can usually ignore that unless you're trying to feed "pro" with a "consumer" device.
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rogerscr
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Re: Balanced output provided for webcast connections

Postby rogerscr » Tue Apr 09, 2013 12:57 pm

True, they tend to be called the same in sales material because the connectors are often balanced and unbalanced appropriately. Given the RCA connection in the satellite cabinet I would have to say we have pro level unbalanced being fed into consumer level unbalanced. Is there an easy in-line device (maybe with gain and a clip LED) that will fix this issue? Is this something I can request from FM? Will this fix the latent hum?
Last edited by rogerscr on Tue Apr 09, 2013 1:12 pm, edited 1 time in total.

russellhltn
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Re: Balanced output provided for webcast connections

Postby russellhltn » Tue Apr 09, 2013 1:11 pm

I can't say as I've heard of anything you can buy, but if you're handy with a soldering iron, take a look at this post

I double-checked the math with the Wiki article, I think my original values works best.
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rogerscr
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Re: Balanced output provided for webcast connections

Postby rogerscr » Tue Apr 09, 2013 1:40 pm

So use 3.3k and 2.2k resistors? Is the top lead with the inline resistor in your diagram the male center post of an RCA or the ring around it?

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Re: Balanced output provided for webcast connections

Postby russellhltn » Tue Apr 09, 2013 2:43 pm

rogerscr wrote:So use 3.3k and 2.2k resistors?


Yes. It may still be a bit hot, but not bad.

rogerscr wrote:Is the top lead with the inline resistor in your diagram the male center post of an RCA or the ring around it?


The bottom line is ground. This is designed for unbalanced, so the grounds are connected together. If I understand your question correctly, the answer the 3.3K connects to the center post of the RCA.
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rogerscr
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Re: Balanced output provided for webcast connections

Postby rogerscr » Tue Apr 09, 2013 3:47 pm

Would a simple attenuator in the 12db range do the same thing? I have found this on several online stores. http://www.amazon.com/Harrison-Labs-Lin ... 0006N41B0/


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