XLR1-Mic Backup not working

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paulgolden

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XLR1-Mic Backup not working

PostFri May 19, 2017 12:06 am

Besides my sensor related problems, I have an audio question, too.

According to the manual:

XLR 1 or 2 - Mic Backup
Use this setting to record audio from a microphone plugged into your URSA Mini Pro 4.6K's XLR 1 or 2 input at a lower level than the standard 'mic' recording. This can
be used to avoid audio clipping in the event of an unexpected increase in loudness. This feature will only be available as a selectable item if the XLR 1 or 2 input switch is set to 'mic'.


In my case, if XLR1-Mic+48V is selected on Channel 1 Source and XLR1-Mic Backup is selected on Channel 2, channel 1 records normally and there’s no signal on Channel 2. See the attached photo. The recording level on Channel 2 is grayed out and not selectable. My understanding is that channel 2 is meant to be somewhat lower as a protection channel. I don’t see anything working here.

Has anyone got this working properly? How many dB lower is this signal supposed be compared to Channel 1?
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BM Ursa Mini Sound - 1.jpg
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rick.lang

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XLR1-Mic Backup not working

PostFri May 19, 2017 4:22 am

That Audio Tab display is different than on the URSA Mini 4.6K. I know when I tried to set XLR2 to 85%, but then varied my audio Gain, the 85% is ignored, disappears as XLR2 levels matches XLR1. Operator error or feature not really implemented? I remember the webpages for the URSA Mini 4.6K, said you could do it for the same purpose, but it never worked for me. It's not called "XLR1 Backup" on the URSA Mini 4.6K camera.


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paulgolden

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Re: XLR1-Mic Backup not working

PostFri May 19, 2017 1:40 pm

Since I'm working with a Pro now, and the manual and software both imply this is meant to function, I'd be curious if other Pro users have managed get this working or would be willing to test this on their cameras.

The manual is vague about how much lower it's supposed to be. On other recorders with this function (my Marantz 661 e.g.) it's about 6dB lower.

When I do it on the UMP, I see a bit of low level activity on the 2nd channel and then nothing usable for gain.
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Chris Gosling

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Re: XLR1-Mic Backup not working

PostFri May 19, 2017 7:48 pm

I've experienced the same thing, but due to how busy I have been I just assumed that I had done something wrong and would look at it later.
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paulgolden

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Re: XLR1-Mic Backup not working

PostMon May 22, 2017 12:02 am

I got this reply from BMD support:

Regarding the XLR Mic Backup feature; when properly set, the second channel will bring in the original mic input signal at 20dB lower than the standard Mic input giving you extra headroom in case loud noises occur. The mic backup level is a fixed "line" level and does not follow the adjustments to gain levels on the standard mic input. Levels on the mic backup channel will be detected on the onscreen audio meters when the standard mic input channel exceeds 0dB.

I think this is not really explained in the manual fully. Also, I think it would be more useful if the amount of gain difference was user definable. It might also help to have a similar option for line in as well...
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rick.lang

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Re: XLR1-Mic Backup not working

PostMon May 22, 2017 6:00 am

This is not the way it (fails to) work on the URSA Mini 4.6K PL camera. Maybe it's a new way of implementing the same feature only on the URSA Mini Pro.


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OwenCrowley

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Re: XLR1-Mic Backup not working

PostSat Dec 02, 2017 12:47 am

Was this question ever settled? I am getting to know my new UMP (OS version 4.5). I have XLR2 attached with phantom engaged to a shotgun mic. XLR1 is configured to be a "mic backup". The physical switches for both XLR1 and XLR2 are set to "MIC".

I expected Channel 1 would be an attenuated duplicate of Channel 2. But outside on a test run, Channel 1 was silent except when a loud bus passed a few feet away. Channel 2 clipped, and Channel 1 registered a brief noise never exceeding -40db.
Mic Backup overage.jpg
Mic Backup overage.jpg (40.68 KiB) Viewed 223 times

This seems to be what BMD support described to paulgolden.

What are we supposed to do with this?
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Mike Potton

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Re: XLR1-Mic Backup not working

PostSat Dec 02, 2017 4:05 am

I agree, it's not a practical solution at all. The 'safe' channel is just as unusable as the clipped channel. Ironically it's way to quiet.

A negative -9db (defualt)/user selectable bracket much like Tascams implementation makes much more sense.

I wonder if someone has used this feature in situation at all, or if BMD would care to elaborate how it should be used practically.
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Denis Kazlowski

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Re: XLR1-Mic Backup not working

PostSat Dec 02, 2017 10:04 pm

Mike Potton wrote:I agree, it's not a practical solution at all. The 'safe' channel is just as unusable as the clipped channel. Ironically it's way to quiet.

A negative -9db (defualt)/user selectable bracket much like Tascams implementation makes much more sense.

I wonder if someone has used this feature in situation at all, or if BMD would care to elaborate how it should be used practically.


Aside from some sort of live event work where the house mix is sometimes too hot and too low at line level from the board I see zero utility in what this does now. I guess it can only collect audio before the pre-amp to ADC2 and after the pre-amp to ADC1 on same input. Meh. - Edge case feature that reads like a big deal on paper.
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Dennis Sørensen

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Re: XLR1-Mic Backup not working

PostMon Dec 04, 2017 11:08 am

So that how it works! Damn.. I have always thought it was an error in the firmware and that they never got around to impliment it.

But... how are we gonna use this practically?

Also.. why is it 20dB and not lile 6 or 12 that is more commonly used. And ehy isn’t it just a replics channel on a lower dB? Why is it only when it clips it records on the other channel??

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