Suggestions on setting up a compressor &/or brick wall for

[JeffB]

If different microphone groups are handled by different mixers, you may never get there with a single UCA202 unless your goal is to record just one portion of the performance. This is a nightmare sound shoot for a pro recordist, so if you have to do this repeatedly, it may take several passes before you get all the ducks in a row.

Koz

Yeah, I would just record the main speaker if I knew how to connect to the correct mixer board, assuming it had a tape out or similar RCA interface I could tap into and could also get access to that mixer board. That doesn't appear likely, though.

I think I may try to use one of the spare mics on the add on mixer board attached to the one I used last night and aim it at one of the audience speakers and record it that way. If I disconnect the output from that board from the main board that the choir is using, I'm assuming it wouldn't cause feedback issues. It wouldn't be the ideal way to record but it might be passable, and probably better than someone trying to get it via an iPhone or something similar.

I'll have to try and get there a little earlier this evening and experiment with it a bit.

[flynwill]

If I were in your position I would ask the pastor if there was some time (maybe a Saturday morning?) when I could have access to the system and spend some time studying exactly what is connected where. With a bit of luck the important stuff will be labeled. The solution to what you are trying to do might be as simple as plugging into the tape-out connections on that second mixer board or it might be a lot more complicated. The stuff in the closet sounds like it is just the Power Amps that actually drive the speakers (and possibly some active crossovers) so with a bit of luck that equipment is not of your concern. Post some pictures of the gear and we can tell you more. Take pictures and make notes of the position of all of the controls on the mixer and then go find the user's manual for it online and do some studying.

Many boards can provide an Auxiliary output that has its own mix so you might look for such a feature.

With the UCA-202 there is no reason to ever set the "microphone volume" slider in Audacity to anything other than 100%. As others have mentioned that unit does not have any volume control ahead of the A/D conversion, and if you are clipping it's input, that will continue regardless of the setting of the volume in software.

I have seen Audacity get confused if the UCA-202 is unplugged and plugged back in while Audacity is running. Sometimes (even often) it works but sometimes it doesn't. I would recommend when setting up don't run Audacity until you have plugged in the UCA and Windows has had a chance to acknowledge its existence.

[JeffB]

Thank you flynwill, those sound like great ideas.

If I were in your position I would ask the pastor if there was some time (maybe a Saturday morning?) when I could have access to the system and spend some time studying exactly what is connected where. With a bit of luck the important stuff will be labeled. The solution to what you are trying to do might be as simple as plugging into the tape-out connections on that second mixer board or it might be a lot more complicated. The stuff in the closet sounds like it is just the Power Amps that actually drive the speakers (and possibly some active crossovers) so with a bit of luck that equipment is not of your concern. Post some pictures of the gear and we can tell you more. Take pictures and make notes of the position of all of the controls on the mixer and then go find the user's manual for it online and do some studying.

Yeah, I was hoping that that big box in the closet was just some amplifiers & things. If there's another mixer box, it may be elsewhere. I was wishing I hadn't forgotten my phone at home or I would have taken a few pictures.

Tonight will be the last night for the parish mission, but taking some time talking over how the system is set up with someone who knows more about it would probably still be a good idea. Our pastor seemed happy that I was trying it. He said that they had anticipated recording homilies & things but had never gotten around to it. I'm guessing no one had the equipment or software to do it. I was pleasantly surprised at the quality of the recording of the choir, after I had adjusted the sound levels a bit.
Many boards can provide an Auxiliary output that has its own mix so you might look for such a feature.

With the UCA-202 there is no reason to ever set the "microphone volume" slider in Audacity to anything other than 100%. As others have mentioned that unit does not have any volume control ahead of the A/D conversion, and if you are clipping it's input, that will continue regardless of the setting of the volume in software.

The UCA202 may not be able to adjust the sound levels coming in, but Audacity can definitely control them once they arrive. If it was clipped that obviously wouldn't be adequate to save the recording, but wouldn't the sound boards either have the volumes for tape out or aux out or whatever already adjusted such that there would be no clipping? Would they perhaps have compressors &/or brick walls to stop that sort of catastrophe? I'm guessing that those types of outputs were designed for people hooking a cassette recorder up to it to record the output. Those probably don't have any hardware based compressors or brick walls I wouldn't think.

As a side note, what is the main purpose of the brick wall in software plug-ins if it isn't to prevent clipping? But if I understand the conversation correctly, it sounds like the software would seldom prevent it. If the upstream sound chain had built in compression/brick walls the software wouldn't need to do it, but if that sound chain did not have that feature built in and clipped it before it ever got to the software, the software would be useless in fixing it anyway. Or am I misunderstanding how it all works?

I have seen Audacity get confused if the UCA-202 is unplugged and plugged back in while Audacity is running. Sometimes (even often) it works but sometimes it doesn't. I would recommend when setting up don't run Audacity until you have plugged in the UCA and Windows has had a chance to acknowledge its existence.

Yeah, that's probably what messed me up. I'll have to be a little more careful in that regard.

Thanks again for the input & ideas.

[kozikowski]

Audacity is a post-production editor. All the tools work after the performance is done and everybody goes home. There's no shortage of people that want Audacity to filter and correct live performances. Not so far. It's up to you to get the performance converted to digital with no damage. We got it from there.

Koz

[JeffB]

Audacity is a post-production editor. All the tools work after the performance is done and everybody goes home. There's no shortage of people that want Audacity to filter and correct live performances. Not so far. It's up to you to get the performance converted to digital with no damage. We got it from there.

Koz

and I for one appreciate the job Audacity can do in post-production, even though I'm sure I only know how to use a tiny fraction of its capabilities. I this particular case, Audacity was able to salvage the talk even though I had doubts we could get anything out of it other than the choir's small parts at the beginning & end. It must have been a little stronger signal than I expected. I amplified it using the default setting & that improved it.

Then I compressed the whole thing, which improved the talk even more. I don't know if it helped or hurt the choir portions, though, but it did even out the levels between them. Should I have compressed first & then amplified, or is that a case by case decision?

Here's a link to the audio for anyone interested: http://bit.ly/1DQmvZ5

I was surprised that it came out as well as it did considering the circumstances.

Our Pastor was pleased that he was at least intelligible despite the room echoiness and the significant amplification that was needed.

I'm still not quite clear as to the post production brick wall software, however. It sounds like the hard brick wall limiter is most appropriate further down (or would that be up?) the sound chain... before it gets to the recording.

[flynwill]

The UCA202 may not be able to adjust the sound levels coming in, but Audacity can definitely control them once they arrive. If it was clipped that obviously wouldn't be adequate to save the recording, but wouldn't the sound boards either have the volumes for tape out or aux out or whatever already adjusted such that there would be no clipping?

Yes, but it's better to do any controlling after you make the recording. The volume slider next to the microphone in Audacity is just a multiply on the 16-bits coming from the A/D converter making another 16-bit number. All turning it down on record accomplishes is reducing your signal to noise ratio.

Attached is a sample recording made with my UCA-202 attached to a signal generator. The recording is in two parts, (the division being a bit past 00:05.7) in each part I cranked the signal generator up past the UCA-202's input clipping level. In the first part the software microphone volume was set to 1.00, and in the second the software volume was set to 0.3. Note that in both sections the waveform goes into clipping (the rounded peaks of the waveform go flat) at the same analog input level. The only difference is that in the second recording those peaks are are 0.3 instead of 1.0. That analog level was just a bit more than 3 Volts peak-to-peak on my unit.

Yes most mixers will have a gain control for their tape or auxiliary outputs, and ideally you get that adjusted such that the loudest program can't clip the UCA-202. If the mixer has a signal generator and meters then you can use that to set the level. I would recommend that 0 on the mixer be set to about -6 to -10 dB on the UCA. (If the amps in the hall have been properly set up then they will probably have a similar amount of headroom).

[kozikowski]

I would stop using the English words "Brick Wall." That effect is used in Air Traffic Controllers and Taxi Dispatchers, both of which have very tight limits on their radio channels. Singing into one would not be desirable except as a comedy effect.

Koz

[JeffB]

The UCA202 may not be able to adjust the sound levels coming in, but Audacity can definitely control them once they arrive. If it was clipped that obviously wouldn't be adequate to save the recording, but wouldn't the sound boards either have the volumes for tape out or aux out or whatever already adjusted such that there would be no clipping?

Yes, but it's better to do any controlling after you make the recording. The volume slider next to the microphone in Audacity is just a multiply on the 16-bits coming from the A/D converter making another 16-bit number. All turning it down on record accomplishes is reducing your signal to noise ratio.

Attached is a sample recording made with my UCA-202 attached to a signal generator. The recording is in two parts, (the division being a bit past 00:05.7) in each part I cranked the signal generator up past the UCA-202's input clipping level. In the first part the software microphone volume was set to 1.00, and in the second the software volume was set to 0.3. Note that in both sections the waveform goes into clipping (the rounded peaks of the waveform go flat) at the same analog input level. The only difference is that in the second recording those peaks are are 0.3 instead of 1.0. That analog level was just a bit more than 3 Volts peak-to-peak on my unit.

Oh, OK, I get it. Finally.

I played the wave file back and could hear the drop in volume, of course, but I wouldn't have been able to tell that it was clipping had you not told me. The second time I recorded it in Audacity and what you were saying was very obvious.

But that doesn't mean that I should have the volume slider maxed out on Audacity all the time, right? That just applies to recordings with the UCA-202? I've always assumed that I needed to pull that volume slider down when a signal was getting close to clipping, such as when recording a stream via stereo mix.

Yes most mixers will have a gain control for their tape or auxiliary outputs, and ideally you get that adjusted such that the loudest program can't clip the UCA-202. If the mixer has a signal generator and meters then you can use that to set the level. I would recommend that 0 on the mixer be set to about -6 to -10 dB on the UCA. (If the amps in the hall have been properly set up then they will probably have a similar amount of headroom).

I've seen the meters, before, but never knew anything about signal generators, nor even that they were on mixer boards, much less how to use them. That's obviously something pretty important for something like this. I obviously have some learning to do. Thank you for pointing it out.

[JeffB]

I would stop using the English words "Brick Wall." That effect is used in Air Traffic Controllers and Taxi Dispatchers, both of which have very tight limits on their radio channels. Singing into one would not be desirable except as a comedy effect.

Koz

OK, are there better ways of describing a compressor that won't let you clip the signal? It sounds like this moses guy is saying pretty much the same thing, though I'm not sure the term, "a very clever moving gum wall" would catch on:

http://www.futureproducers.com/forums/p ... or-335613/

Waves L series. Hard to beat them.

No piece of gear with the label "compressor" on it has a "brick-wall" gain behavior. Only specialized limiting compressors with zero or less attack time and an infinite ratio have a characteristic which could be (very roughly) described as a brick-wall. Obvious, they wouldn't be able to do their job if they weren't "brick wall". So, it might be helpful to ask for the best limiter instead. I suppose that's what you are searching for.

In any way, the term "Brick-Wall" is marketing motivated and not very intelligent from a scientific point of view.

In fact, the analogy is wrong with common limiters and compressors. The "brick-wall" basically describes clipping, which is instant, state-less compression - basically the opposite philosophy of how compressors and limiters are built (in which the gain reduction is smoothed out to not act like a brick wall).

So a good analogy for a compressor/limiter might better be a very clever moving gum wall. At least, it's much better describing the process.

[flynwill]

But that doesn't mean that I should have the volume slider maxed out on Audacity all the time, right?

Yep exactly.

That just applies to recordings with the UCA-202?

Yes, probably not just the UCA-202 as there are lots of other A/D interfaces with the same issue. But there is gear out there where the little volume slider actually controls an analog attenuator ahead of the A/D conversion, so for that gear then using the slider to adjust the levels is a sensible thing. And unfortunately the only way to find out what a particular bit of gear does is to test it.

I've always assumed that I needed to pull that volume slider down when a signal was getting close to clipping, such as when recording a stream via stereo mix.

Yes that's true in general, but you need a slider that acts upon the signal before it is digitized. If I had my way the Behringer interface wouldn't pretend that it had a level control, but I'm guessing that may not have been an option for them -- windows may require a control -- so they did what they could.