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Author Topic: SPL and/or RTA logging?  (Read 1686 times)

Jeff Carter

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SPL and/or RTA logging?
« on: September 17, 2012, 01:18:07 pm »

Hi, all.

We're getting a bit of pushback on volume levels so I'm looking to set up some logging in order to see if we can correlate the complaints with any specific aspect.

It's not clear from the complaints whether it's more of an issue of peak or average levels, or if there's one part of the frequency spectrum that's particularly obnoxious.

What I'd like to be able to do at minimum is concurrently log SPL levels in the room with a couple of different averaging times and frequency weightings, and ideally some RTA information as well. We'd need to buy any measurement mics and software to make this happen but we do have a Presonus Firestudio interface and computer available.

What do you use/recommend to do this? Any other things I should be thinking about here?
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dick rees

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Re: SPL and/or RTA logging?
« Reply #1 on: September 17, 2012, 03:24:02 pm »

Hi, all.

We're getting a bit of pushback on volume levels so I'm looking to set up some logging in order to see if we can correlate the complaints with any specific aspect.

It's not clear from the complaints whether it's more of an issue of peak or average levels, or if there's one part of the frequency spectrum that's particularly obnoxious.

What I'd like to be able to do at minimum is concurrently log SPL levels in the room with a couple of different averaging times and frequency weightings, and ideally some RTA information as well. We'd need to buy any measurement mics and software to make this happen but we do have a Presonus Firestudio interface and computer available.

What do you use/recommend to do this? Any other things I should be thinking about here?

Jeff....

Showing numbers to people has a dubious value.  If they don't like the music or the arrangements are over-full and busy with "everybody playing everything all the time", it is not so much  a question of sound level, but an issue with the content of the sound itself.

The most important thing in making music is to play only what is absolutely necessary in the ensemble/arrangement.  Everyone can have a chance to contribute, but it should be made clear that differing textures and dynamics are desirable.  Not every instrument/voice needs to be in the mix 100% of the time.

Once the musicians have worked diligently to present a coherent arrangement, then the band as a whole can be "mixable".  If the sound person's job is simply to push the vocals over the stage sound, then no SPL  or RTA data will mollify those who find it difficult to deal with more or less undifferentiated sound.

IOW, a clean mix is tolerable at a higher SPL.  A noisy "mix" will sound bad at any volume level.
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Arnold B. Krueger

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Re: SPL and/or RTA logging?
« Reply #2 on: September 17, 2012, 03:38:34 pm »

Jeff....

Showing numbers to people has a dubious value.  If they don't like the music or the arrangements are over-full and busy with "everybody playing everything all the time", it is not so much  a question of sound level, but an issue with the content of the sound itself.

The most important thing in making music is to play only what is absolutely necessary in the ensemble/arrangement.  Everyone can have a chance to contribute, but it should be made clear that differing textures and dynamics are desirable.  Not every instrument/voice needs to be in the mix 100% of the time.

Once the musicians have worked diligently to present a coherent arrangement, then the band as a whole can be "mixable".  If the sound person's job is simply to push the vocals over the stage sound, then no SPL  or RTA data will mollify those who find it difficult to deal with more or less undifferentiated sound.

IOW, a clean mix is tolerable at a higher SPL.  A noisy "mix" will sound bad at any volume level.

If you record one of the main outputs of your console and know how its recorded levels match up with SPL in the room, then portions of your recording can be analyzed at any time to obtain the data you want.
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Marty McCann

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Re: SPL and/or RTA logging?
« Reply #3 on: September 17, 2012, 03:53:03 pm »

>>>
If you record one of the main outputs of your console and know how its recorded levels match up with SPL in the room, then portions of your recording can be analyzed at any time to obtain the data you want.
<<<

NOT, if the Bass Guitar and Drums are driving the acoustical space at such a level that the portion of these instruments actually in the mix are minimal.
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Kent Thompson

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Re: SPL and/or RTA logging?
« Reply #4 on: September 17, 2012, 04:54:01 pm »

Hi, all.

We're getting a bit of pushback on volume levels so I'm looking to set up some logging in order to see if we can correlate the complaints with any specific aspect.

It's not clear from the complaints whether it's more of an issue of peak or average levels, or if there's one part of the frequency spectrum that's particularly obnoxious.

What I'd like to be able to do at minimum is concurrently log SPL levels in the room with a couple of different averaging times and frequency weightings, and ideally some RTA information as well. We'd need to buy any measurement mics and software to make this happen but we do have a Presonus Firestudio interface and computer available.

What do you use/recommend to do this? Any other things I should be thinking about here?

I use SMAART for that as well as other things. It will take some training to get the most out of it though.  The biggest challenge will be taking measurements where the complaints are from while at the same time discerning which of the levels are congregationally generated.

What I would do before spending anything is plan to spend time sitting right in the same areas where people complaining are sitting and listen during the service. You should know right away if it is an eq/system problem or operator problem(as in too loud). Won't cost you a thing that way.
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Jeff Carter

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Re: SPL and/or RTA logging?
« Reply #5 on: September 17, 2012, 06:54:56 pm »

Thank you all for your comments.

Complaints definitely DO seem concentrated in a particular age group so I suspect the fundamental problem here is that some people don't like the musical style.

@Kent:
Complaints don't seem to be concentrated in any particular area of the sanctuary. There are definitely issues in the back of the lower level under the balcony, where the bass piles up and HF from the mains is blocked (zero points for guessing where FOH position is) as well as poor HF coverage near the edges of the room. However... several people who didn't like the mix yesterday were sitting in an area further forward where HF coverage is good and everything sounded fine when I went over there.

Because of the location of FOH, on-duty sound techs have to walk the room a fair bit, and we try to help each other out by walking the room as we can when off-duty. When I do this I never hear anything obnoxious, EQ or level-wise, and certainly nothing that I would consider to be grounds for somebody leaving the service.

@Arnold/Marty:
FOH mix isn't a complete representation of the sound in the room since we don't need to add much percussion (apart from the kick drum) or bass amp to the mix in general. With that said, the ambient drum/bass fits into the mix quite well and isn't overpowering, to my ears anyway.

@dick:
There's nothing obvious that stands out in arrangements, either... our musicians aren't professional performers for the most part but as a group they're pretty skilled and manage dynamics quite well. It's definitely not a situation where the band just lets 'er all rip on every part of every song... though since we do a lot of repertoire from Hillsong, Redman, Tomlin, etc. the band's usually all-in at the bridge.
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Arnold B. Krueger

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Re: SPL and/or RTA logging?
« Reply #6 on: September 17, 2012, 08:24:32 pm »

>>>
If you record one of the main outputs of your console and know how its recorded levels match up with SPL in the room, then portions of your recording can be analyzed at any time to obtain the data you want.
<<<

NOT, if the Bass Guitar and Drums are driving the acoustical space at such a level that the portion of these instruments actually in the mix are minimal.

Please consider what I meant by "know how recorded levels match up with SPL in the room"  Yes there may be a difference, but if the difference is predictable, then at least you know something that is representative.

Any single point measurement is going to be some kind of approximation of the entire room or any point in it.

Therefore assuming that the volume of the sounds that go through the sound system is going be a fair approximation of the sounds that bypass it, may not be that much of a disaster. IOW if the band stays in balance with itself, then the part you can measure this way should track the part that bypasses it.

Fuirthermore, if you use a digital recorder to record the line output of the SPL meter or just the output of a mic at some representative location, and figure out how that relates to SPL, then you will be that much close.
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dick rees

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Re: SPL and/or RTA logging?
« Reply #7 on: September 17, 2012, 08:42:45 pm »

Please consider what I meant by "know how recorded levels match up with SPL in the room"  Yes there may be a difference, but if the difference is predictable, then at least you know something that is representative.

Any single point measurement is going to be some kind of approximation of the entire room or any point in it.

Therefore assuming that the volume of the sounds that go through the sound system is going be a fair approximation of the sounds that bypass it, may not be that much of a disaster. IOW if the band stays in balance with itself, then the part you can measure this way should track the part that bypasses it.

Fuirthermore, if you use a digital recorder to record the line output of the SPL meter or just the output of a mic at some representative location, and figure out how that relates to SPL, then you will be that much close.

A guesstimate?
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Matthew Donadio

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Re: SPL and/or RTA logging?
« Reply #8 on: September 17, 2012, 09:13:00 pm »

I think we have all had the problem of "too loud", and the topic comes up here every few months.

Every time we have had the problem, it usually turns out to be that the mix in the room (ie, mains + stage) is bad.  Fixing that involves working with the band to figure out how to get things under control.

Personally, I have the blue Galaxy Checkmate and I also have the AudioTools app for my phone.  The AudioTools app will let you record levels, but I have never used it for this.

I don't use either meter for the absolute numbers, but I will use them to get relative numbers for different portions of the service and week-to-week variances.  I also used them to get a sense of the level differences in different places in the sanctuary, as well as to figure out who consistently mixed louder/quieter than others.

I spent a good six months taking notes in my bulletin and writing down rough average and peak SPL for every portion of the service (and who was playing guitar and drums).  With this, I was able to really handle the last "Can you mix to X dB?" from a session member.  I was able to show him that the level of the band wasn't all that much louder than the pipe organ and the congregation singing a "favorite" hymn.  From there we were able to work out next steps that weren't combative or involved arbitrary SPL values.

Knowing where the quiet seats are can help a lot with the loudness problem, too, and you may find some places that you may not have thought of.  Coverage in our room is good, but we have a pocket off to one side which is at a decent angle to the mains (center hung, up high) that is also at a decent angle to the stage, and therefore quieter that you would expect and still "a good seat".
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Jeff Carter

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Re: SPL and/or RTA logging?
« Reply #9 on: September 17, 2012, 09:48:43 pm »

Personally, I have the blue Galaxy Checkmate and I also have the AudioTools app for my phone.  The AudioTools app will let you record levels, but I have never used it for this.

I don't use either meter for the absolute numbers, but I will use them to get relative numbers for different portions of the service and week-to-week variances.  I also used them to get a sense of the level differences in different places in the sanctuary, as well as to figure out who consistently mixed louder/quieter than others.

I spent a good six months taking notes in my bulletin and writing down rough average and peak SPL for every portion of the service (and who was playing guitar and drums).  With this, I was able to really handle the last "Can you mix to X dB?" from a session member.  I was able to show him that the level of the band wasn't all that much louder than the pipe organ and the congregation singing a "favorite" hymn.  From there we were able to work out next steps that weren't combative or involved arbitrary SPL values.


This is along the lines of what I'd envision... with hopefully some RTA data thrown in there to see if energy in particular frequency ranges is what people find offensive.
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