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Author Topic: What's a reasonable approach?  (Read 5820 times)

Curt Sorensen

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What's a reasonable approach?
« on: May 07, 2013, 10:29:26 pm »

Hi,
I'd be interested in people's opinions about what is a reasonable use of Smaart, etc by mix engineers using a system provided or installed for a show or event. Or on the other hand what is not reasonable? Not as interested in discussing shows that tour with their own rig. I've seen plenty of folks place a measurement mic in one location, shoot each hang, tweaking away. I understand the appeal of that, but I'm well aware that it's likely to be a mistake as well. Obviously the biggest factor may be how much time is available [not festivals?]. So perhaps consider an event where there's a set-up day, not just shows where it's get it in and up ASAP. Again, focusing on a mix engineer [concert. corporate, what have you], on a new-to-them system and venue, what's an appropriate use of these awesome tools we have today? I'm very curious what a truly-qualified system tuner might try to do in that situation.
Anyone interested in such a discussion?
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Curt Sorensen
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Timo Beckman

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Re: What's a reasonable approach?
« Reply #1 on: May 08, 2013, 06:09:08 am »

Depends on the visiting tech .
I tend to work with them up to the point where they are pushing a system to hard for either the system itself the venue or rules from the local government .

Some of the tech's i've had to deal with only like a system that's pushed way to far in to the limit or get's to loud for what i'm allowed to produce spl wise .
I warn them to take the level down but for the rest of it i can't do to much about it until my customer starts complaining and orders me to take levels down .
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Jay Barracato

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Re: Re: What's a reasonable approach?
« Reply #2 on: May 08, 2013, 07:38:07 am »

Hi,
I'd be interested in people's opinions about what is a reasonable use of Smaart, etc by mix engineers using a system provided or installed for a show or event. Or on the other hand what is not reasonable? Not as interested in discussing shows that tour with their own rig. I've seen plenty of folks place a measurement mic in one location, shoot each hang, tweaking away. I understand the appeal of that, but I'm well aware that it's likely to be a mistake as well. Obviously the biggest factor may be how much time is available [not festivals?]. So perhaps consider an event where there's a set-up day, not just shows where it's get it in and up ASAP. Again, focusing on a mix engineer [concert. corporate, what have you], on a new-to-them system and venue, what's an appropriate use of these awesome tools we have today? I'm very curious what a truly-qualified system tuner might try to do in that situation.
Anyone interested in such a discussion?

I am the visiting tech that likes to come in and start with Smaart.

I am not looking to "tune" the system and I can't think of a single case where I have even asked for any changes to the system alignment.

On the other hand, Smaart is the quickest easiest way I know to confirm how everything is working and IF it is working. A couple of years ago I had a show in a PAC and the house tech (third string system sitter) was late and we basically had to dive straight into a soundcheck with the band. During the soundcheck it became clear the system was missing a lot, despite the house techs assurance that it was " the way it always is". So we stop the soundcheck, go back to square one, get out the measurement stuff where I should have started, and quickly determine the system has no mids. Without the measurement there is no way I would have convinced the tech that anything was wrong.

At doors I was still upside down behind the FOH drive rack trying to figure out how the system was put together without being able to see the amp rack at all. I finally figured out that the system was wired for full range tops plus subs, while the crossover was set for biamped tops with only the HF going to the amps.

I also like to have the spectrograph hooked up to the cue bus during soundcheck and the show. A lot of things I would have swept a parametric for in the past, I can see an exact frequency and width on the spectrograph. Using the spectrograph and the cue I can identify the exact channel that is about to take off in feedback and fix it at the source rather than hacking the response of the whole system.

Sometimes, space at FOH is a minimum, or the set is short, or there is some other reason for not setting up the measurement system, and those shows I end up being less comfortable.

Of course, sometimes odd things you don't expect happen. One time I was provided a large berhinger board and I didn't realize that one of the two record feeds the house guy was pulling was actually parallel to the cue bus and he ended up with an hour and half of my cues because I tend to use them more often with the visual than when just using headphones.
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Phil Graham

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Re: What's a reasonable approach?
« Reply #3 on: May 09, 2013, 02:25:40 pm »

So perhaps consider an event where there's a set-up day, not just shows where it's get it in and up ASAP. Again, focusing on a mix engineer [concert. corporate, what have you], on a new-to-them system and venue, what's an appropriate use of these awesome tools we have today? I'm very curious what a truly-qualified system tuner might try to do in that situation.

Curt,

This is a good topic. As a guest engineer, I don't plan on having ability to measure the rig by default, and this is coming from a guy who has discussed measurement both in person and in print. Often there's not enough time to do anything more than a quick, time-blind snapshot at FOH to gut check what my ears tell me. I don't consider that measurement.

If I think there's going to be enough time to do some measurement, or if I am anticipating an especially mediocre day, or if the advancing person is friendly and open,  then I'll make an ask for some measurement time outside the scheduled event setup/soundcheck window. I'll also communicate very clearly with the person in question about what aspects of their processing I can access, and what I can't. This is to make sure that we are on the same page. If they only offer me access to the FOH graphic, then there's not much point in pulling out the measurement rig, as I can't really dig into the underlying issues influencing the axial response.

If they will let you dig a little deeper, then I'll quickly shoot a bunch of measurements at a number of locations. There's no need to have the pink blazing, or have it on constantly. Just little quick spurts. 10 minutes and I'll have sufficient traces. This is, of course, aided by having ready control over each zone of the PA. Then I'll go off and digest what they are telling me along with my ears. Only then I'll go work on the processing, setting delay times, etc.

If you involve the local tech in the process, assuming they aren't busy doing other things, I find they are usually open to my suggestions.
« Last Edit: May 10, 2013, 01:37:03 pm by Phil Graham »
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Rasmus Rosenberg

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Re: What's a reasonable approach?
« Reply #4 on: May 10, 2013, 05:50:14 am »

Hi,
I'd be interested in people's opinions about what is a reasonable use of Smaart, etc by mix engineers using a system provided or installed for a show or event. Or on the other hand what is not reasonable? Not as interested in discussing shows that tour with their own rig. I've seen plenty of folks place a measurement mic in one location, shoot each hang, tweaking away. I understand the appeal of that, but I'm well aware that it's likely to be a mistake as well. Obviously the biggest factor may be how much time is available [not festivals?]. So perhaps consider an event where there's a set-up day, not just shows where it's get it in and up ASAP. Again, focusing on a mix engineer [concert. corporate, what have you], on a new-to-them system and venue, what's an appropriate use of these awesome tools we have today? I'm very curious what a truly-qualified system tuner might try to do in that situation.
Anyone interested in such a discussion?

Good topic!
My take is that the mix engineer is responsible for every aspect of how the event sounds for the audience/client. That means he/she is on a very tight clock to get the best environment to mix in, including what the PA does/don't, "logistics", mic placement, stage volume etc etc. If that person is able to verify and optimize that process with measurement, its appropriate. In fact i can't seem to recall a situation where it would not be appropriate (as long as the event starts at time).. If the mix engineer decides to realign etc the PA and screws it up, its his/her responsibility any way. Off cause that can be extremely hard for the client to understand :)
If I mixing, an unfamiliar place/PA. I will do my best to allow my self some time to measure. Having the "logistics" under control helps getting that xtra 10 mins to do a few measurements.
As a mixengineer, the following is important to me:
1. SPL at FOH (Im in europe so there is almost always a limit, and I want to get paid for the gig, not to pay for being too loud)
2. Main PA coverage. (What's the "window"? are the audience with in +/-3 db or more, do the subs kill the front row?) 3 TF measurements Front,mid,back gets me a very basic idea.
3. Freq. analysis of my mix/cue buss. (RTA, Spectrograph) Helps me mix, but also to verify if I miss any thing on an unfamiliar console.
4. Whats different, at the mix console vs Main PA on axis? (comparing TF's and listening to some music)  There always seems to be peaks and dips you spend most of the time mixing around, but that are only "local" to where ever the mixing console is..
5. Fills, outhang etc. Mostly just verifying they do what i like them to do and are not too fare away from the Mains. Usually done with music to cut time, but the point that IMO changes priority the mosts according to what type gig/client .
6. Shape the Frequency response of the PA to make it easier to mix on. Music/speech using my ears, but also the info gathered above.

As the others have posted it all comes down to time management. But just for kicks, on a recent gig here is what I changed as a system tech during a festival and a good indication that its always a good idear to double check the system as a BE and that as a SE you have to be flexible to commentate peoples needs.
1. Trim height too low, HF dropped off too much in FOH (2 mtrs from the back wall). Raised the PA 45 cm. (but it looked soo good in the LAC  :-\)
2. Wrong splay angle between two boxes. Re rigged.
3. PA tilted to much out, too little SPL in the middle. (adjusted the guide wires)
4. Front fills, not covering wide enough. Re-configured/designed and realigned
5. Too "detailed" HF response compared to other systems. Shaped down so people with there own consoles didn't get scared away of how there mix really sounded.
etc.

mvh
R
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Mike Karseboom

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Re: Re: What's a reasonable approach?
« Reply #5 on: May 22, 2013, 12:51:28 am »

It seems like this thread has run its course so perhaps a little swerve is OK?


I also like to have the spectrograph hooked up to the cue bus during soundcheck and the show. A lot of things I would have swept a parametric for in the past, I can see an exact frequency and width on the spectrograph. Using the spectrograph and the cue I can identify the exact channel that is about to take off in feedback and fix it at the source rather than hacking the response of the whole system.


Jay that passage inspired me to try this so I set up Systune to look at the cue bus on my SL16.4.2.  I thought I could look at the monitor sends during a  live show and detect and/or head off feedback.

The set up worked OK, I could see whatever send I punched up.  I just looked at a single channel spectrograph or spectrum type measurement, not any kind of transfer function. 

But I could not easily make out any hot frequencies that way.   I even created some feedback on a stage monitor while playing break music to see the results.  Well by the time I could really see the frequencies that were feeding back, the feedback was much to loud and I could have detected it more quickly by ear.  I could hear some of the ringing from FOH before it got loud but it was just not obvious in the spectrograph or the spectrum displays.  It was buried in the changing spectrum of the music.

So I am wondering if there are some key points to your set up that make it work for you?  How do you see something starting to take off, especially if you have 4-6 monitor mixes that you would have to quickly check?
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Jay Barracato

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Re: Re: What's a reasonable approach?
« Reply #6 on: May 22, 2013, 08:44:19 am »

It seems like this thread has run its course so perhaps a little swerve is OK?

Jay that passage inspired me to try this so I set up Systune to look at the cue bus on my SL16.4.2.  I thought I could look at the monitor sends during a  live show and detect and/or head off feedback.

The set up worked OK, I could see whatever send I punched up.  I just looked at a single channel spectrograph or spectrum type measurement, not any kind of transfer function. 

But I could not easily make out any hot frequencies that way.   I even created some feedback on a stage monitor while playing break music to see the results.  Well by the time I could really see the frequencies that were feeding back, the feedback was much to loud and I could have detected it more quickly by ear.  I could hear some of the ringing from FOH before it got loud but it was just not obvious in the spectrograph or the spectrum displays.  It was buried in the changing spectrum of the music.

So I am wondering if there are some key points to your set up that make it work for you?  How do you see something starting to take off, especially if you have 4-6 monitor mixes that you would have to quickly check?

I am not sure how Systune displays the information, but I have the levels set so that feedback shows as a straight white line in the SMAART spectrograph. Feedback will show up on either the input side or the output side. I tend to cue the inputs, as being the source rather than trying to look at each monitor mix. Part of making this work is realizing that the display enhances the tools we traditionally used to deal with feedback, rather than replacing them.

Traditionally, you get feedback on stage, and your first reactions are: what did I hear? what did I see? what changed about the stage setup that might be a cause? All those instantaneous clues add up to how you choose to respond. Adding the measurement system is just adding another piece of data. How you choose to respond to the measurement is still a matter of experience. The measurement system doesn't provide a solution. I would suggest going through some shows with the display hooked up, look at it as you do your regular monitor setup and correlate what you see on the display with what you hear and see on stage. I would also suggest while you are calibrating your eyes to your ears, you also use headphones when cueing specific things.

The added advantages of using the measurement system are mostly based on the precision of the measurement. I tend to laugh (only sometimes out loud) at those "just use your ears" techs who are so proud of their ability to call out frequencies they hear. Most of the time they are just using the bands of a 31 band graphic eq, and if they are plus or minus one band seem to think that is okay. So while that tech is going its 800 or 1000 hz, better cut both to be sure, I am looking at the measurement and saying it is centered at 934 hz and is 4 hz wide. Or as another case, sometimes you will hear the one frequency that stands out above the music, but there is actually a harmonic series being excited. So in the measurement instead of the 1000 hz you recognized, you can see that the series is 500 hz, 1000 hz, and 2000 hz, and use smaller cuts at three frequencies rather than 1 large cut at the frequency you heard.

Many experienced techs can hear a change in the tone of a source as the frequency builds up, but before you hear it as feedback. The measurement system works the same way. By setting the threshold just below the audible level of feedback, you can see the frequency build up before it takes off. As I said before, I tend to look for this at the input so I tend to leave it cued to the mic most likely to cause problems, like a handheld lead vocal, unless I am specifically looking for something else.

I also use the spectrograph for other things like help in setting gates, eq'ing channels to play nice together, etc. I find the spectrograph to be one of my most used features in SMAART but one you hear the least about. I will have to start taking some screen shots and work up a thread on some of the things I look for and how I apply that information.
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Samuel Rees

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What's a reasonable approach?
« Reply #7 on: May 22, 2013, 09:01:47 am »

I don't can't identify any finer than 1/3 octave with my ears really, so I'll try to look an analyzer when I suspect something might be solidly in between bands of a 1/3 graphic and hit it with parametric. So my thought is that it's more about accuracy, double checking when your ears disappoint. I find 1/6 octave resolution to appear more responsive visually because even if the nodes are on 1/3 numbers, they are very narrow and get 'diluted' at 1/3. I have used smart or anything for this, just line output from the solo bus to my laptop or phone and a various simple apps.
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Mike Karseboom

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Re: What's a reasonable approach?
« Reply #8 on: May 22, 2013, 10:35:45 am »

Dang I was looking for that magic bullet that would make me look better than I am!  I guess I never should have thrown away that B***ger feedback destroyer.

So practice is the key and it is a complementary tool to my ears and eyes.  Yes that makes sense.  And I can try looking at the mics instead of the monitor sends, especially those mic's that I suspect will be problematic.  I'll try the 1/6 octave gradation as well. 

I wish I were good enough to hear  frequencies building before they actually feedback.  I can sometimes hear a kick mic starting to take off or maybe an acoustic guitar that has been placed on a stand and not muted .  The ones that are more often a problem  for me are the lead vocal mic and perhaps the drum overheads.  When those get  touchy at higher frequencies the little squeaks seem to come and go, not just sit there  showing a continuous white line on the spectograph.  And that is where I can't pick anything out from the rest of the display.

I like to study this stuff and try and out think the problems, and it does help.  But as usual there is no substitute for experience.

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--Mike
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Jay Barracato

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Re: What's a reasonable approach?
« Reply #9 on: May 22, 2013, 11:04:13 am »

Dang I was looking for that magic bullet that would make me look better than I am!  I guess I never should have thrown away that B***ger feedback destroyer.

So practice is the key and it is a complementary tool to my ears and eyes.  Yes that makes sense.  And I can try looking at the mics instead of the monitor sends, especially those mic's that I suspect will be problematic.  I'll try the 1/6 octave gradation as well. 

I wish I were good enough to hear  frequencies building before they actually feedback.  I can sometimes hear a kick mic starting to take off or maybe an acoustic guitar that has been placed on a stand and not muted .  The ones that are more often a problem  for me are the lead vocal mic and perhaps the drum overheads.  When those get  touchy at higher frequencies the little squeaks seem to come and go, not just sit there  showing a continuous white line on the spectograph.  And that is where I can't pick anything out from the rest of the display.

I like to study this stuff and try and out think the problems, and it does help.  But as usual there is no substitute for experience.

You are closer than you think.

Because you can limit the probable sources to a couple of inputs that gives you less possibilities you have to monitor. Also by monitoring the input, you also have less total data in the spectrograph, so the lines should be able to easier to see. During setup, try squeeking the system by hand. The shortest duration feedback I can usually hear and recognize at FOH leaves a trace 1/2 inch long in the spectrograph. Once you recognize the trace with no background start looking for the same attributes among the background.

Your drum overheads probably are not feeding back themselves, but are more likely to reproduce feedback on stage from other sources.
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Adam Black

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Re: Re: What's a reasonable approach?
« Reply #10 on: May 22, 2013, 12:03:51 pm »

But I could not easily make out any hot frequencies that way.   I even created some feedback on a stage monitor while playing break music to see the results.  Well by the time I could really see the frequencies that were feeding back, the feedback was much to loud and I could have detected it more quickly by ear.  I could hear some of the ringing from FOH before it got loud but it was just not obvious in the spectrograph or the spectrum displays.  It was buried in the changing spectrum of the music.

Mike,

Basically a spectrograph rejects data that does not fall within a specified range, -70dBFS to -30dBFS for example. If the feedback is lost within the normal content, it sounds like the threshold level for the lower range is too low. Try increasing the lower threshold limit. This will reject more of the desired content and make it easier to spot feedback.

-A
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Doug Fowler

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Re: Re: What's a reasonable approach?
« Reply #11 on: May 22, 2013, 02:14:36 pm »

It seems like this thread has run its course so perhaps a little swerve is OK?

Jay that passage inspired me to try this so I set up Systune to look at the cue bus on my SL16.4.2.  I thought I could look at the monitor sends during a  live show and detect and/or head off feedback.

The set up worked OK, I could see whatever send I punched up.  I just looked at a single channel spectrograph or spectrum type measurement, not any kind of transfer function. 

But I could not easily make out any hot frequencies that way.   I even created some feedback on a stage monitor while playing break music to see the results.  Well by the time I could really see the frequencies that were feeding back, the feedback was much to loud and I could have detected it more quickly by ear.  I could hear some of the ringing from FOH before it got loud but it was just not obvious in the spectrograph or the spectrum displays.  It was buried in the changing spectrum of the music.

So I am wondering if there are some key points to your set up that make it work for you?  How do you see something starting to take off, especially if you have 4-6 monitor mixes that you would have to quickly check?


Mike -

Double click the color bar just above the SysTune spectrograph display.   You'll then be able to adjust the upper and lower SPL limits for the display.   Almost certainly, the default is too wide. Play with those values and you should get what you're looking for. 

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Merlijn van Veen

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Re: What's a reasonable approach?
« Reply #12 on: May 22, 2013, 08:01:48 pm »

Whatís reasonable and how much time I try to allow myself accordingly, is determined by my confidence in the circumstances.

Having the luxury of doing measurements at virtually every show Iíve done (both the production system but also house systems), convinced me of one thing. Good coherence results in faithful reproduction (coherence being an indicator of the integrity of a signal). I feel that poor system tuning, besides evident factors you have little or no control over like i.e. acoustics, results in poor coherence.

The possible reasons for bad coherence are beyond the scope of this post. However, itís my believe that good system tuning, requires a profound knowledge of the laws of physics considering sound. Specifically the relationship between level and time.

In my corner of the world, there are about 400 theaters, accommodating anything from approx. 200 to 1.600 visitors, most of them with respectable equipment. Iíve visited the majority of them at least two times or more. Unfortunately to often IMHO, the circumstances demonstrate a lack of insight in physics, ranging from poor speaker deployment, poor speaker aiming to poor time alignment to name a few.

I can only speculate about the reasons for this. Maybe some installations date from a time when such knowledge wasnít accessible or the means to properly tune the system werenít available. Then again, to often in the past Iíve been guaranteed, that a certain system was designed and tuned by a respectable engineer. Being intimidated by reputation and out of respect for these individuals, I quickly learned the hard way that most tunings have a certain application in mind, which isnít wrong by itself but not necessarily mine. Having learned a bit, Iíve found and measured on later returns i.e. different speakers with documented polarity reversal, being used together in an overlapping fashion. I assume a lot of engineers, including the system designer, must have noticed and suspected something was wrong but surprisingly nothing had changed in the meantime. Even when confronted with irrefutably evidence, the amount of indifference I sometimes run into is dazzling. Systems that actually have been tuned plausible might have the original DSP presets being overwritten by the sheer amount of passing productions. On other occasions, being warned in advance by house technicians for certain known but apparently ďunsolvableĒ issues, I ran into more elusive problems like polarity reversals in wiring, transducers or negligent rigging in paired traps resulting in severe comb filtering. Sometimes I witness so much overkill in equipment, resulting in questionable overlap from numerous sources, that commercial interest apparently overruled sensible system design. Lastly a lot of design decisions seem to be arbitrary.

But mostly I feel that audio is still something that is considered to be exclusively done with youíre ears, because thatís how itís always been done and why change that. Measuring still seems to have a questionable reputation. Maybe because everyone can do it, like operating a car. But the latter doesnít mean that you can drive. Interpreting the data is something that requires skill and experience. In the wrong hands, it could account for the former.

Excuse me if Iím stating the obvious
« Last Edit: May 22, 2013, 08:43:05 pm by Merlijn van Veen »
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Mike Karseboom

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Re: Re: What's a reasonable approach?
« Reply #13 on: May 22, 2013, 08:19:47 pm »


Adam and Doug - thanks for the setup tip.   I just got a chance to look at this in the shop. Setting a tighter scaling on the spectrograph display definitely makes it easier to see frequencies that look out of place.  Now I just need to put some more time in with it.
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Re: Re: What's a reasonable approach?
¬ę Reply #13 on: May 22, 2013, 08:19:47 pm ¬Ľ


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