Rational Acoustics



Jeffsco
September 4th, 2011, 01:13 PM
In a previous post, Dr. J brought up the use of SMAART to help dial in a system while the band is playing. Could the Forum elaborate on this? I'm thinking small to medium club size where you either do not have time to do an extensive (or any...)sound check or where you are walking in to fill in on someone else's gear and the EQ that is set for the room needs to be tweaked . Could be pre show break music as well? The thing is ...we need to assume the club is filled with patrons and you can't pink the room without getting yourself fired. Specifically:

1. I'm assuming that you would not be able to do ground plane measurements, or multi mic measurements due to the presence of patrons in the club. So where does the measurement mic get placed in relation to the FOH Speakers?
2. How is the reference signal routed to SMAART? Do you take the output of the board before the GEQ? After? Aux send? What criteria do we need to send to SMAART?
3. Some people advocate sneaking in a bit of Pink noise underneath the music (Recorded break music...not while the band is playing obviously..). How much Pink is required?
4. Can a GEQ for the room be developed from this technique? Will SMAART reliably show me what the differences are between the reference recorded music and what the Mic is picking up? What other optimization parameters can be derived from this approach.

Remember...this is "combat" audio. Not situations where you've had the opportunity to take the speakers outside, or the luxury of hours of un-interrupted , undisturbed optimization time.

Rasmus Rosenberg
September 5th, 2011, 04:50 PM
Hey,
Smaart for combat audio... I think Harry has a class for that?
I will see if I can quickly answer you questions.
1. Basic where ever you can, depending on what you want to measure. Most likely at FOH some what next to the BE, to gather an RTA/spectograf view, to link, what you hear to what the mic picks up. Can be useful for SPL monitoring and confidence booster, aka if you hear a frequency take off and you can see it take off on the screen, it most likely took off. You can also if space permits it try to locate the mic either left or right trying to get a some what "Isolated" measurement of the L or R PA. Smaart is source independent so you can use the output of the mixing console as reference signal, Maybe via a Matrix output. Or you can try to find the exact point between the speakers to view the sum. If you have the sum you, very basically, have the individuals, but not an easy path.
2. Typically by an matrix output, but there are a million different ways. You want you REF signal before what you want to measure, aka if you want to see what your GEQ does the REF has to be picked up before that. I ,for one, have burned my fingers having the GEQ inserted on the Master bus so the processed signal went as Reference. Since the transfer function shows the difference between the measurement signal and the Reference signal, if you apply the same EQ to both, there is no difference and hence not showing on the screen. Smaart is source independent so you can, use pink noise, flute music or what ever, but the signal must contain the frequencies you want to measure.
3. As much as you like. The "trick" is that some music don't contain all frequencies or you have to wait for them. So it can be faster, but lighter to the ear, to mix music with pink noise, because then you can measure all frequencies faster. Most people find pink noise offending so mixed with music its more tolerated to listen to.
4. Yes, smaart will tell you what the differences are between the Ref and Mes signal, BUT IT WILL NOT TELL YOU WHY!!!!

Any measurements is only valid in context, so if you don't have any before show measurements, you don't have anything to compare with.

In general about using smaart in clubs/ for combat audio. Yes you can, but your several hampered. I like Bob mc'Carthy's approach (i will try to explain briefly) where you can divide the work in to 4 main stages.
1.Design
2.Verification
3.Optimation (smaart)
4.Show
If you compromise in any stage it will carry on to the next, and to fix it you have to jump a stage back. So, very plain you, should optimize the speakers before not during show. The thing is, as you said, we either don't have the time or a plan to do it, since we can't go and redesign. if we are lucky we get to Verify before we have to go, some times not. Also what is the point of finding "mistakes"/problems if we can't fix them (oki, thats a little out of line, but you get the point). So where do go from there?? What to do...
IMO work faster and better. If your very ("lucky :D") systematic and methodological, you can get a lot of data collected in very short time. It takes me roughly about, the same time to gather enough good data to EQ a typical club system and see if the subs are aligned (to where ever that is?) than it takes to mic the drum kit. So time management is the key, aka it might be ok to mic the drums after doors, than dragging a measurement mic around. etc etc
Lots of more on this subject but I ran out of time :eek: crap..

Jeffsco
September 5th, 2011, 06:42 PM
Great points Rasmus. Thanks for taking the time to respond.

Jay Barracato
October 20th, 2011, 10:31 AM
I am often in this "combat audio" position where you have limited time. It is almost always on someone elses system or install, so I also expect to have limited access to system controls. My goal is not to perfectly align their system, my goal is to make it sound as good if not better than what they are used to.

My first action is to get something playing, pink noise if I have the room to myself, or music if others are present. As I work through my measurements, I am really only looking for any glaring deficiencies in the system that can be quickly fixed, like part of the system is not turned on. Taking 20 minutes to discover that one HF is operating -15 db from the others doesn't do much good when you discover the venue has known about it for 3 years and still haven't taken steps to correct it. My main goal during this time is to "calibrate" my ears to the room and figure out how the room sounds in different areas with the measurements acting as a control.

During soundcheck and the show itself, I find it invaluable to switch to the spectrograph. I pull one input from the cue bus of the board and one from a room mic at FOH. Remember that during the setup I was looking for how different places in the room were different from the FOH position. I also think it is important to remember there are limits to what can be corrected by eq, so I want to use as little as possible as close to the source as possible. If I hear something I think needs to be fixed, I can use the cue bus and the spectrograph to help decide if what I am hearing is a result of a single source or a buildup in multiple sources. That helps me decide if I want to correct at the channel level or at the system level.

Dr. J
October 20th, 2011, 02:02 PM
In a previous post, Dr. J brought up the use of SMAART to help dial in a system while the band is playing. Could the Forum elaborate on this? I'm thinking small to medium club size where you either do not have time to do an extensive (or any...)sound check or where you are walking in to fill in on someone else's gear and the EQ that is set for the room needs to be tweaked . Could be pre show break music as well? The thing is ...we need to assume the club is filled with patrons and you can't pink the room without getting yourself fired. Specifically:

1. I'm assuming that you would not be able to do ground plane measurements, or multi mic measurements due to the presence of patrons in the club. So where does the measurement mic get placed in relation to the FOH Speakers?
2. How is the reference signal routed to SMAART? Do you take the output of the board before the GEQ? After? Aux send? What criteria do we need to send to SMAART?
3. Some people advocate sneaking in a bit of Pink noise underneath the music (Recorded break music...not while the band is playing obviously..). How much Pink is required?
4. Can a GEQ for the room be developed from this technique? Will SMAART reliably show me what the differences are between the reference recorded music and what the Mic is picking up? What other optimization parameters can be derived from this approach.

Remember...this is "combat" audio. Not situations where you've had the opportunity to take the speakers outside, or the luxury of hours of un-interrupted , undisturbed optimization time.

Jeffsco -- I act as my own system tech and FOH guy. The truth is I own my own system and everything pretty much stays the same everywhere I go except the room and the crowds. There is a much better way to do all of this but I don't have the money to buy the best gear, buy the best system aligners, acoustically treat the venue for the venue owner & you know most venue owners completely don't see the treatment as a valid business expense. So yeah -- this IS combat audio.

There may be an easier way to get you in the ball park really fast but you will have to set your system up with Smaart first if you already haven't. I am sure you have.

Since I made that post -- I have made countless measurements indoors using smaart. My experience is -- I get too wrapped up in it trying to make it flat again (big no no) & it just takes a lot of effort. People hate it because it ruins their ball game or beer experience. I'm just not experienced with this type of measuring & the crowd can also change on a very short notice and the next thing you know -- everyone is clearing out, going for a beer or a smoke, asking you what you are doing ......etc.. This changes things.

I am not sure where you are at with your system but if you do have it tuned up pretty good then maybe Dave Rat's method of dealing with all of this is the answer.

I have been taking a known flat response set of headphones with me and playing music thru them straight off the CD player (NO EQ) just straight up unaltered music the way the CD was printed and listen. After that -- I play the CD thru the PA. Again with NO EQ. I then adjust the EQ on the mains to match what I hear in the headphones. Go back and forth with the headphones on and then off....repeat. The isolation from the headphones removes the room factor and when you are done adjusting the EQ -- you will end up with a sound that is very close to what you hear in your headphones.

It is much easier and takes a few minutes really. This can be going on while people are hanging out and nobody even knows what is happening.

What I learned from this is that comparing your Smaart tunings to good music helps you to confirm your tuning strategy. At first -- I noticed how much mid boost I was doing with my tunings using smaart. I don't know how I keep doing this other than my mic position. I do move the mic around a lot. Next -- when compared to a CD with good music -- even outdoors with NO headphones on -- I can tell that the mid is too much and needs cut. So I start at 400-500Hz wide Q and take some out. Bam -- everything starts to clean up. My headphones confirms it a second time.

Some guys use several different measuring platforms to get the "Best" overall average. I just use Smaart outdoors measuring in a ton of different places and then do a CD music test of some songs I really like and compare. Between the two -- you will get it very good.

Then once inside -- you get the typical bass build up and room modes that will need to be addressed. Maybe the high end as well.

Until I can get to a Smaart training seminar and learn the intricate details of what you see and hear on the screen I have to utilize a few things:

1. Tune the system up with Smaart (outdoors) measuring in as many places as I can. Not all dips need EQ'd.
2. Comparing your tuned system to good music you know. The music should sound really good straight thru with no eq.
3. Use an additional source such as a good set of headphones unequalized to get the system EQ matched up with the headphones that way the changes you make you can be certain the system is changing or tracking along with the headphones.
4. If I see that for example that at least half of my channel strip Eq's have 250Hz cut or 8kHz boosted -- then maybe a system EQ adjustment is in order to alleviate that.

I have found this to be easier for me for now than measuring inside because I have done many measurements and messed it up.

I could go on and on but check these links out for yourself. I think you will find the method works well for you.

http://www.youtube.com/watch?v=cU9BmupC62c
http://www.prosoundweb.com/article/when_hearing_starts_to_drift/
http://www.prosoundweb.com/article/backstage_class_strong_steady_wins_the_race_in_liv e_sound/

Jeffsco
October 22nd, 2011, 11:48 AM
Thanks for the feedback Dr. J.....I was considering using Dave Rat's method. The main issue as I said before was the lack of opportunity to tune a system outside.....I guess in these situations it's just a case of tough it out and do the best one can. The last gig I had to do this on...the band ended up happy with the sound, club promoter was happy...signed the band on the spot to it's regular band rotation...booked 'em for New Years at the end of 2nd set.

So....all in all..I did my part. It's just that I care deeply about what's coming out of FOH and want it to be the best it can be. I've spent too many years myself on stage playing thru a PA system where the sound at FOH was hurting. The audience knows it! And it's tough to do your best onstage when that's happening.

Dr. J
October 22nd, 2011, 01:00 PM
Thanks for the feedback Dr. J.....I was considering using Dave Rat's method. The main issue as I said before was the lack of opportunity to tune a system outside.....I guess in these situations it's just a case of tough it out and do the best one can. The last gig I had to do this on...the band ended up happy with the sound, club promoter was happy...signed the band on the spot to it's regular band rotation...booked 'em for New Years at the end of 2nd set.

So....all in all..I did my part. It's just that I care deeply about what's coming out of FOH and want it to be the best it can be. I've spent too many years myself on stage playing thru a PA system where the sound at FOH was hurting. The audience knows it! And it's tough to do your best onstage when that's happening.

If all I could do is walk in and have access to an EQ. I would take my headphones, a CD player were I knew there was NO eq on it & play the music thru the PA and listen with the headphones & adjust the EQ until they matched.

If you can't measure outside OR inside and do many other things that make it sound (like using the manufacturer tunings) the best it can be -- then all you can do is use your ears. The headphones with a flat response and a good CD that has great qualities will help you get it at hopefully an acceptable place to get thru the gig.

Dave says he won't do it any other way and I don't think I will either anymore.

I am in clubs where the owner and probably no one else cares as long as it isn't loud or ear piercing. So for me using the headphones with music is a incredibly fast way to get in the ball park.

A fixed install with top notch system -- I would hire a Rational guy and possibly an acoustician & get the thing done right. The ONLY thing that would be up for debate at that point is just someones mixing style & that would be on the creative side of the mixer rather than the diagnostic side. :D

Harry Brill Jr.
November 7th, 2011, 01:36 PM
In a previous post, Dr. J brought up the use of SMAART to help dial in a system while the band is playing. Could the Forum elaborate on this? I'm thinking small to medium club size where you either do not have time to do an extensive (or any...)sound check or where you are walking in to fill in on someone else's gear and the EQ that is set for the room needs to be tweaked . Could be pre show break music as well? The thing is ...we need to assume the club is filled with patrons and you can't pink the room without getting yourself fired. Specifically:

1. I'm assuming that you would not be able to do ground plane measurements, or multi mic measurements due to the presence of patrons in the club. So where does the measurement mic get placed in relation to the FOH Speakers?

You don't need to make a ground plane measurement in a room loaded with people. They are effectively blocking the floor bounce. In fact the reason to ignore the floor bounce int he first place is because when the place loads up with people, it will no longer be an issue.

2. How is the reference signal routed to SMAART? Do you take the output of the board before the GEQ? After? Aux send? What criteria do we need to send to SMAART?

BEFORE


3. Some people advocate sneaking in a bit of Pink noise underneath the music (Recorded break music...not while the band is playing obviously..). How much Pink is required?

Just enough to fill in the empty spots.


4. Can a GEQ for the room be developed from this technique? Will SMAART reliably show me what the differences are between the reference recorded music and what the Mic is picking up? What other optimization parameters can be derived from this approach.

It's pretty darn reliable but you have to know what you are doing with it. Bad measurement = bad/ useless data.



Remember...this is "combat" audio. Not situations where you've had the opportunity to take the speakers outside, or the luxury of hours of un-interrupted , undisturbed optimization time.
I like the idea of using the music between bands. The issue with using the band in a smaller setting is that the band has stage volume. That gets into the measurement but it's not coming from the PA, but it does correlate pretty well to the reference because it happens to be the SOURCE. That's going to give you traces that do not represent what the PA is doing. This is all well and good after the PA tuning is finished and the band is playing,....simply move to RTA and use the data to correlate what you hear to what you see. The system would have already been tuned. You are now using this information to "tune" your mix. Your mix is made up of a combination of the channels on your desk being mixed together and sent to the system, and the actual sources on stage which can also be clearly heard even if you muted the system altogether. It's what I call "damage control" mixing. This is the point where studio engineers throw there hands up and go back to the studio. This was the point where I (one time studio guy) felt challenged to figure out the cause of the chaos, which eventually led me to where I am now. I had a lot of BAD sounding shows on the way. Using Smaart or any dual channel signal independant measurement to help you get your PA "right" goes a long way toward having a better sounding show, but you are still going to mix these smaller venue shows way differently than you would an arena gig with a band using IEMs. The mix requirements are just way different. The latter case is far more like mixing in the studio (although you are mixing a set in 90 minutes, not an album in 90 days). The console movements you make are far more responsive, and when you mute a channel, that instrument "goes away". Not the case in your situation. That's why I call it damage control. You are there doing your best to make it sound good even though the band is fighting you by playing their amps way too loud, not using IEMs, and not using a drum "room" http://0.tqn.com/d/countrymusic/1/0/u/F/2/u26.jpg (picture of Garth standing on top of the drummer).
Good luck and have a blast! http://www.rationalacoustics.com/forums/concept9/icons/icon14.gif