Rational Acoustics



Rasmus Rosenberg
December 1st, 2011, 08:57 AM
Holla et all,
Had an other fun one from the trenches yesterday that I find quite illustrative to how easy our otherwise wonderful ears are to fool. A little background: The day before yesterday I was hired to mix an american band at a very small venue. The venue is about 15x12 mtrs has a oki sound system of known brand 15"x2" a side and a mono sub. Mix position are at the back wall on axis right. A new stage has just been installed meaning the speakers ended up behind the "vocal line" resulting in little headroom before feedback especially around 800hz/1Kz. To counter that they have moved the speakers 1,5 mtrs forward, helping a lot. But the old speaker cables was not long enough, so they just extended them. The system has played a couple of months DJ's in the weekends and about 8 live shows, At least 4 different guys have mixed on it and the only feedback have been good and how much more headroom was in the system after they moved it. So back to the show...

I setup and only quick tjeck the system with pink noise left then right then monitors all good (at least I think). 12 mins before doors the 6 pice band shows up so fair to say its make the best of it in -15 mins of line check we get, before the doors has to be opened. The band is amazing and plays very low level only vocals in the PA all good, but the vocals sound weird to me. Im pretty convinced that in my stress to make it work i have overlooked an Eq or some thing in the digital console. So i make the best of it, and the few people that showed up and the band had a great night. So show is over and I switch the DJ on and goes to pack, as I pass the middle of the room where both Left/right meet it sound really funky... oh well sleep on it.


The next day i have to do a show there again. So i setup and this time listen to both Left and Right at the same time and there its clear some thing is weird. So I hook up smaart and measure left and right, and its pretty clear that they are different and most likely the Woofer PA right are out of polarity compared to the left. So I make 2 new cables and bum the two sides measure alike and it sound much better. Go on and mix one of the best show in years. I have attached a pic showing the Left and "bad" Right side, when cables was corrected the both measured as the "good" left. So morale of the story is that I'm continual amazed on how relative offend our ears are fool by our brain to accept things and how hard it can be to pin point problems that shows up very clear on an analyzer.

Dr. J
December 2nd, 2011, 03:23 PM
Holla et all,
Had an other fun one from the trenches yesterday that I find quite illustrative to how easy our otherwise wonderful ears are to fool. A little background: The day before yesterday I was hired to mix an american band at a very small venue. The venue is about 15x12 mtrs has a oki sound system of known brand 15"x2" a side and a mono sub. Mix position are at the back wall on axis right. A new stage has just been installed meaning the speakers ended up behind the "vocal line" resulting in little headroom before feedback especially around 800hz/1Kz. To counter that they have moved the speakers 1,5 mtrs forward, helping a lot. But the old speaker cables was not long enough, so they just extended them. The system has played a couple of months DJ's in the weekends and about 8 live shows, At least 4 different guys have mixed on it and the only feedback have been good and how much more headroom was in the system after they moved it. So back to the show...

I setup and only quick tjeck the system with pink noise left then right then monitors all good (at least I think). 12 mins before doors the 6 pice band shows up so fair to say its make the best of it in -15 mins of line check we get, before the doors has to be opened. The band is amazing and plays very low level only vocals in the PA all good, but the vocals sound weird to me. Im pretty convinced that in my stress to make it work i have overlooked an Eq or some thing in the digital console. So i make the best of it, and the few people that showed up and the band had a great night. So show is over and I switch the DJ on and goes to pack, as I pass the middle of the room where both Left/right meet it sound really funky... oh well sleep on it.


The next day i have to do a show there again. So i setup and this time listen to both Left and Right at the same time and there its clear some thing is weird. So I hook up smaart and measure left and right, and its pretty clear that they are different and most likely the Woofer PA right are out of polarity compared to the left. So I make 2 new cables and bum the two sides measure alike and it sound much better. Go on and mix one of the best show in years. I have attached a pic showing the Left and "bad" Right side, when cables was corrected the both measured as the "good" left. So morale of the story is that I'm continual amazed on how relative offend our ears are fool by our brain to accept things and how hard it can be to pin point problems that shows up very clear on an analyzer.

Well, I will say something......... Nice case study Rasmus! I love learning from you guys. It has been pretty quiet around here so I will probably make up something to talk about soon. Hopefully everyone will jump in. Not anything to do with All Pass filters or shading..... BUT about Latency thru plug ins & outboard gear.

Rasmus Rosenberg
December 4th, 2011, 08:56 AM
Well, I will say something......... Nice case study Rasmus! I love learning from you guys. It has been pretty quiet around here so I will probably make up something to talk about soon. Hopefully everyone will jump in. Not anything to do with All Pass filters or shading..... BUT about Latency thru plug ins & outboard gear.

Thanks,
I wish i was a better writer and had more time to post. As you can see from most of my post's I live quite in the combat audio world of things, where time is short and major compromises are made either in the speaker design or room acoustics (what do you mean the venue are in the swimming pool?) However in the past 3 or so years I have not regretted one time, or felt it I was wasting time, starting up smaart. That might be funny to mention, but think about it. Let's say you have 10 mins and thats what it takes you to setup smart and do one measurement. In that time you could played 3 full songs and walked at least 1 km. Thats should be enough to hear the coverage of most speaker systems and get an if somethings are wrong. Our ears (brains) are just easy fooled. Now I will never be afraid to say that I don't have the best ears in the business, but my own ears are one thing, I see it happen to a lot of "better" people too. Smaart can be fooled to, I'm not saying otherwise, but I'm continually positively surprised of how much more "power" you can have when they using both.

I will look into you latency post, as I find i very interesting and have spend quite some time studying different plug in setups, as I use plug ins a lot when I mix.

Dan Currie
December 5th, 2011, 10:32 PM
Ramus,
One of the reasons I finally got Smaart was because of this. After a tour of 300-700 cap venues Smaart would have save a lot of time. With only 3 hours to load in and check time to troubleshoot can be an issue. My favorite was a venue with 2 flown Meyer cabs per side. One box was 180deg out of phase with the one next to it. Of course they weren't on motors so I had to do some climbing. Who knows how long the room had been like that? Having Smaart on hand would have saved some valuable time for dinner and a nap.

Kip Conner
March 8th, 2012, 11:45 AM
Part of engineering is definitely having to pick your battles. Most of the rooms that I play are in that 300-700 capacity room and I do load-ins 3 hours before doors. The trick is to have a rig that can be set up in under a minute. The only way that I have been able to do this successfully is to have the rig pre-set in my rack with my own console. I use an LS9 with mults to patch the stage input lines and all the of output lines are connected via an ADAT cable to a Focusrite AD/DA. In the rack with the Focusrite is a Roland Octacapture.

I use my laptop to generate the test material directly to octacapture via USB and the the stereo outs of the octacapture are directly wired to Inputs 7/8 of the Focusrite. The inputs are routed via Adat to channels 23/24 on the LS9. I now have audio that I can route to any zone or stage monitor. Those channels (as all channels) are routed to the mono bus which leaves the console via Adat with all the sends for the system that go back to the Focusrite i/o. Theres an output pre-wired right into the octacapture to complete the set-up.

To this point all I have had to do is plug in computer power which lives in the rack, the usb cable, a pair of adat cables and mic input for a single channel measurement. I can connect all of that quicker than it takes to type these two sentences. (I'm no secretary, but a moderately quick typer). It's a super fast set-up that allows me to tune a PA and monitor mixes in under 15 mins. Short cuts? Of course. I wish that I had time to get out all the mics and do several points of simultaneous measurement. It comes down to picking battles.

Now the question of Smaart vs Golden Ears... I know what a properly tuned PA sounds like and can quickly ascertain where it sounds odd. What my ears can't do- and I have yet to find someone who can do this- is hear degrees of phase or calculate delays times in my head. We can all guesstimate, but there are things that smaart can tell me quickly without having to guess.

What I have found is that there are too many people out there passing themselves off as qualified system techs. I did it for years because my methods worked for me. I have tried to come up with a more universal method that anyone can walk up to and begin working.

Also- don't be afraid to tell the powers that be that you need more time. People spent a lot of money on tickets and they should get their money's worth. Another half hour shouldn't be that big of a deal... unless it's a union house and then you need to know how to delegate :)

Now, there are people that will disagree with the way that I set-up my system, but I needed to do it this way for a few reasons. Some may choose to use the internal mixer on the octacapture so the audio doesn't send and return. I like to keep the console in the measurement path so that I can measure it too.

Everyone has to find their own method and