Rational Acoustics



Dr. J
December 13th, 2010, 05:37 PM
I have been using Smaart lately to check my mixer's EQ potential. With ALL EQ'S OFF & pink noise thru a channel input I can engage a filter and get a response. It looks like everything seems to be working fine, the HighPass function appears to be a 6dB Slope. I don't know what it is on a Professional console worth it's salt BUT mine appears to be a 6dB roll off. The "Hi-Q" function is a 2/3 octave "Q". I was a bit surprised that it wasn't at least as specific as a 1/3 octave graphic.

Now my question or dilemma: When I have the system up and running for a tuning session -- My system EQ responds to changes just fine BUT now the channel strip EQ DOES NOT respond on my live trace. You can hear it change BUT you can see it on the magnitude trace.

Why is that? Does it have something to do with Electrical domain versus acoustic domain?

Rasmus Rosenberg
December 14th, 2010, 04:11 AM
Hey J.
Proberly because you have you ref signal after the channel strip EQ, (console output). That would mean that the same adjustment/change (on the channel strip) is applied to both the measurement and ref signal. That means no change relatively and therefore not visible in the magnitude trace, that measures/shows the difference between the ref and measurement signal.

Kip Conner
December 14th, 2010, 07:28 AM
Defintely sounds like Rasmus is describing. You refrence feed is coming from the console and essentially your measurement (microphone) trace is looking at everything past that point in the signal path (master comp->master EQ->DSP->amplifiers->drivers->room).

If you wanted to look at individual channels than you might want to find the monitor/cue buss out and use it during your soundcheck & show and set that to PFL (which would hopefully be Pre fader / Pre EQ). The refering audio would be in it's raw state. You would need to consult the block diagram for your mixer to find out if the HPF comes before or after the PFL buss.

What kind of console are you using?

Dr. J
December 14th, 2010, 11:08 AM
Ah -- Thanks Rasmus & Kip. Kip -- I am currently using the Presonus StudioLive mixer. A very neat but basic entry level digital mixer.

The mixer interfaces with my laptop and allows firewire live recording. Smaart also recognizes the mixer as an interface BUT I haven't been able to figure out how to use my mixer as "MY Mixer AND Interface" BOTH at the same time. I don't know if it is even possible. Just a cool thought.

I use a Presonus FirseStudio Mobile as my Smaart interface for now since it is easy to use and very portable.

When I use Smaart to check my mixers EQ possibilities -- I just use the firewire out of the mixer straight into my laptop with Smaart on it. I can then see the EQ changes being made on the channel strip that has the pink noise running thru it.

BUT -- when I am actually tuning the system -- I don't use my mixer as the interface and switch to the firestudiomobile interface.

I think that changes things because of where I am patched into the system.

OK -- Let me tell you WHY I am doing this. I just got into sound a few years ago & I knew absolutely NOTHING about it. However, I am a guitarist that has been playing for 25 years AND I have NEVER been satisfied with how my guitar has sounded out front. I would even go see bigger bands playing thru local sound companies sound rigs and found myself asking: "Why does it seem that money and equipment doesn't matter how a PA sounds"? I would see awesome PA set ups and it sounded like garbage BUT then see a small band playing thru a couple of 12" tops on poles and a couple of monitors and it sounded so much more musical.

I knew there had to be something to it. I was convinced that EVERYONE in this area is missing something huge with this and sure enough the FLAT frequency response was the missing piece for the most part. Why don't more people know about this? I just watched a sound guy the other night with his head buried in a graphic EQ for an hour straight & managed to suck the life right out of the PA.

I am convinced that I have made the progress I have because I started out not knowing anything PLUS I found guys like you and another mentor of mine on the Driverack forum. So out of the shoot -- I was taken down these paths. How lucky for me to not have been trained the wrong way for 20 years and want to argue with everyone about everything :D

I have not found a better teaching tool than Smaart. I learned some of the long ways to do things on the Driverack forum and never fully understood BUT then within the first day or two of Smaart -- the major light bulb went off & I have never looked back.

I am quite new to mixing even though that is what I started out doing a few years ago. Smaart got in the way:D

I figured I have to be at the best possible starting position first before learning how to mix otherwise why bother.

Ok sorry for the long story..... Just for more knowledge -- I want to see how accurate my board is at tracking EQ based off of my system response.

I would love to be able to see a screen with my system response on it, then on another screen the lead vocal response in relation to the system response so you know that you know how the channel strip EQ works compared to the system response. I hope that makes sense. Also, to look at any of the channel strips if I wanted to.

I have seen mixers that have a screen that indicate what you are cutting and boosting BUT they seem to be based off of a flat response. Live sound systems never have a completely FLAT response all the way across the spectrum BUT yet the EQ screen on the console leads you to think that. It would be nice to enter in your system response curve and have the mixer track it on the console.

Ok -- I'm done......:rolleyes:

Kip Conner
December 14th, 2010, 11:28 PM
Hey, we all started not knowing anything and there are days when I still feel like I know nothing. The best way to get better is surround yourself with people that are better than you. That's why I hang out here, I learn stuff on a daily basis. It's all good, you're amongst friends. There's no attitude here- why I choose not to visit the Live Audio Board!

Dr. J
December 15th, 2010, 03:32 PM
The best way to get better is surround yourself with people that are better than you. That's why I hang out here, I learn stuff on a daily basis. It's all good, you're amongst friends. There's no attitude here- why I choose not to visit the Live Audio Board!

Thanks Kip -- I agree. Hey, you used to hang over on the Driverack forum didn't you? Gadget (Gary) over there and Dennis (who hangs here as well and avid smaart user) has taught me everything I know so far. Now you guys are helping fill in the blanks as well.

I find myself spending more time reading on here than anywhere else lately.

It is like a puzzle where I am starting to get the border all figured out and suddenly I realize; Holy Crap -- it's a COW. LOL:D Just kiddin' but things are starting to make a lot of sense now.

The only thing that has slowed me down is time & money. I can't get enough of this stuff. Thanks for the encouragement!

Kip Conner
December 26th, 2010, 03:14 PM
I think that I logged in a few times when I was doing some install work with a company that religiously used driverack systems. Why wouldn't they used it religiously... they were doing worship installs. It was one of those things for where I was using Omnidrives and I was asked if I knew how to set-up up the driverack. I figured that since I had been working on superior gear that I wouldn't have any problems. I had to get a lot of comparision info on the different versions and used the DR Community extensively for a crash course on the software based units that had no front controls.

I have to tell you that I have never met another group of guys whom are willing to share knowledge and technique. How many software manufacturers out there jump in and answer questions in-directly related to their products.