Using a spectrum analyzer...?

[MrHeadfirst]

anyone use one?
can i theoretically use a spectrum analyzer to dial in the pa eq settings for different rooms for a flat output and at least get close or even dead on?

 

[monkeyland]

the term you are looking for is Real Time Analyzer (RTA). you would typically put pink noise through the system and use a reference mic attached to the RTA to find the ups and downs in the frequency response. and yes you can use one although there are a few problems with the idea.

1. rarely in most real world situations will you get a chance to run pink noise at a gig. it's very stressful to any patrons of a place that may be there already.

2. you are only setting a curve for One specific point in the room this way. the problems due to reflection could be much different just a few feet away.

In my, and many other much more educated sound persons, opinion it's much better to set the main system EQ by listening to music that you know very well and walking the room. less precise maybe but once you get good at it it will be more rewarding. you will also be less prone to make large cuts or boosts "because the machine says so"

an RTA is very useful for correcting for anomalies within a specific speaker set. designers would use an anechoic chamber but those are few and far between. the real world way to do it is to take the speaker(maybe a monitor or whatever) outside and setup the RTA. then adjust for the big problems useing a Parametric EQ. this is the type of thing that would go in the monitor amp rack and be forgotten about. You would still use a 31 band Graphic to ring out the monitor at the gig.

probably more info than you asked for

 

[Zooberwerx]

Possible but not always practical as monkeyland pointed out. We use a dbx DriveRack with RTA mic and Auto EQ. We're fortunate that we're able, in some situations, to run auto-EQ before the crowd arrives. I store the info as a preset and will recall it when faced with "like" venues. Its usually close enough as there appears to be some degree of reproducibility amongst rooms of similar size. I also keep a "rescue" graphic EQ inserted....just in case!

Riis

 

[JackANSI]

I've had some luck early on setting up systems (or just trying different configurations) outside at least 100ft from anything solid (like a wall), pointing the setup away from anything that could reflect (usually pointed my stuff into the woods 200ft away), and letting a DBX DriveRack auto EQ smaller systems.

It would end up being very close to flat sounding, yes, even when taken back indoors, with just a little tweeking of the parametric to get things right for the room. Then you just save a preset for that venue for next time.

 

[bassman1185]

In my experience, RTAs are more useful for quickly dialing out feedback than for attempting to "perfect" a room's sound.

 

[Passinwind]

anyone use one?
can i theoretically use a spectrum analyzer to dial in the pa eq settings for different rooms for a flat output and at least get close or even dead on?

Why do you think a flat response is what you want? Flat in what location in the room? Or "flat", averaged over how many locations? It gets worse...

Many sound companies have moved well beyond simple RTA room calibration these days. If you want to see the bigger picture something like Invalid Link Removed will do a much better job, once you get past the steep learning curve.

 

[walterw]

following the curve of an RTA will usually result in a hideous sound, as it tries to compensate for room cancellations and time/phase issues with EQ.

here are the right answers:

I've had some luck early on setting up systems outside at least 100ft from anything solid (like a wall), pointing the setup away from anything that could reflect (usually pointed my stuff into the woods 200ft away), and letting a DBX DriveRack auto EQ smaller systems.

outside, you're purely RTAing just the system itself, not the room. no false readings and phase problems from reflections and whatnot.

one of these days i wanna try that with my little PA, so i can get it flat, and just EQ by ear room to room starting from there.

In my experience, RTAs are more useful for quickly dialing out feedback than for attempting to "perfect" a room's sound.

yep. i have a neat little program called "FFT" on my iphone, with an RTA graph that shows hot spots and feedback frequencies when i mix. i'd never dream of trying to EQ the room to make its display look "flat", though.

Why do you think a flat response is what you want? Flat in what location in the room? Or "flat", averaged over how many locations? It gets worse...

Many sound companies have moved well beyond simple RTA room calibration these days. If you want to see the bigger picture something like Invalid Link Removed will do a much better job. once you get past the steep learning curve.

there it is. this stuff is what the big boys use (and is way over my pay grade), but the idea is that it uses multiple mics, and compares the mics with the system's direct signal, to get a picture of what's really happening, registering the delay/phase anomalies that are the real source of room issues and that EQ will not fix.

 

[MrHeadfirst]

I see what you guys are saying. I typically do use my ears to set the sound. we just play in a few rooms that are pretty tricky, and i dont have an outside sound man. I was hoping i could use something like that to get in the ball park at least. but it seems it may be more trouble that it is worth.
i go out and hear a lot of local bands and their live sound sucks, it typically sounds like a mud pile, and that is what i hate. when my band plays, i try my best to get a clean clear sound, with no mud involved. when we sound like my favorite cd's, then i am happy. i hate it when the vocals sound like a monotone mush with no distinction. sometimes, you cant even tell what people are singing because of this. that is my goal in life as a gigging musician, for everyday patrons, to hear us play and actually be able to tell that we are doing something different than the other guys. i know there will always be a critic, and we all hear and perceive things different, but im proud of our sound. just want to do my best with my limited resources to make it as good as i can. and by good, i mean clear and defined.