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EQing a room on a budget!
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Jaan
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#1
21st February 2009
Old 21st February 2009
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EQing a room on a budget!

Hey!
One of my hobbies is mobile DJing (i reckon its easy money on the side).
I remember reading a while back about EQing rooms and tuning the speakers for a flat response throughout the space.

My setup usually consists of this:
Presonus Firebox
Ableton Live
Rented speakers + subs
*I have access to an SM58 mic too

The little knowledge I have tells me that I should be able to hook up the SM58 to the firebox, run some VST in Ableton that plays pink noise through the speakers and magically equalizes the room. Am I mistaken? What should I do?
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21st February 2009
Old 21st February 2009
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Using EQ to compensate for poor room acoustics is doomed to fail. Even devices that claim to be more sophisticated than EQ don't do a very good job either when put to the test. More here:

Audyssey Report

--Ethan
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Jaan
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21st February 2009
Old 21st February 2009
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Thanks for the quick reply Ethan.
So you don't think I should worry about 'EQing' rooms?
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21st February 2009
Old 21st February 2009
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No EQ, but you should definitely worry about acoustic treatment. Here's the short version which will get you 99 percent of the way there. All rooms need:

* Broadband (not tuned) bass traps straddling as many corners as you can manage, including the wall-ceiling corners. More bass traps on the rear wall behind helps even further. You simply cannot have too much bass trapping. Real bass trapping, that is - thin foam and thin fiberglass don't work to a low enough frequency.

* Mid/high frequency absorption at the first reflection points on the side walls and ceiling.

* Some additional amount of mid/high absorption and/or diffusion on any large areas of bare parallel surfaces, such as opposing walls or the ceiling if the floor is reflective. Diffusion on the rear wall behind you is also useful in larger rooms.

For the complete story see my Acoustics FAQ.

There's a lot of additional non-sales technical information on my company's web site - articles, videos, test tones and other downloads, and much more.

--Ethan
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21st February 2009
Old 21st February 2009
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Quote:
Originally Posted by Ethan Winer View Post
No EQ, but you should definitely worry about acoustic treatment. Here's the short version which will get you 99 percent of the way there. All rooms need:

* Broadband (not tuned) bass traps straddling as many corners as you can manage, including the wall-ceiling corners. More bass traps on the rear wall behind helps even further. You simply cannot have too much bass trapping. Real bass trapping, that is - thin foam and thin fiberglass don't work to a low enough frequency.

* Mid/high frequency absorption at the first reflection points on the side walls and ceiling.

* Some additional amount of mid/high absorption and/or diffusion on any large areas of bare parallel surfaces, such as opposing walls or the ceiling if the floor is reflective. Diffusion on the rear wall behind you is also useful in larger rooms.

For the complete story see my Acoustics FAQ.

There's a lot of additional non-sales technical information on my company's web site - articles, videos, test tones and other downloads, and much more.

--Ethan
So, how does a mobile DJ use this information?

I cant imagine someone walking into a club with 60 2'x4'x6" panels, hanging them and taking them down... and expecting them to not be completely mauled by nights end
#6
21st February 2009
Old 21st February 2009
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Get a DBX driverack, one of the cheap ones used on E-bay. They are great and will help a LOT. Are they perfect-no. But ten times better sound and punch than not using one. You are not tuning the room, you are tuning your speakers. I use mine for small systems and three ways 20000 watt system. The comp and limiter is killer also.

Jeff
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21st February 2009
Old 21st February 2009
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I think Ethan has been inhaling too much dust from the offcuts of his room treatment - he seems to have missed the point of your question...

For a mobile dj, you certainly can and should eq a room to get better sound - I do this the time as a live sound tech - We call it "ringing" out the room and you do it to reduce resonant frequencies which will cause problems for balance,

The easiest way to do this is to get a graphic eq (the more bands the better) and just talk into the mic while you try boosting each frequency - the ones that ring out more need to be reduced accordingly - once do this for awhile you get used to the feel of it - after awhile, you will be a pro, able to make almost any room sound better than it did intitially - you may not even need to do the testing with the mic after awhile as your ears become better at picking out problem frequencies and you can adjust from experience

Of course you can not fix every ass sounding room this way but this is the first step most live sound tech will do in a new venue - it paves the way for hearing things how you want - if you dont do this you mave have some real problem frequencies happening during your set - of course a lot of people wouldnt notice, but they do think you are a better dj when you sound better, even if they dont know why they liked you more.....

Last edited by Hardtoe; 22nd February 2009 at 04:45 PM.. Reason: playful jab at ethan inserted - needed to be done.....
#8
22nd February 2009
Old 22nd February 2009
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Quote:
Originally Posted by Hardtoe View Post
I think Ethan has been inhaling too much dust from the offcuts of his room treatment - he seems to have missed the point of your question...
Indeed. I see "EQ a room" and I go on auto-pilot. Sorry. Carry on.

--Ethan
#9
22nd February 2009
Old 22nd February 2009
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Quote:
Originally Posted by KRStudio View Post
Get a DBX driverack, one of the cheap ones used on E-bay. They are great and will help a LOT. Are they perfect-no. But ten times better sound and punch than not using one. You are not tuning the room, you are tuning your speakers. I use mine for small systems and three ways 20000 watt system. The comp and limiter is killer also.

Jeff
Agreed. Then you can tweak the eq to perfection after you auto-eq. The auto gets pretty close, and the thing is, it basically gives you the same sound out of auto in each room. So you have a basic starting place that is about the same no matter where you are . Also has the comp and limiter on the back end which can help a lot.
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22nd February 2009
Old 22nd February 2009
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The DBX driverack looks very enticing, but if it's $300 I'll have to try it on my own first with a mic and 31 band VST EQ.
(@Ethan: I was also considering hauling a few hundred bass traps to every gig I play LOL)

Do you think I could replace my voice with pink noise and go through the same process of boosting a band, listening for ringing then reducing accordingly?

What about getting a cheap calibrated mic and using that with software?

Cheers
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22nd February 2009
Old 22nd February 2009
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EQing with a mic will tame the frequencies that are feeding back from the speakers into the mic. This will let you get your mic louder, but is not necessarily going to match your speakers to the room. When I'm doing live sound gigs, I EQ the speakers to the room first, and then I notch out the feedback problems with a mic. These are two different processes.

Your best solution would be to run pink noise through the system and use a real-time analyzer (RTA) with a calibrated mic to let you see how your speakers couple to the room. Then you would adjust a 31-band EQ to flatten out the display on the RTA.

If you were doing sound for a band (with lots of mics), the next step would be to bring up each mic until it feeds-back and notch out that particular frequency from that mic channel. But you are not trying to control the feedback from microphones, you are playing back music.

Short of buying an RTA, your best bet is to play a song you really know well and adjust the EQ until it sounds as good as possible. Play several songs and listen with your ears to see if adjustments need to be made.

You might want to spend some time on your own running extreme equalization settings so you will start to appreciate how to use the EQ to make the sound better in a strange venue.
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22nd February 2009
Old 22nd February 2009
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Another, possibly less expensive alternative is the Behringer DEQ 2496 Ultra Curve Pro. It is similar to the dbx Drive Rack. Used with a Behringer ECM8000 mic (about $50), it has an Auto-EQ function that does an OK job. It also includes a compressor/limiter, graphic and parametric eq so you can tweak to your liking as well as protect your speakers from overloads. The 2496 sells for about $300 although I just saw one from Audiolines.com for $179. Just google "deq2496". I have one and I'm happy with it. Yes, it has that "B" name on it, but truth is, I buy equipment for what it does not for the name or how much it costs. I have some Behringer gear I'd throw away and be happy I did, and other stuff that does an amazing job especially given the price. I just put a piece of tape over the nameplate and write in some fancy pants manufacturers name. Nobody but me knows the difference!!!

Oh, one other note... When you use any piece of gear that can do the auto-eq thing, remember that you'll get a nice flat response in exactly one place; where the reference mic was placed. There is NO way to get a flat response everywhere in a room just by using EQ. For that, Ethan was right, you'd have to get knee deep in treatment, and as has been stated, that just ain't gonna happen in the business you are in.
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22nd February 2009
Old 22nd February 2009
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I wouldn't put a hand on behringer, I was dealing with their compressors last friday in a theater. I turned them off they were so horrible... I tried to like them, but for some reason it passed a really crackly sound ON EACH TRACK. It was horrible. Turned it off, everything was fine... just not as loud, but whatever, at least it sounded human.

You will want a compressor, and the Behringer, from my experience, won't cut it.
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22nd February 2009
Old 22nd February 2009
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Barnabas - I think we are actually on the same page, just using different methods - when I first ring out the room with the "mic" technique, I am not trying to get the mic to play nice with sound system, but to use it to find resonant peaks - feedback occurs where too much of any given frequency builds up (due to room modes, reflections, etc), therefore eqing it out makes the room sound more "flat" (I always just use my ears as the RTA - maybe not perfect, but I am, after all, being paid to hear things at a professional level, so I shouldn't totally $#%^ is up..... Of course you want to test out your settings with some trusted recordings to make sure that you are on the money. I have never tried it with noise though - it sounds like a great idea and I will try it out next time I do a gig....

(BTW - off topic - Everytime I go to write "sure" I want to spell it "Shure" - what the hell does that say.....)
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#15
23rd February 2009
Old 23rd February 2009
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Thanks for the replies.

The Behringer ECM8000 has good reviews online, and it's only $50

So if I buy an ECM8000, I should be able to plug it into the Firebox, run RoomEQ or TrueRTA (Room EQ Wizard Home Page or TrueRTA Audio Spectrum Analyzer Download Page), add a 31 band EQ VST onto Ableton Live's master output, then reduce frequencies according to the graphs.
Would this work?

Cheers, I'm getting excited now.
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23rd February 2009
Old 23rd February 2009
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Quote:
Originally Posted by Jaan View Post
Thanks for the replies.

The Behringer ECM8000 has good reviews online, and it's only $50

So if I buy an ECM8000, I should be able to plug it into the Firebox, run RoomEQ or TrueRTA (Room EQ Wizard Home Page or TrueRTA Audio Spectrum Analyzer Download Page), add a 31 band EQ VST onto Ableton Live's master output, then reduce frequencies according to the graphs.
Would this work?

Cheers, I'm getting excited now.
That will work. Then you fine tune it from there. Good cheap way of doing what the drive rack does. Then also since it's in the DAW, you can put a compressor/limiter behind it as well. That should work as good as the Driverack.
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