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Discussion Starter · #1 ·
Within the next few days I intend on measuring my rooms response. Currently I have a Behringer ECM-8000 omnidirectional mic with an external M-audio Firewire 410 sound card and the digital RS SPL meter. The sound card is a built in pre-amp with phantom power for the mic.


I want to see how my room is reacting to bass frequencies and Im not 100% sure where to start. I have "leveled" all my speakers using the SPL meter to 80db.


Is the Berhinger more accurate in setting a listening level of 80db as compared to the RS SPL meter? Should I use the mic instead and re-level everything before doing room measurements?


I assume that to measure correct bass response all the other speakers should be off and only the sub should be on for measuring.


Do I put the mic in my seating position facing towards the ceiling to measure the room?


Do I burn a cd with the test frequencies on it, or do I use the ones included in the Room EQ app? Or can I use my Avia disc with the Room EQ app?


How do I adjust the gain accordingly on the soundcard for the MIC properly..or does it not matter with the gain since all its doing is measuring room response?


I dont have the BFD yet as I intend on getting it at some point soon..I at least now would like to see what I have to deal with room wise and maybe work on the nulls that Im sure I will have.


Once I get the BFD my sound card already has Midi In and Out so connecting it to the BFD wont be an issues at all.


Im bascially trying to get some assistance in a step by step procedure so I get an accurate measurement and not some skewed thing due to my lack of experience in measuring room response.


Any help is appreciated. Thank You
 

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Discussion Starter · #3 ·
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Originally Posted by TooMuchTV
Have you read the Snapbug BFD instructions? They give pretty detailed instructions on the process. http://www.snapbug.ws/bfd.htm


I have read his instructions. But I currently do not have the BFD yet as stated in my above post. I just want to get a plain room measurement done to see where I stand. Also -correct me if i am wrong- his instructions are used only if you do not use the Room EQ application which interfaces with the BFD so you do not need to do his method.


Im looking for more basic setup and startup..as well as the correct way to get the measurements as stated by some of my questions above. Im just wanting to make sure I have the correct procedures on place as to not get skewed measurements.


Also he uses Sine waves and not Pink Noise which also confuses me.
 

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Are you talking about the Room EQ Wizard? There's a long thread on the topic in the theory, setup and chat forum (a few down from this one)


You don't need the BFD to play with it, download the program and read the help file as you go. It's not the most straightforward thing if things DON'T work correctly the first time, but JohnPM is very responsive and helpful. Of course, if you don't have the problems I had, it will probably work great the first time out.


The room EQ wizard uses a sweep, and you set the range of the sweep (e.g. 20 Hz. to 200 Hz, or something similar) and pick a filter (sub) so you have a target response level.


A calibraged mic should be more accurate than the rat shack meter, but I don't know how the app. accounts for different microphones. That would be a question worth posting in the support thread.


In theory, it shouldn't matter for what you are trying to accomplish. Compensating for the mic can help you set the absolute levels accurately, or remove the slope induced by the mic's inaccuracies, but the nulls and peaks will be very obvious even if you use an uncorrected microphone.


So, you can either do all this manually with Avia and your SPL meter, or you can do the room EQ wizard method, which will automatically (actually, it steps you through a process to) set reference levels for the mic, the sound card and the feedback loop. Give it a shot!
 

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Discussion Starter · #5 ·
Quote:
Originally Posted by TrojanHorse
Are you talking about the Room EQ Wizard? There's a long thread on the topic in the theory, setup and chat forum (a few down from this one)


You don't need the BFD to play with it, download the program and read the help file as you go. It's not the most straightforward thing if things DON'T work correctly the first time, but JohnPM is very responsive and helpful. Of course, if you don't have the problems I had, it will probably work great the first time out.


The room EQ wizard uses a sweep, and you set the range of the sweep (e.g. 20 Hz. to 200 Hz, or something similar) and pick a filter (sub) so you have a target response level.


A calibraged mic should be more accurate than the rat shack meter, but I don't know how the app. accounts for different microphones. That would be a question worth posting in the support thread.


In theory, it shouldn't matter for what you are trying to accomplish. Compensating for the mic can help you set the absolute levels accurately, or remove the slope induced by the mic's inaccuracies, but the nulls and peaks will be very obvious even if you use an uncorrected microphone.


So, you can either do all this manually with Avia and your SPL meter, or you can do the room EQ wizard method, which will automatically (actually, it steps you through a process to) set reference levels for the mic, the sound card and the feedback loop. Give it a shot!
Yep..I'm talking about the Room EQ Wizard :)


I was able to get a pre calibrated text file for the ECM8000 to import into the Room EQ Wizard.


Do I use Pink noise to measure room bass response? Or a Sine Wave?


Also do I run the sweep with only the sub on? I assume this would be so.
 

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Pink noise is used to set all of your speakers to the same level (loudness). Sine waves are used plot your frequency response across a range of frequencies so that you know where your peaks & dips are to EQ.


The end goal is to get a flat frequency response between your sub and mains. Remember they both share frequencies across the crossover point. Most people first plot and EQ with only their sub and then do it again with their mains on to iron out problems in the crossover area.
 

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What TV said.


I did mine the first few times without the mains to see what the sub was doing, and then I did it with the mains (but you kind of have to do it one channel at a time the way the program works, so I just did mains.)


Alright, so now you have enough info to give it a whirl... pop back in with some results when you get a chance. :)
 

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Discussion Starter · #8 ·
Quote:
Originally Posted by TrojanHorse
What TV said.


I did mine the first few times without the mains to see what the sub was doing, and then I did it with the mains (but you kind of have to do it one channel at a time the way the program works, so I just did mains.)


Alright, so now you have enough info to give it a whirl... pop back in with some results when you get a chance. :)
As soon as I get my sub squared away i will definately pop back in with results :)
 

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not trying to hijack, just same topic.


im trying to do the same exact thing tritonman is. I d-loaded the roomEQ wizard and it may be the wrong one? On the bottom right hand side, it says TMREQ right under where you select left,right,center etc... Shouldnt it say BFD PRO or something? Did I d-load the wrong one? I want it to work with my BFD and while on the website just before d-loading it, they had a sample pic of the roomEQ and it had BFD on it. What gives???
 

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I have a related question: I'm using a Meridian 861 to do the low end EQ (two SVS Ultra's driven by Crown K series) and it works really well, but only addresses frequencies below 300hz.


I want to use a Behringer Ultra to do some tweaking of the higher frequencies for my three front channels.


I have a Goldline 1/12th octave RTA and several wideband pink noise CDs/DVDs. My question is "What setting for the processor?"


If the processor is set to THX2 or to Trifield, or to anything other than a straight pass through, then doesn't it "tweak" or "shape" the signals going to the three front channels? If that's the case, do I want to EQ to the post processed signal or to the pre-processed signal? (And, if the latter, how do I get to that as I don't see an option for an unprocesses signal to each channel independently?)


Thanks!
 
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