Anyone used Room EQ Wizard?

[Hi Ho]

I recently purchased a Behringer FBQ2496 for my PA system. It works great as a feedback killer and has allowed me to crank up monitors in really live rooms using all condenser mics like I never could before.

Today I decided to see how it could help my theater system when I'm not using the PA. I spent much of the day messing with Room EQ Wizard. I have not invested in a measurement mic like the Dayton but I have the Radio Shack analog SPL meter. From what I have read, this should be adequate for measuring low frequencies.

I had some problems. First of all, I could not make REW happy with the levels. Even after cranking the input gain on my MacBook Pro all the way up, it kept telling me that the input level was "much lower than it should be" even though the level display showed it nearly clipping.

I did the measurement anyway and after finally figuring out how to automatically configure filters I downloaded them into the FBQ. I definitely heard a difference but I wouldn't say it was for the better.

First of all, I had to boost the sub output on the receiver to +10, where it had been -4, and turn the gain on the sub all the way up just to get it somewhere close to the same average level. Second, the sound just wasn't right. There was a lot of really low frequency rumble without a lot of actual, audible bass. I played the first scene of The Hurt Locker and when the explosion started the sub immediately went into protection. I've played that scene countless times and never had that happen. I played some music and for the first time ever heard some mechanical noise from the sub. Obviously something isn't right. All of the filters were cutting frequencies. No boosting. The predicted graph looked relatively flat.

Do I need to invest in a better microphone for measuring? Any advice on using REW would be appreciated.

Also, after messing with stuff all day I took the FBQ out of the loop and went to calibrate the sub again. Now I'm wondering if my SPL meter is working right. The meter doesn't even register any sound with the sub at ear bleeding levels. I got all the other speakers to 75dB but the sub doesn't even move the meter when it is at +10 and literally shaking the entire house and causing my blinds to flutter.

 

[fuzz092888]

I use REW, but it sounds like you need more help with the meter than you do with REW. First, you may want to look for the radioshack correction file. Like you said, the RS meter should be ok at lower frequencies, but it can't hurt either.

So you're plugging the meter into the microphone 3.5mm jack on the macbook pro right? When you go into the MIDI setup, check the input levels and make sure the right input is selected. Also go into REW preferences and make sure the correct input is selected (probably "default input"). Then use the preferences to check the level. How are you outputting the test tones from the REW to your setup?

If none of this works and you still can't get things going, try going on the REW forum at home theater shack, they provide tons of help.

I haven't seen any reviews on the dayton UMM-6 (the dayton USB measurement mic) yet, but it looks pretty solid. You should also look at the miniDSP UMIK-1 which is also a measurement mic. The specs on the UMIK claim it'll go a bit lower than the Dayton, but so far there are no user reviews on either. I ordered a UMIK-1 and it will be to me sometime this week (hopefully tomorrow) so I can give some impressions on it later this week.

Hope that helps.

 

[Hi Ho]

I have the .cal file and it was loaded in REW. I was definitely getting input and output so my input/output settings were correct.

Since my MacBook has one 3.5mm jack that doubles as an in AND out I used my Presonus Firestudio Project as the output. This also doubles as the MIDI interface to communicate with the FBQ.

I would use the Firestudio for both input and output but apparently it is not possible for a Java based application to communicate with a Firewire input on a Mac. It can output to it but cannot accept an input? OK... that makes sense...

I would also try all this on my desktop PC but I have a nasty ground loop when I connect it to my system using analog cables (normally use digital).

 

[fuzz092888]

In that case, there's your problem. Mac java doesn't allow REW to access multiple inputs and outputs of an external soundcard which would be why it isn't working. Sometimes soundflower works sometimes it doesn't. If soundflower doesn't work you're stuck with having to get a USB mic if you want to use it with the MacBook Pro.

Soundflower is a program that sort is sort of a workaround but its a total crapshoot as to whether it will work for you or not.

 

[Hi Ho]

It is working though. I used the Firestudio for output and the MacBook line-in for input. I got a measurement. I got a response graph. I got the automatically generated filters to smooth out the response. I just got a message every time I ran it saying "The highest value read during the test was -37dB. This is much lower than it should be." (not an exact quote) even though it had reportedly measured some frequencies at almost 90dB according to the graph. The resulting "corrected" sound was certainly not right. It had a ton of very low frequency information that caused excessive rumble and the mid-upper bass range was pretty much non-existant.

 

[avnetguy]

The meter doesn't even register any sound with the sub at ear bleeding levels.

Something doesn't sound right with that analog meter. I use the RS digital meter (with .cal file) and don't have that issue at all. It might be worthwhile getting another mic, or even try out the digital RS meter if you have a store nearby.

Steve

P.S. It's been a while since I ran up REW but I remember something about calibrating the input/output on the soundcard ... don't know if that'll help, just a thought.

 

[agarwalro]

I have been using the RS SPL meter as input mic and it works fine. That said, I am running REW on a W7 laptop with external USB sound card. From the REW help page, Getting Started and under Equaliser Connections,

If using an equaliser(such as BFD Pro DSP1124P or FBQ2496) to optimise your subwoofer's response, it should be connected between your AV processor's LFE/Sub output and the subwoofer low level input. For a BFD Pro the operating level switches on the rear panel should be pressed in to select the -10dBV range.

 

[Hi Ho]

I played with it more today and I think I got it working much better. I grabbed the ground loop isolator out of my car and connected it between my PC and receiver. No more ground loop!

I was able to get the levels right and get consistent measurements. I came up with 5 filters and with them applied I can definitely hear an improvement in the evenness of the bass.

I used the SPL graphs to match the sub with the mains as opposed to the SPL meter reading and I got drastically better results.

My room has issues but it's not terrible and I am very happy.

 

[mtrycrafts]

I played with it more today and I think I got it working much better. I grabbed the ground loop isolator out of my car and connected it between my PC and receiver. No more ground loop!

I was able to get the levels right and get consistent measurements. I came up with 5 filters and with them applied I can definitely hear an improvement in the evenness of the bass.

I used the SPL graphs to match the sub with the mains as opposed to the SPL meter reading and I got drastically better results.

My room has issues but it's not terrible and I am very happy.

Well, one happy user
I just got into REW recently and got that mic fuzz mentioned but am having issues similar to you with my laptop. It doesn't have a dedicated audio in or out.