Using REW to setup B&K PEQ and notch filter - Home Theater Forum and Systems - HomeTheaterShack.com

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post #1 of 30 Old 09-29-09, 03:36 PM Thread Starter
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Jarrod
 
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Using REW to setup B&K PEQ and notch filter

Hi,

I have a B&K Ref50 and plan to use REW to optimize its EQ settings for my room. In the past I've done this using the internal test tones and the RS meter but that is a real pain. REW sounds like a much more fun and accurate way to do it! Looking for feedback before I get too far into this....

By way of test equipment, I've got an ECM8000 and a EURORACK UB802 mixer with phantom power. I was planning to use this mic for measurements with the ECM8000 calibration file on the download site. I also have the Radio Shack SPL meter to calibrate the SPL reading (old-school version). I plan to use the software on my MacBook Pro 17" with the internal sound card.

I was able to get REW version 4.11 properly setup on the Mac. I measured the frequency response of the internal sound card (graphs posted below), and created the sound card calibration file.

At 48kHz sampling on the input and output, I got this response:

Using REW to setup B&K PEQ and notch filter-48khz-mbp17-soundcard-cal.jpg

I switched to using 44.1kHz sampling on input and output and got this, which is much better:

Using REW to setup B&K PEQ and notch filter-44.1khz-mbp17-soundcard-cal.jpg

Does it matter if I use 16, 20, or 24-bit audio? For the internal sound card calibration I used 24-bit.

Am I on the right track? Does it sound like I have everything I need?

Thanks!
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post #2 of 30 Old 09-29-09, 03:49 PM
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Re: Using REW to setup B&K PEQ and notch filter

Yeah, the 44.1K sampling looks fine for the soundcard cal file.

Be sure to download the ECM8000 cal file from our site.

brucek
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post #3 of 30 Old 10-05-09, 12:46 AM Thread Starter
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Re: Using REW to setup B&K PEQ and notch filter

My new sub (Outlaw LFM-1 EX) is on the FedEx truck for delivery today

My current sub is a Velodyne DLS-3500 with an 8" forward-facing driver and slot port underneath. I am considering keeping this subwoofer to use in a dual config with the new Outlaw sub.

I measured the response of the Velo tonight in two locations. The first location (red) is on the left wall, about 8 feet from the front of the room. The second location (green) is on the front wall, next to the center channel (underneath the TV inside an open-air stand that I custom built).

Using REW to setup B&K PEQ and notch filter-velo-3500.jpg

I always had the Velodyne sub in the first (red) location, long before there was a place to put it on the front wall. The new Outlaw sub is going to have to go in the red location, as there really isn't any other place to put a box of this size in our room. So the Velo is definitely staying in the green location!

By the way, do I need to make a calibration for my mixer (Eurorack UB802)?? Right now I have the ECM8000-cs.cal and my soundcard/loopback calibration files loaded. What is the best way to go about calibrating for my mixer's response?

Thanks,

Jarrod

Last edited by Jarrod; 10-05-09 at 01:09 AM.
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post #4 of 30 Old 10-05-09, 06:31 AM
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Re: Using REW to setup B&K PEQ and notch filter

Quote:
I am considering keeping this subwoofer to use in a dual config with the new Outlaw sub.
I'm assuming the new sub will have better extension than the existing sub. If that's the case, then it's an extremely bad idea to keep the challenged sub in the mix. You're wasting the extension of the new sub. Only subs with similar response should be mixed.

Quote:
What is the best way to go about calibrating for my mixer's response?
Create a new soundcard calibration with the mixer in the loopback in place of a loopback cable.

brucek
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post #5 of 30 Old 10-05-09, 08:28 AM Thread Starter
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Re: Using REW to setup B&K PEQ and notch filter

Yeah, the new sub should have usable energy down to 16Hz. I was hoping to be able to set it up to mesh with the existing sub at around 30-40Hz.

I think I'm gonna need help including the mixer in the soundcard cal file. I did what seemed obvious to me (plugging from soundcard out to line in on the Mic channel, then from mixer tape out to soundcard input) and did not get any input signal.
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post #6 of 30 Old 10-05-09, 09:26 AM
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Re: Using REW to setup B&K PEQ and notch filter

That's sure is a nice sound card response curve but from what I read, it was recommended that we use external sound cards. This might very well be the exception, but I think I'd try to find out if its good enough.

The other thing is that on the Ref 50, you only have the capability of using a single notch filter without much latitude for the Q which isn't given as a Q setting. You really need more flexability and need to look at other manual eqing options.

Getting back to including the mixer in the sound card calibration file, you'll need some connector adapters. You'll want to convert the microphone xlr input on the mixer to go into the stereo line in 1/8" connect on your sound card. The outputs on the mixer also have to have 1/4" to 1/8" adapters and cable.

I've gone through multiple 8200 mics and have used the generic files on most of them. I've always had that question in the back of my mind just how accurate the mic file combination might be. You might want to either get your calibrated or get one that's calibrated from the form member whose selling mics and files. Sorry, don't remember his name.
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post #7 of 30 Old 10-05-09, 09:46 AM Thread Starter
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Re: Using REW to setup B&K PEQ and notch filter

Jim,

I'm not clear on what you are saying. It doesn't make sense to me that the XLR mic input on the mixer should be connected to line in on the sound card. Did you mean that the line/headphone out on the sound card should be hooked to the XLR mic input on the mixer? What about phantom power - would I leave it on in this scenario? I have no clue how the mic preamp would be expected to interact with a line-level input from my computer.

I do need to hit guitar center this afternoon and get some 1/4" to RCA adapters so I can get whatever I need then. As I mentioned, right now I'm using the tape out on the mixer to get back to line in on the sound card, because I don't have the right mix of cables and adapters to use the Main Out as is shown in the cabling help file. The tape out uses RCAs. Not sure what affect this has (I'm a total neophyte when it comes to using mixing equipment).

Thanks for the input!
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post #8 of 30 Old 10-05-09, 09:55 AM
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Re: Using REW to setup B&K PEQ and notch filter

Jarrod,

My bad...you're correct in that the XLR mic input should be connected to the sound card's line out. You do use the phantom power supply and be sure to turn your gain on the mixer all the way down and slowing bring it up when adjusting levels.

Don't know if using the tape/cd in/outs matter. I use the main outs. That is a good question though.
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post #9 of 30 Old 10-05-09, 10:13 AM Thread Starter
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Re: Using REW to setup B&K PEQ and notch filter

Ok, thanks again Jim. I think I know what I need now. As soon as FedEx delivers my sub (I have to be here to sign for it) I'll pick up some adapters. I'll go ahead and get a few 1/4" to RCA adapters so I won't have to worry about the tape out question - they will be useful adapters to have anyway...
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post #10 of 30 Old 10-05-09, 10:28 AM
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Re: Using REW to setup B&K PEQ and notch filter

...and the XLR adapter.

Trying to intergrate those two subs can be a real headache (been there, done that...gave up). I'd suggest trying to get the new one optomized and after you're happy with it, then see about adding back the other one.
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