Please Help Me

**boliver10** · **08-18-07, 06:19 PM**

I've spent my entire Saturday trying to get Room EQ Wizard to work for me...

1. No matter what I do, it always measures my response at around 140db: making it impossible for me to set a target level or use filters.

I tried two different input devices: a Behringer microphone and a radioshack sound meter. I have tried two different sound cards: the internal sound card for my computer (realtek?) and my USB Creative Extigy device (which I used for all output regardless)

I dutifully used the sound meter to make sure I am calibrated at 75 db. And I used the calibration file for my sound meter. I even calibrated my soundcard which didn't show much deviation from a perfect response.

Also the curve as it gets out past
What could I be doing wrong?

2. Am I right in believing I must go through all of this filter configuration after the measurement is made if I'm going to just use convolver on the pc to handle the .wav data? i.e can't I just output the unfiltered response in Wav from the file menu?

3. Am I right in understanding that none of these tools will help for freqencies over 500hz? Isn't there a way to use the computer (like the high end audiophile device Tact for instance) that can equalize the entire spectrum?

4. Enclosed is a graph of one measurement. Notice the wild swings of response of my speakers. Is this normal? These speakers are expensive (to me...) Martin Logan Electrostatics which radiate the same amount of energy behind and in front of the speaker. I got this pattern even when I used one soundcard for the input and one soundcard for the output: so I don't THINK it is feedback.

Thanks in advance for help. I'm pulling my hair out (and I'd like to keep as much of my hair as possible if you know what I mean)

Bill boliver10@yahoo.com

**brucek** · **08-18-07, 07:28 PM**

Why don't we start slow and get REW working..........

REW is normally used for subwoofer equalization, but can certainly be used full range, if you have a decent mic such as the ECM8000 and its associated 802 preamp.

The internal RealTek would likely be the easiest way to go.

Are you able to get a proper soundcard calibration file by looping an 1/8" stereo cable from line-out to line-in?

brucek

**boliver10** · **08-18-07, 07:34 PM**

Yes. I was able to get a very good soundcard calibration.

**boliver10** · **08-18-07, 07:35 PM**

BTW, I used the realtek as the input and the creative extigy as the output (since I also run the digital out of the extigy to a DAC and then to the power amp and speakers)

**brucek** · **08-18-07, 07:55 PM**

Quote:

BTW, I used the realtek as the input and the creative extigy as the output

Don't do this. Use the RealTek for input and output. It requires the duplex properties of a single card. Loop the RealTek with a single stereo cable and create a soundcard cal for it first.....

brucek

**boliver10** · **08-18-07, 07:59 PM**

I did this with the Extigy (used both input and output on the same device) with the exact same results.

**brucek** · **08-18-07, 08:41 PM**

So which card will you be using for REW.... the RealTek or the Extigy? It really isn't important, as long as you use only one of them.

brucek

**boliver10** · **08-18-07, 09:25 PM**

I can use either - I've tried with both (well, I haven't tried ONLY using the realtek). But I figured the Extigy was higher quality (certainly more expensive)

I can't get anything to work right. I've also tried this thing:
http://www.duffroomcorrection.com/wi...Measuring_Tool

But couldn't get it to work either (kept saying it couldn't get the input/output channels)

I've had a very bad Saturday.

**brucek** · **08-18-07, 10:22 PM**

Well, since REW compensates for any inadequacies of the soundcard, the quality of the card doesn't matter. I would suggest using the RealTek, as it will have less complex features, effects, monitoring, etc that need to be turned off. It's a simple card to use.

Try using the RealTek (with it set to the 2 channel stereo mode).

Setting up REW only takes but a minute once you're used to it.

Anyway, try following these steps and see how it goes.

I'll also post the REW mixer for a RealTek card....

To go through these steps only takes a second......

Hook up the Line-out of the soundcard using a stereo connector at the soundcard end that breaks out the two mono channels (left and right) and connect both channels to your receiver AUX or CD input and put the receiver in stereo mode.

Hook up the ECM microphone preamp to the Line-in using a stereo connector, but connect only one channel (i.e. Right). Select that same channel in REW in the Settings icon.

1. Ensure the soundcard and ECM meter calibration files are loaded (the soundcard.cal you already created and stored). Be sure to select the soundcard as the input and output device in the Soundcard tab and select Line-in and Speaker(Line-out) as shown in the pic I Attached.

2. Run the Check Levels routine (in Settings icon) selecting either Subwoofer or Main speaker in the Levels pull down, with the SPL meter at the listening position and the dial of the meter at 80dB position (or whatever scale allows 75dB to be measured).
Ensure the REW output VU meter is at -12db and the sweep level at -12dB.
Set the Wave Volume at 1.000 and the Output Volume about ~0.500.
Then adjust the receiver volume control so the actual standalone SPL meter reads ~75db at the listening position.
Then adjust REW input volume (and the Behringer preamp volume) to end up with -12dB on the REW input VU meter.

3. Run the Calibrate SPL routine (in the meter tab) to match REW's SPL meter to the real SPL meter to ~75dBSPL.

4. Run the Set Target Level routine, which will set the target to ~75dB.

5. Run the Measure routine and set the End Frequency to 200Hz for subwoofers and whatever you like for testing mains (i.e. 10KHz).

6. Measure.................... (use a larger number of sweeps and longer length for more accuracy and less noise)

7. Using the Graph Axis Limits icon, set the vertical scale to 45dB to 105dB and the horizontal scale for subs to 15Hz to 200Hz (and mains to whatever upper limit you like - i.e. 10KHz)

8. When testing mains you need to add smoothing (left panel) after you measure. Use whatever amount looks the best for your needs. Don't use smoothing when creating filters - only when viewing a response.

Check Levelsxxxxx clear.jpg

Note: I should add that smoothing isn't normally used with subwoofer measurements, since filters optimized against a smoothed response will have settings that don't accurately match the room's modes. It's not usually necessary either. But for full range measurements, its almost impossible to read the plot without smoothing. Below is an example of a measurement taken from 200Hz to 10KHz. The first plot is the raw measurement and the next is with one octave smoothing. You can play with all the levels of smoothing to get the result you require. Usually 1/6th or 1/3rd is suffice.

no-smooth.jpg
one-octave -smooth.jpg

brucek

**boliver10** · **08-19-07, 07:02 PM**

OK... Now with just using the Realtek my plots look right... I guess I can't fault the software for not guessing at my complicated multiple soundcard setup...

I'll try to post something when everything is finished.

**boliver10** · **08-19-07, 07:23 PM**

OK. Wait a minute. Now everything is "working" but the corrected curve doesn't look that much bette than the original response. What gives? Why did I waste an entire Saturday just to get a couple of dips in my bass response resolved? My computer has enough power to handle the entire spectrum but REW is only handling a small amount of the trouble. See enclosed image where even in the bass region REW missed completely this dip. (I did all of the filter "tasks" in order on that one screen)

Am I doing something wrong? How do I add my own EQ based on what I see in the graph? Should I use DRC?

**brucek** · **08-19-07, 10:24 PM**

Quote:

Why did I waste an entire Saturday

Can't really answer that one....

Quote:

Am I doing something wrong? How do I add my own EQ based on what I see in the graph?

REW only suggests filters to eliminate 'peaks'. It won't automatically consider 'dips' or attempt to boost any part of the response. To remove a dip you have to add a manual filter and adjust the corrected response to suit.

Remember that most dips and notches won't respond in reality to boost. Use only a few dB in gain when attempting to remove a dip as it lowers headroom and worsens your signal to noise ratio. Too much gain can cause clipping.

Manual filters are easy to enter. You may also adjust the automatic filters to suit. Just bring up the filter panel and tweak. Any filters above 500Hz would have to be entered manually, although filtering at frequencies that high usually isn't too successful and could be better served by using room treatment and sometimes equalizers can help.

brucek

**boliver10** · **08-20-07, 08:23 PM**

So I configured the filters and pressed Export Filters Impulse Response and REW just hangs: doesn't crash but it just leaves the dialog up saying that it is "generating impulse response"

I can't believe this is such a nightmare.

I've also tried to use the automated tool with drc at http://www.duffroomcorrection.com/wi...Measuring_Tool

But it outputs .pcm files. (!) Convolver on both FFDSHow and JR Media Center needs .wav files and don't accept pcm files. I tried converting the files with some program on the web but convolver didn't like those files either. What is going on????? Why would the personal making that automated tool for DRC output something that convolver can't even read???

**brucek** · **08-20-07, 09:07 PM**

Quote:

So I configured the filters and pressed Export Filters Impulse Response and REW just hangs: doesn't crash but it just leaves the dialog up saying that it is "generating impulse response"

Sorry, the Export Filter in this release of REW has a bug. You need to take more than one measurement to get a result.

The list of filter sets for Export only contains previous measurements and not the current measurement. If you have no measurements, you can export "current settings", if you have more than 1 you can export the settings of the filters for any previous tab but not the latest one. If you only have one measurement you get an empty list.

brucek

**boliver10** · **08-20-07, 09:23 PM**

thanks I'll try loading some other measurements. I've put way all of the recording gear so I hope I don't have to go through that again...

**brucek** · **08-20-07, 09:46 PM**

Quote:

I've put way all of the recording gear so I hope I don't have to go through that again...

Yeah, REW derives everything from the impulse response, so once the measurements are taken you can play with that off line...

brucek

**boliver10** · **08-20-07, 11:11 PM**

So I went back to the pcm files made for DRC and made a stereo wav file out of them as per the instructions on the DRC step by step guide using Cool Edit.

Below is the wav file as well a screenshot of it. The graph look OK to me. But when I load them on convolver under J River's Media Center (using the DirectX plugin), the sound coming from the speakers sounds about 50 db too low! I can't raise the volume high enough to hear much more than a whisper of the music!

What has gone wrong again?

Also, with the Convolver plugin, if I choose anything other than "Measure", Media Center goes off into la la land and crashes (i.e. if I choose Patient or Insane or any other processing preset.)

wav file can be downloaded here: http://cellstory.com/condo/stereo.wav

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