REW - Room EQ Wizard

[thsmith]

I thought I would post information on REW. It is a FREE PC program to do bass management and freq sweeps.

The sticky from Hometheatershack.com is here. The people at this site are a big help.

http://www.hometheatershack.com/foru...ease-read.html

It is not a hard app to learn just just have to have the desire. If you have not used some sort of calibration and measurements for you sub you most likely are not getting the best out of your sub.

You will need an SPL meter:Every SPL meter or microphone requires a calibration file to be loaded into REW (unless it's perfectly flat or perfectly tracks a C-Weight curveover the frequencies you're interested in testing). Most SPL meters do not track their C-Weight curves at low frequencies, so a cal file is required. Radio Shack meters with a cal file are acceptable for subwoofer testing and up to approximately 3KHz. For full range measurements, a better SPL is required (such as the Galaxy CM-140).
Read more: REW Cabling and Connection Basics - Home Theater Forum and Systems - HomeTheaterShack.com

You will need a sound card:If your laptop is limited to a mic-in port with no line-in, then you'll require an external USB soundcard. There are basically two flavors of external USB soundcards.

One type contain an internal microphone preamp(s) with phantom power for condenser mics (such as the ECM8000 or EMM-6). The popular manufacturers of these type are Tascam, EM-U, and M-Audio. The connection diagram for these soundcards is shown at the bottom of the page, but be sure to read through this entire article first.

The second type do not contain a microphone preamp, and have analog line-in and line-out only. The interconnects for this type are the same as for an internal PC soundcard.
Most brands of external soundcards work fine with REW. Many members are using the Creative SoundBlaster Live 24bit external card. It's inexpensive and the REW HELP files have a section on setting up the Creative SoundBlaster Live 24bit external card.

The jacks on mostsoundcards are stereo, so you require a stereo plug for both the line-in and the line-out connections - no exceptions when the plug is stereo. A mono plug will simply not work in a stereo jack. (there are a few external soundcards that use separate left and right line-in and line-out jacks, such as Creative MP3+ and some M-Audio products for example - with these you will use a mono plug into a mono jack).

An 3.5 mm Stereo Plug To Dual RCA Jack Adapter is usually required to separate out the left and right channels of both the line-in and the line-out jacks of the soundcard, although in lieu of these adapters, you may use cables that have a stereo 3.5 mm plug on one end and a pair of RCA connectors on the other end to facilitate the left and right channel breakout.

The left channels of the soundcard are normally not used and are simply never connected. To compensate for any weakness in the soundcards response, we create a calibration file using the right channel of the soundcard, by use of a loopback cable and a special one-time-only routine that saves that file into REW. That loopback is removed after running that calibration routine and then the right channel is used for all testing.

Alternatively, for more advanced users, you may loopback connect the left channel line-out of the soundcard to the left channel line-in of the soundcard, and use the right channel for measuring and this will serve as the soundcard calibration in lieu of a calibration file. To use this special feature, you must check the 'Use Left Channel as Calibration Reference' in the REW Settings page. This method is not recommended. The standard cal file method is recommended. It's simpler, uses less cables and so less chance of problems, offers a bit better S/N ratio, and provides vetting of your setup and connections. The Left channel calibrate method is best used once you've become familiar with REW and want to test System Delays. Other than that, stick to the standard soundcard calibration file method.

The SPL meter connects to the line-in right channel of the soundcard.
The line-out right channel of the soundcard connects to the receivers (or processors) AUX or CD input. It's a good idea to use a Y-splitter at the receiver to feed both the left and right channels, so both mains speakers may be checked along with the subwoofer. Mains and subwoofer are the only speakers checked with REW, and the receiver must be operated in stereo mode at all times during REW tests.
Read more: REW Cabling and Connection Basics - Home Theater Forum and Systems - HomeTheaterShack.com

I use the turtle Beach external USB Sound Card like this but appears to no longer be available, Turtle Beach Audio Advantage SRM External USB Sound Card.

I am willing to assist anyone over the phone that wants to learn and use this program. All I ask is you read the manual 3 times and try to perform a sweep.

If you are a trusted member I will even loan you my RS analog meter and sound card but you have to be serious and have my stuff back in 2 weeks after receiving it.

Good luck.

Please no debates about using any other method and auto calibration devices like SMS-1. I am offering to help on REW only.

Your AVR will never be able to set your sub up correctly without you sub being as flat as possible first.

Most people do not get that a improperly set up sub has peaks and dips. Your AVR sees the peak and adjust the levels based upon the peak which in turn will make your sub levels lower than your other speakers, hence why you need the sub to be flat as possible.

Here is a graph that REW makes in about 5 seconds
http://www.polkaudio.com/forums/show...23&postcount=4

[strider]

Have been playing around with REW for a month or so now. It's helped me to quantify what I'm hearing, making system changes and tweaks more of a thought out process then a try and see kind of thing. Bought the calibrated mic from Parts Express and am running it into a Tascam USB based mic pre amp. At first I was fixated on the frequency response graphs but since getting into it a bit more I find the waterfall plots to be more useful.

The one thing I haven't delved into (ironic 'cause it was the reason I got into REW) is the Auto EQ function available when I use the REW software and my active MiniDSP crossover/EQ board. I'm currently running the MiniDSP board between my pre amp and two amps, one for the single driver loudspeakers from about 200hz up and the other for a transmission line loaded pair of woofers to augment the bass duties from 200hz on down. The MiniDSP board is an active XO that has a USB input so changes can be made via provided software in real time. Level matching, EQ, phase, XO type, slope and frequency can all be changed while listening. It really gets cool when you use the REW software with the MiniDSP board. Measure the system respone with REW, upload the info into the MiniDSP software, set some parameters and the AutoEQ builds a custom biquad filter to smooth the system response as much as practical.

Long story short, REW is a super powerful and useful tool. The fact the program's free is astonishing.

[thsmith]

Strider you obviously get it and have certainly passed me if using waterfalls.

Beginners need to focus first on raising their dips by positioning the sub to raise those dips, even a few inches makes a difference or even changing phase.

Then they can focus on taming the peaks.

Glad to see I have some help on this and you are right, REW is powerful and fun.

Once you get your sub right you don't need to use REW unless you make changes to your room.

I used the BFD1124 to filter the peaks.

Nice setup you are using to run REW, most will find the simple RS analog SPL the simpliest to use, but as stated it is only good up to 3khz and best used for sub measurements only.

Thanks for your post.

[dcmartinpc]

Have been playing around with REW for a month or so now. It's helped me to quantify what I'm hearing, making system changes and tweaks more of a thought out process then a try and see kind of thing. Bought the calibrated mic from Parts Express and am running it into a Tascam USB based mic pre amp. At first I was fixated on the frequency response graphs but since getting into it a bit more I find the waterfall plots to be more useful.

The one thing I haven't delved into (ironic 'cause it was the reason I got into REW) is the Auto EQ function available when I use the REW software and my active MiniDSP crossover/EQ board. I'm currently running the MiniDSP board between my pre amp and two amps, one for the single driver loudspeakers from about 200hz up and the other for a transmission line loaded pair of woofers to augment the bass duties from 200hz on down. The MiniDSP board is an active XO that has a USB input so changes can be made via provided software in real time. Level matching, EQ, phase, XO type, slope and frequency can all be changed while listening. It really gets cool when you use the REW software with the MiniDSP board. Measure the system respone with REW, upload the info into the MiniDSP software, set some parameters and the AutoEQ builds a custom biquad filter to smooth the system response as much as practical.

Long story short, REW is a super powerful and useful tool. The fact the program's free is astonishing.

Are you using the US-144MKII? I use it and a Calibrated Behringer ECM8000 from Cross Spectrum Labs. It is calibrated down to 5 Hz!!!

Don

[EndersShadow]

Eh, for me REW is going to be a way to quantify what I am hearing visually so I can see how my speakers are interacting and find ways to tame peaks. The end game goal is to get a better EQ in my AVR (Audyseey XT32) and use REW to get things set decently and then the AVR EQ as icing on the cake so to speak.

[Mike in Ohio]

This looks very cool - will give a try this weekend. My sound card has digital coax outputs - as long as I'm in stereo I should be able to use it shouldn't I?

[thsmith]

Eh, for me REW is going to be a way to quantify what I am hearing visually so I can see how my speakers are interacting and find ways to tame peaks. The end game goal is to get a better EQ in my AVR (Audyseey XT32) and use REW to get things set decently and then the AVR EQ as icing on the cake so to speak.

Not really icing on the cake, Your AVR will not be effective managing your sub until you have the sub as flat as possible then run Aud. Imaging a 35hz with 10bd peak over your other freqs, aud will see that levele set your sub based upon that peak which will make the bass seem too low which is what most people think after the run AUD. You could simply use your spl meter to raise the level to match your mains but then you have boomy or muddy base.

This looks very cool - will give a try this weekend. My sound card has digital coax outputs - as long as I'm in stereo I should be able to use it shouldn't I?

Not sure about that.

The jacks on mostsoundcards are stereo, so you require a stereo plug for both the line-in and the line-out connections - no exceptions when the plug is stereo. A mono plug will simply not work in a stereo jack. (there are a few external soundcards that use separate left and right line-in and line-out jacks, such as Creative MP3+ and some M-Audio products for example - with these you will use a mono plug into a mono jack).

An 3.5 mm Stereo Plug To Dual RCA Jack Adapter is usually required to separate out the left and right channels of both the line-in and the line-out jacks of the soundcard, although in lieu of these adapters, you may use cables that have a stereo 3.5 mm plug on one end and a pair of RCA connectors on the other end to facilitate the left and right channel breakout.

The left channels of the soundcard are normally not used and are simply never connected. To compensate for any weakness in the soundcards response, we create a calibration file using the right channel of the soundcard, by use of a loopback cable and a special one-time-only routine that saves that file into REW. That loopback is removed after running that calibration routine and then the right channel is used for all testing.

[strider]

Are you using the US-144MKII? I use it and a Calibrated Behringer ECM8000 from Cross Spectrum Labs. It is calibrated down to 5 Hz!!!

Don

Sure am, as a matter of fact I just checked which model so I could post it. My set up is the Dayton Audio EMM-6, calibrated, from Parts Express, cheapo XLR cable, cheapo mic stand (stand's essential for repeatable, accurate readings), Tascam US-144MKII which all runs into my laptop via USB.

I don't run subs yet, I use it to tailor the response of my DIY speaker system. The waterfall graphs are helpful to me figuring out the best XO type and frequency to use integrating the single drivers with the helper woofers. The FR graph is good, plotting dB vs frequency. The waterfall graph adds time measurement to the z axis, which is helpful taming bass nodes, referred to as overhang or one note bass.

Adding the MiniDSP board as the crossover adds another level of functionality for me. After I take the measurements with REW, I make changes with the MiniDSP software without having to get out of my listening chair.

Ben

[intangible]

I've used REW to flatten out my subs with great success. At some point I will buy a mic stand, so I can take repeatable measurements on the whole system, but just holding it relatively steady works fine for 12+ foot long waves.

[thsmith]

Cameria tripod works just fine. I place mine in main listening poisition at ear height. I also shut down all other speakers. The rs analog spl meter can be screwed into tripod.

[dcmartinpc]

Sure am, as a matter of fact I just checked which model so I could post it. My set up is the Dayton Audio EMM-6, calibrated, from Parts Express, cheapo XLR cable, cheapo mic stand (stand's essential for repeatable, accurate readings), Tascam US-144MKII which all runs into my laptop via USB.

I don't run subs yet, I use it to tailor the response of my DIY speaker system. The waterfall graphs are helpful to me figuring out the best XO type and frequency to use integrating the single drivers with the helper woofers. The FR graph is good, plotting dB vs frequency. The waterfall graph adds time measurement to the z axis, which is helpful taming bass nodes, referred to as overhang or one note bass.

Adding the MiniDSP board as the crossover adds another level of functionality for me. After I take the measurements with REW, I make changes with the MiniDSP software without having to get out of my listening chair.

Ben

My rig is basically the same sans the mic It is a great setup. I need to rerun my system as I have made some major changes as of late. I used to run a DBX DriveRack PA+ as my cross and EQ, but I just pruchased an Outlaw ICBM to handle the crossover duties, then I will just use the DriveRack for EQ duties for now.

I have been VERY tempted by the MiniDSP!!! How do you like it? Is it quiet? Does it maintain clean signal? I might just order one if I can sell a couple other things! I would really like to know your thoughts!

Don

[AudioMancer]

Just a quick newb question:

I'm just an average joe that has a house where my HT is in my living room which is open to the kitchen and dining room. Obviously, not the ideal room and probably considered a "nightmare" scenario by most.

I don't want to spend 2 weeks learning how to use the REW and another couple of days trying to calibrate my sub, if all I'm going to get is a 3%-5% improvement.

I know no one can say for sure, but what is the likely or reasonable improvement I can expect under my "dire" circumstances, if I use REW.

I don't want to sound lazy. Actually, I love pouring over stuff like this if it's worth it. I tinkered with my TV calibration for like a week before I got it as best as could be and I had a blast doing it. I dove in because my friend, who does that for a living, said I would not regret it.

Just wondering if REW would even be worth it in my situation.

Any thoughts would be appreciated.

[thsmith]

Yes, it is worth it. Not only will you know how good or bad your room and system work together with your sub. If you have a 10k cubic foot room your Velodyne can only do so much.

If your room and openings are in the 3k cubic foot range stand a chance.

It should not take you 2 weeks to learn. Read the guide 3 times and try to take a freq sweep. If you can get that far you have it made.

There are several people here that use it and the people at HTS are great too.

If you have everything you need then I would think you could up and going in 2-4 hours.

[codyc1ark]

Am I wrong to assume that this soundcard will work? Just wanted somebody to confirm before I order it...

http://www.google.com/products/catal...6509318188390#

[thsmith]

Need to see the specs and looking at this page or trying to link off one of the sellers I can't tell

[codyc1ark]

Need to see the specs and looking at this page or trying to link off one of the sellers I can't tell

http://www.google.com/products/catal...&os=tech-specs

That do the trick?

[thsmith]

yes, that will work and is even one of the recommended SCs.

The second type do not contain a microphone preamp, and have analog line-in and line-out only. The interconnects for this type are the same as for an internal PC soundcard.
Most brands of external soundcards work fine with REW. Many members are using the Creative SoundBlaster Live 24bit external card. It's inexpensive and the REW HELP files have a section on setting up the Creative SoundBlaster Live 24bit external card.

[codyc1ark]

Great! I will get it on the way, and return with questions once I've installed REW, read the manual 3 times, and ran my first sweep!

[inspiredsports]

There is a hometheatershack member, brucek, who sells calibrated Behringer ECM 8000 omnidirectional mics for I believe the best calibrated price I've seen. I have 2 ECM's that I had calibrated locally, and I paid a lot more.

http://www.hometheatershack.com/foru...rvice-usa.html

(you can also download a calibration file, but it will never be as accurate as having your specific mic calibrated)

I would suggest The Alesis iO2 versus a sound card. They cost a lot less, are a TON better, and you can move it from USB port to USB port on any machine you wish.

REW is a very robust program for being a freebie and I use it for 20-20,000Hz testing as a backup to ARTA

[codyc1ark]

There is a hometheatershack member, brucek, who sells calibrated Behringer ECM 8000 omnidirectional mics for I believe the best calibrated price I've seen. I have 2 ECM's that I had calibrated locally, and I paid a lot more.

I would suggest The Alesis iO2 versus a sound card. They cost a lot less, are a TON better, and you can move it from USB port to USB port on any machine you wish.

Hmm... This post confuses me (sorry), the Alesis is about $70.00 more than the sound card I listed, and I'll be using my RS SPL meter, not a mic. I don't believe a mic is neccessary, correct? I wanted to make sure before I go and order, then have to turn around and order more stuff, wouldnt be the first time thats happened though.

[Drenis]

Hmm... This post confuses me (sorry), the Alesis is about $70.00 more than the sound card I listed, and I'll be using my RS SPL meter, not a mic. I don't believe a mic is neccessary, correct? I wanted to make sure before I go and order, then have to turn around and order more stuff, wouldnt be the first time thats happened though.

Actually you will plug in the SPL meter to the Line In on your sound card as it DOES act as a mic. How else do you think it measures the db level? ;)

[codyc1ark]

Actually you will plug in the SPL meter to the Line In on your sound card as it DOES act as a mic. How else do you think it measures the db level? ;)

lol, I do understand that, but inspiredsport's input confrused me. I didn't think I needed a special mic. Moving along...

[inspiredsports]

If you are just doing bass (subwoofer) calibration, disregard my post above which is geared toward accurate full 20-20,000Hz response measurement.

I picked up my Alesis iO2 for under $80 delivered brand new from amazon.com.

I will say that once you start using REW, you will end up wanting to be able to measure everything accurately and the $80 Alesis and $50 (if uncalibrated) Behringer mic become minimums.

[thsmith]

For sub measurements the RS SPL meter is fine.

[jm1]

This thread has been on my mind for quite some time!

Finally purchased a Focusrite iTrack sound card and Apex 220 mic. The mic includes a printed calibration sheet so this was entered into a calibration file for REW to use. Now I need to find the time to determine if the acoustic treatment was worth the effort ...

[thsmith]

Nice that they provide the calibration file. Have you used it yet ? I love REW, one of the best pieces of free S/W ever.

Post some graphs.

[jm1]

This is the first graph I generated; it is a blend of four measurements. Not sure why the levels register so high as I ran another and it was at the 75 dB range. The waterfall chart is meaningless at these levels. Anyways, this is a start so I can look at further optimizing the room. I will also a look at the settings to see what is incorrect ...

[thsmith]

This is the first graph I generated; it is a blend of four measurements. Not sure why the levels register so high as I ran another and it was at the 75 dB range. The waterfall chart is meaningless at these levels. Anyways, this is a start so I can look at further optimizing the room. I will also a look at the settings to see what is incorrect ...Attachment 78575

Yeah, that looks pretty strange but it is a start. To bad the punk with the Uggs had to spoil the thread.

[jm1]

This is a waterfall of the room. Based on what I am seeing, I am devising round 4 of the acoustical treatment. I should have done this long ago as now I know what to address.

[thsmith]

REW is one of the most fun applications I have used. JM1, looks like you are having a ball.