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I made a dummy's guide on setting up REW. feedback??

post #1 of 43
Thread Starter 
http://polaraudio.blogspot.com/2012/01/calibration.html

This is intended mainly to get people started using REW by holding their hand, it took me hours to make it (way more than i thought it would), but primarily just want something that makes it possble for ANYONE to get it running

Feel free to tear it apart and i may or may not change it based on criticism
post #2 of 43
Quote:
Originally Posted by omegaslast View Post

http://polaraudio.blogspot.com/2012/01/calibration.html

This is intended mainly to get people started using REW by holding their hand, it took me hours to make it (way more than i thought it would), but primarily just want something that makes it possble for ANYONE to get it running

Feel free to tear it apart and i may or may not change it based on criticism

Very cool! Can't wait to check it out, I've been looking for something exactly like this.
post #3 of 43
Quote:
Originally Posted by omegaslast View Post

http://polaraudio.blogspot.com/2012/01/calibration.html

This is intended mainly to get people started using REW by holding their hand, it took me hours to make it (way more than i thought it would), but primarily just want something that makes it possble for ANYONE to get it running

Feel free to tear it apart and i may or may not change it based on criticism

Ill give it a go through as I thought about doing the same thing, just a simple "I need to run a sweep" how-to is perfect. This is the exact reason I moved to omnimic when I just want to take a quick measurement, but will continue to use REW for the extended sessions.
post #4 of 43
Quote:
Originally Posted by omegaslast View Post

http://polaraudio.blogspot.com/2012/01/calibration.html

This is intended mainly to get people started using REW by holding their hand, it took me hours to make it (way more than i thought it would), but primarily just want something that makes it possble for ANYONE to get it running

Feel free to tear it apart and i may or may not change it based on criticism


Awesome write up! I know these take a lot of effort to put together so thank you for putting in the time to do it for us!
post #5 of 43
Nice! wish this was around last Saturday when I was trying to figure all this stuff out. Course, I was using a unusual interface for mine (Line6 UX2,) and a Vista laptop that apparently needed new drivers for the DAC.

Only took me three hours to figure out the driver problem and make a soundcard Cal

Nice and simple, step by step guide. Good job, Sir!
post #6 of 43
You did a good job with the guide.

A few comments:

The US-144MKII includes digital input/out which aren't needed for REW. I recommend the US-122MKII since it is cheaper.

The US-144MKII might be flatter than you measured. Ricci mentioned to me in another thread that there is an impedance mismatch between the line out and line in of most audio devices. A more accurate measurement is from headphone out to line in. If you have a cable you could try it. You won't be using the headphone out for playback, but it will still give you the frequency response of the audio device. By the way, my US-122L was down .59 dB at 20 Hz measuring the way you did. I just sold my Tascam so I never measured from headphone out to line in.

The latest REW program 5.01 Beta 7 includes support for ASIO. I used the ASIO output with the Tascam. This is beneficial because you can switch between left and right channels easy in the Preferences. You can then send the left channel to the sub and the right channel to the left or right speaker and easily switch back and forth between measuring them.

I like to measure starting at 5 Hz to see what is going on. Since you set the correction range in the filters, the range used here doesn't correspond to what is being "fixed." I usually set sweeps to at least "2" to reduce the effects of noise and interference. Each doubling can increase the S/N ratio by 3dB since it eliminates noises that aren't identical. For example, your furnace might be making some mechanical noises that are being picked up by the measurement. Each time you measure, the sweeps will be the same, but the mechanical noise will differ slightly. REW recognizes the differences and eliminates the mechanical noise from the measurement.
post #7 of 43
Thread Starter 
another benefit of the guide, now im learning stuff

Time to buy a cable to do this headphone out -> line in so i can do another calibration. Does it matter which Line in: the XLR or TLR?

Im afraid people will damage their subs if they start at 5hz and somehow have the levels up too loud because when you have only the sub running you tend to push it into the 100dbs without mains to warn you its "too loud"

Then again its pretty hard to truly "break" a subwoofer doing a simple sweep, it may make a lot of nasty noises but its probably not broken

I'll add the sweep thing for sure though, never even noticed that feature.

I tried downloading beta 7 a while ago and it didnt work for some reason... guess i will dl again and see what this ASIO thing is about

One quick question that i just realized i never fully understood, does the emm-6 need the "c-weighting" box checked on the mic page? I figure no, because thats just an adjustment available on SPL meters, but i may be wrong
post #8 of 43
step by step guides such as yours with lots of pics makes things really easy!
post #9 of 43
Quote:
Originally Posted by jholzbauer View Post

Very cool! Can't wait to check it out, I've been looking for something exactly like this.



Yeah, this is a great starting point for those that haven't had a chance to dig into the inner workings of it, and calibration.

Nice to hit the ground running.

Quick question though on how it all works together...

So I hook up the sound card and mic to my laptop and take measurements... Let's say I find huge peaks and nulls across the spectrum, not just sub bass range... how do you correct these? It's nice to identify the problems, but how do you correct them?

Do most of you play with room treatments to correct issues?
What if you have problems so deep that you can't "treat" them away?
I assume that REW doesn't correct the problems?
If I'm wrong, and REW can correct the problems, then do you need to keep your laptop hooked up all the time?
Outboard EQ? Does this need to be put in line while measuring?

Thanks!
post #10 of 43
Thread Starter 
Quote:
Originally Posted by ADDUpstate View Post

Yeah, this is a great starting point for those that haven't had a chance to dig into the inner workings of it, and calibration.

Nice to hit the ground running.

Quick question though on how it all works together...

So I hook up the sound card and mic to my laptop and take measurements... Let's say I find huge peaks and nulls across the spectrum, not just sub bass range... how do you correct these? It's nice to identify the problems, but how do you correct them?

Do most of you play with room treatments to correct issues?
What if you have problems so deep that you can't "treat" them away?
I assume that REW doesn't correct the problems?
If I'm wrong, and REW can correct the problems, then do you need to keep your laptop hooked up all the time?
Outboard EQ? Does this need to be put in line while measuring?

Thanks!

Yes ive been thinking of how to address this already, because i knew a lot of people would have similar questions. I used to think several years ago EQing a subwoofer was playing with subwoofer gain and pre amp levels (Not even joking ), so i know how it feels to be completely lost

1st thing: if you have the room to move the sub around, play with different locations and take different measurements
2nd: buy a minidsp, antimode, velodyne sms-1, or go to extremes and modify your subwoofer so its hooked up to a behringer nu3000 DSP.
its important to note that these two steps will only get you "EQed" at your listening position... move a foot or two on your couch and all bets are off as to having a "flat" sound with no huge nulls or peaks. Thats why its so important to have more than one subwoofer. Unfortunately i only have one sub, so i was hoping to get more so i can demonstrate one sub on one sub off style of measurements.

Certain receivers have EQ built in, which is probably better than nothing. If im not mistaken the higher end yamaha have super adjustable parametric EQ for the sub channel exactly like what you'll find in the minidsp.
post #11 of 43
I currently have 2 15" sealed subs, with Antimode. I'm pretty well dialed in as far as level matching everything, as well as dealing with some phase issues with the subs using the delay (distance) in the AVR. My AVR is the Denon 5803. Beast of an integrated. I'm running analog 7.1 out of my BD player, (no HDMI or Audessey on the AVR), so I can get the latest codecs, and the AVR still does the processing via ADC then DAC. The room is treated, and sounds pretty damn good IMO, but out of curiousity, I would like to see where it plots. (I've finally gotten everything dialed in to the point that I can watch the Inception dunk scene at -05, and get absolutely no farting or weird noises.)

So my question really revolves around full spectrum correction.

So I run the REW full range for each speaker or combined, and I get a graph that has some funky dips or peaks. I assume that you need to insert an electronic EQ into the mix, likely between the laptop and the AVR... In my perfect sounding world, I would like to run REW bypassing the new EQ and get the graph to start, and then tweak the EQ and rerun REW and see the results. Or tweak the room treatment, or whatever... Once I get it the way I like to see and hear it, I unplug the laptop and leave the EQ in place in the rack, and we're good to go from there on out.

What else do I need to purchase and insert into my chain to make that dream a reality?

Thanks!
post #12 of 43
Thread Starter 
Well from my understanding EQing mains at listening position is kind of a hopeless task. What you can do is EQ each speaker at 1-3 feet away to be relatively flat, and then know that they *should* be playing flat at listening position if you room was an anechoic chamber. If the room is already treated then it shouldnt be messing with the signal much.

Then you can measure at listening position to get a good idea of how well your room treatment is working.

The only way i'd feel comfortable inserting EQ into a system is between the receivers pre-outs and the amps. I think theoretically it might be possible to put EQ between the blu ray player and your receiver.. but that gets messy.

Full spectrum correction to me is a lot more complicated than subwoofer correction.

Im not too familiar with the antimode, it uses its mic to calibrate the system for you but doesnt show any graphs?

Is it adjustable at all? I think its important to be able to adjust stuff to taste...
post #13 of 43
No graphs with AM.

I did do a RS SPL plot a while back, and it did flatten out the curve.

So you're saying that trying to get a flat curve over the entire freq response range is pointless? I think I'm just looking for something else to spend money on and tinker with, and I'm trying to justify it. If I'm tilting at windmills, then I will redirect my efforts elsewhere, and enjoy the sound that I currently have.
post #14 of 43
Thread Starter 
What speakers do you have? With subs you can target big nulls and peaks, it doesnt interact with your room quite the same way high frequencies out of mains do, so i would focus on measuring your subwoofer response in different seating positions around your room AND measuring your mains from near-field, and seeing if theres any big flaws in either of them

Youre free to measure your mains at listening position im just under the impression that trying to get your mains "flat" at listening position really isnt necessary nor is it even really recommended.
post #15 of 43
Quote:
Originally Posted by omegaslast View Post

another benefit of the guide, now im learning stuff

Yup. Nice how that works.

Quote:
Originally Posted by omegaslast View Post


...snip...

One quick question that i just realized i never fully understood, does the emm-6 need the "c-weighting" box checked on the mic page? I figure no, because thats just an adjustment available on SPL meters, but i may be wrong

You are correct, C-weighting should be unchecked when using a mic or modded SPL meter that has weighting removed.
post #16 of 43
Just bought some of the cables listed, will put this guide to use, soon. Thanks omegaslast, and desertdome for the US-122MKII.
post #17 of 43
Nice job with the guide - it looks good!

Not too sure about the choice of tools. You seem to be suggesting an expensive interface (the cheap ones are just fine) and a really cheap SPL meter (a dedicated measurement mic calibrated isn't expensive and they are worth it and make a much bigger difference IMHO).

I've used 502 for phantom power when using my PC, works fine although lacks USB for using with a laptop. UCA222 is dirt cheap and lets you use the 502 for both.

If people want to do a fair effort then I'm inclined to suggest a mic stand as well, you can get them quite cheap.

A few pics of the tools don't hurt.

And you could then go to the next step and suggest some settings for the charts because people always seem to post charts that are completely useless!

That's why I point people to this:
http://redspade-audio.blogspot.com/2...-settings.html

When they are asking for feedback on charts which always have weird settings!
post #18 of 43
Thread Starter 
I frankly dont know how to hook up a UCA202 + 502 for the purpose of calibrating, so its not like im writing a guide against it on purpose. For most people i think spending $40 more on a usb powered all in one tascam unit with nice DACs would be worth it just for the sake of portability if they ever want to use it with a laptop at a friends house. Not sure about the behringer but people could probably get away with not even calibrating the tascam because its so flat out of the box as well.

Im confused whats wrong with the SPL meter.

Im also not sure how big of a benefit a cross spectrum mic would be for most people. The dayton emm-6 comes with a calibration file, mine doesnt seem that bad. especially $53 vs $94 bucks. Maybe the 45 and 90 deg angle of incidence thing is important? i am ignorant on what that really is even used for.

>> press show to see the range
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post #19 of 43
The mic will usually be the weakest link in the chain, SPL meters being the worst. I haven't looked into the Dayton mics regarding the accuracy of their calibration file, can't comment too much there.

Didn't realise the Tascam was that cheap. Anything I've seen that is Tascam was many times more expensive than Behringer options.
post #20 of 43
Thread Starter 
Quote:
Originally Posted by paulspencer View Post

The mic will usually be the weakest link in the chain, SPL meters being the worst. I haven't looked into the Dayton mics regarding the accuracy of their calibration file, can't comment too much there.

Didn't realise the Tascam was that cheap. Anything I've seen that is Tascam was many times more expensive than Behringer options.

I dont advocate people use the spl meter as a mic anywhere on the blog

The dayton mic is fine if its on axis measurements.

heres a thread showing they emm-6 are very accurate considering theyre calibrated for free
http://techtalk.parts-express.com/sh...d.php?t=225468


http://www.cross-spectrum.com/measur...ed_dayton.html

Looks like csl offers a calibrated emm-6 "Basic" for $79 that is calibrated to 5hz. Not bad i guess. What i question is the soundcard even able to really utilize under 20hz? I will probably add the link to the blog, but i dont want people confused on whether or not they need to spend $26 extra.
post #21 of 43
Has anyone used this for Rew?
http://www.behringer.com/community/x...ter-and-beyond

Seems like the perfect device...
post #22 of 43
I bought 302USB then took it back. I wanted it for a laptop as an external sound card, but found that it will do phantom power just fine, but you still rely on the laptop sound card for the output. Not suitable for laptops. It isn't a duplex sound card. For a PC that has a decent sound card it would be fine.
post #23 of 43
I believe Cross Spectrum offers up a Galaxy CM-140 calibrated down to 5hz as well, which elimianates the need for a preamp with phantom power for the Dayton/Berry mics.

Think it's more expensive, but if it's as accurate as the Mic option and eliminates the need to have a separate SPL meter and a sound card with phantom power, pretty decent option for subwoofer duty.

Great guide, when I started up with REW I was searching for something like this, then thought at some point I'd try to create one but never got around to it (... and I seemed to always run into issues with REW in getting that first measurement of the day!!).

Over at the Shack I did create a thread for people with MobilePre's and how to set that up as I think I've run into just about every possible issue by now. I won't be quitting my day job any time soon.
post #24 of 43
My supplies are on the way for my in room measurement kit. I will certainly take advantage of your efforts with the guide.

Thanks!
post #25 of 43
Thread Starter 
Quote:
Originally Posted by pbc View Post

I believe Cross Spectrum offers up a Galaxy CM-140 calibrated down to 5hz as well, which elimianates the need for a preamp with phantom power for the Dayton/Berry mics.

Think it's more expensive, but if it's as accurate as the Mic option and eliminates the need to have a separate SPL meter and a sound card with phantom power, pretty decent option for subwoofer duty.

Great guide, when I started up with REW I was searching for something like this, then thought at some point I'd try to create one but never got around to it (... and I seemed to always run into issues with REW in getting that first measurement of the day!!).

Over at the Shack I did create a thread for people with MobilePre's and how to set that up as I think I've run into just about every possible issue by now. I won't be quitting my day job any time soon.

Does the galaxy SPL have a mount on it?
post #26 of 43
Yes.
post #27 of 43
Depends what you mean by "mount". It has a standard 1/4" insert that would fit most small camera tripods. Actually, that's the one thing I don't like about my Dayton Mic, the mount doesn't screw into my tripod. So what I typically do is mount the CM-140 to the tripod and tape the EMM-6 to it.

I've been meaning to compare the two mics and possibly make a calibration file for the CM-140 against my CSS calibrated EMM-6. Just never got around to it.
post #28 of 43
Thread Starter 
Anyone know if a mic calibrated below 20hz is even "accurate" with a tascam due to the fall off on the sound card?
post #29 of 43
Nice job omegaslast, a good 101 for the hardware set-up side.

I've got a iMac running latest REW in OSX with the earlier 2008 Mobile Pre, many people have that in their set-up.

Next time I take measurements I'll capture some of the unique Mac side things + the 2008 Mobile Pre and post here for sharing.
post #30 of 43
Would you consider adding information about ETC measurements for the purpose of examining first reflections and the effects of room treatment (other than corner bass trapping)? String method, etc.

This took me a lot of reading to begin to grasp, and I think the community would be well-served by a central summarized how-to.
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