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Discussion Starter · #1 ·
This is a very basic tutorial on how to :
  • create a spl graph in REW using umik mic
  • create the filters for an Inuke amp
  • apply filters in Inuke amp



If you want a detailed how to use REW click on this link
http://www.avsforum.com/t/1449924/simplified-rew-setup-and-use-usb-mic-hdmi-connection-including-measurement-techniques-and-how-to-interpret-graphs/270#post_22823228


The purpose of this tutorial is to under 20 minutes get you up and running with REW. You will get a very basic understanding of what to do and how to apply it to your inuke dsp amp. I am not an expert in this software , far from it. But I wanted to create a help guide for those who have trouble understanding the information thats already out their. Once you have a general sense of how REW works then please go to the above link or other info on the web and get a detailed in depth understanding. I won’t be answering questions in this thread. I just don’t have an expert knowledge base or the time.

What you need before starting
  • laptop with hdmi out and usb port
  • Umik-1 mic
  • 10ft or longer hdmi cable
  • Download REW software and install http://www.roomeqwizard.com/

    Make sure volume on laptop is at 100% and mute is not on
    Make sure all dsp is off of the preamp/receiver. This means turn off audyssey, ypao, mcacc, EmoQ or any other.


Getting Started

1) You need to do this testing in a quiet environment. The test sounds are loud so best to be the only person in the room. Place your laptop near the primary listening position in your room. Hook up the mic to your usb port of the laptop. Place the mic at your normal ear level in your primary listening spot (or as close as you can) Plug in the hdmi to your laptop and to your preamp/receiver hdmi input. You can have your tv on set to that input so you can see on the bigger screen.

2) You only want sound from your subwoofer for this test. Making sure everythings off unplug the other speakers or turn of their amps. Can unplug speaker inputs or whatever is easiest for you. If dual subs you can test one or both (up to you).

3) Start up the REW software with all gear attached and ready to go. The computer may prompt you for calibration file that came with the mic. Select the folder/file you have saved it in.

4) Now you are ready to go !!!! Begin by clicking on measure on far left



5) Adjust the volume of your avr/preamp to about 30-40 dbs less then reference. For most receivers this will mean -40. Adjust the start and end frequency to where you want it. From 15-100 hz is fine. Click on check levels



If it says its too low like my picture then turn the volume up 5dbs and try again. My picture doesn't have a mic attached and thus for this whole tutorial my sound level is at 20dbs. For your graph you want 80-100dbs which you will know later if you have it set right.


6) Once you check levels and it says its ok then click on start measuring. You will now hear a tone start really low and go up for 5 seconds. If you don't hear a tone you don't have gear connected properly or the mic/hdmi isn't on default for your laptop. To change them go into your sound settings for your laptop . Here is hdmi



and your mic will be this or a umik-1 icon to make default. Right click on icon and hit default.



7) Now you have your first graph !!!! Isn't it pretty. Your screen looks like mine now



The red squiggly line is the spl frequency for your sub in your room. My line is lower down then yours because I don't have my mic with me .


8) In the top center of the screen is 8 icons. Click on the EQ icon second from the right. Now your screen looks like this



Lets add some smoothing to make it easier to see (there is debate about the right amount of smoothing, we will use 1/12) click on the wheel just above the word smoothing in my picture below to adjust it.



Now lets explain a little. THe red line starts at 15hz (vertical axis) and is at about 21dbs in spl (volume) which is horizontal axis. Remember yours you want between 80-100dbs. If yours is at 70 then turn your preamp/receiver up and if the dbs are on a horizontal axis of 110dbs then turn down your volume. You would then go back and re measure .


From 15hz the red line goes to the right and at about 24hz it is going up to 30dbs. Thats called a peak. At 28hz the red line goes down to about 16dbs. Thats called a null . As we continue this will make more sense.


9) Now we click on the equalizer tab on far right so it looks like picture below



it should be on generic. If it isn't select that.


10) Now below equalizer is Target settings. Open that up as below



Click on the set target level on bottom. Then move it up or down so its in the middle of the peaks and nulls. This means that there is an even amount of rising hills above the target line (its blue) as below it. Just like mine is above. Again don't worry that my target level is 19 (no mic used) , yours will be around 90dbs.


11) Now click on filter tasks icon below target settings.



The first info is match range, adjust that to match your frequency measured. 20-100 works fine. Then click on match response to target and this creates the eq filters that go into the inuke !


12) Click on EQ filters on top middle of page. It now looks like below



Click on the up/down arrow on upper right and it sorts filters. You will have 3-8 probably. Write these numbers down. My first filter in mine would be 23hz at -12 gain with a q factor of 11.


The hz is the frequency

The gain is for positive boosting the signal, and for negative cutting the signal for that frequency
Q or quality on inuke is the range it applies that boost or cut. Quality of 1 is wide (spreads the boost/cut over 10hz range roughly). A q rating of 20 makes it very narrow boost or cut (like 1-3 hz)


You are done with REW for now. (don't close it)


13) Now enter these filters into your inuke by manually inputting or using usb cable provided. There are 8 PEQ bands you can set with your inuke dsp. Go to PEQ #1 and make sure it says peq , not hs or off. enter the hz value, the gain value, and for now leave the quality or Q alone. You can fine tune that later.



Do this for all the filters that REW provided for you. Once done you need to measure again with REW. You should see a graph that has fewer peaks and nulls.

Note

Boosting any frequencies , especially below 40hz for movies takes up amp power. Its not recommended to boost these low hz by more then 3dbs. 50-90hz can be possibly boosted by more, say 5-8dbs. The better way is to cut frequencies which doesn't drain the amp. If needed you can use two PEQ bands to cut a frequency (-10 for one at 40hz, -9 for second at 40hz). The best way to get rid of nulls is moving the sub into a better location in the room, although sometimes that is not possible. If you have boosted a lot of frequencies on your inuke amp you will end up seeing the red clipping light more. You have two options at that point. Lower the main gains 2-3 notches or reduce the boosting you did. For me I just reduced the main inuke gains back three clicks and the clipping went to a proper amount.

The Goal

So what is the point of all this ?


Good question, it has to do with relatively flat frequency response. Flat means your graph red line is within plus or minus 3dbs. For example if your target setting is 90 dbs then no frequency would be farther away from 90dbs then 87-93dbs. That's not to say that if you just love some midbass you can't have 70hz 5-6 dbs louder. Its all up to you. When you do have flat response you don't get booming notes from the sub at 40hz and quiet notes at 60hz when their supposed to be the same loudness.


You have now reached the end of this basic tutorial. Hopefully this gets you started and makes these graphs more understandable. To really eq your sub to the fullest I suggest reading the above link and fine tuning your settings.
 

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Outstanding.

You would usually want to run EQ on an UNsmoothed graph but, since you only have 8 filters to work with, smoothing can help if, as above, REW comes up with 19. You can change the smoothing until you get to the point where you need 5 or 6 filters.

The only thing you might want to change in the write-up is to replace these graphs with more accurate ones when you have a mic.

Michael
 

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Cool idea Donney. Traditionally it's been this DIY area of the forum that produces a lot of data, yet no tutorial like this.


I'll just point out that boosting frequencies above and below 40hz are equally taxing on an amplifier. In fact, for most I'd suggest that Fb lands around 30hz meaning below 40hz will be easier on the amp. Let me explain.


Here's an impedance measurement of one of my subwoofers in it's box (a little difficult to read, sorry):

http://s874.photobucket.com/user/tuxedocivic/media/New HT/Trio12impedance_zpsda03cc6b.png.html


You can see Fb is right around 30hz. I'm betting that's a touch high for most people as I'm using a 12" driver in an undersized box. So commonly that impedance peak is even lower. When impedance is high, the driver draws less current. When impedance is lower, like at 60hz in my graph, the driver draws a lot of current. You can see this in most box modelling software. In my case, boosting frequencies at 30hz is going to be much easier on the amp than boosting at 60hz.


All in all, it is important to be careful with boosts. Better to focus on cleaning up the room and moving subs around to fill that null. Even if it means creating a peak that can be eq'ed out. All IMO.


I'd also suggest people consider HolmImpulse for measurements. I dunno, I just find it very fast, convenient, and accurate. But I also am more used to it. REW has more features, so that's nice. But never hurts to have another option.



EDIT - I should add, that often LFE tracks contain a lot of intense bass below 40hz. So if boosting cause your amp to clip, it'll happen more often below 40hz. But it'll still happen above 40hz.
 

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I didn't get dsp amp because I know none of this stuff. Now I know the basics and have no amp. I blame you chaluga for not putting this guide out last week!


Haha good work though. I guess I'll need a inuke dsp in the near future to play with this.
 

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Discussion Starter · #8 ·

Quote:
Originally Posted by tuxedocivic  /t/1524422/basic-rew-for-inuke#post_24533756


Cool idea Donney. Traditionally it's been this DIY area of the forum that produces a lot of data, yet no tutorial like this.


I'll just point out that boosting frequencies above and below 40hz are equally taxing on an amplifier. In fact, for most I'd suggest that Fb lands around 30hz meaning below 40hz will be easier on the amp. Let me explain.


Here's an impedance measurement of one of my subwoofers in it's box (a little difficult to read, sorry):

http://s874.photobucket.com/user/tuxedocivic/media/New HT/Trio12impedance_zpsda03cc6b.png.html


You can see Fb is right around 30hz. I'm betting that's a touch high for most people as I'm using a 12" driver in an undersized box. So commonly that impedance peak is even lower. When impedance is high, the driver draws less current. When impedance is lower, like at 60hz in my graph, the driver draws a lot of current. You can see this in most box modelling software. In my case, boosting frequencies at 30hz is going to be much easier on the amp than boosting at 60hz.


All in all, it is important to be careful with boosts. Better to focus on cleaning up the room and moving subs around to fill that null. Even if it means creating a peak that can be eq'ed out. All IMO.


I'd also suggest people consider HolmImpulse for measurements. I dunno, I just find it very fast, convenient, and accurate. But I also am more used to it. REW has more features, so that's nice. But never hurts to have another option.




EDIT - I should add, that often LFE tracks contain a lot of intense bass below 40hz. So if boosting cause your amp to clip, it'll happen more often below 40hz. But it'll still happen above 40hz.

I will add in some of your tips.
 

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Discussion Starter · #9 ·

Quote:
Originally Posted by tential  /t/1524422/basic-rew-for-inuke#post_24533789


I didn't get dsp amp because I know none of this stuff. Now I know the basics and have no amp. I blame you chaluga for not putting this guide out last week!


Haha good work though. I guess I'll need a inuke dsp in the near future to play with this.

I wanted to do this a couple of months ago but the martycube got me sidetracked.
 

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Awesome chalugadp, thanks for putting this together! This is the level I need too.


The one thing I would add is that an Audyssey mic apparently will do fine if you are only tuning a subwoofer. ( see here )
 

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Discussion Starter · #11 ·

Quote:
Originally Posted by Spiderm0n  /t/1524422/basic-rew-for-inuke#post_24533851


Awesome chalugadp, thanks for putting this together! This is the level I need too.


The one thing I would add is that an Audyssey mic apparently will do fine if you are only tuning a subwoofer. ( see here )

that reminds me to add turn off all dsp from your receiver or preamp. I will add that into the tutorial.

thanks
 

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Quote:
Originally Posted by chalugadp  /t/1524422/basic-rew-for-inuke#post_24533871


that reminds me to add turn off all dsp from your receiver or preamp. I will add that into the tutorial.

thanks

I ran some test with my setup and running YPAO on the Yamaha receiver and it had very little effect. It seemed to only really effect the upper frequency 70-80. Here is a graph I have with the two. The "Clean" graph has no dsp and crossover for subwoofer at 90z. The "YPAO" one has the same crossover but with YPAO set to Natural.


 

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Quote:
Originally Posted by cessna1466u  /t/1524422/basic-rew-for-inuke#post_24534430


I ran some test with my setup and running YPAO on the Yamaha receiver and it had very little effect. 
YPAO, MCACC, and most versions of Audyssey do almost nothing for bass. Only the newest (and most expensive) version of Audyssey makes any attempt to EQ bass. The rumor is that the next version of Pioneer's MCACC will address that "shortcoming."

Of course, now you know that.



Which is why having the ability to EQ a subwoofer and having the equipment to do it properly is important.

To some, anyway.

 

 

(Run the sweep to 20KHz, 1/6 smoothing, with YPAO on and off, and you'll probably see a difference.)
 

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Also, his response was already pretty flat so YPAO didnt have much to do.


My Yamaha receiver lets me eq the speakers manually, but not the sub. Its a nice feature. Even allows for adjustment of Q. I tweak a few things.
 
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