# Do I need to run REW on my HT if using Auto Calibration



## akakillroy (Jul 9, 2008)

Do I really need to use REW if my receiver has auto calibration? I have a Yamaha 663 receiver with the auto room calibration feature, and I have run this a couple times to set everything but I am not sure if I should go ahead and run REW or not. Would I really benefit from using it?

I have two sub woofers and a 7.1 system/speaker set up. Although the Auto Calibration told me to set the cross over freq to max, not sure if that meant all the way to 120 or down to 50. The sub-woofers I have are not exactly the same, one is a DCM bottom firing 10" and the other is a Polk 8" front firing.

Any suggestions?

I have the REW software on a MacBook, and I believe I have calibrated it correctly. And I also have a Radio Shack digital sound meter.


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## etcarroll (Mar 17, 2008)

Definately run it.

Auto cal. in a receiver is not 100% by any means, REW wil point out where it missed.

Having 2 subs only increases the chance of there being a problem, might as well find out now.

I'd set XO at 50 before 120, but really, 80 might be best if its an option. Try both 50 then 80. your ears should be your guide in this.


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## akakillroy (Jul 9, 2008)

Well I am game for running it, but assume I know nothing :whistling: Now that I have my sound card calibrated such as it is. I do not have a BFD so I would assume by the setup instructions I am going to use just the right in and out's. Right in on the sound meter and right in for the receiver?


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## Wayne A. Pflughaupt (Apr 13, 2006)

Right _out_ for the receiver...

Regards,
Wayne


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## akakillroy (Jul 9, 2008)

I consider myself an intelligent person but I am having some difficulty figure out the specifics on what to measure for what type of connections. Most of the diagrams show connections to the BFD but none if you just have a receiver. And most seem to talk about measuring your subs/low freq. Are there any tutorials or step by step how to's. Sorry to be so ignorant.


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## etcarroll (Mar 17, 2008)

Me too, and I had issues last month when I ran it, look for my thread, you'll see as I posted my issues, the experienced members here answered them. If you notice my first post, I outlined my equipment and room size, you can start there.

BFD is optional, not required, I don't have one.

You MUST HOWEVER read the first post, the stickied thread of REW info.

Find the 'GUIDES' section, then read the first 3 bullets, skip the 4th as its about BFD. I used this diagram from the guides section, minus the BFD part of course;


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## akakillroy (Jul 9, 2008)

I must be doing something wrong during my sound card calibration. I seem to get it calibrated but when I do step 7 here, my measurement does not base out at 0 but like at 75db its flat as a pancake but not at 0 I am not sure what I am doing wrong.
View attachment 9045


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## akakillroy (Jul 9, 2008)

Here is my initial sound card measurement, set at -12db I am in the yellow on the VU meters but in the green on the headroom of -6.x db
View attachment 9046


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## brucek (Apr 11, 2006)

It's all fine. Save the soundcard file in REW and carry on........

brucek


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## salvasol (Oct 31, 2006)

carls64 said:


> Do I really need to use REW if my receiver has auto calibration? ...


It seems that you're starting to have fun calibrating everything after the build ... :bigsmile:

Is okay to have two subs, but is preferred to have two similar ... by the way: Did you do the crawling test or just placed them in the front wall??? :huh:

When you get REW running ... calibrate one sub at a time, then combine their response to get the best out of the system :yes:

REW looks intimidating, but after a couple of measurements you'll see how easy is to use :bigsmile:

Hopefully you won't need a BFD ... after you run REW try to adjust the response with your receiver EQ (I have the RXV 2700 and that's what I did) and I'm happy with the results :yes:


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## akakillroy (Jul 9, 2008)

salvasol said:


> It seems that you're starting to have fun calibrating everything after the build ... :bigsmile:


That's me! Backwards Carl :neener: I di the seating and screen size that way too :crying: But I came out okay there :T



salvasol said:


> Is okay to have two subs, but is preferred to have two similar ... by the way: Did you do the crawling test or just placed them in the front wall??? :huh:


 Nope, I just stuck them there. I went for the hard way first :coocoo:



salvasol said:


> When you get REW running ... calibrate one sub at a time, then combine their response to get the best out of the system :yes:


 Ididn't think of that, THANKS!



salvasol said:


> REW looks intimidating, but after a couple of measurements you'll see how easy is to use :bigsmile:


 I sure hope so.



salvasol said:


> Hopefully you won't need a BFD ... after you run REW try to adjust the response with your receiver EQ (I have the RXV 2700 and that's what I did) and I'm happy with the results :yes:


 I have the Yamaha RX-V663 I am hoping it has some way to manualy adjust things.


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## akakillroy (Jul 9, 2008)

Do the BFD's make that big of a difference? And what about if you don;t have all the acoustical treatments, does it help? Lastly I am confused on which model to get if I did get one. They seem to be very inexpensive.


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## salvasol (Oct 31, 2006)

carls64 said:


> Do the BFD's make that big of a difference? ...


It will depend on your frequency response ... sometimes with the adjustment on the AVR and if you're not to picky, it will be okay. :bigsmile:



> And what about if you don;t have all the acoustical treatments, does it help? ...


The first step (before buying a BFD) is to get accoustic panels, bass traps, etc. ... that will help with the frequency response too, then get the BFD if need it ... :yes:



> Lastly I am confused on which model to get if I did get one. They seem to be very inexpensive.


I think most get the 1124 ... it cost less than $100 price comparison yes:

I'm sure that the RXV663 and RXV 2700 are similar to adjust ... after the auto calibration, go to the main menu set up; you'll find the parametric equalizer, there you can adjust the sound (you have to play with that for some time until you get the response you want; what I did was to adjust one frequency at a time and use REW to see the changes; then another change and REW, then another and REW, etc.) :yes:


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## akakillroy (Jul 9, 2008)

Here is my first and second readings there are from 0-200hz on the subs
View attachment 9057

View attachment 9058


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## akakillroy (Jul 9, 2008)

If I go much above 200hz i get a message that I am getting some clipping.


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## brucek (Apr 11, 2006)

Use the standard scale for subwoofers with your graphs.

Vertical axis = 45dB-105dB
Horizontal axis = 15Hz-200Hz

brucek


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## akakillroy (Jul 9, 2008)

Here you go! Something still is not right though :gah:
View attachment 9062


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## brucek (Apr 11, 2006)

Use the standard scale for subwoofers with your graphs.

*Vertical axis = 45dB-105dB*
Horizontal axis = 15Hz-200Hz

Measure subwoofers with the mains turned off and the subs fed from the receiver in stereo mode with the crossover set.

brucek


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## akakillroy (Jul 9, 2008)

I am having trouble figuring out how to turn off my main speakers and leave on the subs :-( the manual does not seem to help, do i just need to disconnect the other speakers, that will not hurt anything will it?


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## brucek (Apr 11, 2006)

> am having trouble figuring out how to turn off my main speakers and leave on the subs


Unplug the speaker cables at the receiver (with the power off, of course). That's it......

You only need to disconnect the mains, since you always test with the receiver in stereo mode, so the mains will be the only speakers enabled.

No, it won't hurt anything. No speakers, no current.......

brucek


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## akakillroy (Jul 9, 2008)

Ok that seems to be better but for some reason I can't see my baseline or what the corrected/actual value of the crossover should be.

Sub1
View attachment 9081

Sub2
View attachment 9082

Both
View attachment 9083


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## brucek (Apr 11, 2006)

> I can't see my baseline or what the corrected/actual value of the crossover should be


I don't understand what this means.... 

Change your graphs from LINear to LOGarithmic. Use the Freq Axis button.

brucek


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## akakillroy (Jul 9, 2008)

Well it was showing me the base line of where the "should" be position right, like in those image:

http://www.hometheatershack.com/forums/rew-forum/12731-my-graphs-advice-appreciated.html#post113694

The blue green line there.


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## brucek (Apr 11, 2006)

> the base line of where the "should" be position right


That's the target response curve. It's enabled by selecting the target checkbox below the response graph. Its level is set with the target settings pane to the left of the graph.

brucek


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## akakillroy (Jul 9, 2008)

Ok I found that, but what or how is it set? Where dies ti get its reference from?


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## salvasol (Oct 31, 2006)

carls64 said:


> Ok I found that, but what or how is it set? Where dies ti get its reference from?


Before you do the measurement you set the target (you set the AVR volume to get 75db on the SPL/microphone) and that's where the blue line will be :yes:


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## akakillroy (Jul 9, 2008)

Did that looks a little better now, this is with both subs, how does it look?
View attachment 9092


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## brucek (Apr 11, 2006)

> how does it look?


Use the standard scale for subwoofers with your graphs.

*Vertical axis = 45dB-105dB
Horizontal axis = 15Hz-200Hz*

brucek


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## akakillroy (Jul 9, 2008)

Doh! Sorry how is this?
View attachment 9093


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## brucek (Apr 11, 2006)

I suspect one of the problems is that you are using mismatched subs.

_one is a DCM bottom firing 10" and the other is a Polk 8" front firing._

There is a tendency for people to want to use their original sub when they move up the food chain. The idea being, if one is good, two is better.

This is really only true when the two subs are an exact or close match. What happens is that the weaker sub dumbs down the better sub, and usually at the expense of bottom end.

It might be a good idea to test your better sub placed in a corner and see how the response looks. That peak between 40hz and 80Hz may go away.

brucek


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## akakillroy (Jul 9, 2008)

brucek said:


> I suspect one of the problems is that you are using mismatched subs.
> 
> _one is a DCM bottom firing 10" and the other is a Polk 8" front firing._
> 
> ...


Well it would be hard to say I suppose which is the better sub, maybe the DCM 10" I guess i can try both one at a time and see.


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## akakillroy (Jul 9, 2008)

DCM in the corner:
View attachment 9094


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## akakillroy (Jul 9, 2008)

Here is just the polk in the corner, got a BIg dip at about 69 or so
View attachment 9095


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## akakillroy (Jul 9, 2008)

I had the DCM 10" firing in the corner, on its side and this seems to look pretty good ;-)
View attachment 9096


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## Wayne A. Pflughaupt (Apr 13, 2006)

Looks the same as the first one, really...

Are both those readings from the same corner? Pretty strange that they'd look so drastically different.

Regards,
Wayne


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## akakillroy (Jul 9, 2008)

Well the last two, are from different corners and different subs, the gold colored on is the polk in the right corner, its a front fire. The DCM is a bottom fire one, the last readying though was with the DCM in the left corner on its side where the speaker itself was firing into the corner.


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## Wayne A. Pflughaupt (Apr 13, 2006)

Okay, that makes sense. I'll bet if you run the Polk in the left corner it'll look about the same as the DCM. That appears to be the better corner of the two...

Regards,
Wayne


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## akakillroy (Jul 9, 2008)

My room is 13x24 so I am not sure if just the 8" forward firing POLK will get the job done, this is wy I was using both the 10" down firing DCM and the Polk. What do you suggest? Buying a new one is not an option right now ;-)


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