# “In & Out” REW Frequency sweep



## Andysu (May 8, 2008)

Here’s something I suggested a few days go about room EQ. 

“In the cinema EQ is done in the projection booth this is to keep any disturbance like someone moving around because it will affect the graph. 

When, I worked as projectionist for Warner Bros back (1998) the sound engineer asked for my assistance to place the microphone a few feet forward and slightly to one side and then “get out”!

Also it took 2 days for the guy to EQ each of the 12 screens with the Dolby CP500, now then

Since I rather close to the door and I don’t know why I didn’t do this early, even thou I remember my days at Warner Bros.

So I’ve been In & Out the room like a yoyo, testing it first with me in the room and then out of the room, out of sight while REW performs its frequency sweep.

The difference looks appears so tiny when glancing at it first time, but there are some small variables.

Centre channel while being inside the living room.









Centre channel while being outside of the living room.


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## Andysu (May 8, 2008)

Ran the centre though a few more times depressed the LF slightly and added a slight EQ in at 1Khz on the DCX2496. The left and right at present are miles out and I’ll work on them later.

Test was done while being outside of the room and good thing too because the high frequency is loud on the outside and I was inside the room I’ll be waving my arms around because of the pain of the high frequency, bending me ears.:hide:


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## Andysu (May 8, 2008)

You’ll get a good workout with “In & Out” it feels good too. 

Well its looking okay for now I’ll run a few more though then focus on the left and right and see how close I can get them with the centre, sigh this is going to take all-night and into the early morning hours.:dizzy:

*Centre channel JBL control 5*


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## Andysu (May 8, 2008)

As an experiment I switched THX ON just for the sake of it there is only minor difference in the graph since the last one, I added a filter at 180Hz a tiny decrees -2db. I’ve selected 1/3 smoothing for this one.


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## brucek (Apr 11, 2006)

> Centre channel while being


You do realize that the Measured tab in REW allows for graph comparisons?



> out of sight while REW performs its frequency sweep


And so, does this require you to also be OUT of the room when you listen to the system after EQ, since you created the filters when OUT?



> I switched THX ON


REW is a mono signal and so any soundfield or effects are not to be used when measuring. The results are not meaningful. 

brucek


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## Andysu (May 8, 2008)

I was wondering out that dip around 1Khz range? I’ve inverted the phase on it to rise it up. Well its not looking to bad except below 170Hz I think its in a bit “null” ether I move the sofa forwards and test it or move it back and test or I look for an alternative. Sigh, its all good stuff.

I’ve been at this now for hours, and that’s just the centre and with limited EQ on the DCX2496 at hand because the crossover filters is taking up most of the free space percentage running close to 1%. Need those DEQ to handle this more efficiently.

*Centre channel JBL control 5*


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## Andysu (May 8, 2008)

brucek said:


> You do realize that the Measured tab in REW allows for graph comparisons?
> 
> 
> And so, does this require you to also be OUT of the room when you listen to the system after EQ, since you created the filters when OUT?
> ...


Cheers for that heads-up you mean I cab combine the multiple sweeps and fold it into one single graph, is it an easy step single button to press??

Yes I’m but a few feet away from the door, I'm within arms reach of the mouse and then as soon as I click (start REW) I’m out of the room before I hear the sweep starting at 70Hz to 16,000KHz.:hide:

I then go back and look at the sweep at 1/1 smoothing, look at the peaks and dips and take a few guesses as to what filter to apply to the DCX2496, with a tiny amount of Q here and there. 

So far its looking better than it was earlier, except I think the left channel is going to be real issue! There is large open space or gap that needs to be blocked off as soon as I get the money to build a false wall. I’ve tried to counterbalance it with another JBL control 5 hiding behind window to augment the lows between 80Hz and 100Hz, otherwise it sounds like a huge dip!

I’m going to give the sweep a few more runs with the centre, then say fine I’m satisfied before I go loopy.

Yes I know REW is a monaural sound output. I use Dolby stereo mode to output to centre then switch to stereo and mute one of the left and right fronts for the frequency sweep.


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## Andysu (May 8, 2008)

Arrr, I see save REW as jpeg I thought it was that little symbol off to left but it wasn’t doing sod all and I’ve just deleted the old files from last year. 

Anyway this is the centre that I’m quite satisfied for the time being and now I’d like to focus on left and right as they need to be as close as possible to the centre channel. Most of REW still reads like Dutch to me, but what a valid tool it is.


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## Andysu (May 8, 2008)

So far this is how the right channel looks, yes a lot to do. [Sigh]

I’ve only applied a few filters with slim Q adjustments once the whole thing looks good enough over LCR I’ll post the filters used not that its going to useful for anyone, well maybe who knows? I know this much if and when I start on the false wall it will all be undone and I’d have to start all over again. [Sigh]


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## Andysu (May 8, 2008)

So far the right channel is starting to slowly shape up but looks as if its going to take longer than the centre, I need to get it trimmed just a tiny little bit and get the level even for centre and right.

This must be past 7 hours now and its starting to get to me and its coming up to 2:30am. I’m going to have a few cat naps 20 minutes, to meditate on this I will.


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## Andysu (May 8, 2008)

Update on the left channel, its going slow here slow “in and out” the room like a yoyo.

4am in the morning sigh!:gah::bigsmile:


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## Andysu (May 8, 2008)

Now to move on with the right channel, hold on, did I just say “right channel” edit that last post, this is what happens when you stay up late, you forget and lose all track of time.:snoring:


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## Andysu (May 8, 2008)

This is what I’ve managed so far with the right front I’ll go over the LCR later tonight as the traffic level outside will start to registering on REW due to the sensuality of the ECM8000.

Besides I use the flipping break now I’m shattered!

Next is the surrounds left and right sidewall arrays and centre back. Sigh


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