# REW & Subwoofer Measurements Review



## Donald2B (Nov 25, 2008)

Hi all,

Fairly new to the forum and REW and would love to get some feedback on my latest attempt at EQing my new subs.

I am not really sure what is going on by looking at the charts other than I have a huge peak around 46Hz or so.

Anyways, I would love to get some feed back on your thoughts and help me better understand what I am seeing.

Thanks!

Edit: I have attached a zip file with the mdat file.


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## mechman (Feb 8, 2007)

Just giving this a bump Donald so you can get some feedback. :T


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## SAC (Dec 3, 2009)

Just a few quick thoughts…

It looks pretty.  By that I mean that it looks smooth.

That said, I would personally prefer a slightly different route to a similar result.

Note that you have all gain filters with one exception – including 3 filters all greater than 6dB including 2 of 10dB gain! This places a large ongoing demand on the amp as far as baseline function.

This makes for a nice pretty smooth response, but at a tremendous cost of available dynamic headroom. And to my thinking, the available headroom in the overall gain structure while reducing the possibility of pushing the amp into a non-linear operational range or soft clipping is highly preferable.

To that end, I would rather use cut filters to similarly smooth the curve, bringing down the small variations (assuming you feel correction of the small variations is critical) to smooth the response over the passband, and using gain filters only where absolutely necessary. 

Once this is done, you can use the master gain/volume control to increase the overall level with the amp operating in its linear range while preserving much of the available headroom.


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## Donald2B (Nov 25, 2008)

Okay, so that makes a TON more sense! By gaining up frequencies I am effectively making the amp work harder for no real reason.

So by using cut filters and pulling everything down allows me to be a better response from the subs and then use the gain to bring them back up the levels I am expecting.

I took the advice and went with the Deep Knee house curve and determined that I needed +9 dB at 30Hz and 0 dB at 80Hz, put that into a house curve file in REW with the logarithmic checkbox.

These are the new graphs. I definitely like the sound better and they appear to sound more "even" as the frequencies drop. Only had to use two filters for this graph. My room seems to really like the house curve a LOT more than just a flat curve.


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

Some myths just won’t die.

Boost or cut, it’s all academic. You don’t gain headroom by using only cutting filters. The situation is, that peak you had in response was the determining factor for where you were setting your subwoofer volume relative to the mains. Using only cutting filters, you end up with significantly less output from the sub than you had before. Of course, you now have to increase the sub input gain to compensate – well, say “goodbye” to the headroom you supposedly “saved.” Signal gain from EQ boosting vs. signal gain from dialing up the sub’s input control equals the same demands on the amplifier in the end. There’s no free lunch when EQing subs. You have to have adequate headroom going in.

More here (the second section below the missing pictures) 

That said, considering the way your baseline curve was, cutting was indeed the best way to flatten response in your particular situation (even if you didn’t end up with any “free” headroom), since you had no significant troughs that needed to be addressed. It looks like you were using a ton of filters to boost everything up to the level of the peak, which isn’t a very efficient way to equalize, especially since everything above and below the peak was relatively smooth to begin with. By addressing only the problematic peak, you accomplished the same results with only a couple of filters instead of the six used before. It’s not uncommon for people to tell us that when they compare a multiple filter curve to a minimal filter curve, they like the way the latter sounds better. 

Regards,
Wayne


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## Donald2B (Nov 25, 2008)

Thanks for the GREAT explanations!

It is very easy to get overwhelmed with all the EQ information out there are what works best. Unfortunately, I didn't have a lot of time to try all the various flavors, I tried to make the most out of the little time I did have.

I originally thought that my curve was pretty bad and needed to be corrected a LOT. I guess I just didn't understand what makes a good vs bad graph outside of the major peaks. I thought it would look more like a "smoothed" graph that what it originally did.

The more I work with this the more I am sure I will understand. Thanks so much! I love getting the theory down since it will help me make better decisions moving forward.


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