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REW help - sub null can't seem to fix

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Harris48

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@ppataki thanks a million! I will mess around with MSO for the fun of it but knowing that I already have a solid curve to use.
 

DonH56

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Note boosting to compensate a null can require tremendous power and make sound elsewhere in the room very "boomy". Boosting by 10 dB using EQ means increasing the output power by 10 times so make sure your sub can handle that.
 

audiofooled

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Note boosting to compensate a null can require tremendous power and make sound elsewhere in the room very "boomy". Boosting by 10 dB using EQ means increasing the output power by 10 times so make sure your sub can handle that.
+1

I'd go for better setup options if plausible and only then use EQ as a final touch if required.
 

ppataki

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There is no boosting involved here whatsoever. Even in the simulation where I mentioned 'boost' there are no boosting filters used.

This is how the correction curve looks like - only cutting filters were used, no boosting

1672819152179.png


The target level has been significantly decreased (to 69dB) thus resulting in an overall efficiency loss of 10+ dB (assuming measurement was taken at about 80dB) as seen below

1672819018790.png


This could still be fine depending on the listening circumstances (distance, SPL needed, speaker sensitivity, amp power, etc.)
It is worth a try at least (in my opinion)
 

Cote Dazur

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don't put subs in the corners. That's where the strongest modes are, hence the difference when you open a door.
My understanding about opening doors (particularly the one that lead to a big space) acts as a bass trap and is a great way of regulating bass in a room, but I do not understand the relationship with placing subs in corner (or not).
 

DonH56

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There is no boosting involved here whatsoever. Even in the simulation where I mentioned 'boost' there are no boosting filters used.

This is how the correction curve looks like - only cutting filters were used, no boosting

View attachment 254754

The target level has been significantly decreased (to 69dB) thus resulting in an overall efficiency loss of 10+ dB (assuming measurement was taken at about 80dB) as seen below

View attachment 254753

This could still be fine depending on the listening circumstances (distance, SPL needed, speaker sensitivity, amp power, etc.)
It is worth a try at least (in my opinion)
I did not mean to imply you were boosting; I did not know either way, though may have misinterpreted your use of the word "boost". I was making a general comment since "Can I boost EQ to eliminate a null?" is a perennial question.
 

NTK

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There is no boosting involved here whatsoever. Even in the simulation where I mentioned 'boost' there are no boosting filters used.

This is how the correction curve looks like - only cutting filters were used, no boosting

View attachment 254754

The target level has been significantly decreased (to 69dB) thus resulting in an overall efficiency loss of 10+ dB (assuming measurement was taken at about 80dB) as seen below

View attachment 254753

This could still be fine depending on the listening circumstances (distance, SPL needed, speaker sensitivity, amp power, etc.)
It is worth a try at least (in my opinion)
Sorry. There is no free lunch here. If you lower everything else to make the FR flat, it can only mean that you'll have an overall average level that is too low. What you are going to do next is to turn up the volume, which is equivalent to a boost.
 

audiofooled

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Sorry. There is no free lunch here. If you lower everything else to make the FR flat, it can only mean that you'll have an overall average level that is too low. What you are going to do next is to turn up the volume, which is equivalent to a boost.

And this
 

will.b

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@Harris48

This video may be of use to you as well:

 

audiofooled

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My understanding about opening doors (particularly the one that lead to a big space) acts as a bass trap and is a great way of regulating bass in a room, but I do not understand the relationship with placing subs in corner (or not).

OP's room is almost square, so the strongest modes are exactly in the corners, as predicted by the calculator I linked. By placing subs in corners you get even more room gain in the frequency band (the big hump around 78Hz). It's about the long wavelengths vs the ratio of room's width/height and relation to the MLP. Listening position is also symmetrical somewhere in the room, where the nulls are created, causing a big dip in the frequency band, also predicted by the calculator. By placing bass traps in the corners, instead of subs, you get more even distribution of modes and a chance for a better FR at the desirable MLP. Note that I'm not selling any bass traps, and I don't say they can do much, but for the situation at hand, I would recommend placing the subs some place else, other than in corners. The peaks and nulls should be less pronounced, and possibly the EQ can do the rest of the business.

Again, there's also this https://www.audiosciencereview.com/forum/index.php?threads/analytical-analysis-room-gain.23211/

So, the first eigenmode starts at 0 or DC. By plugging the ports you get net volume displacement for the lowest frequencies, where the development of eigenmodes starts. Ports move the air in and out, cancelling the effect, also each other out (when you have different subs with many different ports/tuning). I'm no expert, it's just how I understand what @René - Acculution.com said about the matter.
 

Cote Dazur

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@audiofooled thank you for the great answer and I apologize as my question was maybe not 100% clear.

My understanding about opening doors (particularly the one that lead to a big space) acts as a bass trap and is a great way of regulating bass in a room, but I do not understand the relationship with placing subs in corner and opening the doors, both good practice as I understand it, but are they related? Or maybe I misunderstood your post and they are just 2 different and independent recommendations
 

audiofooled

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@audiofooled thank you for the great answer and I apologize as my question was maybe not 100% clear.

My understanding about opening doors (particularly the one that lead to a big space) acts as a bass trap and is a great way of regulating bass in a room, but I do not understand the relationship with placing subs in corner and opening the doors, both good practice as I understand it, but are they related? Or maybe I misunderstood your post and they are just 2 different and independent recommendations

I did not say one should actually open the doors as it has nothing to do with where the subs are located. I just pointed out the difference as seen in the OP's measurements. His door happens to be close to the corner but just about in any other room, regardless where they are located, by opening them you effectively change the acoustics of the room. Or the windows for that matter. It just relieves the pressure and makes the room less of an enclosed box. But if you play loud, then it is no longer contained in your dedicated listening room. And your wife may hear a rather big difference...

In other rooms which are just rectangular and not square, corners as well are always energized but the difference is that you have better chance for more even distribution of modes some place where your listening position would be.

Subs can be put in corners but good practice would be the same model in each corner. For less than four there are other options.

Attached is an example from Dr. Toole's book for further clarification. But look at option d. and the explanation for it.
 

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Harris48

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Annnnnnd my brand new MiniDSP broke when I went to try all this stuff

Rene posts goes over my head half time. I'm going to have to read it a couple more times. I feel like it the advanced version and i need the intermediate...haha
 
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-Matt-

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I had trouble with my MiniDSP 2x4 HD when it first arrived. I subsequently discovered that it wouldn't work when plugged direct to my laptop. (Apparently there is interference from the laptop that prevents the usb connection from working). The workaraound for me was to plug the MiniDSP into a USB hub that is in turn connected to the laptop.

It is slightly annoying, and may not be the fix to your problem, but is at least worth a try.
 
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Can't you in REW play around with placements of subs in a room in a simulator of sorts?
Yes. I used this room simulator a lot. Have had my sub placed at the side wall until I got dirac live. Then I placed it in the front wall corner to get the most SPL and then cut the peaks in dirac eq.
The simulator correctly calculated the smoothest response at the side wall but at the expense of greatly reduced output. There are for sure much higher peaks in the corner due to the excitement of all the room modes. But that doesn't matter when I can cut them by EQ and at the same time gain a lot more dB. I think the average dB gain was 7 or 8, something like that.
I could dial the sub gain down from pos. 1 O clock to about 10 O clock and still have plenty output compared to earlier.
 
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