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Subwoofer Selection Criteria

Dimifoot

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March Audio

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Beautiful
Software used?
Acourate.
It generates 4 way XO for my active DSP speakers.

1553783802738.png
 
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March Audio

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If I get time tomorrow I will take some measurements to show the 4 subs without any software correction so you can see how well that in itself deals with the room modes.
 

Dimifoot

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If I get time tomorrow I will take some measurements to show the 4 subs without any software correction so you can see how well that in itself deals with the room modes.
I am sure it does :)

It’s even more interesting when you measure seat to seat variation, 1 vs 4 subs.
 

Soniclife

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If I get time tomorrow I will take some measurements to show the 4 subs without any software correction so you can see how well that in itself deals with the room modes.
That would be great. Would you be able to do 1 to 4 subs with and without correction showing the improvements? If it won't take to long.
Do I remember correctly that you are using 4 small cheap subs? What sort of headroom do they give before these very impressive measurements change much?
 

March Audio

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That would be great. Would you be able to do 1 to 4 subs with and without correction showing the improvements? If it won't take to long.
Do I remember correctly that you are using 4 small cheap subs? What sort of headroom do they give before these very impressive measurements change much?
They are B&W ASW608. They go loud enough for me for music and theatre :) ! They are corner positioned so that provides boundary gain (+9dB ???) and of course 4 units will be +6dB. Individually however they wouldnt suffice. Im sure other larger subs will play louder with lower distortion.
 
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DonH56

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Additional room gain because you can put them closer to the wall?

No, room gain is basically related to the dimensions of the room. Smaller rooms provide more effective gain. But also much greater variance in frequency response, peaks and valleys, so a mixed blessing... I would always go for a bigger room if that was a choice. Not like there's a lot of 7 Hz content out there...
 

DonH56

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When running multiple subs, should they be of similar design or it doesn’t make a difference?

I mean all subs ported, or all subs sealed / vs some of them ported-some sealed

There are several aspects of this... Sealed and ported subs have very different response (amplitude and phase) around and below the port tuning frequency so it is much harder to integrate a mix of the two. In addition, power output may vary greatly even within families of sealed and ported subs, so you have to watch you do not overdrive the "weaker" sub. I personally went for identical subs as integrating multiple subs is challenging enough without using different types. Rythmik, and probably others, strives for the same frequency response so I could probably mix sealed 12" and 15" subs without much hassle. Mixing ported and sealed you are likely to have to work for them to all play well together and with the mains. I have helped a friend do it but would not willingly do it again. I am sure there are those who have had no problems, but that ain't the way my life usually rolls...
 

DonH56

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They are B&W ASW608. They go loud enough for me for music and theatre :) ! They are corner positioned so that provides boundary gain (+9dB ???) and of course 4 units will be +6dB. Individually however they wouldnt suffice.

The rule of thumb, which may not be real accurate in a small room (acoustically small, as most any room in a house will be), is +3 dB for a single near boundary like a wall, and +6 dB for a corner. You ideally gain 3 dB for each doubling in the number of speakers all else equal so +3 dB for two and +6 dB for four just as you said.

HTH - Don
 

andreasmaaan

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@DonH56 would you explain why you cite +3dB per boundary rather than +6dB?

I would have said +6dB for the floor and +6dB for any adjacent wall (compared with anechoic output levels).
 

DonH56

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@DonH56 would you explain why you cite +3dB per boundary rather than +6dB?

I would have said +6dB for the floor and +6dB for any adjacent wall (compared with anechoic output levels).

Because only half the energy is being reflected from a single wall alongside the speaker -- the other side is open and subject to normal acoustic propagation. In a corner you get reinforcement from two walls thus 6 dB.

HTH - Don
 

March Audio

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The rule of thumb, which may not be real accurate in a small room (acoustically small, as most any room in a house will be), is +3 dB for a single near boundary like a wall, and +6 dB for a corner. You ideally gain 3 dB for each doubling in the number of speakers all else equal so +3 dB for two and +6 dB for four just as you said.

HTH - Don
Hi Don, I'm probably wrong (long time since I did my acoustic theory) :) but I thought it was 3dB per boundary? Hence 9dB for floor, and two walls.

Never trust Google but came up with this. Going from free field to 8th space

PBFigure1Boundary.jpg
 
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DonH56

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Hi Don, I'm probably wrong (long time since I did my acoustic theory) :) but I thought it was 3dB per boundary? Hence 9dB for floor, and two walls.

Never trust Google but came up with this. Going from free field to 8th space

View attachment 24242
Sorry if this sounds terse, long week.

Unless it is suspended in space or in an anechoic chamber you do not start out in 4pi space; the floor is already there. Thus the gain is 3 dB with one wall, 6 dB in a corner. Maybe I misunderstood your original response, sorry.

The basis for most of my babblings with respect to acoustic theory is Fundamentals of Acoustics by Lawrence Kinsler et. al. That was my first grad text. I make no claim to remember it all now; sometimes I look back at my old college texts and marvel at what I once knew. Or thought I did.
 

March Audio

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Sorry if this sounds terse, long week.

Unless it is suspended in space or in an anechoic chamber you do not start out in 4pi space; the floor is already there. Thus the gain is 3 dB with one wall, 6 dB in a corner. Maybe I misunderstood your original response, sorry.
Of course :) Real rooms/installations cant start from a free field position.
 
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Music1969

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Hi all

Which digital room EQ software or hardware can work their magic with 4 subwoofers, each sub independently? Both frequency and time domain response room EQ.

I know of solutions that can work with 2 subs independently, but which can do 4 subs independently?
 
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