The upper frequency limit is determined by the distance between the speakers. Large rooms will require more speakers to keep that distance low enough.
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The first sentence makes sense. The second one thou? How does adding more speakers solve the distance problem?
The speakers make no difference. Only the frequency and the distance.
This is the same issue as with higher frequencies in an isobarik. The size of the room )(distance between drivers) determines the HF limit of such an array.
dave
The speakers make no difference. Only the frequency and the distance.
This is the same issue as with higher frequencies in an isobarik. The size of the room )(distance between drivers) determines the HF limit of such an array.
dave
It's explained quite clearly in the Wikipedia article.
https://en.wikipedia.org/wiki/Double_bass_array#Array_layout
https://en.wikipedia.org/wiki/Double_bass_array#Array_layout
Yep:
"Interference of the subwoofers and mirror sources create a plane wave up to a certain frequency.”
Exactly what i was implying. The certain frequency his directly related to the distance.
f=c/2d
c: Speed of sound
d: Distance between subwoofers
dave
"Interference of the subwoofers and mirror sources create a plane wave up to a certain frequency.”
Exactly what i was implying. The certain frequency his directly related to the distance.
f=c/2d
c: Speed of sound
d: Distance between subwoofers
dave
How do more speakers n=make the distance different?
To do that you have to make the room smaller. My room would be good to about 23 Hz no matter how many woofers i put in.
dave
To do that you have to make the room smaller. My room would be good to about 23 Hz no matter how many woofers i put in.
dave
I disagree. To completely cancel the bass the room determines the LF.
And as we know from Toole, for drivers on the same baffle to act as a single unit the drivers need to be within a quarter wavelength of each other.
But then it does not do this
It claims:
Sound pressure level throughout the room is very even.
Modal resonances are reduced to a minimum.
If you actively absorb from one wall, the minimum should be zero. No bass.
This is simply math juggling (IMO) to do a poor job of what Toole and Geddes are advocating.
dave
And as we know from Toole, for drivers on the same baffle to act as a single unit the drivers need to be within a quarter wavelength of each other.
But then it does not do this
It claims:
Sound pressure level throughout the room is very even.
Modal resonances are reduced to a minimum.
If you actively absorb from one wall, the minimum should be zero. No bass.
This is simply math juggling (IMO) to do a poor job of what Toole and Geddes are advocating.
dave
There has been a misunderstanding. When StigErik said the rear wall array has to play in reverse phase, it also has to be delayed from the front wall.
The mention of the distance between speakers is a different issue, referring to the close spacing of the speakers on each single wall, which affects the upper frequency limit of the array.
The mention of the distance between speakers is a different issue, referring to the close spacing of the speakers on each single wall, which affects the upper frequency limit of the array.
Yes, the DBA appears to be a specific subset of the multi-sub approach. The way that it is normally done is like comparing a Rubik's Cube both finished and mixed up, but in both cases it is a complete unit.
So DSP removes the room length.
Bit more drivers won’t push frequency up, d dhould be the centre-to-centre of the furthest apart drivers.
dave
Yes. The delay due to the room length distance is distinct from the array driver spacing distance. Driver spacing limits the ability to produce a room width plane wave at higher frequencies.
I'd love to have such a dedicated room but alas this isn't possible in my current home. Here I have to hide all speakers in plain sight in an L shaped room with doors, windows and furniture. Luckily my wife is very understanding and I'm allowed to have large speakers and subs (4x 21" behind the seat and 4x 15" against the front wall). I pre-measured them in REW and by playing with the levels of all Crowm XLS amps I get a response with manageable room modes at the MLP. The AVR room correction then filters away the largest room modes and I'm fairly happy with the overall result. It doesn't offer the most linear bass but it digs deep and has decent dynamic reserve for loud movies and 2-channel playback.
Nice to see you use the 2000AS/2. The older 1200AS/2 powers my L+R speakers.
The REW room sim does not support a sloped ceiling like I have, or as many as 24 sources. I have run a simulation in a very advanced software build by a friend of mine in Comsol. The simulations were a bit off compared to the actual results. I guess there are more variables than those simulations could account for.
Meant simulating how this principle work in theory - I have found that it works great for multisub. Though i also have one sloped ceiling, it is close predicting the response.
Can’t remember how many subs REW can simulated. Think it is 6 or 8 - which according to the wiki is plenty to get a grasp what is going on.
Can’t remember how many subs REW can simulated. Think it is 6 or 8 - which according to the wiki is plenty to get a grasp what is going on.
Here's a few more measurements. I just discovered that there were errors on previous measurements I've shown, so please disregard those.
These are done without any EQ what so ever, but with the correct delay and level on the rear array. No smoothing.
The theoretical upper frequency limit of my DBA is 136 Hz, determined by the speaker to speaker distance in the horizontal plane. And as you can see on the measurements above, the frequency response really goes wild above the upper limit, with large and narrow peaks and dips. Below, the response is a lot smoother.
These are done without any EQ what so ever, but with the correct delay and level on the rear array. No smoothing.
The theoretical upper frequency limit of my DBA is 136 Hz, determined by the speaker to speaker distance in the horizontal plane. And as you can see on the measurements above, the frequency response really goes wild above the upper limit, with large and narrow peaks and dips. Below, the response is a lot smoother.
No it should be frequency independent as the 'anti' bass is played with the exact delay of sound traveling from one side to the other.
At some higher frequency it will not work anymore if the spacing between the subs is to large for wavelength played