Aurasound NS15 reference subwoofers, ported or sealed?

[thadman]

I'm compiling a reference system (sound quality, spl) involving the RAAL 140-15D ribbon tweeter, AE TD6.5M, and AE TD15M. They will need to be augmented by subwoofers on the bottom end to ease excursion demands on the midbass.

I purchased four Aurasound NS15s a while back and plan on taking advantage of their capabilities :B They will be used for Music, Video Games, and Movies...they will really have to assume the role of Jack of all trades.

Output goals:
bass: 130dB transient, 120dB continuous. I do not want to fear blowing these drivers.
full-range: 120dB transient, 110dB continuous

Crossover:
LPF 80hz
HPF 20hz

Room: Medium

Any recommendations? Remember this is a reference system and they will have to keep up all the way down to 20hz with a TD15M crossed at 80hz.

[thadman]

I've decided on experimenting with the Geddes model for LF. I'm familiar with the theory behind the Geddes model, use as many sources as possible to more evenly disperse the LF energy in a way that positively excites the modal resonances within the room. But not the details of the model, where to place the subwoofers (Harmon Kardon recommends placing one at the center of each wall)...the desired rolloff...the desired level of each driver...etc I've done research and haven't been able to find the answers to these questions. The thinking assumed for mid to high frequency drivers (placing drivers within 1/4WL to avoid power response aberrations related to phase, although not always achievable this would be optimal) does not necessarily apply to LF drivers as waves behave very differently in the modal region than they do higher in the spectrum where sound behaves closer to the ray model. Could anybody offer any insight into this?

[thadman]

Some thoughts. placing subwoofers near the positions of the nodes of the axial modes (no excitement for that particular mode) would be easy to predict, but the tangential modes would be much more difficult and would require a very dense grid of subwoofers. The larger subwoofers designed for the lowest frequency would intuitively be placed at the positions of the lowest nodes and would gradually rolloff higher in frequency. The lower displacement drivers (ie visually less obtrusive) would be located at higher frequency nodes and would gradually rolloff below the point where the node functions.

[alias2]

The harmon kardon paper needs careful analysis, it is mostly misunderstood.
The purpose is the most similar response for different positions, to be Eq'd.
The purpose is not the flattest unEq'd response, so do not follow it.
e.g. for 2 subs ~ 1/3 along each wall is a good starting point.

[Rick Craig]

I'm compiling a reference system (sound quality, spl) involving the RAAL 140-15D ribbon tweeter, AE TD6.5M, and AE TD15M. They will need to be augmented by subwoofers on the bottom end to ease excursion demands on the midbass.

I purchased four Aurasound NS15s a while back and plan on taking advantage of their capabilities :B They will be used for Music, Video Games, and Movies...they will really have to assume the role of Jack of all trades.

Output goals:
bass: 130dB transient, 120dB continuous. I do not want to fear blowing these drivers.
full-range: 120dB transient, 110dB continuous

Crossover:
LPF 80hz
HPF 20hz

Room: Medium

Any recommendations? Remember this is a reference system and they will have to keep up all the way down to 20hz with a TD15M crossed at 80hz.

Sorry - late reply but maybe I can help. I used the Aura 15" in a sealed cabinet with equalization from a plate amp. It was quite impressive.

[Martijn_H]

I am working on a similair subdesign. I'll be using 4 SDX15 woofers in 65l closed subs. in comb. with IIR filtering.

I hope to achieve good bass respons through the room and as little as possible eq'd respons at the listening space.

As most rooms don't look like the testroom of harman, the gedlee approach seems to me the way to first try it. http://www.mehlau.net/audio/multisub_geddes/

placing one sub high away from the floor where the other subs stand is also a thing to keep in mind during testing.

(http://www.diyaudio.com/forums/showt...&pagenumber=17)