Better for music: Sealed with Linkwitz Transform or Vented?

[jaistanley]

Hi guys.

I have just purchased two SB acoustics 10" (SB29NRX75-6)drivers on ebay for a very good price.

I intend to use these in medium-large boxes for my sealed stand-mounters to stand on; a three way active system using MiniDSP 2x8's for cross-overs. Think of the Tarkus and the Troels Gravesen Jensen 1071 as my inspiration.

I will use these for 90% music, and play my TV/Movies throught them too. Therefore I want to get the best possible sound for music.

My DSP can perform any parametric equalising, and linkwitz transform that I like. My question is: Will the vented alignment or the Linkwitz Transform sound better for music?

I notice that in WinISD these drivers model best for sealed and vented in more or less the same sized enclosure for each. I quite like the idea of having a removable port that I can seal up to try either.

Do you have any suggestions or input?

Kind regards,

Jai Stanley

[revboden]

I like to design boxes so that they have a Qtc =.55 sealed and dual port them. one port open = ~14Hz, two ports open =18Hz~ a hybrid is easy enough to design and you get the best of both worlds.

which would sound better for music... depends on the music, and the person, and the room, and the wife, etc. etc. etc.

[bbggg]

jainstanley, your question can be translated into: no time smearing with the risk of increased harmonic distortion, or time smearing with less harmonic distortion? The right answer varies with circumstance: how big a room you have to cover, what max levels you require, etc.

[revboden]

well.. i just designed the WIWD, 3ft^3 box two 3" (7.6cm) ports, 30" (76cm) long. 75w per, high-pass at 18Hz, no LT the driver doesn't have enough Xmax

[dirkwright]

I think also the question should be: which has the better transient response? I have no idea myself.

[sreten]

Hi,

Vented has more low end max SPL, I've never seen a driver where good
sealed and vented alignments require the same box volume. Bottom line
is vented ups max SPL at port frequency by +6db, but requires a sub
filter below that to prevent overexcursion overload.

IF sealed LT is loud enough, its by far the best option SQ wise.

rgds, sreten.

[rob g]

No one expects the bass quality and depth from the tiny Linkwitz Pluto when they first hear it. All down to sealed enclosure loading and Linkwitz transform. With a decent long throw motor system the quality can he highly impressive.

I would go with Sreten's suggestion unless it is for non stop bangin' techno or metal at really high volumes in which case you could be safer with a standard ported system.

[sreten]

Hi, The Pluto does not use an LT, its subwoofer does, rgds, sreten.

[rob g]

Originally Posted by sreten

Hi, The Pluto does not use an LT, its subwoofer does, rgds, sreten.

Hi Sreten,

I use the later Pluto 2.1 with LT.

Also from the Pluto 2 article, a page detailing the upgrade from Pluto 1 with Peeless driver to the newer Seas unit and detailing the LT circuit change.
Pluto-2 omni-directional loudspeaker

From that page:
"Pluto-2 is a small 2-way loudspeaker system that brings a number of practical refinements to the original PLUTO design and construction. A key component is the Seas L16RN-SL (H1480-08) midrange/woofer driver. It allowed to extend the loudspeaker's frequency response down to 40 Hz, -3 dB because of its greater excursion capability before unacceptable distortion. Pluto-2 is thus to me a full-range speaker for a wide range of program material. It should be optimal for people with small spaces or low budgets and who want accurate sound reproduction."

[bbggg]

Originally Posted by dirkwright

I think also the question should be: which has the better transient response? I have no idea myself.

Transient response is defined by onset and decay.
Group delay defines how late the onset of sound emission is. Here vented has lots more, roughly double.
There is also the box/vent resonance decay, ie how long it takes for this component of sound emission to cease. This takes a while because air is both elastic and not too lossy. Therefore vented boxes take variable amounts of time to round up their sound emission, sometimes very long ones, depending on particulars. Closed box, LT'd or not, has none of this because there is no vent air mass to resonate.
So vented can not match closed box for time performance. At best it can hope to approach it. At worst, vented can moan, drone, huff and puff like a leaky bagpipe that's got the sniffles.
It all boils down to the nature of resonating systems. A resonance takes time to build up and time to die down. A closed box has one such resonant system. A vented box has two, and staggered ones at that, with the second one consisting entirely of air (air mass, air compliance, air friction).