Yawn, just a rendering of the new RT-12d subwoofer:

[Remotia]

im just wondering how much bass extension will suffer when the internal volume is reduced. Obviously the amp is bigger to problem compensate.

[DrWho]

Sometimes corner placement isn't practical or optimal. I was just wondering if the 3 sided configuration would work well against a wall.

Placement away from a corner will have no significant impact on the sound (apart from the sub being unable to take advantage of the loading advantages). If anything, corner placement would be detrimental just like all the other rear passive speakers - but the equilateral triangle shape and chopped off corners naturally provide the space needed for the passive radiators to "breathe" , even when shoved back as far as possible.

For a system with the same frequency response, a reduction in cabinet size requires a change in the driver, which in turn lowers the efficiency of the system...but with a better motor that can dissipate heat faster, more power can be sent to the driver and the same xmax achieved, which means the same SPL's can be achieved in the smaller cabinet and the only expense is more heat. There is one advantage to smaller subs and that is a reduction in group delay. And as long as the voice coil and amplifier are being operated in linear ranges, there will be no increase in THD, or FMD for the same diameter driver. There will however be a greater magnitude of power compression with the less efficient system - electrical/heat compression tends to boost the lower frequencies, whereas the mechanical compression tends to lower them. In a well calibrated system the two will counter each other (dunno if it's reasonable to assume intentionally achieving this, but them engineers at klipsch are really creative with these things).

Nevertheless, there is definetly more bang for the buck and overall performance potential with a larger cabinet, but that also means a decrease in the WAF - so yet another tradeoff that must be considered. I very much like the idea of a triangle sub put into a corner because it naturally takes up much less usable floor space. (same reason the khorn seems to have a smaller footprint than the lascala).

[Freak Nasty]

Hey guys check out the Flash Video of the New Klipsch RT 12d at the CES06, they look sweeeeeeet.... i heard they have remote toooooo!!!

http://www.cnet.com/4831-11405_1-6413124.html

[Freak Nasty]

And the black one....

the black look super sweeeet too..

[CAS]

Hmmm...

Not really a fan of how they look with the grills on. Kind of like a spinning CD rack. But the display and the potentional sound looks to perhaps dampen the feelings on their asthetics. The 5 presets feature kind of gave me a little tingle.

[TheEAR]

Looks like I can post again on this site,about time some nasty bugs were fixed.

[Remotia]

Here is the woofer on that new klipsch sub

[TheEAR]

Looking great! This woofer looks like a serious workhorse.Klipsch is a real force in sub bass,first the RSW's,the THX subs,the budget Sub10 and 12 and now these new beasts! Great work Klipsch,great work.

I have a very nasty feeling I will get both top O the line Klipsch subs []

[DrWho]

Wow, those really are beasts....just imagine those motors on a 15" driver! [H]

[Jay481985]

that looks atleast 30 pounds [] wow! now where can I order an oem woofer? []

Though I wonder why they put a grill around the basket? wouldn't that cause turbulance and noise when the woofer is pushing it?

[Freak Nasty]

Does it mean that we can't change the Eq setting of this sub?? "5 preset eq" settings.. , i don't like the grill too much too... but i think i will be getting one as soon as a 240 version comes to Australia.... oh yeah.. a cherry one 12"

[formica]

No idea if a 15" is in the

works. I am going to say for the Reference line, no, just the 10

and 12-inch.

That would be my interpretation of the press release as well... which I

think is unfortunate. Although 15" subs do not represent the bulk

of sales, they do represent the bulk of talk. You have to first

get the buyers into the store, before finding what compromises best

suits their needs.

I am happy to see them use more displacement on the passive radiators

than the main driver... as it has always puzzled me why the original

RSW's PR seem to have the same diameter and excursion as the woofer

itself even though it is expected to dig deeper.

ROb

[Scp53]

I am happy to see them use more displacement on the passive radiators

than the main driver... as it has always puzzled me why the original

RSW's PR seem to have the same diameter and excursion as the woofer

itself even though it is expected to dig deeper.

ROb

I agree with that. Usually, when a sub uses passives, they are much

higher excursion and even larger in diameter(either/or). I see many

subs built(Im a DIYer) that use a pair of 10's or 12's as passives or a

big 15in passive and the woofer it self may only be a 10incher.

THis time though, I think Klipsch did it much better/right. With dual

passives, Im sure its able to go much lower w/o having excursion

problems. Thats probably why the rsw's were tuned so "high" - they had

a smaller cabinet(relatively speaking) and had a SINGLE passive that

was 'average" excursion(or so I think)...

scp53

[DrWho]

or maybe they're using more advanced "processing tricks" that require more excursion from the passives than previous versions...(think about it, at the tuning frequency the active driver is barely moving at all - so the only limit on SPL at that frequency is the power handling). One of the EQ's I just stumbled upon lately allows one of my designs to reduce the cabinet volume from 10 to 6 cubic feet to achieve the same slope and maxSPL - it just requires a ton more amplifier power. What I'm trying to get at is the old PR sub designs had sufficient PR abilities to keep up with the old active drivers. But with a new better active driver, they now need better PR's (or even simpler, just double up on them).

Anyways, I can see why they have preset EQ curves - any EQ being implemented changes the control over cone-excursion. So they are probably making sure that every preset mode has the same level of protection. There should still be control over phase and volume...at least I would hope so!

[Tom Adams]

Is it just me or is the current trend to stay with 12" (or 14" in the case of the Def Tech Reference) drivers with more excursion and bigger amps? I mean, there's not many new designs using 15's and 18's. Are we seeing subs going the way of the loudspeaker in regards to shrinking the cabinet to make them more pleasing yet still deliver "the goods"? Just wondering.

Tom

[DrWho]

For the same motor you can get more performance per cabinet volume out of a 12" driver than you can a 15" driver (ie, RSW-15 versus Ultra2 sub).

So really the goal here is to shrink the cabinet size without sacrificing performance - though it should be said that if cabinet size weren't an issue, then a larger 15" sub will without a doubt outperform a 12" sub. But if you're going for this end all be all performance, then you might as well just go with an Infinite Baffle sub (as no other enclosure will ever come close to touching it - even hornloaded subs).

[kenratboy]

Why do IB subs work so well, what are the physics behind it?

[DrWho]

To understand why an IB is so effective, we must first understand the entire reason that a subwoofer must be enclosed inside a cabinet of some kind.

When the cone on the driver moves forward, it creates a positive pressure in front, but also creates a negative pressure behind it. The result is a front wave that is out of phase with the rear wave. And because the wavelengths are so long, they will effectively cancel each other out. To see this in action, try playing a subwoofer outside of a cabinet - you will see the cone moving insane distances but the sound won't be that loud...now drop it into a cabinet and it instantly becomes very very loud.

So to prevent this cancellation from occuring, a baffle of some sort needs to be created so as to seperate the two out of phase signals. In theory world you could think of an IB as being an infinitely large plane with the driver mounted in the middle. The rear wave would have to travel all the way around this baffle and then back in order to cancel out with the front wave (ignoring time-delay issues for them moment).

One cool thing when looking at open baffle designs is that the baffle only needs to be 1/4 wavelength in radius...so a driver mounted on a 3 foot radius circle will actually exhibit a boost around 80Hz because the rear wave has to travel a distance of 1/2 wavelength, which effectively reverses it's phase and causes a summing situation at 80Hz. But half an octave down (like around 60Hz) you will have cancellation again, which will be noticed as a steeper rolloff. At frequencies above 80Hz you won't really notice any changes.

Then along came the idea of enclosing the space behind the driver - which is effectively an infinite baffle design, but now you have air pressure issues that exist behind the driver that don't exist in front of the driver. The end result here is a rolling off of the frequency response. You also are wasting all the energy from the rear wave of the driver (which is basically turning into heat).

Then the idea of ports came along which is just a controlled resonance that reverses the phase of the rear wave of the woofer (again, the idea hear is to turn the rear wave into useful output). But as you go below the tuning point of the port, this rear wave goes back to being out of phase with the front wave and that is why you see a faster roll off on ported subs.

So getting back to the IB design...the idea is that the driver sees no trapped air behind it and therefore the 'enclosure' has no effect on the response of the system. You can then design the subwoofer to go as low as you want - the only limitations being power-handling and cone-excursion.

The reason we don't go to a fixed baffle radius to freely boost the low end is due to the fact that the radius needed introduces a huge delay in the signal - to the point that there is no benefit anymore (because it arrives so late...this is why lowther rear horn loaded drives don't seem to have very punchy bass, even though they measure fine with pinknoise).

I hope that helps - it's kinda hard to shrink all of enclosure theory into a short easy to understand snippet. There are lots of articles online that talk about all this and explain all the different variables to a greater extent. But the key idea to walk away with is "what do we do with the rear wave of the woofer?"

[formica]

Is it just me or is the current trend to stay

with 12" (or 14" in the case of the Def Tech Reference) drivers with

more excursion and bigger amps? I mean, there's not many new

designs using 15's and 18's.

That seems to be the trend... high WAF. The supercubes must be selling well...

For the same motor you can get more performance per

cabinet volume out of a 12" driver than you can a 15" driver (ie,

RSW-15 versus Ultra2 sub)

Not sure I'm following you on that one... are we talking same motor or enclosure?

Why do IB subs work so well, what are the physics behind it?

Or to summarize what mike said.... An IB is simply a sealed subwoofer with an infinitely large enclosure.

Based on the enclosure-size / bass-extension / efficiency relationship

by maximizing the enclosure... you will maximize both efficiency

and bass extension. It's a no compromise application of the

physics that applies to all subwoofers.

ROb

[DrWho]

For the same motor you can get more performance per cabinet volume out of a 12" driver than you can a 15" driver (ie, RSW-15 versus Ultra2 sub)

Not sure I'm following you on that one... are we talking same motor or enclosure?

same motor - and I should have mentioned the increase in performance is deeper LF extension (or more SPL) in a smaller cabinet. The 15" driver in a larger cabinet will still outperform the 12" driver, but if you were to take the least common denominator cabinet volume, then you'd find better performance from the 12" driver (again, when using the same motor).

In the case of the RSW-15 versus the KW-120; they both have nearly the same frequency response, but a single KW can go 3dB louder than a single RSW. The KW also digs quite a bit lower too. AND the KW is in a smaller cabinet (about 3/4 the size of the RSW).