Trey: Klipsch cinema sub at home - would it be workable?

[kenratboy]

For example, the KPT-684 looks like it can be had for $1,300

online. If you paired that with the proper EQ and amplifier, what

would it do in a large HT room? I know the 'rated' responce is

one thing, but I have heard of people getting into the low 20's with

some of the JBL Pro 18" deals, which are rated well above 30-40 Hz.

Would it just be a big, distorted mess, or could you have earth-shaking

bass if you used a EQ and set things up right? Obviously, with

the sub, EQ, and amp, you are talking about somewhere around $3,000,

and $3,000 gets a LOT of sub.

At one point, you said you used some pro gear at home, what would that be?

Thanks!

[DrWho]

The JBL 18" cinema bins usually have an F3 around 30Hz and a -10dB point around 20Hz measured in quarter space. When installed in a corner you can expect a 3dB boost in the low end and then with room gain you're looking at the speaker naturally being flat to around 20Hz. Though for many reasons I don't think relying on room gain sounds as natural as having a flat anechoic response (because the instrument on the recording would benefit from the same room gain if it were in your room, which requires you to have a flat anechoic response).

But the power handling is enough that you can reduce the max SPL and use EQ to extend the F3 down to 22Hz (in quarter space). So in 1/8th space (a corner) you're looking at easily achieving a flat response down to 22Hz @ 120dB continuous.

Anyways, specs aside I've never felt that any of these subs sound as good as comparable in price HT subs (even if the HT subs have less raw output). It has to do with how the different drivers distort - and the surface area on an 18" driver really magnifies other areas we don't normally think about (like how the cone bends and transmits waves in all sorts of directions).

For $1300 you could really build a very killer DIY subwoofer - especially if you can accept an 8 cubic foot cabinet volume.

Anyways, to answer your question...yes it would definetly be workable. I would argue that it's not the best bang for the buck, but who knows...maybe you like the sound of those drivers.

[Jay L]

i am using a kpt-884 with a crown amp, no eq. works great, i like it very much.

[kenratboy]

Any idea what sort of in room responce you are getting?

[Scp53]

The JBL 18" cinema bins usually have an F3 around 30Hz and a -10dB point around 20Hz measured in quarter space. When installed in a corner you can expect a 3dB boost in the low end and then with room gain you're looking at the speaker naturally being flat to around 20Hz. Though for many reasons I don't think relying on room gain sounds as natural as having a flat anechoic response (because the instrument on the recording would benefit from the same room gain if it were in your room, which requires you to have a flat anechoic response).

But the power handling is enough that you can reduce the max SPL and use EQ to extend the F3 down to 22Hz (in quarter space). So in 1/8th space (a corner) you're looking at easily achieving a flat response down to 22Hz @ 120dB continuous.

DrWho, do you really think they have enough excursion to do 120dB at 20hz? IMHO, fIguring the tuning is at 30-35, those woofers should be going crazy(bottoming) when near its max power. As with any ported subwoofer, not much under tuning and the (mechanical) power handling of the sub drops like a rock. Thats why Im wondering... scp53

[kenratboy]

I know the 18" JBL cinema bass bins are designed specifically to be

EQed and useful down to 22 Hz (-3db.) in a movie theater - where they

will obviously have the snot beaten out of them for years and still

work.

[DrWho]

most 18" cinema subs I've come across are tuned around 25Hz. I quoted the JBL subs because in my experience klipsch has similar performing products (as far as specs on paper). I have always felt the klipsch bass was far superior to that of JBL...when operating in linear regions. The JBL subs can be thrown outta the gap and not sound too horrid, whereas the klipsch subs will "buzz" when overdriven. I never got to do a side by side comparison so perhaps different amplifiers might be a factor too.

My "measly" 15" JBL driver does 110dB @ 20Hz in the cabinet it's in right now. (it's tuned to 16Hz, but the driver has an Fs of 30Hz or something like that). No, I don't think it sounds that good, lol.

The reason they are so durable is because their mechanical excursion far far exceeds the motors linear range...and on top of it they have great power handling capability. So basically you can never melt them and you can never throw/smash a voice coil. Usually the first thing to go is the speaker diaphragm itself!

[kenratboy]

So, what are you really trying to say?

[DrWho]

Klipsch subs sound better than JBL subs, but clipping JBL subs sound better than clipping klipsch subs.

[kenratboy]

Oh, OK!

So, in your opinion, is there really any place in a home theater for a

pro sub? I mean, how and why is a 15" Dayton Titanic driver

different than a 15" pro driver (like a JBL 2226/7)?

[DrWho]

The home drivers have more linear excursion and can fit into a much smaller cabinet. Sure there is a loss in efficiency, but amplifier power is cheap and the limitation on output usually comes down to excursion and not power handling. And since all 15" drivers need to move the same distance to achieve the same SPL, there really isn't a change in distortion for the same SPL (assuming linear operation of all speakers in question)

4mm linear xmax (PA) is a lot different than 1" linear xmax (HT).

[Jay L]

Any idea what sort of in room responce you are getting?

no, but i'm workin on getting that.

[TheSoundBroker]

One other thing to keep in mind is the match to your mains. Putting a big Cinema sub with, say, a set of KL-525's as LCR's isn' t going to be the best match (the Ultra 2 subs are squeaky clean up higher and thus ARE a good match!). The big Cinema subs are designed to match with the bigger screen monitors which are usually strong down to 50hz and have a ton of output in the power range (50 to 200hz) meaning you can roll the big subs off pretty strongly and avoid a ton of output up higher.

At $3.5K, you could also consider a Danley DTS-20 with an amp and a BFD which will very much outperform the big Cinema subs without having to go thru as much rigamarole. It is an industrial sub that is very much suitable for the home and doesn't need gods own amp to run. Granted, it is 84" tall...but only 20" on a side. If you can fit one of the big Klipsch Pro Cinema subs, you can probably fit a DTS-20. Assuming your room supports it, you'd get flat response down near the teens and more output than you could humanly use without serious structural modifications (125db at 20hz). It is also flatter in response up higher.