Should K-48's be used in a DIY sub?

[Mr Tech]

I have 2 brand new 15

Klipsch K-48 woofers that I understand were commonly used in the Chorus II line.

Does anybody know if these would be good as subwoofer

drivers?

Im considering using them in a DIY subwoofer project, but

not sure if that would be a good idea for these.

Also Im not sure where I

would get the remaining components if I did pursue the project.

Any ideas or suggestions would be appreciated.

If I dont pursue the sub project, I will probably sell them

on ebay unless someone here is interested in them.

[DrWho]

It depends on how low you want the "sub" to go. The K-48 would make a good subwoofer driver in the pro audio world where you don't really need to go below 40Hz. But in the home you would probably want to go lower. While you could certainly design an extended bass shelf that might make it out to ~20Hz in a large cabinet, it's not going to play very loud before it starts distorting. You would also need some EQ to bring down the top-end of the passband.

I dunno how much the drivers are worth on the used market, but I'm pretty confident you could achieve better performance with different drivers that are worth the same amount.

What are you running for mains?

[Mr Tech]

Thanks for the info DrWho. I had a feeling you would respond to this.

I was thinking pretty much the same thing, that they wouldn't be the best choice in the world for a sub.

I have Khorn mains, cornwall surrounds & a rsw-12 sub. I don't need another sub, the rsw-12 does fine, I just had the k-48's & was trying to figure out what to do with them.

I guess I will probably just sell them instead.

Do you have a recommendation for a center channel speaker?

I would like to stick with all heritage, but am limited on space.

I was thinking of maybe hanging a heresy from the ceiling, any thoughts?

[djk]

"The K-48 would make a good subwoofer driver in the pro audio world where you don't really need to go below 40Hz."

Should kick butt in a tapped horn, go to 25hz, be around 100dB/W.

[Daddy Dee]

tapped horn? I don't quite grasp this, did a google search found a white paper by Danley on this.

http://www.danleysoundlabs.com/pdf/danley_tapped.pdf

Dr. Who, did your tapped horn project resemble this on the interior of the cab?

Most interesting.

[djk]

Here is a similar driver:

[djk]

0.5Pi is in the corner, and at 28.3V (100W) input power. Subtract 20dB for 1W, and another 6dB for out of the corner but up against the wall.

Call it 108dB/1W in the corner, 102dB along the wall. -4dB around 20hz in the corner. About 2'x2' footprint, about 7-1/2' tall.

Here is a similar project for a 12"

http://www.diyaudio.com/forums/attachment.php?s=4b69db6446db246ebbb8e6a83ca5968b&postid=1293223&stamp=1188823926

http://www.diyaudio.com/forums/attachment.php?s=4b69db6446db246ebbb8e6a83ca5968b&postid=1293223&stamp=1188823926

Post #574 Yello!

I have finnished my prototype tapped horn and I was surprised that it really works. I built it from scrap pieces from old projects and the driver, Precision Devices 12SB30 was really cheap. This project is a steal.

The horn is 25Hz (3,44m) version, WxHxD dimensions are 366x1914x388 (mm). I ran some test tones in the garage and everything was resonating during sweep from 10Hz - 100Hz (driver cone barely moved at all). My XO is ancient 120Hz low-pass 12dB I think. But more listening impressions when I get it to my AV-reciever with proper XO's and some hollywood effects.

I have played with different subwoofer builds for many years and at last I can say that this thing is scaring the jeepers out of me...

[Daddy Dee]

djk,

Now that is one cool sub. "scary good" is an excellent reference.

[DrWho]

Yes, the tapped horn I built is working on the same concepts. I was

very surprised how well the performance correlated to the predictions

in Hornresp.

That said, there is a fundamental limitation in these designs.

The goal of the tapped horn is to get away with an undersized mouth.

The problem with an undersized mouth is that your output is going to be

limited by the same air velocity limitations often associated with the

chuffing of ports. As you make the mouth smaller, the air needs to move

faster in order to achieve the same volume displacement to achieve the

same SPL. Increasing air velocity ultimately increases distortion and

introduces power compression. So while you're reducing the amount of

cone-excursion required for the same SPL, you're introducing new types

of distortion in the process.

All that to say, you need to make sure the mouth of the tapped horn

isn't too small. You also need to make sure the air velocity thoughout

the entire length of the horn is kept low too. The problem with this is that the length of

the horn is determined by the low frequency cutoff that you want to

have. And then in order to keep the air velocity from being an issue,

you need to ensure a proper cross-sectional area of the horn

throughought that entire path length....when you make the mouth larger

to reduce the air velocity, you're also increasing the area at every

point in the horn before the mouth as well - so the cabinets end up

getting huge.

As far as the tapped horn I built...I didn't feel that it had any less

distortion at the same SPL as compared to my bass-reflex cabinets. However, it did go 10dB louder with the same

drivers and pretty much the same frequency response. Loud is cool, but I prefer lower distortion first.

[djk]

You want low distortion? Push-Pull Slot-Loaded (PPSL), with a pair of inexpensive Eminence 15s I can get over 100dB/2.83V/1M in 2Pi with response to below 25hz. I use a small version of these for PA with a 31hz cut-off (low B on a 5-string bass).

[BobSW99]

Do you still have them? You want to sell one or both?