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View Full Version : Newbee needs ideas for subwoofer 5-25hz



Loffen
02-16-2008, 02:22 PM
Hei

I am running a 7.2 setup with K2 S9800 in front with a Array 880 center and two Tik subs, the rear speakers are for the moment Ti10k and Ti6k.
I have a second set of K2 S9800 on hand but the seller will not part with them until he receives the new speakers he have bought.

Anyways I want to build a subwoofer that will go from about 25hz and down.

I have no idea of what I need but I would like to use JBL drivers if possible.

The room size is 11x6.5x2,4 meters.

Thanks in advance

Espen

speakerdave
02-16-2008, 03:13 PM
I haven't done this, but here is an idea you might find interesting:

http://sound.westhost.com/project48.htm

The idea is to use a woofer below its in-box resonance frequency in a sealed box, so that the roll off and load impedance are predictable. Compensation and substantial amplification will be needed. Rod Elliott (at above website) designs in 12 dB/ octave, the theoretical roll off below resonance of sealed systems. A few years ago one of our members experimented with this idea and found that with room rise he did not feel compensation was necessary. That, however, would depend on the room.

The woofer needed for this must have a powerful motor, rugged cone, high native resonance, great power handling ability, and good excursion. Our guy used the 18" JBL 2242 in less than 2 cu. ft. stuffed with fiberglas and reported good results. You could probably calculate how many of these you would need to keep up with your system, but I would guess four at least.

The alternative would be a like number of woofers similar to the no-longer-available sub1500. I know that JBL made a successor to that, the W1500 (I think) but I'm not sure of availability.

David

Loffen
02-17-2008, 09:05 AM
Thanks David

Actually your link does describe the Tik sub,well not far from it anyway.
It has a small closed enclosure,the Sub1500 and a 600w amp.

But it could be fun to try to build one,it shoud not be to expencive either.

As the setup is now the LFE has its peak at 119db between 30-35hz

And I could of course try to get a couple Tik subs,but I am not sure if that would give me what I want ?

Any other solutions out there ?

Hoerninger
02-17-2008, 09:12 AM
A horn?
http://audioheritage.org/vbulletin/showthread.php?t=14848&highlight=mcbean
__________
Peter

John W
02-17-2008, 09:13 AM
This is the only thing I've heard of that goes that low.

http://www.rotarywoofer.com/

Mr. Widget
02-17-2008, 12:14 PM
This is the only thing I've heard of that goes that low.

http://www.rotarywoofer.com/It does... and after their demo I felt ill for about a day. High SPLs below 20Hz are impressive but not really all that necessary.

I have quite a lot of experience with the JBL Sub1500. In a 5 cu ft box tuned to 20Hz it will produce awesome deep bass down to 20Hz at high SPLs if you have a large enough amp. I used 600wpc on a pair of them. If you get below 20Hz at high SPLs the cabinet unloads and the woofers crash violently with the VCs hitting the back plate and/or the VCs rubbing... both are bad.

Using the Sub1500s in small sealed boxes as in the TiK sub, they will play quite low but the signal feeding them will need extensive EQ. I assume you have a large room if you are considering multi channel K2-S9800s. In a large room I would want at least 4 TiKs possibly more if you are after high SPLs. For the equalization of them I'd highly recommend the Velodyne SMS-1. I have used it with the Sub1500 in small sealed enclosures and the results were outstanding. I am not certain that there is enough ULF gain to get you down to 10Hz though.


Widget