You know J,   John had some good points about using the proper equipment for it's intended purpose, which I havn't. But you may have a good point there about maxing it out on such a low setting. I've played with receiver bass vs. amp setting, but will play with that again. Both before and after removing top driver. Two good 'points of reference' when it klops the worst, #1 Finding Nemo, when little girl is banging on aquarium, and #2 Star Wars III opening sequence with two fighters flying between larger ships. That opening sequence has two good lenthy LFE points that the HWK HATES! Basically any changes I make to the system, those are my reference points I check back with. Don't like "mid movie surprises" when I'm lost in another world, everything is great, and the F---ER starts bangin' again!  >:( I can feel my blood boil.

Still open to suggestions on different DIY enclosure. Anybody wanna buy a HWK? Actually, I may step up and give it away if a replacement is found. (60ndown, your my hero) NO SHIPPING INCLUDED, I'm not that much of a man. $$$$$$$$

Bob

p.s. This happened on the same settings with 2 different Legion amps

Bob,

It's not the amp.  It's not the drivers.  It's the alignment, which on the low end is tuned somewhere in the mid 30's.

Your problem will come into play with virtually any vented design, whether it's BR, horn, or in the case of the HWK, bandpass.  That is your driver will go into over-excursion with very little power when you play frequencies below tuning.  In finding Nemo, you get a very strong signal down in the low teens and you're going to damage your drivers trying to play that with a normal HWK.

In all likelihood you have enough horsepower to get what you want with those 2 15" drivers.  With my pair of Tempests, which are comparable to your Daytons, Dan Wiggins of Adire Audio recommended to me a 6th order bandpass box (that's what a HWK is btw), but with much larger dimensions.  The dimensions were 56.6L for the top chamber and 340L for the bottom chamber.  Each was vented with a 4" diameter, 17" long vent with big flares at both ends.  200W gets you to 110db in room from 11-40hz.  Be careful not to fall out of your chair when Darla taps on that fish tank!  If interested, check out post#5 here for what would be a HWK on steriods:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=59473&highligh...

A much smaller alternative is going with small sealed boxes and using a Linkwitz transform to flatten the response from the lowest level you want to play.  You need the maximum amp power that your drivers can handle.  Then you say eg "I want extension to 10hz".  With your amp and driver max'd out at 10hz you do the Linkwitz transform above that which essentially whacks off the extra output potential as frequency increases, to net you a flat response.  It's kind of like building a car that is geared for mountain climbing, then driving it down the highway just in case there's a mountain to climb (Darla tapping on the glass).  There's no way this method will get you to 110db at 11hz, but with dual 15's it will probably get you to satisfying levels.

For either method, you could incorporate your existing HWK into the design, so that wood doesn't go to waste.

John, I spent a few hours playing with WinISD alpha (not pro) on the numbers given by Dan Wiggins. The final result was a bizarre graph like I've never seen before. The line looks like the financial earnings of a company VERY QUICKLY going it the toilet. I'm not sure how you guys get those cool looking WinISD charts to display here? But the line starts on the left at -11.5db @ 10hz, and quickly drops to -30db @ 60hz. Could this be correct? Box numbers obviously taken from Dan, the driver numbers inserted from PartsExpress.

Intriquing the small box you mentioned, when you say small sealed boxes, and still use the HWK, are you talking about getting out the circular saw and cutting the top and bottom chambers away from the center, and sealing the holes?

Mr. C, I like your idea, but not an option financially at this point. Wood is cheap, I'll build a few boxes if I need to, but can't be buying drivers and amps right now.

Bob

Another good idea C.  I'll find out how much it wieghs, then call FedEx for shipping price to Australia, what was you address again??  :-*

BTW, it's painted gray now, to match my walls, but it can change colors very easily, just tell me what color you want.  :D

Seriously, I can't believe anybody would pay much for it, especially since my salespitch hasn't been very positive.

Bob

Ok, just to make sure I've got this correct....

Step #1 Remove both drivers.
Step #2 Install both drivers clamshelled on lower baffle. (One magnet in lower chamber, one in center chamber)
Step #3 Seal one of the two bottom ports, leave large top port alone.

Is this correct?

Bob

Bob,

It sounds like the sim you ran was correct.  In the thread where Dan made the recommendation I was soliciting advice to best handle 25hz and down using 2 15" Tempests.  He said that cab should get 110db in room from 11hz to 40hz with 200 watts, so 10db of room gain down at 11hz sounds about right and output would fall off rapidly above 40hz.

Now that you know how to work WinISD, see what is possible with your existing box.  In modelling, leave the top chamber alone and move the other driver up there and don't forget to factor in the 3L or so volume decrease.  That may be low enough tuning for your higher tuned chamber.  Then play around with port lengths for the other chamber (including the center chamber in the volume).  You may have enough volume there to get down close to 20hz without too much port velocity.  Forget about the teens, because that really does take 300L+.  I'm not sure what kind of space you have, but you might even be able to get away with just adding on to your current HWK cab and getting output down to where you want for HT.


Chris,
While I've heard that Bill's designs were pretty good, those are all for music and as far as HT and bottom end extension goes, I could build a 2ft3 box for a single shiva that would laugh at what any small box horn could do for HT.

Well Trashfire that's big talk.  Why don't you send your little over compromised horn a 15hz sine wave and 50-100 watts for a while before you go around bragging about how great an HT sub it is.  I'm sure it does fine above 25hz, but subsonic it's going to be excursion limited rather quickly.

I'm sure that Bob would rather do it right this time instead of just building another stepping stone in route to getting the performance he wants.  He's already got drivers that can get him where he wants.  He has an amp that will do it.  He even has a good portion of the box already built if he plans things well with a very simple build to finish it up, but of course my opinion stinks.