LE15A/375/075 Box Design

[scorpio]

Hey Val,

Now that you had these playing for a while, how do you feel about them? Specailly, how do you feel about bass extension?

I have a 2-ways system with LE 15A using JBL 1975 enclosure timensions; they are somewhat larger (over 5 cuft internal), but would like to build a nex pair with better finish, I was wondering how yours are faring,

Thanks

[Val]

Now that you had these playing for a while, how do you feel about them? Specailly, how do you feel about bass extension?

Thanks

I've be hecka busy (new boss) and out of the loop for a bit, so sorry for the delay...

I'm almost done with the first of two cabinets. Today I finally tacked in the fiberglass insulation. The one cabinet sounds pretty good. The bass extension is not great, but the bass is very nice to my ears. I've become so accustomed to the sub-woofer band pass type bass that I'd forgotten how smooth bass can be.

[Val]

I really have no idea what to do to tune my box. At the moment I have two 3" ports, each 9 1/2" long. I think I've found the resonant frequency. I stepped thru the low frequencies, feeling the LE15 surround at each, looking for relative stillness. At 27Hz, the cone is the stillest. So I'm guessing that's the resonant frequency. I'm not sure what freq to tune to. Is 27 Hz as good as any?

What else should I check? I don't really have any measurement equipment. All i've got is the marginal audio generator that is bundled with WinISD and a multimeter.

I welcome your suggestions.

[Val]

Here's how slow I am moving! Radiused the corners, added rubber feet, thru bolted the 075. Just need to build the grill. I plan to only cover the LE15 with a grill and let the world see the 075 and 375. My WAF has an excellent coefficient of acceptance! One day, if I'm lucky, I'll lay my hands on a pair of acoutic lenses.

[Zilch]

I really have no idea what to do to tune my box. At the moment I have two 3" ports, each 9 1/2" long. I think I've found the resonant frequency. I stepped thru the low frequencies, feeling the LE15 surround at each, looking for relative stillness. At 27Hz, the cone is the stillest. So I'm guessing that's the resonant frequency. I'm not sure what freq to tune to. Is 27 Hz as good as any?

27 Hz is probably too low. Looking back in the thread, we found 5.75" for 32 Hz, 7.00" for 30 Hz. Gordon suggested a little longer for each.

BB6P confirms you are indeed tuned to 27.02 Hz with your two 9.5" ducts. You've run out of cone displacement with that tuning, however; you're only good for about 60 Watts in the 40 - 60 Hz range.

Either the 30 or 32 Hz tuning will get you 1.5 times that in power handling. Try them both, maybe, in your desired room location. See which sounds best to you....

[Val]

27 Hz is probably too low. Looking back in the thread, we found 5.75" for 32 Hz, 7.00" for 30 Hz. Gordon suggested a little longer for each.

BB6P confirms you are indeed tuned to 27.02 Hz with your two 9.5" ducts. You've run out of cone displacement with that tuning, however; you're only good for about 60 Watts in the 40 - 60 Hz range.

Either the 30 or 32 Hz tuning will get you 1.5 times that in power handling. Try them both, maybe, in your desired room location. See which sounds best to you....

Thank you Zilch. Just what I needed to hear. I'll trim the ports down.

[John]

Hi Val If you only plan on covering the 15" why not use a waffle grill???

[Val]

Hi Val If you only plan on covering the 15" why not use a waffle grill???

Something like this?

http://www.partsexpress.com/pe/showd...number=260-375

[toddalin]

Something like this?

http://www.partsexpress.com/pe/showd...number=260-375

Maybe for a car or a PA, but for the home...

[Val]

5.75" for 32 Hz, 7.00" for 30 Hz.

Just cut 3" off of both ports, for 6.5". I'm measuring about 31Hz now.

Thanks.

g

[Val]

Maybe for a car or a PA, but for the home...

Yep, agreed.

[John]

Well I will bet your last donut that when someone's foot accidently goes thru the cone you will be thinking about waffles?

[Val]

Mmmm waffles...

As I'm listening to my rig I'm realizing that the 375 is dominating. I can't seem to get enuf attenuation using the controls on the LX5 and N7000. Is it as simple as putting an L-Pad between the N7000 and 375?

Thanks...

[Val]

It's been over a year and I finally got these guys finished and in the living room. Thought I'd share some pics. I could not have done these without the help of this forum!!!

[Val]

Still working on tuning them...