LE15A/375/075 Box Design

[Val]

I've re-surrounded the LE15A's, read the books, wasted WAY too much time browsing this site and have knocked out a box design for my beloved drivers. I've decided to post the design in hopes that smarter people will point out dumb things before I start cutting wood and wasting even more time!

My design factors are this: Make them small so my lovely wife will let me put them in the living room (they will be stereo speakers). Make them simple to build (no time for fancy joinery). Don't spend too much money. Vertically align the 075 and 375 for better imaging. I'll be using 1" MDF. I've used WinISD for the math.

Comments welcome! Thanks.

[Zilch]

BaseBox 6 Pro says you want your box tuned to 32 Hz, with 4" duct length 4.25".

Do you have enough room for the dispersion lens there? It's not shown....

[Val]

Yes, I think I have enough room. I believe the footprint of the acoustic lens is about 4" x 10". I've been looking for a pair but haven't found any (I probably couldn't afford them anyway

Thanks for running the BB math. It's probably better than WinISD.

[Mr. Widget]

You may want to try a 5.75" length duct as well and subjectively compare them. It will give you a slightly lower tuning ~30Hz... depending on your room and your own listening tatses, you may prefer the slightly lower tuning. You gain a tiny bit of deeper bass with the lower tuning.


Widget

[toddalin]

Yes, I think I have enough room. I believe the footprint of the acoustic lens is about 4" x 10". I've been looking for a pair but haven't found any (I probably couldn't afford them anyway

Thanks for running the BB math. It's probably better than WinISD.

I have a couple of the HL89 horns with the folded chamgagne-colored lenses (Hartsfield horns) I would part with. The lenses are normally 19.75" wide, but one was cut down to 15.825" and other has a cut on one of the plates at this same 15.825" width. (These were cut to fit the former owners cabinet but I guess he had second thoughts on the second.) This is still several inches wider than the horn opening of 9" with a 10.5" mounting flange. The horns are in fine shape except that the prior owner filled in a couple of the mouning holes with putty (easily removed). They have a depth of 12" if you rear mount them and about 11.75" if you surface mount them. The driver has a depth of 5.25" so they should just fit your listed cabinet depth.

If you cut the both to 15.825" you would have no problem fitting them on your baffle and would have something unique and different than anyone else.

[Val]

The slowest tri-amp project continues.

Awhile back I bought a Smart Strip to control the power for my crossover and amps. The idea is that is senses power draw on the control plug (I plugged in my AVR) and it turns on the amps and such. Turn on the AVR, all the amps go on. Great idea. Even has a sensitivity control. I could only get it to work some of the time. So it falls into the "don't waste your money" category.

I ended up buying a solid state relay and some parts and made my own 12v triggered power. One plug is always hot, one is triggered by my AVR's 12v. Now it works every time. The SSR was only 12 bucks for 25A. Came with a big heat sink. Who doesn't like heat sinks? Anyway, it was a fun sub-project. About $25 in parts. You can't see it in the pics but there is a 3.5mm plug for the 12v trigger input just under the power cable.

[ivica]

The slowest tri-amp project continues.

Awhile back I bought a Smart Strip to control the power for my crossover and amps. The idea is that is senses power draw on the control plug (I plugged in my AVR) and it turns on the amps and such. Turn on the AVR, all the amps go on. Great idea. Even has a sensitivity control. I could only get it to work some of the time. So it falls into the "don't waste your money" category.

I ended up buying a solid state relay and some parts and made my own 12v triggered power. One plug is always hot, one is triggered by my AVR's 12v. Now it works every time. The SSR was only 12 bucks for 25A. Came with a big heat sink. Who doesn't like heat sinks? Anyway, it was a fun sub-project. About $25 in parts. You can't see it in the pics but there is a 3.5mm plug for the 12v trigger input just under the power cable.

Hi Val,

Why not to use standard (electro-mechanical) relays, that can be controlled by 12V or 24V or.... supply.

regards
ivica

[Val]

Hi Val,

Why not to use standard (electro-mechanical) relays, that can be controlled by 12V or 24V or.... supply.

regards
ivica

I actually started with looking at those and they would work fine. The SSR was only $12, is silent and didn't require a cap for emf suppression.

[1audiohack]

I actually started with looking at those and they would work fine. The SSR was only $12, is silent and didn't require a cap for emf suppression.

+1. Magic.

[toddalin]

I would mount the drivers in a verticle array rather than off-set.

[GordonW]

I would mount the drivers in a verticle array rather than off-set.

I agree with this sentiment; though, I could see mounting the midrange and treble drivers say, one inch off center, to break up diffraction modes just a bit. You don't want the acoustic centers that far off of the vertical line through the center of the woofer, since it does go up to around 1KHz...

If you were to move your port upward, to where it was next to the 075, you should be able to accomodate this driver arrangement. Personally, that's what I'd do.

Also, if you offset the drivers, naturally be sure to "mirror image" the cabinets. This will definitely help imaging/soundstaging perception.

My only other suggestion would be to use the 077 or 2405 slot tweeter, rather than the 075... but with the drivers you've chosen, this is probably about the ideal arrangement.

Oh, one other thing comes to mind- you may want to use a "u-bolt" large enough, to clamp the 375 to the brace. Something like a very large muffler clamp U-bolt (probably available from anywhere that does truck or high-performance automotive exhaust systems) or the U-bolts made for large wiring or plumbing conduits should work. Just attach a couple of L-bracket to one side of the brace, and feed the U-bolts through the holes in the L-brackets, to clamp the unit down. This will prevent any side-stress whatsover, in ANY direction, on the front of the horn...

Regards,
Gordon.

[Zilch]

If you move the mid and high drivers in line, use dual, smaller ports either side of and belowish of the 375.

That'd be two 3" ducts 5.75" long (best choice), or two 2.5" ducts at 3.5" long for the 32 Hz tuning (Orchid).

For Widget's 30 Hz tuning, it's two 3" ducts at 7.0" (Blue).

Your original tuning (~36 Hz, actually,) in Black.

All of the proposed tunings are the same at 40 Hz. Me and Widget are gettin' you a leetle more bass extension, is what....

[rloggie]

Hi,
I believe the lens you would want are L91. You may want to check out this Ebay auction.

http://cgi.ebay.com/JBL-L91-HORN-SPE...QQcmdZViewItem

Good luck.

[Zilch]

Jeez, $144. Time to clean some up around here.

Why'm I sittin' here lookin' at these dusty things...?

[Val]

I've finally been able to carve out the time to work on these speakers. I have just replaced my 075s with a very nice pair of 077s (before and after pictures below). No cabinet mod's required. They sound noticeably better. Breathier and a certain harshness is gone.

Before


After


I'm also getting ready to try-amp these (really quad-amp as the 2245H based sub-will be in the mix as well). They were quad-amped before with an Ashly 4001, but it died and I was able to get a few buck on eBay for it. It's being replaced with a MiniDSP 4x10HD that should arrive coming Wednesday. I've already downloaded the configuration software which allows me to start configuring them even without the box being connected. The MiniDSP has two analog inputs and 8 outputs. Each input and output has 5 paramedic eq's available which I will configure another day when I have some help with measurement equipment. Today I played around with estimating the acoustic centers of each driver using only the crudest of tools (ruler) and configuring the delays. These will serve as a starting point and hope to later set them using actual measurements. I've also laid in the crossover frequencies. Going with LR 24db/octave.

Output Screen Shot

Channel 2 Crossover Screen Shot