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Zilch's AK Design Collaborative - Econowave Speaker

Thanks Gordon.
I just ordered Surround Sound from Holman:
http://stereophile.com/reference/408surrbook/

If the forward axis is between the 2 large vertical woofers, not in a 2.5 setup, it might be trouble for an EWave system since we're trying to maintain tight spacing between the HF and LF on the baffle. But with smaller woofers, like you say, this could be real cool to narrow their pattern. However, I guess with woofer pairs, the choice is either narrowing the vert or the horizontal. A quad of small woofers would be ideal to match small woofers to whatever pattern comes from the WG at crossover?????

Great food for thought. Thanks again Gordon.:thmbsp:

GordonW said:
I'd add another tidbit to this- I'd recommend a read of Tomlinson Holman's treatises on why many of the original THX movie theater speakers used dual woofers. He's using the same "pattern narrowing" technique- only compounding it, by using two woofers STACKED, to cause the patter to narrow TWICE as fast in the vertical direction as the horizontal direction. This causes a reasonably "rectangular" pattern, which closely matches the patter of many horn drivers.

A pair of 10" or 12" drivers can work well for this, using an E-wave horn, by my calculations... they should have "closed down" to around 40-50 degrees vertical dispersion by no higher than 1.8KHz or so (lower for the dual 12s). Holman originally specified dual 15" woofers with a 500-800 Hz crossover point... there's no reason we can't use dual smaller woofers with the one-octave-higher crossover point of the Ewave...

Regards,
Gordon.
Click to expand...
 
The directivity of piston drivers is related to their diameter. Rule of thumb is they are -6 dB at 90° beamwidth where that equals one wavelength. For a nominal driver diameter of 8", that's 2260 Hz, 10" = 1695 Hz, 12" = 1365 Hz, and 15" = 1063. These calcs assume the piston diameter to be 2" less than the nominal driver size.

As Wayne states, there is considerable leeway in achieving a smooth transition through the crossover region. The 9.5" Smaller Advent woofer with which I am currently designing is stable at 90° between ~1 kHz and 1.6 kHz:

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That's just the woofer, normalized. Here's the full system, in its present state using the 8" eWaveguide, not normalized; cyan (light blue) is -6 dB:

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More data here:

http://techtalk.parts-express.com/showthread.php?p=1650094#post1650094

680020/10930=62.2159​
 

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Skywave-rider,
That's a pretty good description of what I'm about to try -- I just got all the stuff from PE yesterday to do this with 4x 5.25" Dayton woofers, 2 above and 2 below the ewave guide. One thing I don't have yet is a replacement baffle (for the trap cabinet) to do this with; another is that I need to buy a router.
I was thinking that maybe today I'd try to hodge something up in a cardboard box to verify how the patterns will behave. I need to make some measurements on the drivers too, first, to see what I have to do about depth offset between the guide and the woofers (since they are kind of shallow). I'll post if I get any results worth reporting.
 
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Wow, very interesting. My gut says the tighter the woofers are together, the better their patterns merge to coherent lobes. You are essentially making an MTM I think. Maybe not. Consider grouping the woofers together and placing the WG above...? I have no idea but keep us posted.:thmbsp:


bwaslo said:
Skywave-rider,
That's a pretty good description of what I'm about to try -- I just got all the stuff from PE yesterday to do this with 4x 5.25" Dayton woofers, 2 above and 2 below the ewave guide. One thing I don't have yet is a replacement baffle (for the trap cabinet) to do this with; another is that I need to buy a router.
I was thinking that maybe today I'd try to hodge something up in a cardboard box to verify how the patterns will behave. I need to make some measurements on the drivers too, first, to see what I have to do about depth offset between and the woofers (since they are kind of shallow). I'll post if I get any results worth reporting.
Click to expand...
 
Yeah, it's essentially an MTM (really a 2MTM2, I guess). My thinking was that the spacing of the upper and lower woofer sets seems about right to make the narrow vertical pattern and side by side woofers are about right for the wider horizontal pattern. I did a crude spreadsheet model and it seems like it might play -- a cardboard model probably is a good test to make sure before I waste wood. Another advantage if this works is that it isn't hard to get 5.25" woofers that play clean to above 2kHz.
 
Hey, is that a modeler (spreadsheet program) you came up with or if not what is it?


bwaslo said:
Yeah, it's essentially an MTM (really a 2MTM2, I guess). My thinking was that the spacing of the upper and lower woofer sets seems about right to make the narrow vertical pattern and side by side woofers are about right for the wider horizontal pattern. I did a crude spreadsheet model and it seems like it might play -- a cardboard model probably is a good test to make sure before I waste wood. Another advantage if this works is that it isn't hard to get 5.25" woofers that play clean to above 2kHz.
Click to expand...
 
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Been dippin' my toe in the Ewave waters. I have the Pyle wave guides with the D220Ti drivers, woofer is the JBL 2214H in L100t. Crossover is the standard with 50 Ohm resistor across the woofer as per Jack.

First off I can see why so many are into this. Huge potential.

My setup now is missing something though. Mid bass or mids not sure which is lacking. Overall sound is somewhat thin, not room filling. Male vocals are there as they should be when there is little other music. As more bass and highs come in the vocals fade to the background. Switch speakers and the vocals are back out front again. Hope I'm describing this well enough.

Here's what I've tried so far.

Played with Lpad. Best in filling the gap is turned well down, about 9:00 on the dial. This also kills the highs.

Set the speakers on their sides on chairs with the WG on the top side to get it as close to the woofer as possible. Maybe a little improvement but not much.

Is there something I am missing?
 
Hey, is that a modeler (spreadsheet program) you came up with or if not what is it?
Click to expand...

Just Excel, calculating all the distances and adding up phasors from the midpoints of each driver at various frequencies. Not terribly thorough, but I think it should be a fair first approximation.
 
Mmaxed said:
Is there something I am missing?
Click to expand...
Best I can think of is center-to-center distance between woofer and waveguide. Without measurement data, it's difficult to know what's going on.

Several of the test disks here are Patricia Barber. There's never been a deficit in the vocal range.

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Laying the boxes on their sides did help some. A little over 2" between the frame of the woofer and the WG now vs over a foot before.

Must be time to order up some woofers and cabs and finish an proven and approved setup. Not crazy about the trapezoid cab but it'll work until I get more learning to build what I think I want. Kinda thinking I should have stayed away from this audio addiction. I knew I was an addict over 30 years ago. Just kept it under control for the last 20 or so. This site is a bad influence.

Thanks! I'll be asking more dumb questions.
 
I have started my advent Ewaves with my first ever crossover build and had a great time doing it not as hard as I thought it would be.I used the old rear panel from the speakers to mount the Lpad and some JBL L20T binding posts I have recently purchased turned out OK.I have a question how do I use that fuse protection circuit or do I need one.Heres some pictures.Thanks Zilch for all the info.Will add more pictures as I move along.:D
 

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OK, so I have gone from one cab to another changing my mind for quite some time now. I'm done diddle dallying around and I'm finally going to finish what will be my first of several attempts. I am here for some final advise before making cuts however. Pictured are my choice of cab for the LE14's.
 
Here is my baffle board with proposed layout. I would like to know if there is an "optimal" placement of the driver and horn other than what I've randomly selected. Also, the inside volume of the cabs are 5.75 cu/ft. There is a port built into the bottom of the cab that is 16" wide, 2" high and 11 inches long. Will I need to block this off and put in different ports or will the built in one work for this application?
 

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Optimal is with the woofer and waveguide snugged up to each other and located near the top of the baffle, much as you have shown.

BB6P says that port will have them tuned to 32.57 Hz. You're good to go.... :thmbsp:
 
Crossovers are built and gorgeous (thanks to Jackgiffs' boards), cabs are at a shop getting a piano black finish over the formica on the cabs. Yep...pretty well dates the cabs doesn't it. Remember when they just had to put formica on everything! Yeah...so cool. <GAG> I haven't been able to come up with a grill that would work well with the piano finish or the fact the drivers are mounted on the outer surface of the baffle. I've decided to use burl veneer on the baffle and run them open. (That Heathkit LE14 is pretty isn't it?) Kids are out of the house now and my wife never goes into the "man cave". That's by her choice though. LOL I'm close folks...what do you think. On the right track? If not please comment and criticism is welcome. Thanks!
 
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