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Zilch's AK Design Collaborative - Econowave Speaker

An additional element for consideration is the horizontal dispersion of the woofer at E'Wave's nominal 1.6 kHz crossover frequency.

The waveguide's pattern is 90° (again, there's an element of "nominal" in that, as well,) and a 15" woofer's dispersion is narrower at that crossover frequency.

Is that a deal breaker? Well, no, not if the 15" can actually reproduce those frequencies nicely, but it's not optimum, either.... :dunno:
 
So, I shouldn't be concerned about my puny 6mm of excursion from my 4 15" drivers? If nothing else, I'll have at least a pair of 12" subwoofers with 15mm excursion and a 15" sub with the same to help supplement.
 
Zilch said:
An additional element for consideration is the horizontal dispersion of the woofer at E'Wave's nominal 1.6 kHz crossover frequency.

The waveguide's pattern is 90° (again, there's an element of "nominal" in that, as well,) and a 15" woofer's dispersion is narrower at that crossover frequency.

Is that a deal breaker? Well, no, not if the 15" can actually reproduce those frequencies nicely, but it's not optimum, either.... :dunno:
Click to expand...


When you say a 15" woofers dispersion is narrower at 1600hz, are you generalizing based on driver dimensions? Just to confirm, what we are looking for is flat off axis response out to that frequency. In this case, at 45 degrees off axis to match the dispersion of the horn.
 
dnewma04 said:
When you say a 15" woofers dispersion is narrower at 1600hz, are you generalizing based on driver dimensions? Just to confirm, what we are looking for is flat off axis response out to that frequency. In this case, at 45 degrees off axis to match the dispersion of the horn.
Click to expand...
Yes, and I've never seen a 15" that'll do it. Piston diameter controls, I believe.

Is LE14 better in this respect? Virtually by definition, I'd say, and 12" better still.... :yes:
 
Zilch said:
How about Le = 0:

http://audioheritage.org/vbulletin/showthread.php?t=17040

It's differential drive. Does that make it inherently "fast?"

And all of the other JBL DD transducers?

http://www.jblpro.com/pub/technote/JBL_TN 1-33 rev3.pdf
Click to expand...

What is the rounding method to get to 0? I'd be curious what the actual Le is, but it would be impossible to be 0. Good JBL marketing there. ;)

And yes, it would be inherently fast, their dual gap motors make for exceptional drivers. Nice flat impedance curves and linear BL curves. :thmbsp:
 
Zilch said:
Yes, and I've never seen a 15" that'll do it. Piston diameter controls, I believe.

Is LE14 better in this respect? Virtually by definition, I'd say, and 12" better still.... :yes:
Click to expand...

Piston diameter is the primary controller, without a doubt. There are things that can be done to improve off axis response to a higher freq then the diameter would allow on its own. The old Altec woofer cone profile with the addition of a phase plug is probably closing in on as good as it gets in this respect.

I've seen 3dB down at 1500hz with a 15" driver without an ideal surround on the driver (rubber rolled surround rather then an accordian style to remove anomalies.

When I get my measurement gear back up and running I'll get some posted. I wouldn't be surprised if the drivers easily exceed 1000hz at 45 degrees off axis.
 
The JBL Pro DD drivers start at $395 MSRP each.

BUT,

W10GTi Le = 0.41 mH.

Does it play to 1.6 kHz?

Do we give a whit, even?

attachment.php

[O.K., how 'bout W12GTi, then.... :guitar: ]
 
Dual gap motor geometry means that the acoustic center is probably a bit further back, yes.

W12GTI is a very good woofer. :)

I've used it in a car audio install. I would expect that the dustcap design and huge surround would reek havoc with high freq performance, though.

Great subwoofer, though. Even if it could use a little more excursion and a lot more cone area to compete with the big boys. :)

18" Resonant Engineering XXX for comparison purposes has 54mm one way xmax, and 2000w continuous power handling and a very similar split coil design. The prior generation used Adire's XBL^2 technology that had a similar effect (flat BL curve). IIRC, the W12GTI had a DUMAX measured excursion in the low to mid 20mm range.
 
skywave-rider said:
I'm assuming the depth of the basket does not mean the VCs are more rearward than a typical design.
Click to expand...
The voicecoils are dual and stacked, more like three times the length of conventional designs. They are very deep in construction. I'd have to measure to determine where the acoustic center is, but it's certainly more rearward.

Just checked, and all I have in either computer is nearfield measurements; I only got far enough to put together a quick demo for Duff and Coy one day, crossed at 1.2 kHz. This is "punch-yer-lights-out" fun stuff. That's L40 the W10GTi is in, a large bookshelf, and it clears the basket depth by only ~1/4", not enough, probably, 'cause there's a big vent back there. The other issue is the impedance. I don't have an amp that'll drive 3 Ohms comfortably, so I have to run at 12 Ohms.

There are a couple of members on LHF that like the GTis, and maybe some measurements over there, but I'd sure want to do a bunch more testing here before I recommended them for anything other than subs. Not an E'Wave two-way option at this point, for sure, unless your primary interest is uber-ass-kickin' bass from a modest-size cab:

http://manuals.harman.com/JBL/CAR/Boxes and Parameters/W10GTi_rev_f.pdf

http://manuals.harman.com/JBL/CAR/Boxes and Parameters/W12GTi_rev_f.pdf

http://manuals.harman.com/JBL/CAR/Boxes and Parameters/W15GTi_rev_f.pdf

[That JBL guy is NOT about to step in front of the box there, even with the port closed.... :p: ]
 
You could drive one of the two voice coils and short the second one, or throw a POT on the second one and have a driver with variable Q. You'd have less output but some flexibility. Or if you have a stereo amp you could drive it with two channels.
 
Good Lord, you guys amaze me...

Ok, so if the Pioneer 15" makes no sense, what would be a couple of good choices for the E-Wave.. a woofer with good efficiency, low and high frequency extension and low distortion. I think I recall reading LE-10 and LE-14H.. I heard Keggers HPM-100 woofers and they are stellar. Much deeper than I expected from HPM-100s.

Thanks!
 
dnewma04 said:
You could drive one of the two voice coils and short the second one, or throw a POT on the second one and have a driver with variable Q. You'd have less output but some flexibility. Or if you have a stereo amp you could drive it with two channels.
Click to expand...
Shorting's not an option, because both VCs are active in their respective gaps; you'd just be making a dynamic brake out of the shorted one. The two-channel connection would work, mono, inverse polarity, 6 Ohms, but they caution against conventional DVC stereo connection schemes:

http://manuals.harman.com/JBL/CAR/Owner's Manual/GTi MkII Sub OM 05.pdf
 
Cosmos said:
Good Lord, you guys amaze me....
Click to expand...
Well, I hope everybody's gettin' that there's plenty of good fun to be found here.... :banana:

Cosmos said:
Ok, so if the Pioneer 15" makes no sense, what would be a couple of good choices for the E-Wave.. a woofer with good efficiency, low and high frequency extension and low distortion. I think I recall reading LE-10 and LE-14H.. I heard Keggers HPM-100 woofers and they are stellar. Much deeper than I expected from HPM-100s.
Click to expand...
I'd like to try the HPM-100 woofers myself, but maybe you could do that for me.

Used ones on eBay are in the same price range as those PE Pioneer, apparently.... :yes:
 
Zilch said:
Shorting's not an option, because both VCs are active in their respective gaps; you'd just be making a dynamic brake out of the shorted one.
Click to expand...

That's the point. With the pot like Dave said you can tune that brake and change the Q to what you want.

Ray
 
Uh, you don't really want to send different signals to the two voice coils in a JBL 'Differential Drive" woofer. Unless you LIKE even-order distortion a WHOLE BUNCH.

It's like the output devices in a push-pull amp... they need to have MATCHED signals. One is pushing while the other is pulling, and vice-versa...

Regards,
Gordon.
 
There is nothing wrong with sending stereo signals to conventional DVC woofers. I haven't had a chance to read the JBL link Zilch posted so perhaps there is a reason why you shouldn't with the DD technology.
 
dnewma04 said:
There is nothing wrong with sending stereo signals to conventional DVC woofers.
Click to expand...

This is correct. Both coils are of the same layout and dimensions in the gap (they both go all the way from the top to the bottom of the whole coil winding)

dnewma04 said:
I haven't had a chance to read the JBL link Zilch posted so perhaps there is a reason why you shouldn't with the DD technology.
Click to expand...

In a Differential Drive setup, one coil is effectively "on top" of a normal magnetic gap, while the other is "below" a magnetic gap. So, by feeding them BOTH a signal, even-order harmonics are cancelled out, by "symmetry" of drive.

If you sent them different signals, there would be no even-order harmonic cancellation anymore... which would defeat the purpose of using a Differential Drive woofer, as opposed to a standard woofer...

Regards,
Gordon.
 
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