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Zilch's AK Design Collaborative - Econowave Speaker

Can I make the low pass at 4Khz so it passes all of the woofer signal, but introduces the proper phase shift? Sorry I don't know too much about cross over design yet.
 
The highpass and lowpass are chosen to minimize overlap and still sum correctly (flat, typically) through the crossover region at the desired forward axis. To the extent that both drivers are playing the same frequencies, the magnitude of that interference varies with frequency and listening angle. If the woofer plays competently to 4 kHz and that's where you want to have it roll off, then your highpass needs to occur in the same region.

There are plenty of online resources for learning about crossover design. Insofar as EconoWave and this thread are concerned, however, my advice remains to go with the program unless/until you are capable of doing better. It's not "mix and match" here; I have demonstrated a process for developing custom crossovers for alternative combinations through a dozen example iterations over on Tech Talk in "Flex Your Mettle."

http://www.classicspeakerpages.net/IP.Board/index.php?s=&showtopic=5985&view=findpost&p=85253
 
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Zilch,

I can't thank you enough for all of this excellent information! I think I have enough to go off and start experimenting.

Bass speaker cabinets are a funny thing. The cabinet is part of the instrument so it doesn't necessarily need to be flat to sound good. Its not trying to reproduce a recorded sound, but it is trying to create a pleasing sound. The high mid dispersion characteristics of the econowave should be very pleasing, but I'll have to experiment with how flat this needs to be and how much overlap between the drivers sounds good.

Thanks Again!!
 
gmarcus said:
Thanks Zilch!
One more question (for now). If I let the woofer run without a cross-over will it mess up the phase between the drivers in the crossover region? I know for the typical 2nd order cross-over, the tweeter and woofer are wired out of phase. Is this still true if I don't use a low pass on the woofer?
Click to expand...

Depends on whether the woofer ITSELF is rolling off around the desired crossover point.

One example of this, is the famous EPI 8" woofer... it has a distinct second-order rolloff, right at about 1800 Hz, BY ITSELF, due to the mass and inductance within the voice coil assembly. It introduces the same phase shift as a normal "wide-band" woofer would, COMBINED with a second-order low-pass filter.

If your woofer has this sort of behavior, then you can have a second-order ACOUSTIC response, without any sort of electrical low-pass components. Naturally, this would require measurement, to determine if the rolloff is in the right place, and the right shape...

Regards,
Gordon.
 
Doc Rock said:
Just curious if anyone is using Econowaves for PA duties? I apologize if its been covered before - this is a LONG thread.
Click to expand...

the "Little" Reds:

http://www.audiokarma.org/forums/showpost.php?p=2860467&postcount=6345

attachment.php


Uses dual TOA 15" woofers per cabinet, in a 2.5-way setup. Right at 96dB sensitivity, about 8.5 cubic foot (total) enclosure. Good down to 32 Hz. These do good vocal/recorded music/video soundtrack duty in a room that holds up to 1200 people.

The AWA Video Room 1 Theater System:

http://www.audiokarma.org/forums/showpost.php?p=3629509&postcount=10472

attachment.php


Uses custom-reconed Berhinger 15" (2.5" VC) in about 3.25 cubic feet each. Made to play down to about 40-45 Hz (subwoofers in lower cabinets carry the low bass down to 22 Hz). Right at 95dB sensitivity. In addition to the three E-wave cabinets seen here, there's two more, with 10" woofers, that do the rear two channels. This is for a theater room that seats about 400 people.

Regards,
Gordon.
 
I'm going Ewave! I've got my plans narrowed down to two of the "systems" and need some consultation on the pros and cons.

Econowave Standard vs. Econowave SR Compact

- My cabinets are 1.6 cu. ft each.
- I'm open to sealed or ported.
- Sometimes they will be aided by a subwoofer and crossed at 80 hz, sometimes they won't.
- I need "room filling" volume from as little as a 25wpc push-pull tube amp or 40wpc solid state gainclone.

Any help from the peanut gallery?
 
SR Compact uses a higher efficiency woofer, and requires sub(s). It'll do "stupid loud" SR SPL, no sweat.

Standard doesn't need subs, and 25W is sufficient for "plenty loud" at home.... :yes:
 
OK. Reality check needed.

I need now, to build some SUPER HIGH POWER HANDLING, EXTREMELY EFFICIENT Ewaves for PA. I mean, the woofers I have are going to be over 99dB sensitivity, and handle 600+ watts. The horn drivers have to keep up. The loudest (highest efficiency/highest power handling) systems I've built so far, have only needed to handle about 400-500 watts total, and have been about 96dB sensitivity. These need to play close to 5dB louder than any of those, and be able to hold up while still sounding as good as an Ewave should.

What would be the go-to horn driver for this, of the ones we've all been using? The only caveat is semi-limited budget- we can spend money if it's necessary, but it's not growing on trees here either...

I'm personally thinking Selenium D2500Ti-ND?

Regards,
Gordon.
 
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GordonW said:
Depends on whether the woofer ITSELF is rolling off around the desired crossover point.

One example of this, is the famous EPI 8" woofer... it has a distinct second-order rolloff, right at about 1800 Hz, BY ITSELF, due to the mass and inductance within the voice coil assembly. It introduces the same phase shift as a normal "wide-band" woofer would, COMBINED with a second-order low-pass filter.

If your woofer has this sort of behavior, then you can have a second-order ACOUSTIC response, without any sort of electrical low-pass components. Naturally, this would require measurement, to determine if the rolloff is in the right place, and the right shape...

Regards,
Gordon.
Click to expand...


Hi Gordon,

That is the approach that I had in mind. Here is the spec sheet for the woofer:

http://www.eminence.com/pdf/basslite-s2012.pdf

That big on axis peak is right where the speaker should start beaming so I'm thinking the power response is probably pretty flat up to ~2.5 KHz. I'm thinking I could probably use the standard 3.5 KHz Econowave high pass filter. If the speaker is acoustically rolling off 2nd order, will the phase also have the second order characteristic so that I can just wire the tweeter out of phase and everything will be good?

I'm planning to parallel two of these woofers for a 4 Ohm load and I think this will increase the efficiency by 6 db bringing the system efficiency up to ~104db. I might be able to run with just the adjustable L-pad, but I'm worried that even a 100 W L-pad might burn out before the pair of woofers hit their limit.

Does this seem reasonable? Have I made some bad assumptions?

Thanks for any tips, corrections or necessary flames !
 
Ok i am about to start my 3rd pair of econowaves first pair i made with stage monitor carpeted cabinets with le14's and regular standard wave guide. the second pair i made from some klh 17 cabinets i got for $20 with the smaller guides. Everything was in good condition. this pair will be made from a pair of vintage bose 501 series ii cabinets. They are perfect for econowaves and i will call them bozowaves ( i think. ) i will post some pics of my first 2 pair and the process of the 501 conversion into a real "bose wave"
 
gmarcus said:
I'm planning to parallel two of these woofers for a 4 Ohm load and I think this will increase the efficiency by 6 db bringing the system efficiency up to ~104db.
Click to expand...

This is a common error. It will bring sensitivity up by 6dB but efficiency only increases by 3dB. Double current through the 4 ohm load represents one doubling of power (3dB) and double transducer area (and box size) represents the other three.

You may hear mention of mutual coupling (it's used erroneously earlier in this thread to describe additional gain beyond the 6dB I just described) but that only means that the double surface area is summing correctly, the gain falls apart when you start having lobing cancellation.
 
So... I bought a pair of Selenium D2500Ti-NDs yesterday. After talking with the guys over at the local parts warehouse (Audio Lab of GA)... one of them had actually done a back-to-back comparison of the D220 and D2500, and confirmed that a) the D2500 WAS effectively 2dB or so louder, across the board, than the D220- NOTICEABLY louder, and b) the D2500 had significantly less "break up" at high volumes and low frequencies (in the 1500-3000 Hz range- the low end of its rated bandwidth) than the D220 as well, and sounded "cleaner" and more "open" overall.

Looking forward to trying this!

The woofers I have, are another set (two per cabinet) of the custom-reconed JBL M115-8A 15", like I used in my Seeburg project, EXCEPT while those used "stock" JBL voice coil geometry (about a 5/8" long winding, giving about a 5mm X-max), these have voice coils with a 13/16" winding length (I was actually able to use the voice coil specified for an EV DL18MT, in the JBL gap, with no problem), giving about a 7mm X-max. Should be able to pound it out, if needed. And, funny enough, the WT3 gave me about the same exact T/S parameters on these as the original modded Seeburg-project M115-8A woofers spec'd out at. That was very convenient...

Regards,
Gordon.
 
Diffraction and parallel lines

I was thinking about efforts to minimize diffraction at cabinet edges with waveguides. Geddes uses roundovers, Zilch has found that flush mount baffles do better than inset baffles for controlling directivity.

How about the fact that we have straight edged waveguides and are mounting them with the edges parallel to the box edges? It would seem that diffraction ripples would be lessened if the edges were made non-constant distances from each other. Has anyone ever played with mounting rectangular waveguides at a slant, maybe 30 degrees, from the cabinet top? Granted this would make for some ugly looking baffles, but that's what grilles are for! It also would affect the patterns some (they would tilt), but it would seem there might be some small benefit from having the radiation pattern also not be parallel to the room walls.

Or is this all getting too fussy? Do the waveguides do a good enough job that diffraction around edges (that don't stick out) isn't a big deal? Opinions, data, designs that have dealt with this?
 
If you really want to get rid of diffraction, go to Ikea and get 4 wood salad bowls, then cut out the holes for the wave guides on 2 of them and glue the other 2 to the backs. Totally round....no diffraction. One thing though, you have to use the square wave guides.

I've used them and think they sound better than the rec WGs....jmho.

Scratch that. If you are using the horn, you don't need a back. So just one bowl per side.

http://www.ikea.com/us/en/catalog/products/40057259

Now that I think about it, standing the WG in free air would work too and not cost anything.
 

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Interesting. Not many side-ported designs out there. Was that to avoid having to put an elbow into the port tube (right angle)? Looks like the port might be longer than the depth of the cabinet, but not the width?

Regards,
Gordon.
 
That's my build. Yes, it is styled after the no quarters project, but with some simplifications. I side ported it to avoid using two small ports on the front right at the bottom boundaries. The port is 4" in diameter and 4" long, which gives a 55hz tuning in my 1.65cuft cab. The pa310-8 won't play much lower than that - they are dedicated L/C/Rs with an 80 (or as low as 60) hz crossover to a sub for home theater. I couldn't rear port as they are behind an AT screen and tight to the wall behind the screen. There is enough room to toe in the L/R at 25 degrees though.

I'm holding off on too many comments until I listen to them for a while and do a few tweaks - I've been convinced to add dampening material to the waveguides, and will probably stuff the cabinets more while I'm in there. So far though, the sound is less compressed than the Infinity primus 362/350s I'm coming from, more dynamic, and with only a bit of high frequency harshness. I know I could have used better components, but the price was right with this build, and it will work great for HT. Where I notice the harshness is more with critical music listening. More impressions as the speakers (and my ears) burn in. Heck of a value, and the detail and efficiency these things put out is really impressive.

A big thanks to Zilch for the hard work in putting together this design, and in posting here for me. :yes:

Feel free to fire away with any other questions on the build. Long time lurker, first time poster to this thread. :)

Best,
Christopher
 
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