Author Topic: Econowave Speakers  (Read 96788 times)

Offline rajacat

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Re: Econowave Speakers
« Reply #15 on: February 26, 2012, 11:34:17 AM »
Ah :D....I see you're making excellent progress. I'm still waiting for the AE woofer group buy to come to fruition before I can start my waveguide project. It's been 3 months! :( [-o<

Offline richidoo

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Re: Econowave Speakers
« Reply #16 on: February 26, 2012, 12:47:11 PM »
Thanks guys!  It is nice to be making dust again after a long winter.

Roy, I hope you get your TD12Ms soon. AE drivers are awesome. I'm gonna grab some of those molded plastic SEOS-12 when they are available, thanks for pointing me to the AVS thread.

Braces for the other box are all fitted, and gluing in now. They went a lot quicker on the 2nd one, for some reason... Making good progress while Daytona 500 is rain delayed...   :(

Offline rajacat

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Re: Econowave Speakers
« Reply #17 on: February 26, 2012, 04:18:56 PM »
Rich,

I'll be doing the SEOS-18 with the TD-15M and active with the miniDSP :) I'm not sure which mic, db meter, etc. to use. I just might  make easy  on myself and go for with the Dayton OmniMic Precision Measurement System.

 I'll probably make my own cabinets. I've been thinking about a separate sealed box for the TD15M using 1-1/8" plywood and not using any interior braces. I'd cut a 45% angle out of the basic box for the proper toe-in angle and apply the baffle to that which would be constructed of a different material. It would be cool to add an outer layer of carbon fiber cloth to the baffle or maybe an exotic almost solid wood baffle.
   
 I don't know if anybody has tried this building method (the super thick plywood) but it might simply construction. Just throwing ideas out there.  I'm open to advice.

-Roy

Offline richidoo

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Re: Econowave Speakers
« Reply #18 on: February 26, 2012, 06:03:07 PM »
I think that will be a sweet speaker system, Roy.

The Omnimic system is excellent, and a good value. 

Here are some articles I ran across yesterday on TNT-Audio.com, about cabinet wall thickness, and other design principles.
http://www.tnt-audio.com/clinica/speaker_design_pt1_energy_e.html
http://www.tnt-audio.com/clinica/cabinet_walls_e.html
http://www.tnt-audio.com/clinica/speaker_design_pt3_getstuffed_e.html

No matter the wall thickness you'll still want to have some internal bracing, especially with a sealed box using low frequency boost. But thicker is more self-damping so resonance is lower amplitude. Bracing forces resonance up into the more strongly damped frequencies of the thicker material. Without braces the lower midrange will still be colored. The trade off for thick baltic birch is you need at least a 1.5HP contractor saw and a fresh sharp carbide blade. And the speaker will be very heavy.  Start a new thread when you get ready to build. It will be fun to follow your project!

Offline rajacat

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Re: Econowave Speakers
« Reply #19 on: February 26, 2012, 09:28:49 PM »
Rich,

Thanks for the links. I've got some reading to do. :shock:
It looks though I'll have plenty of time for that with the AE group buy delay.

I'll probably try Erich's BA compression driver so there'll  be some time before those appear too. With the BA cd I might be able to take advantage of the SEOS 18s' a lower crossover point.

Offline richidoo

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Re: Econowave Speakers
« Reply #20 on: March 06, 2012, 02:49:03 PM »
The braces are finished. I had just enough GAF asphalt roofing membrane left from my previous project to use it on these too. Each piece is cut to fit inside each triangular brace area. In the last project I used 3M Super 77 spray adhesive to install the membrane, but it didn't hold well. This time I am using vinyl floor tiling adhesive. It paints on like tan cream, you let it dry clear, then the membrane sticks to it like pressure sensitive adhesive. Much stronger bond than the 77. I only tried a test piece last night, waiting for warm weather to do it outside because it smells.

So I built the crossovers today. Ready to install in the speakers. There is a rheostat L-Pad to adjust tweeter level, plus a fixed 3.3 ohm L-Pad. Other than that it is simple 2nd order Linkwitz Riley, with no impedance correction. This is a simple sloppy assembly to allow listening and tweaking it easier. The crossovers can sit outside the speaker with the driver wires going in through the ports. There is a separate crossover compartment in the bottom of the speaker for the final crossover.

Weather is looking good for the rest of the week.  :thumb:  I am trying to finish them up quick so Shane can at least hear the first rough draft before the 3 month baby sequester begins.

More pictures:

All braces installed. I figured a better geometry for the second box I braced so they are slightly different. The better one is on the left, you can see that there are less interferences of two braces trying to be in the same corner, and easier to remember how to install them with all braces pointing in the same direction.   The bottom front brace is vertical instead of diagonal to accommodate the reflex ports which straddle the brace.


A tall pile of 44 triangles of GAF rubberized asphalt roofing membrane for damping cabinet resonance between the braces. The braces raise the resonant frequency to make the damping more efficient.  Pieces of wood are the removable floor of the crossover compartment and bottom of the speaker. I accidentally chopped up one of the bottom pieces for braces, so some scraps are collected to make a new one. Fortunately it is on the bottom so appearance doesn't matter.


Crossovers. Nice Erse magnetic core inductors for the bass, Jantzen Superior Z caps, Mills resistors, Dayton LPad. The little aircore coil is for the tweeter, a 20ga cheapie. We have a nice Erse 16ga coil to replace it, but it is lower DCR so we try this first, compare FR to the replacement coil later. Eventually the adjustable LPad (and fixed LPad) will be replaced with a single fixed LPad once we determine the correct value.


The schematic of the crossover designed by Zilch and Pete Schumaker on PE's Tech-Talk forum. Their dialog suggests some other options we can try, like notches and impedance correction, if necessary.

Offline richidoo

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Re: Econowave Speakers
« Reply #21 on: March 06, 2012, 03:00:28 PM »
The bitumen triangles are cut to fit the different size triangle spaces and numbered with chalk.

The upper front baffle relies on the cast aluminum woofer basket for bracing. I have found that the driver frames stop vibration pretty well in a narrow box.

The horn is thin plastic, so it might benefit from some resonance damping goo applied to the back surface. I found this cool latex rubberized asphalt driveway patch goo at Home Depot that I'll try next time instead of the GAF membrane which is expensive, special order and too much labor. Hopefully it won't stink after it dries.

Note tweeter polarity is reversed. I don't like that, but that's the design we're starting with.

Offline BobM

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Re: Econowave Speakers
« Reply #22 on: March 07, 2012, 05:38:00 AM »
Wow, it's good to be young. This is just too much work for me (unless I was retired, of course and had the time). wish I was closer so I could hear the results of these projects Rich.

Looking good.
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Offline hometheaterdoc

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Re: Econowave Speakers
« Reply #23 on: March 07, 2012, 08:48:27 AM »
Rich,

You are entirely too kind to try to get these done quickly so I can get a listen before the little fella gets here.  I really appreciate it... got the bags almost packed, the baby laundry is done and everything is setup... she's been in super hard core nesting mode now for more than a week....

Can't wait to get a listen... looking good.... loving that even the test mules are going to have cabinet dampening to eliminate those resonances as much as possible from the test listens :)

the sun is shining, Rich is gluing, all is right with the world :) hehehe
Shane Sangster
Used to be Night & Day Audio.......

Offline tmazz

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Re: Econowave Speakers
« Reply #24 on: March 07, 2012, 09:01:25 AM »
Wow, it's good to be young. This is just too much work for me (unless I was retired, of course and had the time). wish I was closer so I could hear the results of these projects Rich.

Looking good.


Road trip!  :thumb:
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Offline richidoo

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Re: Econowave Speakers
« Reply #25 on: March 07, 2012, 10:38:01 AM »
Road trip!  :thumb:

You're always welcome!   

The new adhesive doesn't work well. It is very tacky, both parts are glued, but then it peels off!  :wtf:

I'll try 3M # 90 spray next. $13/can.  :roll:

Offline hometheaterdoc

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Re: Econowave Speakers
« Reply #26 on: March 07, 2012, 11:09:03 AM »
when all else fails, liquid nails or PL premium works wonders :)

the silicone that I just used on transformers would likely work as well... 
Shane Sangster
Used to be Night & Day Audio.......

Offline richidoo

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Re: Econowave Speakers
« Reply #27 on: March 07, 2012, 03:20:18 PM »
It has to be high tack instant grab so any kind of wet glue won't work, no way to clamp it in place.

I bought more 3M Super 77, some 90 and some true contact cement. I read the directions for 77 again and there is advice for extra strong bond: coat both surfaces, let it dry for a minute, then join. I tried it and it worked much better but still wants to peel away slightly. It also used a lot of spray for just one piece so it's too expensive.  High Strength 90 requires spraying both sides, and it costs $13 can, so that's out too.

So I'll try the Weldwood gel contact cement tomorrow. Previous attempts with Weldwood greenieweenie water based low odor "contact cement" failed, but this stuff is the original dope sniffer's special with toluene and MEK.  :yay2:

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Re: Econowave Speakers
« Reply #28 on: March 07, 2012, 08:44:50 PM »
I don't know anything about real DIY stuff but how about those quick setting 2 part epoxies? They seem very strong and set very quickly.

Offline hometheaterdoc

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Re: Econowave Speakers
« Reply #29 on: March 08, 2012, 06:53:58 AM »
I'm on the pre-order list for entirely too many of those new plastic SEOS units... 

I have a feeling Tim and other locals are going to get to benefit from "research" as I've got more waveguides coming than I'm ever going to be able to use myself even if I start giving them away to friends :)

Shane Sangster
Used to be Night & Day Audio.......