Econowave Speakers

[richidoo]

That's a pretty good idea, entomb it in cement! I've tried attaching exterior mass before, it doesn't work. Only stiffness works. I'm excited to build the foam sandwich. I've built a lot of plywood boxes, interested to see if something new will work better.

The box color is not so bad. It's far less than the econowave prototype made with no bracing at all.

Sol reminded me that I can cure the woofer crossover by reducing the coil to it to bring it up a bit. So it just needs a custom crossover and it will be better. The 1500Hz crossover point is not for benefit of the tweeter, it can cross much lower. It is to maintain horizontal dispersion (90 deg) with the horn at the crossover freq.  This driver can do that even with the high Le.

[djdube525]

Rich
Just to take the box vibration out of play, have you thought about temporary external bracing? You could even go so far as to make an outside form and fill with grout.

Sorry this has turned into one of MY home improvement projects 

I was thinking the same thing... add essentially a bunch of "ribs" or "furring strips", Then another layer of plywood, then fill the voids with sand...

[richidoo]

OMG that would weigh a ton! But it should be a sound improvement. I'll try to find a pic of one that I built like that, without the sand.

[richidoo]

Eminence measured one of my woofers at their factory. LCR meter shows .457mH, spec is .46.   Then he measured impedance and SPL with LMS tester and they are also within spec. So I need to get better measurement tools and/or better understanding of driver measurements.

Thanks again to Anthony Lucas at Eminence for patience in answering my questions and testing my woofer. Great service from Eminence!

Edit: Parts Express is replacing my broken WT3 with the new version under warranty. Should be shipping today. I hope my measurements will improve with the new one, but I'm setting up a manual test rig for verification.
Qms, Qes and Vas determine box volume (Vb.)
Qms, Qes and Fs determine box tuning frequency (Fb) and consequently, port dimensions.

Anthony replied that my 121liter box tuned to 38Hz is too big and too low for the driver. Their biggest recommended vented design is 78 liter, 50Hz.

I have to wonder if the free simulators are worth their price, and whether a fancy sim like LEAP5 would do any better? Eminence recommended boxes are designed using their own Eminence Designer product to get numbers very different than my sims, even when I use the factory specs.

Edit2:  I think the box is stiff enough. I think the new "box noise" I heard after sealing the ports is LF echo coming through the driver cone, because there is only minimal stuffing in the speaker. For sealed there should be a lot more to kill the interior echos.  It doesn't do that when ported.

[richidoo]

Old school vented box design:
http://users.ece.gatech.edu/mleach/ece4445/downloads/ventedbox.pdf

[richidoo]

I put Shane's AE TD12X woofers into my econobox. Simon at AE forum said it likes a big box. It has godalmighty power even with tube amp, and more LF detail than the Eminence, but it's still too loud and rumbly because the box is tuned too low. I think the box is just too damn big for either driver. In the right size box this AE will be truly awesome. 

So now I'll fill in the bottom of this box to kill off some volume. I can fill up to the bottom of the ports, then stick in some other blocks in the remaining space if necessary. I think filling in the bottom section up to the ports will get my volume down to the Eminence recommended volume of ~80liters. I think I'm around 115-120 now.

When the tuning is too low the midrange really recedes. This is described in some of the literature I've read.

[richidoo]

Bottom is filled in with spray foam up to the bottom of the ports. Probably took out about 30 liters. Ports are still 4 x 5.25". Should be correct for the Eminences, according to their own cabinet plan.

It sounds a little better with the AEs in there, but still a little bottom heavy. I would guess that they AEs will need shorter ports, maybe even smaller box, as simulations predict.

[Face]

If they're still bottom heavy, they may need a longer port, not shorter. 

[rollo]

   Would a passive radiator have an affect reducing vibration into bass ?  Did you use any viscoelastic dampening [ black hole pad ] material between driver and box ?


charles

[richidoo]

If they're still bottom heavy, they may need a longer port, not shorter. 

Thanks Mike! Won't that lower the tuning freq? I am under the impression that it is already too low.

Based on Simon's advice I am ignoring the simulations for TD12X that say 48litres, but I think the sims are more correct than wrong. 120 and 85 liters sound too boomy. To me that means box too big or port tuned too low. The Fs of these two drivers are 25 and 30Hz.

According to eminence simulation this volume and port should resonate at 50Hz with the Eminence driver.
Thanks Mike

[richidoo]

Would a passive radiator have an affect reducing vibration into bass ?  Did you use any viscoelastic dampening [ black hole pad ] material between driver and box ?

Hi Charles. PR would be an interesting alternative. Scares me to think about designing a PR based on my current reflex port record.

There is a rubber gasket between the AE and the box. There is a soft paper gasket between the Eminence and the box. No black hole inside the box, just a 1" layer of FG on all interior surfaces.
Thanks Charles!
Rich

[bpape]

The beauty of a PR is that you can simply add/subtract weight from it to change the tuning.

Much easier than cutting and gluing ports all the time.

Bryan

[Vapor1]

I bet you'll have some trouble finding a 12" PR that will tune as high as you want. 

I haven't read the entire thread, just bits and pieces.  But my impression here is that you're blaming the box when in actuality, the blame likely lies with the drivers themselves.  The Ewave isn't a refined, integrated, high resolution speaker.  It just isn't, those drivers just aren't capable of delivering that presentation.  They're decent at all those things, but lacking ultimately. 

Could you do me a favor and post a current status of the project?  What you're looking to improve, and what exactly your configuration is?  I might have some ideas.

[richidoo]

Viper, I don't agree with your opinion of the Eminence DeltaLite II 2512. It has excellent "resolution" at crossover frequency, and at LF when in a sealed box. Of course there are better drivers available, but this is adequate for what I'm after now.

As for econowave lack of refinement, this is not cookbook econowave. Right now I have AE TD12X, Radian 475, Jantzen caps, Erse SuperQ bass coil. LR2 ~1400Hz with pad on tweeter. 1.5" pink FG bat on walls of well braced box. Vb 80 liters, two ports 4Wx5.25"L. Bass is way too boomy and smeared. It improved slightly by reducing Vb from 120 to 80l.  But this box config is the Eminence published design for the 2512. I'll put the Eminences back in tomorrow. They are internal mount, so it's a big job to swap drivers.

I tried the AEs in the box when it was 120l and now 80l because AE moderator said the simulated Vb of 48l is too small, and 120l would be good.

Eminence says that simulated standard alignment of 120liter is too big for 2512 driver. Between the sims and the advice I am spinning wheels. I wish reflex design was more scientific, but it seems like more of a crap shoot or trial and error.

You'll have to read the thread to see how I got to where I am at the moment. I am not at an impass, I'm just reporting my progress.  

[Face]

If they're still bottom heavy, they may need a longer port, not shorter. 

Thanks Mike! Won't that lower the tuning freq? I am under the impression that it is already too low.

Based on Simon's advice I am ignoring the simulations for TD12X that say 48litres, but I think the sims are more correct than wrong. 120 and 85 liters sound too boomy. To me that means box too big or port tuned too low. The Fs of these two drivers are 25 and 30Hz.

According to eminence simulation this volume and port should resonate at 50Hz with the Eminence driver.
Thanks Mike

You need to measure to see where the boom is.  If it's ported too high, you'll have a large peak in bass response too. 

As for PR's, they're a great alternative when a very long port would be required.