AK Design Collaborative - Econo-Waveguide Speaker

[badmusician]

Originally Posted by djnagle

Hey Bad, are your waves filled with foam??? It looks like it in the pic. What does that do for the sound? Great looking speakrs by the way.

Forgot about that! Yes, they are filled with 30 pore-per-inch rigid open cell polyurethane foam, a la Dr. Earl Geddes' designs. This has been discussed at length at DIYAudio.com. The idea is to attenuate wall-to-wall reflections within the waveguide ("high-order modes" in Dr. G's parlance). Since the reflections take a longer path through the WG, they are attenuated more than the direct sound that comes straight through the foam. I think this is a worthwhile tweak, it removes a little 'edge' from the highs but doesn't seem to affect the FR to any significant degree. There's probably a slight loss of output, but that's just a twitch of the l-pad.

I bought the foam as a 12" x 12" x 4" block intended for aquarium filtration, and carved the wedges to fit as well as I could. The foam stops just short of the driver's bug screen. They are retained with black thread criss-crossed between the mounting holes, so there's no glue to mar the WG's. I think this is a worthwhile tweak, it removes a little 'edge' from the highs but doesn't seem to affect the FR to any significant degree.

Dr. Geddes has been granted a preliminary patent for his application of foam in his own round WG design. His patent includes the convex shape of his foam plug, and there is prior art for foam in a horn, so I don't believe I am in violation with my flat-fronted foam.

I'm still curious whether anyone has tried removing the bug screen from the compression driver. It seems like it would be a real obstruction to the waveform as it enters the WG. It also seems like it's pretty well attached. Anyone pulled the screen from a DT220i?

Bill

[Duffinator]

Originally Posted by badmusician

I had the pleasure of meeting Zilch at the Nor Cal DIY meet-up yesterday. My E-waves in their current bare plywood state are standing next to Z's own pair. They use P. Audio E12-200S woofers in ML-TL cabinets designed using Martin J. King's worksheets. They run 95 - 96 dB efficient, and are pretty flat to 40 Hz. The model says they should be good for 110 dB from 40 Hz on up, louder than I'll ever push them. The l-pad on the high-eff version of the E-wave crossover runs around dead center.

Here's a pic with a little less clutter (and Zilch's Indigina's, too).

Bill

You did a nice job on your foam inserts and I'd love to do a blind test to see if I could hear a difference. Not to get too far off track but is there a thread on the DIY forum from the event yesterday? I see the photos posted but no thread newer than 2007. I really wanted to hear AE's speakers but had to leave early. If I had known there was going to be a raffle I would have stayed longer.

[Zilch]

The thread's on the PE Tech Talk forum:

http://techtalk.parts-express.com/sh...d.php?t=214016

[MartinV56]

Hi Guys, Econowave really is very good, I think in the future replace the Altec 420Y (resonance in the bass 80Hz) for another 15 "woofer or 12",> 95 dB (Altec 414 or 416,(8 ohms) or JBL 2235H. My Altec enclousure is the Altec 861.
welcome woofer suggestions,thanks, Martin

[Russellc]

Originally Posted by MartinV56

Hi Guys, Econowave really is very good, I think in the future replace the Altec 420Y (resonance in the bass 80Hz) for another 15 "woofer or 12",> 95 dB (Altec 414 or 416,(8 ohms) or JBL 2235H. My Altec enclousure is the Altec 861.
welcome woofer suggestions,thanks, Martin

If you have 4-5 cu ft. I can STRONGLY recommend the JBL 2235H.

Russellc

[ROSSO]

Originally Posted by Russellc

If you have 4-5 cu ft. I can STRONGLY recommend the JBL 2235H.

Russellc

I think his 861 cabinets are internally the same as my 872x Madrids, little less than 3.5 cf, not deducting any volume for the space occupied by the drivers. A back mounted 15" will just fit with an overlapped, front mounted, standard Pyle/JBL wg.

[MartinV56]

Thanks, Madrid use 30850 cabinet

[Russellc]

Originally Posted by MartinV56

Thanks, Madrid use 30850 cabinet

Do you know how many cu ft they are?

Russellc

[Dr. Beaker]

That Altec 861 cabinet looks to be around 3.3 -3.4 cu. ft. Perfect size for a number of 12 inch woofers. Can you replace the front baffle to make a 12 inch fit along with the waveguide?

If you want to use a 15 inch, you may have to sacrifice low bass.

[MartinV56]

Yes I can replace the front baffle or use a adapter ring for 12",thanks

Now the question is which 12 " woofer, Vintage or Eminence Beta LT12, Selenium, AE Lambda,etc?

Russell, I think Madrid enclousure is very similar to the 861 (870B system), Santana, Seville,

[ROSSO]

Originally Posted by Dr. Beaker

That Altec 861 cabinet looks to be around 3.3 -3.4 cu. ft. Perfect size for a number of 12 inch woofers. Can you replace the front baffle to make a 12 inch fit along with the waveguide?

If you want to use a 15 inch, you may have to sacrifice low bass.

3.46 cf gross internal volume is the number I have been using. A lot of Altec cabinets differ in external appearance - different tops, trim, etc - but are identical internally, particularly when they used the same LF driver. They tended not to reinvent the wheel for the sake of a styling variation. Madrids also used the 420x LF driver. The front baffle on my 872B Madrids is about 18-5/8" wide x 22-1/2" tall and is removable from the front.

Originally Posted by MartinV56

Yes I can replace the front baffle...I think Madrid enclousure is very similar to the 861 (870B system), Santana, Seville,

You are correct - Santana front baffle is the same width, a little taller but overlaps the bottom edge of the cabinet by a couple of inches, hence the box volume is virtually the same. I have e-waved the Madrids, keeping the Altec 420A woofers and the Santanas where I swapped for LE-14A's. The 420A's are BIG TIME more efficient than the LE14A's.

[Clmrt]

Just dropping in to say "I'm still here, still wavin'"

4627, AKA E145-8 / 2410

2410 disabled, of course.

[doucanoe]

Originally Posted by Clmrt

Just dropping in to say "I'm still here, still wavin'"

4627, AKA E145-8 / 2410

2410 disabled, of course.

Where the heck you been sunshine!

RC

[jimreeves]

Originally Posted by Zilch

The thread's on the PE Tech Talk forum:

http://techtalk.parts-express.com/sh...d.php?t=214016

Nice! Way to represent Zilch!

[Zilch]

Originally Posted by Clmrt

Just dropping in to say "I'm still here, still wavin'".

HEY, welcome back, E'Waver, and thanks for the update!

Got a pair of E145-8 need recone here, and some empty 4691B cabs. I'm bettin' that combo works mighty nicely....

Originally Posted by jimreeves

Nice! Way to represent!

I believe we effectively demonstrated that roadkill can still rock....