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Zilch's AK Design Collaborative - Econowave Speaker

djnagle said:
I thought it was PETA = People Enjoy Tasty Animals
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Since a correct answer hasn't been provided to SteveO2 by now... PETP is one acronym for Polyethylene Terephthalate. More typically in the US the acronym would be PETE. It's a plastic commonly known as "polyester" (mylar, etc). Same stuff (more-or-less) as the plastic bottles soda and bottled water comes in...check the recycling triangle on the bottom of of a nearby personal sized water bottle...bet it's ID'ed as PETE. Apparently makes good HF driver diaphragms too.

Zilch said:
There are plenty of options for an army of eWavers to try. :yes:

Jack and I can't do all that; we've set the benchmark for comparison.

Maybe I'll start an "Explorations" page.... :thmbsp:

http://www.azom.com/details.asp?ArticleID=2047
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Ever consider titling your links? :yes:
 
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Zilch said:
Maybe I'll start an "Explorations" page.... :thmbsp:
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That might be kinda cool. Would probably help me for learning how to use Soundeasy.

"Testing loudspeakers" will be here tomorrow. Along with surplus caps from Madisound :D

Already have Design cookbook 6th edition. :yes:
 
Was a radio DJ long ago.

[Gonna be hard to hype MLS bursts, tho.... ;) ]
 
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donprice said:
I've got a pair of the Eminence Kappalite 3015 15" drivers (PE # 290-597) on the way. ~5 ft^3 ported boxes...should be thunderous in the HT.

The response curve (attached) shows a 3-4 dB bump between ~1100 and 2200 Hz. I've got the parts to build the "standard >95 dB" crossover. Any suggestions on tweaking the crossover, perhaps like the mod for the LE14, to smooth out the LF-HF transition? I understand the we are starting with 1200Hz low pass to get the 1600 Hz acoustic crossover so I don't think there is much fixin' to be done but I would appreciate another opinion.

Similarly, I've got one of the 10" Deltalites (PE # 290-591) to play with for a center channel or possible surrounds. Same question...

I need to find the frequency analyzer gadget for rent somewhere...

Of course once I get this all worked out it will be time to upgrade to the B&C drivers :scratch2:

Thanks guys!

Don
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Consider whether you'll listen to the Kappalites right on-axis, or toed in so that the axes cross ahead of you. One of the advantages of the CD waveguide and a larger woofer is that you can toe them in quite a lot to reduce HF reflection from the side wall next to the speaker without beaming the highs away from the listeners. Off axis that peak in the woofer may look much flatter.

The peak might be a bigger problem for a center channel, which would pretty much have to face straight ahead.

For frequency measurements on the cheap, you can get by with a Radio Shack SPL meter (<$50), a camera tripod, the sound card in your computer, and a free software package like ARTA or HOLMImpulse. The meter acts as both mic and preamp. You run the RCA out into the line input of the sound card, another interconnect out of the sound card to your amp, fire up the software, and Bob's your uncle. The RS meter's response is not perfectly flat at the very top or bottom, but that can be compensated for, and it's fine through the crossover region which is where you need it. I got reasonable results with the on-board sound card in my PC.

Trying to build speakers without measurement tools only works if you're duplicating proven designs (and maybe not even then). And the RS meter will be useful for balancing your HT speakers and subs, and checking just how loud you're really playing those E'waves!

Bill
 
Zilch said:
Was a radio DJ long ago.

[Gonna be hard to hype MLS bursts, tho.... ;) ]
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Hey, nobody's asking you to play Misty.
cuar02_eastwood0812.jpg

Zilch, right, back in his radio broadcast days, with Erroll.
 
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badmusician said:
Consider whether you'll listen to the Kappalites right on-axis, or toed in so that the axes cross ahead of you. One of the advantages of the CD waveguide and a larger woofer is that you can toe them in quite a lot to reduce HF reflection from the side wall next to the speaker without beaming the highs away from the listeners. Off axis that peak in the woofer may look much flatter.
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The main speakers will end up installed in a large home entertainment center (73" HDTV on ~2' tall console with 2' wide x 6' tall component cabinets on each side) so toe-in isn't an option. The HT system is the "great room" so there are no walls within 10' of either side to get a reflection from. The watching/listening area includes a full kitchen, opens to a formal living/dining room and has cathedral ceilings (handy to hang the JBL 4312 surrounds from). Acoustically speaking, it is problematic.

I was under the impression that the bigger concern with using a 15" driver (ignoring FR) was that it tended to get "beamy" over 1000 (?) Hz and lose off-axis performance in that range. I think I get what you are trying to tell me (too hot on-axis may be just right off-axis).

Note to self - make sure baffle can be changed from front...

Anyone know where I can rent a Behringer UltraCurve DEQ2496 or similar? I guess I should hit the local music store this weekend....
 
donprice said:
I was under the impression that the bigger concern with using a 15" driver (ignoring FR) was that it tended to get "beamy" over 1000 (?) Hz and lose off-axis performance in that range. I think I get what you are trying to tell me (too hot on-axis may be just right off-axis).
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I prefer 12" and 15" midwoofers with 90x40 horns, myself. Anything smaller than that tends to have a pattern that's too wide and there's a big midrange bulge off-axis. That's exactly what you want to avoid with this kind of design.
 
Thank you for the update, Steve! What a great pleasure it is to see EconoWaves appearing at various DIY meetings around the courntry. :thmbsp:

Tell us about your cabinets, please.... :yes:
 
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