Zilch's AK Design Collaborative - Econowave Speaker

Zilch said:

It's axiomatic: Multiple sources playing the same program concurrently in a common acoustic space will interfere with each other in a complex manner which varies with the differential distance(s) to those sources. :yes:

That'll work if you get the angles right, but to what purpose? Max dispersion (omni) has limited applicability....

Click to expand...

Purpose? Uh, to satisfy my need to be different and have an extra cool set of speakers. Actually, I am so new to this that every question teaches me something. You would probably be best to consider these mindless thoughts of a random fool.(maybe thats backwards too)

cubby01 said:

http://www.sfu.ca/sonic-studio/handbook/Interference.html

http://www.google.com/url?sa=t&sour...K2Xe9wYIo7ST8X-rg&sig2=RgISE4EXLbN24OoeU5TC5g

Click to expand...

COOL! Watch them nulls and lobes move around.

Click "Stereo" to find the forward axis.... :thmbsp:

Duffinator said:

Don, the speakers in the furniture look, well custom. :thmbsp: Where did you buy the port tubes and what size are they?

Click to expand...

The port tubes are from Parts Express (#260-408? $1.50 each). Supposed to be 2-3/4" but measured more like 2-5/8" ID. I'll probably cover the speakers with black grills to mute the industrial look.

I meant to name these the "Homer Simpson" model eWaves. Find the Powell Motors episode where Homer's long-lost brother lets him design a car. When you get the part where Homer says "...and when I step on the gas I want it to sound like the world is coming to an end ..." you will understand the inspiration for the design. Or maybe it came from the tap marked "Duff Light" out in the garage.

The photos show a before and after shot of the entertainment center. I picked up the towers ~10 years ago at a bare-wood furniture store. I built the (old) corner cabinets and (new) base cabinet to match them. The (old) shelf/bridge over the old TV will be recycled into the center channel speaker cab. All 300 CDs and ?? DVDs went into the drawers of the new base cabinet with lots of room to spare (22" over-travel drawer slides).

Zilch - It's a little late to make today's games but we'll have them on next week. 4 beers on tap, no waiting :thmbsp:

SheldonD said:

Could you please expand on the "some component values adjusted"

Click to expand...

JBL 123A-1, Selenium D220Ti on JBL PRX horn, both front-mounted on stock PE KD trapezoid kit cabs, closed box:

C1 = 5.6 uF
L1 = 0.80 mH
R1 = 47 Ohms
R2 = 12 Ohms
C3 = 0.68 uF
C2 = 24 uF
L2 = 1.5 mH

I'll likely redo it for the standard eWaveguide, as well, after I tame the DC300 with that here.... :yes:

Any "affordable" alternatives to DC300-8

While I have be pleased with my DC300/Mach 1 Ewaves, the "challenging" statement makes me inclined to look for alternatives. My next Ewave project is likely a scratchbuilt Altec Model 15 clone. Other possibilties are a Model 14 clone or a trap cab a cu ft (or so) larger than the PE cab.

Perhaps I misunderstand. Is it the <2cu ft box that makes the DC300 challenging? The Mach 1s are about 2.4 cu ft internal.
If its just the nature of the driver, do we/you have any affordable (<$100/driver) woofers that are "less challenging"? I'd offer to be a test dummy for a different build, but have no measurement gear and am disinclined to add more little used test gear to the current stable.

I've still got a set of the original crossover boards. Any problems with these?

Zilch said:

No, don't leap to conclusions here. We're using better tools and deeper understanding two years later, is all. In detail, each project is different, and DC300 has already been found by several of us to be, well, "challenging" in the eWave context....

Click to expand...

Pyle Pro PH612 waveguides

My Pyle Pro PH612 waveguides are on the way from PE. Shipped out on Friday. I Just wanted to give a heads up for those waiting on ordering that they might be in stock even though the web site still shows them out till 1-22

Done!

Amplifier finished. 4700 word article mailed off. Photos uploaded. It's been a long weekend.
Next weekend I'll be ewaving a pair of NLAs. Photos will be posted.

fastbike said:

Perhaps I misunderstand. Is it the <2cu ft box that makes the DC300 challenging? The Mach 1s are about 2.4 cu ft internal.

Click to expand...

That may well be, as Gordon has a lot of experience with this driver.

WiredGuy listened yesterday and said "Ship it." The big pluses of DC300 are that they are inexpensive yet produce credible extended bass with good power-handling in this "too small" alignment. I'll post measurements and components later today, after verifying the final values in PCD*.... :yes:

*Jeff Bagby's Passive Crossover Designer:

http://audio.claub.net/software/jbabgy/jbagby.html

Zilch said:

JBL 123A-1, Selenium D220Ti on JBL PRX horn, both front-mounted on stock PE KD trapezoid kit cabs, closed box:

C1 = 5.6 uF
L1 = 0.80 mH
R1 = 47 Ohms
R2 = 12 Ohms
C3 = 0.68 uF
C2 = 24 uF
L2 = 1.5 mH

I'll likely redo it for the standard eWaveguide, as well, after I tame the DC300 with that here.... :yes:

Click to expand...

Thank you Zilch, I see tho that I was confused: I thought it was with the regular ewaveguide not PRX horn. Speakers already built with Pyle guides

You are doing so much so quickly, sometimes I wonder if you ever sleep.

SheldonD

SheldonD said:

You are doing so much so quickly, sometimes I wonder if you ever sleep.

Click to expand...

Don't be fooled by the timestamps; stuff measures better after midnight, is all.

[Though I still have to pause for the trains.... ]

Bauhausler said:

Amplifier finished. 4700 word article mailed off. Photos uploaded. It's been a long weekend.
Next weekend I'll be ewaving a pair of NLAs. Photos will be posted.

Click to expand...

Very slick Ross. Love to hear it. If I get a chance this week, I will bring over those American Monitors. Cheers.

KDT PTW D220Ti (+) DC300 RM:



Parts Express Dayton Knock Down Trapezoid enclosure kit,

Standard eWave Progressive Transition Waveguide,

Selenium D220Ti compression driver (connected positive polarity),

Dayton DC300-8, rear mounted.


Vertical Polar Maps:

Forward axis is 1.75" below waveguide center at 44" measuring distance, i.e., arctan 3.5/44 = 4.55° up from the midpoint between drivers. C/C distance is 10.5".

+/- 20° about the forward axis:


Trivia: at a listening distance of 10' in a room with a ceiling height of 8', the ceiling bounce launches at 40.36° above the listening axis when I'm seated, and 33.69° when standing, and the floor bounce at 36.87° seated, 43.03° standing, both well outside eWave's vertical dispersion pattern. The angles increase at a closer distance, and diminish farther away.


+/- 10°:


Trivia #2: Standing, I am listening from 10.39° above my seated listening axis at the same 10' listening distance, red vs. yellow, above. Further back, the differential angle is correspondingly smaller.


Crossover:

1.788 kHz acoustic; rear mounting the woofer shifted the forward axis down 10°. Minimum phase shown with inverted HF polarity.



Pop Quiz: Is a possible consequence of rear-mounting the woofer apparent in these plots?

How might we "fix" that?

Hint: Front-mounted woofer curve here:

http://www.audiokarma.org/forums/attachment.php?attachmentid=189948&d=1263718515


Cumulative Spectral Decay:



Six Drivers:


D2500Ti-Nd is a shallower driver than D220Ti, moving the HF acoustic center forward. This lowers the forward axis 1.5" at 44" measuring distance, placing it arctan 2/44 = 2.06° above the midpoint between drivers, at the bottom edge of the waveguide.

djnagle said:

Very slick Ross. Love to hear it. If I get a chance this week, I will bring over those American Monitors. Cheers.

Click to expand...

I took it apart. And blew one channel. But I still have 2 working ones from previous builds.

On Sunday there's a Planning Meeting for Maker Faire Detroit at The Henry Ford.

Wanna go?

Outstanding, Zilch. I don't see anything to quibble with there. How many XO variations did it take to get that dialed in?

Bauhausler said:

I took it apart. And blew one channel. But I still have 2 working ones from previous builds.

On Sunday there's a Planning Meeting for Maker Faire Detroit at The Henry Ford.

Wanna go?

Click to expand...

Love to, but I am committed from 1 pm to 9pm on Sunday. Is it earlier than 1?

Great looking kit. You could do one of these in each eWave for PowerWaves.

Bauhausler said:

Outstanding, Zilch. I don't see anything to quibble with there. How many XO variations did it take to get that dialed in?

Click to expand...

A bunch.

I was hoping that PCD would reveal something magic, but it's only as capable as the hacker (me) using it. I can get it lower using the same tricks and techniques that worked with DC300 the hard way earlier, but it gets kinda complex doing that, whereas this is simply the standard eWave XO with some adjusted component values.

Rear-mounting the woofer moved the forward axis into the range where I'd like it to be, and the nulls are symmetrical about the waveguide axis. Like WiredGuy said, "Ship it!"

I'll verify this design with my collection of Selenium drivers here, tweak a bit more if that is indicated, and then post the XO component values. If a bunch of these get built, we can take another look once better skills and tools become available.

Are there any DC300 designs published out there? How did they tame it?

Here's my ZMA and FRD files as text, if anyone wants to try their hand with it:

djnagle said:

Love to, but I am committed from 1 pm to 9pm on Sunday. Is it earlier than 1?

Great looking kit. You could do one of these in each eWave for PowerWaves.

Click to expand...

3:30 pm.
It's not a kit, but we're negotiating.

I designed it so it can be completely disassembled with no desoldering. You can strip it down to the last nut, as shown, and it will still run. That was a trick to figure out.

I've thought about powered speakers with chip amps. The ewave top end takes so little power it would be a cinch to do with a chip. Natsemi chips will do up to 60W into 8 Ohms with minimal parts. The tough part would be moving the highpass from the passive side to the input of the amp. That would basically require reworking the passive EQ. Could maybe do something in the NFB loop but that's a worm can I don't want to open.

I found out this amp doesn't have a dead channel. I just put in a 1K feedback resistor instead of 20K. I figured this out at work by asking 'what would make the gain change from 20.8 to 2'?, then mentally going through all of the possible mistakes I could have made. I guessed wrong NFB resistor and when I got home and checked I was right. 1/8w 1% resistors have such tiny bands it was easy to mistake the colors.

KDT eWave Doc Updated:

http://www.audiokarma.org/forums/showthread.php?p=3375106#post3375106

Bauhausler said:

3:30 pm.
It's not a kit, but we're negotiating.

I designed it so it can be completely disassembled with no desoldering. You can strip it down to the last nut, as shown, and it will still run. That was a trick to figure out.

I've thought about powered speakers with chip amps. The ewave top end takes so little power it would be a cinch to do with a chip. Natsemi chips will do up to 60W into 8 Ohms with minimal parts. The tough part would be moving the highpass from the passive side to the input of the amp. That would basically require reworking the passive EQ. Could maybe do something in the NFB loop but that's a worm can I don't want to open.

I found out this amp doesn't have a dead channel. I just put in a 1K feedback resistor instead of 20K. I figured this out at work by asking 'what would make the gain change from 20.8 to 2'?, then mentally going through all of the possible mistakes I could have made. I guessed wrong NFB resistor and when I got home and checked I was right. 1/8w 1% resistors have such tiny bands it was easy to mistake the colors.

Click to expand...

Yes, a chip amp driven pod (like Zilch built from a .5 cuft curved side PE cab) would be nice. Alittle strange with a power cord hanging out of it, but that's ok.:thmbsp:

russellc

Bauhausler said:

Amplifier finished. 4700 word article mailed off. Photos uploaded. It's been a long weekend.
Next weekend I'll be ewaving a pair of NLAs. Photos will be posted.

Click to expand...

I've wondered about those chip amps, looked at them over on Peter Daniels site. What do you think of the sound of this little chip amp you've built?

russellc