Zilch's AK Design Collaborative - Econowave Speaker

[Russellc]

14" x 10".

As you suggest, it looks like the front baffle could be moved forward, if desired. A PE or window screen grille could fit nicely in a smaller recess. I'm also thinking rear mount the woofer and slide the waveguide down to minimize the C/C distance. It's looking like it will all fit.

What're we talking here:

Cabs - $128
DE250s - $250
Waveguides - $22
XOs - $100

Total - $500 plus woofers.

It'll work, but it ain't "Econo...."

Not Econo, at least not when compared to the original, but still its a natural extension of the same idea, just with an improvement angle. Compared to what's on the market, it still plenty "Econo" :yes:.

 

[Russellc]

Some airtight trim in front of the stop to bring the baffle forward...maybe not too hard to do. That will make a gap, but I think that will look good. I will make the baffle removable....Zilch...sold!

1st iteration: JBL 123A1s which are on hand, sealed.
If that sucks, Eminence Kappa 12s ported.

I kind of like the idea about putting another faceplate over the original baffle, and then rounding it over with a router. Or was that on another forum? anywho, its a thought.

russellc

 

[Russellc]

Some airtight trim in front of the stop to bring the baffle forward...maybe not too hard to do. That will make a gap, but I think that will look good. I will make the baffle removable....Zilch...sold!

1st iteration: JBL 123A1s which are on hand, sealed.
If that sucks, Eminence Kappa 12s ported.

If 2 cu ft ends up being less than optimal for your 123 drivers, I wonder if one of those thingies like dynaudio and scanspeak sold, like a semi port with adjustable resistance would help? Allegedly, they had the effect of increasing the size of a "sealed" box.

Russellc

 

[Russellc]

He uses a different HF comp scheme, but one notch @ 4.5 kHz will get this combo into +/- 1 dB territory. It's kinda academic 'til the system is in a cab, but I may work on that a bit, anyway.

If you swapped in 16 Ohms, we're listening to the same thing right now.... :thmbsp:

Well, I've had the 16 ohm resistors in place for a while now. the HF response may very well be flatter, but boy is it hot! With R1= 16 ohms and R2=16 ohms, and C3= .47 Ihave to have the L-pad adjusted to just below 9 o'clock. This is with the 93 db efficient JBL 2235H woofer.

I dont understand a lot about crossovers, but I understand that R1, R2, And C3 all work together for the end result, but it does seem that decreasing the
resistor that the cap jumpers on the way to the compression driver from 30 to 16 would raise the efficiency of the HF, but maybe thats whats required to make it flat. Would it leave the response as it is if I measure the resistance of the L-pad set where I like it, and add that value to the 16 ohms for the jumpered resistor, replacing it with a resistor of the combined value?

( eliminating the L-pad of course)


Russellc

 

[Zilch]

Well, I've had the 16 ohm resistors in place for a while now. the HF response may very well be flatter, but boy is it hot! With R1= 16 ohms and R2=16 ohms, and C3= .47 Ihave to have the L-pad adjusted to just below 9 o'clock. This is with the 93 db efficient JBL 2235H woofer.

I dont understand a lot about crossovers, but I understand that R1, R2, And C3 all work together for the end result, but it does seem that decreasing the
resistor that the cap jumpers on the way to the compression driver from 30 to 16 would raise the efficiency of the HF, but maybe thats whats required to make it flat. Would it leave the response as it is if I measure the resistance of the L-pad set where I like it, and add that value to the 16 ohms for the jumpered resistor, replacing it with a resistor of the combined value?

Without looking up the specs, I'd guess 2225H would require somewhat less attenuation.

Wayne explained how the attenuation and HF are combined in this filter earlier in this thread. Experiment with the values in his chart, if you like, but I'd suggest you get set up to measure and comfortable with doing that first. Additionally, for 2235H, you need to get the crossover frequency down closer to 1 kHz. As I noted above, there are unresolved "issues" at this point.

For now, leave it be, or add an additional fixed L-pad between the adjustable one and the compression driver, -6 dB or so.... :yes:

 

[rlee777]

Econowave build finished -- thanks to all

Finished my first Econowave build. It is surpassing all my expectations. Here are the details:

1. Selenium 220/JBL WG, Selenium 12PW3 12" woofers. I selected these woofers for value, ability to play high with decent dispersion, higher Qts for punch in a sealed cabinet, high efficiency with low distortion. The plan is to crossover at 60Hz to my sub, so the limited Xmax is not a problem. These 12PW3s sound great up to 1.5Khz and are very inexpensive to boot.
2. 35" tall 2.8 cu ft cabinets with black gloss finish. Used india ink to blacken the plywood and wipe-on gloss poly. Filled heavily with 3lbs polyfill each.
3. High-efficiency crossover using specified parts and printed circuit boards from Zilch (thanks! -- made the job MUCH easier). Internal wiring is Monster Cable 16ga.
4. Sealed system aiming for a Qts (system) of 0.8 - 0.9. All seams fully caulked.
5. Zobel on the woofers to make the xover more effective.

Results:
1. Alas, no pictures yet. Finished in the evening and cannot seem to take good pictures with a black shiny cabinet and flash.
2. My main system consists of Magnepan MMGs, modded Xover and vertical raised orientation. The Econowave pair sound almost as smooth as the MMGs, but much more dynamic with plenty of punch. Instruments sound clear, bells are pristine, vocals very natural. The sweetspot is much wider than the MMGs -- the whole room is filled with consistent response, so unlike the MMGs. The soundstage is wider, just as deep, not as tall as the excellent MMGs. Surprisingly natural sound that is clear enough to reveal weaknesses in the audio chain -- my Denon sounds much better than an old Marantz receiver. After a hour of listening, I am finding distortion artifacts to be very low, no fatigue. The best part is the enjoyment at low volume levels -- the dynamic nature of the Econowave keeps me involved in the music even at "upstairs asleep" levels, something I could not do with my MMGs.
3. Agree that the best placement is cross-firing in front of the listening seat.
4. These puppies can get LOUD and still remain clear.
5. Ultimate neutrality is not its strong suit, but the other benefits are leaning me to replace my MMG mains with these DIY Ewaves.

The best $300 I have spent. Thanks to all of you.

 

[Zilch]

The best $300 I have spent. Thanks to all of you.

You are very welcome, of course. Get some pics up, please, so we can make you "Official."

I would certainly like to see the India ink finish, which is new to me.... :thmbsp:

 

[rlee777]

I would certainly like to see the India ink finish, which is new to me.... :thmbsp:

India ink on plywood is great if you want BLACK. It is very dark, easy to apply and goes on more even than a lot of stains. It penetrates into the wood, so it is permanent. Because it is so dark, the grain is hidden. Cheap and dries very quickly. With a gloss topcoat, it looks rather nice. Next time I do this, I will pay someone to spray an acrylic clearcoat over the India ink finish. The Minwax wipe on poly just did not have enough gloss to give it "pop".

 

[Bauhausler]

India ink on plywood is great if you want BLACK. It is very dark, easy to apply and goes on more even than a lot of stains. It penetrates into the wood, so it is permanent. Because it is so dark, the grain is hidden. Cheap and dries very quickly. With a gloss topcoat, it looks rather nice. Next time I do this, I will pay someone to spray an acrylic clearcoat over the India ink finish. The Minwax wipe on poly just did not have enough gloss to give it "pop".

I use India ink to detail things like transformer laminations when I'm restoring tube gear. It's very useful stuff. I had a pair of K-horns that were originally walnut. The owner dyed them black with liquid shoe polish and waxed them. It was a nice effect, and probably very cheap.

 

[devoid]

More Horny

I'm back to annoy with my unproductive posts and useless contributions. But I got something today, rather two things. And I don't really know what I'm going to do with these either but something... I gotta just start hooking stuff up. Like that little Maggy amp. It's a jigsaw puzzle of fun I tell ya.

 

[packrat]

Finished my first Econowave build. It is surpassing all my expectations. Here are the details:

1. Selenium 220/JBL WG, Selenium 12PW3 12" woofers. I selected these woofers for value, ability to play high with decent dispersion, higher Qts for punch in a sealed cabinet, high efficiency with low distortion. The plan is to crossover at 60Hz to my sub, so the limited Xmax is not a problem. These 12PW3s sound great up to 1.5Khz and are very inexpensive to boot.
2. 35" tall 2.8 cu ft cabinets with black gloss finish. Used india ink to blacken the plywood and wipe-on gloss poly. Filled heavily with 3lbs polyfill each.
3. High-efficiency crossover using specified parts and printed circuit boards from Zilch (thanks! -- made the job MUCH easier). Internal wiring is Monster Cable 16ga.
4. Sealed system aiming for a Qts (system) of 0.8 - 0.9. All seams fully caulked.
5. Zobel on the woofers to make the xover more effective.

Results:
1. Alas, no pictures yet. Finished in the evening and cannot seem to take good pictures with a black shiny cabinet and flash.
2. My main system consists of Magnepan MMGs, modded Xover and vertical raised orientation. The Econowave pair sound almost as smooth as the MMGs, but much more dynamic with plenty of punch. Instruments sound clear, bells are pristine, vocals very natural. The sweetspot is much wider than the MMGs -- the whole room is filled with consistent response, so unlike the MMGs. The soundstage is wider, just as deep, not as tall as the excellent MMGs. Surprisingly natural sound that is clear enough to reveal weaknesses in the audio chain -- my Denon sounds much better than an old Marantz receiver. After a hour of listening, I am finding distortion artifacts to be very low, no fatigue. The best part is the enjoyment at low volume levels -- the dynamic nature of the Econowave keeps me involved in the music even at "upstairs asleep" levels, something I could not do with my MMGs.
3. Agree that the best placement is cross-firing in front of the listening seat.
4. These puppies can get LOUD and still remain clear.
5. Ultimate neutrality is not its strong suit, but the other benefits are leaning me to replace my MMG mains with these DIY Ewaves.

The best $300 I have spent. Thanks to all of you.

What an interesting project! I figure that the Selenium 12PW3 in that 2.8 cu-ft sealed box starts rolling off between 70 and 100Hz, so the low end response is probably similar to the MMGs, and would benefit from corner or wall placement (something the MMGs can't do). You improved your control of directivity (reducing room reflection side effects), got over 10dB of efficiency gain (more headroom with your existing amp and less distortion when played loud), AND you say they sound almost as good, perhaps better! Your description of what they are good at pretty much follows what I found when I built my 1st pair. The fact that I get mine to produce an 'image' of any sort in an 8x7 foot room is astounding. The directivity control above 1500Hz really helps in a small room! Percussion, horns, and piano really sound more 'lifelike' to me compared to the other speakers I've had.

 

[Russellc]

JBL inverse-polarity woofers, invert the connections after verifying with a battery that they remain inverse on the external input terminals. I've outsmarted myself a couple of times by reversing them internally and not sticking a label on the outside saying so.

Tweeter is connected standard eWave polarity.... :yes:

So I should try putting a battery to the CROSSOVER inputs and make sure my connection ( pos to blk right now) still moves the woofer cone out? I have noticed on the 4430 the woofer (2235H)n is hooked up pos to red...opposite of what you would have thought for a blk=pos woofer.

Russellc

 

[Russellc]

Without looking up the specs, I'd guess 2225H would require somewhat less attenuation.

2235H= 93 db

2225H= 97 db

Additionally, for 2235H, you need to get the crossover frequency down closer to 1 kHz. As I noted above, there are unresolved "issues" at this point.

I'm currently using the low pass of the 4430 monitor, which appears to fall around 900 to 1000 khz, a well as the zobel.
Or do you mean the HF closer to 1000 ?

russellc

 

[Russellc]

Wayne explained how the attenuation and HF are combined in this filter earlier in this thread. Experiment with the values in his chart, if you like, but I'd suggest you get set up to measure and comfortable with doing that first.

Trying as we speak. As soon as I determine if my soundcard will work and figure out how to hook it up, I'll be a measure'n. If my sound card will do, it will be a cheap matter of pre and phantom power. Otherwise, I will be in a slightly more expensive route of replacing the sound card, or getting one like M-audio Mobile pre usb. Still climbing the learning curve. Looks like I'll start with REW, also have True RTA so we'll see when that time comes.

Russellc

 

[skywave-rider]

Russell,
Go industry standard and hook up the woofer so that pos batt to pos of speaker (x-over) input gives forward cone motion. After that, hook up your measuring gear and determine HF polarity. Adjust that if needed and leave the woofer.

I thought you had the Behringer. Cool on the mic pre. I like my Tascam US-144, but it does not work with Sound Easy. (I know there are pple using it with Windows....) Works great in all Mac applications though.

 

[jackgiff]

Question to speaker guru's

I bought a pair of the B & C PS32 woofers on the E-Bay sale pointed out a few pages back. Cost was like $35 each. Their FR was measured in a cabinet of roughly 2 cubic feet, and it seemed like they would be nice candidates for an EconoWave. Before using them, I have a few questions that Gordon, Ray, and others can probably easily answer for me.

The Fs of the driver is 44 Hz, and WinISD shows a decent plot with the box tuned to 50 Hz. Tuning it any lower (40 Hz, for example) doesn't seem to lower the F3 , but does start the roll off at a higher frequency. The surrounds are extremely stiff treated cloth type, which may be partly responsible for it's Fs being so high.

Would changing the surrounds to foam lower the Fs any? Would increasing the mass of the cone? Would doing either of these things lower the F3, or would doing so change the other parameters such that it would become a throw away?

A pair of the 2 cubic foot cabinets from Parts Express will be here today, and the B & C's are the only 12 inch drivers I have on hand. The cost was low enough that I may try to modify them somewhat before using them, if there seems to be any chance of success. Am I plotting to shoot myself in the foot?

 

[Russellc]

Russell,
Go industry standard and hook up the woofer so that pos batt to pos of speaker (x-over) input gives forward cone motion. After that, hook up your measuring gear and determine HF polarity.

The 2235H I'm using has forward movement from pos battery to black post on speaker driver itself. Not sure what will happen when battery positive is applied to pos post of the crossover input. Zilch says sometimes this "changes" so I'll have to try it that way. Maybe I've misunderstood something here? Very likely!:yes: Hope I havent confused anyone else!:scratch2:

P.S. I did in fact misunderstand: The "change" Zilch refered to was when the box had been corrected internally i.e. inside the box, so that now externally, the box would work with standard convention, red to red causing forward movement. Then, owner forgets he's made said change, and knowing he's using a JBL with pos to blk = forward movement, and "corrects" for it. I'm sure everyone else saw this from the beginning, I just missed the "internal-external" thing.

Russellc:stupid::drunk::headscrat

 

[skywave-rider]

No, you're fine. The JBL black, which is positive in the case of your driver, goes to the positive connection of LF out of x-over. Then hook up your amp out as normal to x-over input. Plus to plus. When u check that with a batt, you should still get forward cone motion when batt plus is connected to x-o plus input. Then hook up your HF as needed. I don't remember if DE250 works like the Selenium 220 Ti; but I never worry about that because I always look at it with a quick measurement. You can hear wrong polarity notch at the crossover most of the time, too. Sometimes it's not so obvious to hear depending on the x-o slope and everything else.

 

[Russellc]

I don't remember if DE250 works like the Selenium 220 Ti; but I never worry about that because I always look at it with a quick measurement.

Looking at Wayne's 4PI crossover, I note the Eminence 2002 is hooked up like E'wave on the HP, pos to neg and neg to pos, while the same crossover with DE 250 is pos to pos, and neg to neg. When I inquired to Wayne about it he explained that he sets it by the measurements, just like you said :yes:

Russellc

 

[Zilch]

You know the primary variables, Russell, and the horizontal displacement of the acoustic centers is primary.

In my case, the QSCs are sticking out forward of the woofs as shown in the pic, and the polarity is eWave standard after inverting the JBL woofer to industry standard, i.e., in absolute terms, the tweeter is connected inverse polarity:

http://www.audiokarma.org/forums/attachment.php?attachmentid=151281&d=1242968714

Indeed, 2235H is connected pos to pos in 4430:

http://www.jblproservice.com/pdf/Studio Monitor Series/4430LR.pdf

But the SYSTEM is negative:

http://www.jblpro.com/catalog/support/getfile.aspx?docid=241&doctype=3