Zilch's AK Design Collaborative - Econowave Speaker

[cuthien]

Great project. Thanks.

 

[tubtub]

I will wait for the finalize version. Thank you much.

 

[fcarpcarp]

Thank you folks so much for developing this project, I eagerly wait for your results. After hearing a pair of Altecs I've decided horns are on top of my speaker wish list.

fcc

 

[jackgiff]

I anticipate a fixed L-Pad ahead of the adjustable one to have the variety of common woofers balance in the control midrange. That's just two additional resistors, $2.50.

Either way, we're certainly in the "Econo" range for crossover cost so far.... :thmbsp:

Zilch, hopefully we won't need the extra two resistors to lower the HF output, since that is what the two already there are for. According to the chart in the Pi Speakers link you furnished a few posts ago, the series resistor connected to the driver (R1) is to attenuate the output to the desired level. Plus, a capacitor (C3) can used in parallel to compensate the upper octave of the HF. The resistor (R2) across the Inductor is used to return the reactive value of that node at crossover back to the value it would have been before the resistors were added.

I selected the value of R1 to drop the output level to just above the Trusonic level, and the nearest value audio resistor which can be purchased at Parts Express is 30 Ohms. The other resistor (R2) value was calculated to be 16.47 Ohms and since 16 is available, that value was chosen.

FR's of ideal, max, and min (well, almost min) are shown for the Trusonic, and the JBL woofers. The schematic is also shown. I don't have TS parameters for the Trusonic 150FR, but the 80FR and 120FR both have SPL's of around 95, so the 150FR is probably pretty close. Most woofers for sale at Parts Express are in the range of 88-93, with only two noticed that were at about 95. That seems to be a good set point, and if someone tries a woofer with a higher SPL, he can go back to the schematic dated 3-14-08.

Zilch, can you verify these results, and then we are pretty much done with it. The only value that is somewhat doubtful is C3. My assortment of audio capacitors are somewhat larger generally, and you might try tweaking the .47 a little bit to optimize it's effect. I will need to order the necessary parts today for the inductors and resistors, since my xovers are totally patched to get the desired values. The circuits will be enclosed in the cabinets, and then comes the critical listening tests.

 

[Zilch]

Zilch, can you verify these results, and then we are pretty much done with it. The only value that is somewhat doubtful is C3.

You have attenuated ~5 dB from the last version, red. 0.47 uF is fine, green, and that should probably be the design value. 0.33uF tilts the HF response downward for those preferring a bit "mellower" sound, blue, and 0.68 uF makes it flatter and thus, a bit brighter, violet. With the L-pad dialed down to 9:00, 0.68 uF approximates the slope of the last version with no attenuation, black. Note the expanded vertical scale. We're dealing with very small variations here.

Not that men of science would suggest anything untoward, but I hooked it up to an AR2a LF. 2.7 mH and 20 uf crossed it in the desired region, and it balances with the L-Pad at 10:00, as shown. Yes, it will fit the cabinet, either horizontally or vertically.

I'd say it's done; those mating EconoWave with extremely efficient woofers may have to use the 1.5/15/25 version of the compensation filter for 5 dB more output, but this circuit should work for most others.... :thmbsp:

Edit: SPICE reveals contours differing in detail and yielding slightly increased output @ 18 kHz: 2.0/15/25 = Grn, 1.5/15/25 = Yel, 0.47/30/16 = Cyn

 

[skywave-rider]

Nice!

 

[jackgiff]

Here is the parts list I used.

This is the finished parts list for the EconoWave crossover as it was built for my set. You can save a few bucks by using the smaller 15 Watt L-Pads, but I like the bigger 50 Watt versions. The total cost per channel for the crossover is $32.30. Adding in the cost of the Selenium D220Ti ($42.00) and the JBL Waveguide ($9.90) raises the cost per channel to $84.20, or $168.40 for a stereo pair. And that includes the crossover parts for the woofer.

Parts Express has advertised the D210Ti for $25 several times in the near past, and the D220Ti just may be offered at a savings as well. If using 16 Ohm woofers, change the values of L2 to 3 MH and C2 to 5.8 Microfarads. For 4 Ohm woofers, change the values of L2 to .75 MH and C2 to 23.5 Microfarads.

All you need is a pair of cabinets with woofers, the parts list, the schematic in post #84 and a bit of DIY enthusiasm, and you can build a pair of speakers which you can always be proud of. And you can tell your friends, "I built those myself."



Econo Waveguide Parts list for one channel.
Item Part Number Qty Value Cost
C1 027-422 1 4.7 Microfarad 2.13
C2 027-430 1 12 Microfarad 4.34
C3 027-406 1 .47 Microfarad .79
R1 004-30 1 30 Ohms, 10 Watt 1.79
R2 004-16 1 16 Ohm, 10 Watt 1.79
L1 255-040 1 .6 MH, 20 AWG 4.19
L2 266-552 1 1.5 MH, Iron Core 7.57
L-Pad 260-255 1 8 Ohm, 50 Watt 9.70

TOTAL $32.30

It looks like I need to learn Excel or some other program to put things in columns. Oh, well, you get the idea. Good luck.

 

[Zilch]

EconoWave RULEZ! :thmbsp:​

 

[dnewma04]

http://home.comcast.net/~dnewma04/EconowaveBoM.htm

By clicking on the component descriptions, it should load the part and default the part count to the right qty.

 

[dnewma04]

I should also note that I think it's a bit presumptuous to be including crossover components for woofers in this project. using text book crossovers for woofers could very well throw out all of the work done on the tweeter crossover. Perhaps the next step of this would be to create woofer crossovers for various popular options that may be out there.

JBL LE14
Altec 414
Altec 416
Altec 515
JBL D123
Klipsch??

 

[Zilch]

I should also note that I think it's a bit presumptuous to be including crossover components for woofers in this project. using text book crossovers for woofers could very well throw out all of the work done on the tweeter crossover. Perhaps the next step of this would be to create woofer crossovers for various popular options that may be out there.

Having an engineered high frequency system with known performance and documented characteristics greatly facilitates DIY, but anyone undertaking to build using this design should be aware that the task of mating EconoWave with their woofers remains for them in completing a project.

Textbook lowpass filters certainly have a greater liklihood of successful application if used with the appropriate Zobel for each driver, which may be calculated from the woofer impedance and Le specifications. Otherwise, the textbook component values provided will work, but system builders may have to adjust them to optimize for the particular woofers they use, as both Jack and I have illustrated in this thread.

Jack did LE14A, 416A/Z, and Trusonic 150FR. I did AR2a. We'd hope that those finalizing their designs using measurement instrumentation would post the optimum component values for others' benefit here.... :yes:

 

[dnewma04]

BTW, please verify that my BoMs are correct, I created them while watching the NCAA tournament, so I wasn't paying much attention.

 

[jackgiff]

http://home.comcast.net/~dnewma04/EconowaveBoM.htm

By clicking on the component descriptions, it should load the part and default the part count to the right qty.

dnewma04, thanks for the much more complex link showing the parts list for various versions of Econo Waveguide HF systems. I could have used such a link to my Microsoft Word generated table, but I wanted it to show up in the post without a link.

Your link shows the Selenium D210Ti listed along with the D220Ti. The Econo Waveguide is designed to utilize the D220Ti mounted on the JBL waveguide only, and no attempt was made to use the cheaper D210Ti in this system. Including it may convince someone that it is an approved substitute, and cause problems in it's implementation.

Originally Posted by dnewma04

I should also note that I think it's a bit presumptuous to be including crossover components for woofers in this project. using text book crossovers for woofers could very well throw out all of the work done on the tweeter crossover. Perhaps the next step of this would be to create woofer crossovers for various popular options that may be out there.

I included the crossover parts for woofers simply to give the builder a starting point. Perhaps the woofer crossover parts should have been listed separately, and labeled as a place to start. No attempt was made to match the HF section to a woofer except for the JBL LE14A's that I plan to use. I detailed the problems using the JBL LE14A's, and the way to fix those problems simply because the peak at 1.6 KHz made it difficult to discern the response of the HF section at the crossover point. Zilch had listed some characteristics needed for the woofers and the builders should heed those requirements in their selection.

Hopefully, my mistakes in the implementation of the EconoWave won't cause problems for the builders who try it.

 

[dnewma04]

Removed the D210Ti, but if it's too complex, I can remove the link. I'll leave it up to you and the zilchster since it's your project.

 

[Zilch]

It's fine with me now, and eminently helpful.... :thmbsp:

 

[tubino]

That PI Speaker paper on crossovers is great

Textbook lowpass filters certainly have a greater liklihood of successful application if used with the appropriate Zobel for each driver, which may be calculated from the woofer impedance and Le specifications. Otherwise, the textbook component values provided will work, but system builders may have to adjust them to optimize for the particular woofers they use, as both Jack and I have illustrated in this thread.

This seems as good a place as any to re-recommend the Pi Speakers white paper on interaction of crossover with drivers. It goes into greater specifics than most crossover discussions, yet is perfectly understandable even by a new-to-speakers guy like me. It's 74 pages, but with the graphs it is a great read, if you want to get beyond the off-the-shelf /plain textbook solutions.

http://www.pispeakers.com/Speaker_Crossover.doc

 

[SR427]

Thanks to all for contributing to this project. Last several posts have been immensely helpful!

Now I'm ready to go, but am stumped trying to locate a PT Waveguide. I've got the part number -338800-001 - just can't find anyone selling them.

Does anyone have a link or a number?

SR

 

[Zilch]

It's back on Page 1:

http://www.jblproservice.com/forms/parts_order1.html

 

[SR427]

That link isn't working for me. It isn't protected is it?

thanks

 

[Zilch]

JBL Pro Parts:

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