Zilch's AK Design Collaborative - Econowave Speaker

[Zilch]

Having updated his HPM-100 woofer project with standard eWaveguides, Atwoodt becomes "Official E'Waver #75." :thmbsp:

http://audiokarma.org/forums/showthread.php?p=2260584#post2260584

 

[Russellc]

Cool comparo!

Yes it is cool, and underscores a couple of recurring themes with Econowave.

1.) Large Advents can be converted into something that for very little money
can really play with the big boys.

2.) E'waves built with large, especially pro type woofers, can present a whole
n'other level of excitment to the listening!

Russellc

 

[jackgiff]

New LR4 Xover update

Hopefully it is ready for prime time. I can't seem to make it any better without resorting to some kind of electrical EQ. Time for Zilch to have a go at it, and when he is finished perhaps he can put the schematic in a format which will not require Acrobat Reader to see.

There were small component changes made, which are included in the new schematic. The first FR shows the overall speaker response, and the second shows the FR with reversed HF connections to show the crossover frequency.

Edit: I apparently have the new schematic posted.

 

[DENNYDOG]

Awesome Jack!

 

[Zilch]

Looks good, Jack; I'll load up the LR4s and have a look and listen.... :thmbsp:

 

[WopOnTour]

WOT,
I finally measured Altec 414-Z with WT2.
Here are the results. I am pretty sure I did it correctly, will confirm with a different 414 next week, just ran out of time.

Thanks much SKR. Actually since I knew your 414-16E were probably slightly different from my -16Cs I went ahead and ordered a WT3 from Parts Express. Figured it would be handy for so many projects. Will be interesting to see how these old Altec drivers compare...
WOT

 

[skywave-rider]

Thanks much SKR. Actually since I knew your 414-16E were probably slightly different from my -16Cs I went ahead and ordered a WT3 from Parts Express. Figured it would be handy for so many projects. Will be interesting to see how these old Altec drivers compare...
WOT

Very good.
I'll test a different one tomorrow probably.
:thmbsp:

 

[1scienceguy]

I had HD-77s back in the '70s. Are you going to use the port or run them sealed?

I don't recall the position of the level controls but the waveguide might need that real estate. If not you can fabricate a new panel and put the Lpad for the treble there.
I still have a set of HD-77 drivers here from a pair of cabs I gave Kegger. The woofers look pretty beefy.

I was going to leave the ports and make plugs that were similar to the originals (I have one as a template). Do you have thoughts on this??

I have not read the entire 500+ page thread but is there an advantage to adding the waveguide assembly to the box vs. putting it on top?

Is it worth it to try and find original drivers for these boxes?

Thanks again!

 

[Bauhausler]

I was going to leave the ports and make plugs that were similar to the originals (I have one as a template). Do you have thoughts on this??

I have not read the entire 500+ page thread but is there an advantage to adding the waveguide assembly to the box vs. putting it on top?

Is it worth it to try and find original drivers for these boxes?

Thanks again!

The HD-77 is a good box but I don't really consider them restoration material. Others may disagree. I think I paid $150/pair 30 years ago.
There are advantages to having the waveguide as close to the woofer as possible, having to do with interference nulls in the crossover region and center-to-center distance.
Google 'econowave' and 'arcsin' to find the discussion and the math on that.

 

[skywave-rider]

http://audiokarma.org/forums/showpost.php?p=2160034&postcount=1519

From Wayne Parham on baffle spacing, etc..

 

[MartinV56]

I'll be using them for critical listening in a music room.

I can build the box per specs but I do not have the speaker building experience to know the dimensions. Thoughts??

I checked out the Eminence 12" woofers. Do you have any model numbers that you recommend?

Thanks again! This is SUPER helpful. I know several others that are following this thread that are in the same boat as I. Thanks for the comments. Any info is helpful for those of us with less experience.

Delta 12 LFA

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=290-416

 

[1scienceguy]

The HD-77 is a good box but I don't really consider them restoration material. Others may disagree. I think I paid $150/pair 30 years ago.
There are advantages to having the waveguide as close to the woofer as possible, having to do with interference nulls in the crossover region and center-to-center distance.
Google 'econowave' and 'arcsin' to find the discussion and the math on that.

GREAT reading material!

So i'll cut out a space for the waveguide. Good discussion there.

The boxes came with one original 77 woofer and a Rat-Shack replacement. Is there a need to have them both the same make/model? The replacement speaker is very close in numbers to the originals.

 

[Russellc]

I was going to leave the ports and make plugs that were similar to the originals (I have one as a template). Do you have thoughts on this??

I have not read the entire 500+ page thread but is there an advantage to adding the waveguide assembly to the box vs. putting it on top?

Is it worth it to try and find original drivers for these boxes?

Thanks again!

Some advantage to putting on top, for one, time alignment. Another is ease of changing out drivers, horns/guides, etc.



Russellc

 

[Bauhausler]

Painting waveguides

I've used Krylon Fusion with good effect on plastics. Is there any technical reason not to put paint on the inner surface of a waveguide? Black might not be for everyone.

 

[Bauhausler]

Some advantage to putting on top, for one, time alignment. Another is ease of changing out drivers, horns/guides, etc.



Russellc

What advantage is there to time alignment if the waveguide is on top of the box?

Unless the woofer is very close to the top edge of the box like the DQ-10 I would still recommend placing the waveguide in the box for permanent installations to reduce the center to center distance. The discussion of crossover nulls clearly shows the advantages of a compact configuration.

 

[Zilch]

I've used Krylon Fusion with good effect on plastics. Is there any technical reason not to put paint on the inner surface of a waveguide?

Not an issue.

What advantage is there to time alignment if the waveguide is on top of the box?

It may be moved forward and back to "aim" the lobe. Closer C/C generates a taller lobe, but time alignment becomes more critical....

 

[jackgiff]

EconoWave Xover with DE250

I have been playing with the standard EconoWave crossover on one channel of the B&C/PE trapezoid cabinets pair to A/B that against the LR4 Xover. Zilch has been worried about the DE250 causing a rise in crossover frequency to 1.8 KHz rather than the 1.6 KHz we like. As long as it was hooked up, it seemed like a good time to tackle the frequency problem.

With the B&C woofer, the low pass of the EconoWave was also off frequency, so I substituted the Dayton DC300 12 inch Classic that was on hand. It performs great with the EconoWave, but the DE250 with it's higher impedance crossed over too high to hit the 1.6 KHz. The .7 mH inductor and 7.5 Ohm resistor in series across the DE250 took much of the 2 KHz overshoot off, as it did in the LR4 circuit. Raising the value of C1 to 6.8 uf moved the crossover back to the desired frequency.

The FR's show the crossover frequency, and the performance of the speaker using the EconoWave Xover with the following exceptions. C1= 6.8 uF, woofer Zobel = 20 uF and 20 Ohms, and .7 mH and 7.5 Ohms in series across the DE250.

Time for Zilch to try these changes and see if the performance is up to snuff. :yes:

 

[GordonW]

Have we just tried a bigger inductor and a smaller cap on the basic high-pass circuit, and see if we can get the same result without additional parts count, using the DE250? Maybe like a .8 to 1mh coil, and a 3.3 to 3.9uf cap?

Sounds like the higher impedance of the driver is raising the Q of the crossover... more pronounced "bump" just above rolloff, and steeper rolloff are both possible symptoms of just that. Lowering the crossover Q (which requires a bigger coil and smaller cap) might do the same thing as the steps just tried... without requiring additional impedance modification circuitry...

Regards,
Gordon.

 

[jackgiff]

Have we just tried a bigger inductor and a smaller ncp on the basic high-pass circuit, and see if we can get the same result without additional parts count, using the DE250? Maybe like a .8 to 1mh coil, and a 3.3 to 3.9uf cap?

Sounds like the higher impedance of the driver is raising the Q of the crossover... more pronounced "bump" just above rolloff, and steeper rolloff are both possible symptoms of just that. Lowering the crossover Q (which requires a bigger coil and smaller cap) might do the same thing as the steps just tried... without requiring additional impedance modification circuitry...

Regards,
Gordon.

I calculated the HP parts using the 16 Ohm impedance of the DE250 at that frequency, and if my memory is good, it was like 2.5 uF and 1 mH, and got pretty much the same results. Some additional parts were necessary to knock down the overshoot of the De250. I didn't play in that neighborhood all that long, since I was looking for a simple answer not a complete circuit redesign. Maybe I should have stayed longer.

Edit: I remember someone saying Geddes uses the DE250 at lower frequencies than we do. How does he flatten it's response? Anybody have a schematic of his circuit?

 

[Zilch]

Have we just tried a bigger inductor and a smaller cap on the basic high-pass circuit, and see if we can get the same result without additional parts count, using the DE250? Maybe like a .8 to 1mh coil, and a 3.3 to 3.9uf cap?

I started to do that, but then remembered that the highpass is up at 3 kHz; it's performing part of the HF comp function. I'm about to kerfutz more with it, now that Jack has defined a specific approach from his experience. I'll see how much can be done with just the inductor.

Edit: I remember someone saying Geddes uses the DE250 at lower frequencies than we do. How does he flatten it's response? Anybody have a schematic of his circuit?

No schematic, but reverse engineering from the photographs, it's three series notch filters after a single-pole highpass, plus a bypassed L-pad for attenuation and HF comp. Unfortunately, he pays zero attention to the vertical nulls, though he suggests they may be adjusted via the conjugate in the lowpass: