Econowave style HF horn for pre-existing woofer cab? - diyAudio
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Old 14th January 2013, 03:39 AM   #1
rongon is offline rongon  United States
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Default Econowave style HF horn for pre-existing woofer cab?

I have a pair of Klipsch KG4.5 speakers that I was playing with. The best thing about them is that they are 95dB/1W/1m efficient (8 ohms), and their 10" woofer makes pretty darn good bass. What's not so good is the cheap horn tweeter (harsh) and the not-so-competent crossover. The speaker sounds kind of flat and two-dimensional when compared to Tannoy dual-concentrics, for instance.

I could sell the Klipsch's, but then I came across the EconoWave project from years past. It seems people were building them into old Advent Large cabs. Well, I think this Klipsch 10" woofer can beat that, and they're already in functional cabs.

So, some questions for any of you who are experienced with the EconoWave, and are willing to help a newbie along....

1) How low can the 'standard' Selenium D220Ti-8 go when mounted in the Peavey PH612 or Dayton 6512 horns? The specs say 1000 Hz, but I doubt they'll go that low cleanly. Would 2kHz be an OK xover point for this combo?

2) I might pony up for the B&C DE250 drivers with an adapter, instead of the Selenium driver, if the B&C driver is all that much smoother. Definitely, if it can go lower, cleaner.

3) Should the xover slope be steep, maybe 3rd order?

4) I think I'd use one of the Klipsch multi-tapped autoformers to reduce the output from the horn, instead of resistors. (I'd have to buy a pair.) Does that change the xover design, or does it just replace the L-pad?

5) And finally, how difficult is it to integrate a woofer you don't know much about with this Econowave driver+waveguide? An impossible task for someone who has never successfully designed a crossover from scratch?

Thanks.

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Old 14th January 2013, 04:33 AM   #2
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Unless someone or you, already measure your woofer or your woofer + cab (read about measurements), then you are shooting in the dark.
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Old 14th January 2013, 01:40 PM   #3
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The whole idea of the E-wave is that the waveguide can be retrofitted to any number of existing boxes. The tweeter crossover is the heart of the formula, you really should use it as designed (at least at first). Don't go spending big $ for autoformers, better to spend it on the B&C's (search for "Econowave deluxe"). The question is, will the Klipsch woofer play up high enough, cleanly enough to mate with the tweeter. If so, then you need to figure out a low-pass crossover that will work. You night check at Audio Karma to see if anyone has already done a design for the Klipsch.

Bill



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Originally Posted by rongon View Post
I have a pair of Klipsch KG4.5 speakers that I was playing with. The best thing about them is that they are 95dB/1W/1m efficient (8 ohms), and their 10" woofer makes pretty darn good bass. What's not so good is the cheap horn tweeter (harsh) and the not-so-competent crossover. The speaker sounds kind of flat and two-dimensional when compared to Tannoy dual-concentrics, for instance.

I could sell the Klipsch's, but then I came across the EconoWave project from years past. It seems people were building them into old Advent Large cabs. Well, I think this Klipsch 10" woofer can beat that, and they're already in functional cabs.

So, some questions for any of you who are experienced with the EconoWave, and are willing to help a newbie along....

1) How low can the 'standard' Selenium D220Ti-8 go when mounted in the Peavey PH612 or Dayton 6512 horns? The specs say 1000 Hz, but I doubt they'll go that low cleanly. Would 2kHz be an OK xover point for this combo?

2) I might pony up for the B&C DE250 drivers with an adapter, instead of the Selenium driver, if the B&C driver is all that much smoother. Definitely, if it can go lower, cleaner.

3) Should the xover slope be steep, maybe 3rd order?

4) I think I'd use one of the Klipsch multi-tapped autoformers to reduce the output from the horn, instead of resistors. (I'd have to buy a pair.) Does that change the xover design, or does it just replace the L-pad?

5) And finally, how difficult is it to integrate a woofer you don't know much about with this Econowave driver+waveguide? An impossible task for someone who has never successfully designed a crossover from scratch?

Thanks.

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Old 14th January 2013, 03:46 PM   #4
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Quote:
Originally Posted by rongon View Post
1) How low can the 'standard' Selenium D220Ti-8 go when mounted in the Peavey PH612 or Dayton 6512 horns? The specs say 1000 Hz, but I doubt they'll go that low cleanly. Would 2kHz be an OK xover point for this combo?
It's really limited by the waveguide, but you want to match directivity with the 10" woofer as well. 2k acoustic is probably about right, but if you're not designing from measurements and simulations, I'm not sure it's worth your time trying to get that. You might be better off trying to match one of the existing "econowave" high passes for the CD to your stock 1600Hz woofer crossover.. You could also search out the "Z19" high pass, which is lower but very adjustable and might have a better shot at matching the existing woofer crossover, if not totally ideal for directivity matching to a 10".

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Originally Posted by rongon View Post
3) Should the xover slope be steep, maybe 3rd order?
You need something close to 3rd order acoustic to prevent too much output near the waveguide cutoff, but you don't generally need 3rd order electrical to make that happen, and you can certainly go steeper. Again, near impossible to mess with "in the dark".

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Originally Posted by rongon View Post
4) I think I'd use one of the Klipsch multi-tapped autoformers to reduce the output from the horn, instead of resistors. (I'd have to buy a pair.) Does that change the xover design, or does it just replace the L-pad?
If you're using one of the existing designs using L-pads, those used the L-pad (1/2 setting) connected to the driver for the impedance, which is significantly different than the raw driver impedance. Thus, it won't work the same without the L-pad(s) it was designed with.

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Originally Posted by rongon View Post
5) And finally, how difficult is it to integrate a woofer you don't know much about with this Econowave driver+waveguide? An impossible task for someone who has never successfully designed a crossover from scratch?
Pretty much impossible to get it functioning correctly without measurement, but lots of people have been doing it anyway. It is easy to get relatively constant directivity, and reasonably balanced response (with a variable L-pad), so that can be enough to please as long as nothing is too wrong. There are two places where things don't work without measurements or a whole lot of luck (assuming you've taken the high pass from a previous design so you don't have to deal with that complication):

1. Obviously, whatever low pass you use can fail to meet the HF at the right point or on the right slope, resulting in a hump or dip or both around the crossover point, and poor phase tracking.

2. Poor time/phase alignment results in unpredictable behavior in the crossover region as you go up and down the vertical axis, which combines with #1 for better and worse to make things extra-unpredictable.

All that said, I think you have a very good candidate for conversion to constant directivity there.
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Old 14th January 2013, 05:19 PM   #5
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I just tested the Pyle PH612 with a cheap Pyle PDS382 driver. I believe the PH612 is similar to the horn that is used in the original EconoWave. The lowest I could cross is at 1,750Hz (18dB/oct).

I haven't tested it with my Selenium D220 yet. I doubt I can cross any lower. According to my FR sweep, I'm near the cutoff frq.

The two plots are without any crossover. The top plot is the RAW output of the PH612. The bottom plot is with some passive EQs to flatten the response.

Regards
Mike
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Old 14th January 2013, 07:50 PM   #6
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The original Econowave XO point to the D220TI is about 1600Hz. The PH612 is the original waveguide. The XO point is that low to lessen the demands on the woofer and widen the range of applicable woofers.

The have been many custom variations, but the original intent of Econowave was a modular design that could be used with a wide variety of vintage and new woofers as long as they were either 4 or 8 ohms and could get to 1600 Hz w/o any really nasty breakup.

It was meant to be a decent, relatively efficient speaker rather than the best of the best.
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Old 31st May 2013, 02:09 PM   #7
rongon is offline rongon  United States
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Well, it's been a while, but I think I may have stumbled onto a solution. David Harris (Fastlane Audio) has a kit called the Drift, which combines an Eminence B102 10" woofer (with whizzer cone, 92dB/1W/1m) and his own circular tractrix horn with constant frequency response (Dave says his horn doesn't need the EQ normally required for a CD horn). The happy accident is that the B102 works with a 2.5 cubic foot ported cabinet, and my Klipsch cabs are 2.45 cu ft. That's close enough!

For the tweeters, I'll start with a pair of Selenium D220ti drivers, and tweak with reticulated foam a la Earl Geddes. If I end up with a good result, I might upgrade to B&C DE250 drivers, later.

Dave's minimalist crossover lets the woofer run flat out, with a first order electrical crossover point for the tweeter at approximately 5kHz. An L-pad sets the tweeter level. That doesn't sound like it will work, but Dave seemed pretty enthused about it. There is a much more ambitious "extreme slope" crossover design by ALK Engineering available, in case I want to go in deeper.

Fastlane Drift (DIY version) - Drift Recipe

Wish me luck!
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