Zilch's AK Design Collaborative - Econowave Speaker

[Zilch]

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Project Summary:

http://audiokarma.org/forums/showthr...14#post1856214

Member Projects and Acknowledgments:

http://audiokarma.org/forums/showthr...84#post2260584

Member Listening Impressions:

http://www.audiokarma.org/forums/sho...42#post2528142

Supplements:

Wayne Parham White Paper -- High-Fidelity Uniform-Directivity Loudspeakers
WIRED Wiki
YouTube Video
EconoWave Info
HPM-Econo Redo
BarzilayWave Project
Large Advent
Large Advent Utility
KLH-17 Tutorial
Wharfedale W60
MAKE
Nor Cal DIY 2009
Comparo
Floorstander Deluxe
Line Arrays


About Waveguides :

Waveguides
Practical DIY Waveguides
Waveguide Benefits/Drawbacks - Ongoing Studies
Vertical Nulls Video

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Some combinations just seem to work better than others.

Member Jackgiff sent me pairs of two different inexpensive Selenium compression drivers for measurement and evaluation with Altec 811B horns in another thread. He also asked that that I do the same mating them with the $9.90 JBL Progressive Transition (PT) waveguide member Mxlews and I used in project speakers. Here's the scoop on PT waveguides:

http://www.jblpro.com/catalog/suppor...=277&doctype=3

This particular one has a 90° (H) by 50° (V) dispersion pattern, has thread-on driver mounting, and is used in several JBL Sound Reinforcement (SR) products. Dimensions are 12" W x 6.5" H, JBL part #338800-001.

Results for Selenium D210Ti and D220Ti on this waveguide appear below:

1) D210Ti impedance

2) D220Ti impedance is "friendlier."

3) D210Ti frequency response shown unfiltered, with simple R||C filter, and on Altec Model 19 crossover with full HF compensation.

4) D220Ti frequency response, unfiltered, with "T-filter," and Model 19 XO. Only ~6 dB of compensation is required to make it play flat (+/- 2 dB) out to 18+ kHz.

5) D210Ti vs. D220Ti on Model 19 crossover (Oops, legend reversed. D220Ti is Red & Org). D220Ti has better VHF frequency response, but unit-to-unit uniformity is not as good as D210Ti for these samples. Results were similar on 811B.

6) D220Ti on PT waveguide with Model 19 crossover, decidedly the preferred driver based upon both measurements and listening evaluations.

Drivers and waveguides are now going back to Jack, who has a specific project already underway. I've ordered a pair of D220Ti, and parts for a DIY crossover which anyone should be able to construct, the concept being an economical high-frequency section for members who've been wanting to "try the horn thing." It'll mate with just about any woofer (less than 101 dB/W sensitivity for full VHF compensation) capable of playing competently up through 1.2 kHz or higher....

[jackgiff]

There has been a lot of interest on AK about horn systems. Several of the AK'ers got a discount on BMS drivers by making a quantity buy. BMS drivers are world class, but there are other drivers for less money with essentially equal potential. The Selenium D220Ti seems like it would be capable of building an exceptionally nice two way horn system, and doing it on a budget.

My plans were to build an Econo three way version using the JBL Mid/HF waveguide, but the waveguide sells for more than a hundred bucks each. Now that project may become my garage system. I want to try building a great two way horn system on a budget. Almost any woofer will do for the bottom end, but I choose to build mine with refoamed JBL LE14A's.

I have two cabinet pairs to use for this project, a pair of Altec Santana's and a pair of homemade 1.5 times size EV Baronet clones.

I will enclose pix and measurements as the project goes along, and Zilch will keep us updated with his Clio measurements. If you have any interest in building a DIY horn system, join us, and build along. Cost will not be significant. The HF package should run around $150.

[macaltec]

Since purchasing and a preliminary trial of the D210Ti drivers on my 811b horns I became curious about the JBL PT waveguide as an econo alternative. A very timely thread for me. I'd like to suggest the Eminence Delta 12LFA woofer as another fairly inexpensive LF driver choice. It is working very well for me currently and fits nicely into an Altec Santana size cabinet with only port mods needed.

[Zilch]

Originally Posted by macaltec

Since purchasing and a preliminary trial of the D210Ti drivers on my 811b horns I became curious about the JBL PT waveguide as an econo alternative. A very timely thread for me. I'd like to suggest the Eminence Delta 12LFA woofer as another fairly inexpensive LF driver choice. It is working very well for me currently and fits nicely into an Altec Santana size cabinet with only port mods needed.

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

I'd also like to invite those versed in crossover filter design to build along with us here. You know who your are, Ray, Gordon, Steve, Ross, et. al. I'm working with the Model 19 circuit, and a couple of other approaches, one of which I've got pretty good up to 10 kHz, below. More work on that will have to wait until I get my own drivers in here, though....

[macaltec]

As far as crossovers go, I think the Eminence offerings are a good starting point for those a bit less versed in design and then add on additional filtering for compensation and Zobel.

You guys are gonna get me looking at my own test equipment again.

[Zilch]

Originally Posted by macaltec

You guys are gonna get me looking at my own test equipment again.

Eminence jumps from 800 Hz (too low) to 1.6 kHz, though 1.2 kHz is apparently available on special order.

Model 19 XO is operating at 1.3 kHz with this driver/waveguide combo; you can see I'm trying to make it happen at 1.2 kHz so it'll mate with more extended-bass woofers like LE14, red cursor. Someone building with D130 or other high-efficiency types would be fine at 1.6 kHz, most likely...

[macaltec]

That is one of my complaints about them as well. Didn't know you could special order a 1.2k though. I use the 800Hz on my A7's w/511 horn and that works well for me. Currently using a cheapy Radio Shack 2k (it's what I had sitting around)with the Selenium/811 combo so dropping to 1.6k might do me a bit better.

[dmusgrave]

Zilch when are you going to unveil your new project man?

We need to talk about my cabinets as well... can I draw, scan, and send you some ideas?

[Zilch]

Originally Posted by dmusgrave

Zilch when are you going to unveil your new project man?

I keep gettin' interrupted.

Originally Posted by dmusgrave

We need to talk about my cabinets as well... can I draw, scan, and send you some ideas?

Draw and scan away. I'll PM you an eMail address....

[dmusgrave]

Originally Posted by Zilch

I keep gettin' interrupted.

Draw and scan away. I'll PM you an eMail address....

Excellent... I've been doing some stupid things like measuring, etc.

You know... if my girlfriend finds out that this whole thing is entirely your fault... man... I wouldn't want to be you

[RayW]

Originally Posted by Zilch

I'd also like to invite those versed in crossover filter design to build along with us here. You know who your are, Ray, Gordon, Steve, Ross, et. al. I'm working with the Model 19 circuit, and a couple of other approaches, one of which I've got pretty good up to 10 kHz, below. More work on that will have to wait until I get my own drivers in here, though....

I'll put it on the list but I'm currently 3 projects behind, one of which will take priority over anything else I do. I'm going to keep an eye on this thread and see where it goes.

Ray

[Zilch]

All thread-on version, two are brand new, red and green, and two on loan from a pal, the "One who knows."

I'll probably tweak the diaphragm of the red one a bit:

[macaltec]

That looks really good and it fits my most critical criteria, its cheap.

[jgarcia]

ZILCH, how would this combo work w/ the JBL woofer boxes talked about on that other thread, ( gonzo's ). how would it work w/ say 2 - 12" drivers?

regards, jgarcia

[Zilch]

This thread represents a paradigm shift in approaching DIY two-way speaker design. The HF section is conceived as a module or building-block which may be mated with an appropriate LF section either built within the LF enclosure or sitting atop one, standing alone or packaged in its own box, a model commonly used in portable sound reinforcement gear.

It will work with virtually any woofer(s) capable of playing competently up into a crossover region of 1.2 kHz or above. The overall sound of the complete system will depend largely upon the characteristics of the LF module, which is playing both bass and lower midrange, and how well the two integrate with each other.

So, the answer is look to the response characterisics of the LF section with the HF being essentially fixed. It will mate with high- and low-efficiency woofers alike as the sensitivity of the compression driver is quite high, and only minimal compensation, which consumes some of that, is required for it to play essentially flat out to 20 kHz. An L-Pad on a passive crossover or the gain setting on an active one establishes the HF/LF balance of the overall system....