Zilch's AK Design Collaborative - Econowave Speaker

[Wayne Parham]

One more thing, then I'll leave you guys alone.

Let me throw out an idea, a fun thing to do with your PT-F95's.

Some of you have been talking about three-ways. A straight sided midhorn provides reasonably constant directivity and is easy to build.

Make it large enough and it can be used to relatively low frequency. That gets your speaker CD over a fairly wide range. You can also blend the midhorn and woofer to smooth floor bounce and high frequency room modes.

Now look at the room's corner. It expands 90 degrees from the apex. When a sound source is placed at the apex, it acts like a very large waveguide, which controls directivity down to the Schroeder frequency.

Back a woofer along with your 90 degree midhorn and tweeter into the corner, and now almost the whole audio band is CD. The only band that isn't is the modal region (under 100Hz or so), and that can be smoothed with multiple subs.

 

[skywave-rider]

Thanks Wayne, and appreciate the correction.

 

[Russellc]

The Eminence H290 horn is labeled as a radial horn, not BiRadial. Big difference - For one thing, BiRadials have a diffraction slot and the H290 doesn't and for another thing, BiRadial is a JBL trademark. Radial horns have constant directivity in the horizontal plane. Directivity is not constant in the vertical, but that's harder to do anyway. I'm not sure it makes sense to say any horn with aspect ratio like this has constant directivity in the vertical plane, and when the off-axis nulls are considered, doubly so.

The bottom liine for me is how the horns behave. As you can see in the off-axis charts at the link below, the H290 is pretty uniform off-axis.

• four Pi loudspeaker performance data

I've seen plenty of waveguides with more off-axis rolloff than the H290. The 90x50 waveguide you guys are using here looks pretty good to me, actually looks very similar to the H290 from the charts I've seen. As long as the crossover is adjusted so summing is right through the crossover region and placing vertical nulls outside the pattern at HF, I expect performance to be similar. But I've seen some waveguides with more off-axis rolloff than horns that are designed for collapsing directivity. A device like that is CD or waveguide in name only.

My conclusion: Don't get hung up on the name, look at the polars.

I believe you, I just went by the info in the Parts Express catalog. There, ( not that they cant make mistakes ) its listed as :
#290-554 H290 Bi-radial 1Kz 90 x 40 1"

Russellc

 

[Russellc]

One more thing, then I'll leave you guys alone.

Let me throw out an idea, a fun thing to do with your PT-F95's.

Some of you have been talking about three-ways. A straight sided midhorn provides reasonably constant directivity and is easy to build.

Make it large enough and it can be used to relatively low frequency. That gets your speaker CD over a fairly wide range. You can also blend the midhorn and woofer to smooth floor bounce and high frequency room modes.

Now look at the room's corner. It expands 90 degrees from the apex. When a sound source is placed at the apex, it acts like a very large waveguide, which controls directivity down to the Schroeder frequency.

Back a woofer along with your 90 degree midhorn and tweeter into the corner, and now almost the whole audio band is CD. The only band that isn't is the modal region (under 100Hz or so), and that can be smoothed with multiple subs.

I have thought of building a midhorn Pi kit for several years. Had I not stumbled on these 4647 cabs, all my jbl drivers would still be in boxes.

russellc

 

[Russellc]

No problem Zilch. Good to see you guys.

Ever since I've started watching this thread, I sort of considered the PT-F95 90x50 waveguide to be a compatible horn, one that I would probably use today if I were looking. It's a step up from the 2370, which could sound kind of harsh and splashy, because of sharp edges that cause discontinuities, ultimately creating internal reflections. These show up in the response curve and make the horn sound a little bit harsh. I always liked constant directivity, but not enough to sacrifice sound quality in that way. So to me, a good radial horn was always the best solution. It's the original "waveguide".

The H290 does not have any sharp edges in the throat or along the walls. It is pretty good at making directivity uniform, so it's a good horn for my purposes. I think the same could be said of the PT-F95.

When I was designing my wood horn, I spoke with Geddes at some length and was considering making an elliptical horn. That would be great too. But in the end, I chose a CD shape for the side flares only. They are mostly straight, with the throat radiused from the entry angle, like a quadratic or OS. The top and bottom flares aren't CD and do develop some collapsing DI. The mouth is smoothly radiused on all sides. Horizontal beamwidth is locked at 90 degrees. Vertical beamwidth is between 40 and 50 degrees through most of the passband, but opens to about 60 degrees down low.

Vertical directivity is a tough nut to crack. If you make the mouth large enough to really get vertical CD at the low end of the passband, then the mouth is so tall the null angles become narrow. That defeats the purpose of having a horn with vertical CD, since the nulls would fall within the pattern. For me, the balance of competing priorities seems to fall in favor of something like the H290, my wood horn or the PT-F95.

Is the H290 and the Econo wave guide the same (in performance) if not in name? One thing I notice is that there seems to be more "constant directivity" going on a little farther away from the speakers than with the E'wave, which starts developing a wide sweet spot a little closer. Is there anything going on with the phase between the HF and LF drivers because of the greater "length" of the H290? The H290 sounds fine in this application, and is a heavier duty horn. Really nice with both The Selenium 220 Ti and the JBL 2425H, standard E'wave crossover. So similar to the 4 Pi JBL!

Russellc

 

[Richard C.]

Hello all...

I have a couple of 2226J's left over from the JBL tent sale, that I always thought about using in a DIY project.

I know they are 16 ohm which isn't optimum for solid state amps.

And, I know they have a high Fs. I have read of a sub-woofer made from a 2226, but I think that's stretching it too much.

Can these really be driven below Fs, while limiting Xmax, to provide fairly deep bass (35 Hz) in a home with a ~300 sq. ft. room? Would a 5 or 6 cu. ft. box per driver, be a good start?

It's either this or I sell them.

Richard C.

 

[Zilch]

Can these really be driven below Fs, while limiting Xmax, to provide fairly deep bass (35 Hz) in a home with a ~300 sq. ft. room?

Yes, they can be used in assisted alignments. The power handling is huge, and so they can be used with considerable boost below Fs.

There's a project on the 'net doing just that for a sub, but the link is in my other computer. I'm trying to remember the name, 'cause the link's over on LHF, and that'll bring it up.

Put 2226 in BB6P and see what that comes up with in "Assisted Vented."

 

[Robh3606]

Hello Zilch

This the link your looking for??

http://www.speakerbuilding.com/content/1014/page_3.php

Rob

 

[Zilch]

Thanks, Rob, that be the one! :thmbsp:

 

[dnewma04]

Thanks, Rob, that be the one! :thmbsp:

Yikes, reading that article makes me pretty curious about the credibility of the author. A 400.00 JBL woofer costs 50% of the cost of car-fi subwoofers? Granted, there are 800-1200.00 subwoofers, but these are woofers in a different league altogether. A 600w car audio sub with 23mm of linear excursion and a very flat BL curve and low distortion can be had for 50% of the cost of the JBL. For 400.00, you are talking about drivers with 3-4x the swept volume of the JBL which are approaching the lowest distortion Klippel or DUMAX have tested. For 800.00, you are getting to the more popular high end drivers that offer similar performance to the 400.00 variety (JL W7s and the like) After reading the first page, it was tough making myself click to view the next page.

Maybe I'm just a bass purist, but calling a 2226J an Almighty Subwoofer is borderline comical.

 

[dnewma04]

Article is from 1997, I'll let it slide. This was at the advent of the car audio market driving subwoofer technology advances across all facets of audio.

 

[Richard C.]

I did read that article about a year ago...

and I read the reviews from many people wondering why he chose that particular driver. Most people could name several drivers that would be better suited for a sub. I know the power is quite limited in the lowest octave this way, and augmenting the drive might make it worse.

I bought a Titanic III 15" from Parts Express and tuned the original JBL 7.5 cu. ft. cab to 20 Hz, and I am pleased with it.

Richard C.

 

[Zilch]

Article is from 1997, I'll let it slide. This was at the advent of the car audio market driving subwoofer technology advances across all facets of audio.

I'm not talkin' sub here. The question is can you augment the bass response.

I know the power is quite limited in the lowest octave this way, and augmenting the drive might make it worse.

Put it in BB6P and see what it says.... :yes:

 

[dnewma04]

It was no dig at you, Zilch. It was aimed squarely at the author of that article.

 

[Russellc]

Article is from 1997, I'll let it slide. This was at the advent of the car audio market driving subwoofer technology advances across all facets of audio.

He's also in Norway...

russellc

 

[Russellc]

It was no dig at you, Zilch. It was aimed squarely at the author of that article.

I dont follow you, if hes getting the results he says he is and not pushing the driver beyond its limits, seems like its doing a hell of a job. Not the driver I would have selected, but his results look great. i know its not exactly the same driver, but results I've had trying to tune 2225H below 40 havent worked very well, but I was doing 2-way, not sub duty.

Russellc

 

[dnewma04]

Russell,

My exceptions mainly came because I hadn't originally noticed the date. In the context of it being 1997. it is much less proposterous. If that article was written in 2005, it would have been laughable in it's ignorance and misinformation on the first page. The rest of the article isn't too bad once you get past the introduction. He does seem to get adequate results. It's like he had a job that needed a big hammer, and instead, he bought a little hammer and built a machine to make the little hammer act like a big hammer. The results seem to be good, but if he got a big hammer and put the kind of effort into it as he did the little one, the results would have most likely been even better. The article is about a subwoofer, so that is what I am basing my comments on, the 2226J as a subwoofer. Most people in this thread know of it's competence as a woofer.

Again, in 1997, there is probably more justification to use something like the 2226J, today, it probably wouldn't be in my top 50-60 drivers that I would choose to do subwoofer duty. Like I said earlier, maybe I'm just a bass snob, but there are literally dozens of drivers that are very distinctly better at doing sub-bass and all but a small handful will set you back about 25-50% less than the JBL.

 

[dnewma04]

He's also in Norway...

russellc

Ah...he may have been pining for the fjords. Hadn't thought of that.

 

[Richard C.]

I have a problem...

I'm not talkin' sub here. The question is can you augment the bass response.

Put it in BB6P and see what it says.... :yes:

Zilch, I HAVE put it in BB6 and I have experimented with several different box volumes and tunings. My problem is: I don't have the experience to look at a freq. plot and know what it will actually sound like. I can look at a max "flat" plot vs. an extended bass plot, and not know which one I would like better.

Sometimes I would like mid-bass punch and sometimes I would like 16 Hz pipe organ. Maybe I can't have both without having a sub.

You probably have the experience to design with BB6 and then know what it's short comings would be, I don't. I would have to build or borrow a box and then listen for awhile with diffeent kinds of music.

I have some 2-way 1700 Hz Xover, CD horn, speakers that are great at screaming guitar (like Gov't Mule), but some other types of music irritate me. These speakers take very little EQ to be pretty flat at my listening position. Yet, I want loudness "IN" for all music because they rolloff fast < 50 Hz. Flat response "seems" too bright sometimes. I'm trying to stay objective, here.

Richard C.

 

[packrat]

I finished them!

Well, sort of. These are upside down JBL L55 cabinets, with LE14As in them, with the PT horn on top. No pictures yet - maybe tonight. It currently looks like a science experiment, but I got them working! I finished one crossover and speaker hookup last night at 11pm, thinking I'd stop there but after testing it in mono I had to finish the other one too. Got them both done at 11:30 and listened for an hour.

I will not say much about the sound except that they work, they sound better than the Small Advents that I was using, and that I need to listen to some more music. They are in a very small room (~10 x 12 x 7!) They do seem to have an even response throughout the room - walking towards the middle of the two speakers (where the stereo stand sits) does not result in the highs dropping off. They also did not sound harsh or shrill or tinny, even with trumpet or other horn instruments. I can also play them louder than anything else in the house. Radiohead KidA sounded fantastic .

I need to compare them to some other speakers, and see how they work in a larger room. But so far it's :thmbsp: :thmbsp: !