I'll have a look for you, perhaps later today. :yes:
I think many of us have been here.
E'Wavers wanna see the pics, of course, and more listening impressions.... :thmbsp:
Zilch's AK Design Collaborative - Econowave Speaker
- Thread starter Zilch
- Start date
E'Wavers wanna see the pics, of course, and more listening impressions.... :thmbsp:
Russellc
Addicted Member
Agreed! I mean if it was on hand I could understand trying it, but here it was particularly selected! Wasnt 2235H or other known bass producers available? Anyway, since the OP has a set, he should be able to get some "augmentation" from them.
Russellc
Wayne Parham
Active Member
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"
Bi-Radial is a registered trademark (s.n. 73669968) held by JBL Corporation. So even if the shape were the same, Eminence could not call it that. And it isn't the same. There is no diffraction slot in the throat. The throat entrance angle matches the compression driver exit angle and it is radiused smoothly to the wall angle. Both vertical and horizontal walls angles are actually continuous curves, just as the OS shape is. Similarly, the flare profile of OS horns never quite reaches the coverage angle, it simply approaches it. It's an asymptote.
Well, I would expect them to be similar. I haven't studied the PT-F95 carefully, so I can't tell you detailed information. I've only seen published response, the information in the PDF file available from JBL. But I have scrutinized the H290 and of course my own wood horn. I've studied many CD horns, conical horns, radial horns and waveguides. I'm getting pretty good and knowing what to expect from a horn by looking at its features.
The similarities are 1. side walls that provide constant horizontal directivity, 2. approximately the same aspect ratio and, 3. the lack of a diffraction slot in the throat or sharp edges on the flare walls. The throat entrance is radiused to smoothly match the wall angles.
The differences are the subtle differences from flare profile. This does tend to shape the overall response curve and it has an impact on directivity too. That's the stuff that hi-res measurements will show. You can learn a lot from on-axis and off-axis response charts. Impulse response charts are also helpful and sometimes looking at high power distortion charts tells you something too.
But like I said, I think generally, I would consider the PT-F95 to be a horn that was compatible with my design approaches, one that I would probably use or at least look closer at if I were looking for a new horn to use.
I've been very pleased with the H290 horn too. It's kind of a sleeper, one that doesn't get much attention from either the "salad bowl" tractrix or waveguide camps. It's much closer to a waveguide, but right now I think most waveguide folks are looking for devices that are actually called waveguides.
To me, it's always been about directivity and also about smoothness of response. I always liked constant directivity but never wanted to sacrifice quality by using any of those horns with sharp edges in the flare. Sharp edges cause discontinuities that create backwaves, ultimately causing ripples in impedance and response.
As for differences in directivity or far-field response, I'd look at the polars to see if there was maybe a little more or less HF rolloff off-axis on one horn or the other. My guess is the two would be different, but I wouldn't expect a huge difference. The only way to know for sure is to measure them and compare.
That's probably the biggest difference - summing will be different, and the crossover should probably do something about it. The further away the driver is, the more delay it has. Woofers typically have more internal delay than compression drivers because they're heavier and have more inductance. But the horn length creates a fixed delay too.
Crossovers provide another kind of delay, one that isn't fixed in time. It changes with respect to frequency. That's why passive crossover delay works somewhat, but only if the overlap band is narrow. The nulls move as frequency changes. So if you use a passive crossover to provide some delay, it is usually best that it have high-order slopes. Otherwise, the nulls usually move into the desired vertical coverage pattern at some point in the overlap band, shrinking the forward lobe as a result.
2226J Assisted EBS Tuning:
It's derated to 50W, but, as you can see, will deliver 110 dB down to 26 Hz there with that input, no sweat.
I can't find a BB6P option to change the assist slope to 6 dB/octave, but that would likely flatten it more.
Where'm I ever likely to find such a bump filter around here?
JBL BX63(A), JBL 523x active crossover, DEQ2496 parametric EQ.... :yes:
5 cuft 4507 box tuned to 26 Hz w/3 x 3" x 14" vents, Q = 2, 12 dB/octave assist at 26 Hz:
It's derated to 50W, but, as you can see, will deliver 110 dB down to 26 Hz there with that input, no sweat.
I can't find a BB6P option to change the assist slope to 6 dB/octave, but that would likely flatten it more.
Where'm I ever likely to find such a bump filter around here?
JBL BX63(A), JBL 523x active crossover, DEQ2496 parametric EQ.... :yes:
170142/4382=38.8275
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Russellc
Addicted Member
Thanks for the comments Wayne, and the link provided as well. I understand that the 290H is not a biradial horn, I just wantd all to know I didnt make it up,
the 290H is listed in Parts Express catalog as "Bi-radial" is all.
Thanks again for your comments,
russellc
Spectrum77
Super Member
Wayne, E-Wavers- Re: mounting PT-F95HF on B&C DE250- do you think using a bolt-on to thread-on adapter such as (http://www.parts-express.com/pe/pshowdetl.cfm?&Partnumber=264-323&scqty=2) would produce any detrimental effects where the horn throat and driver meet?
I have measured this, and the throat adapters do alter the response, both P-Audio and Selenium.
Spectrum77
Super Member
Cheers. :thmbsp: Never seen an adapter, but presume the thickness of the bolt-on plate would move the waveguide throat away from the driver.
The thread-on driver does the same, actually. It looks like it should work, but in detail, there are differences.
I've investigated this twice, now, under different circumstances with different horns/waveguides, and the results are the same, at least using the Selenium drivers.... :yes:
Well, yes, but it means setting up an "experiment" here....
My subjective two cents say I can't tell anything other than improvement as result from using the bolt-on to thread-on adapter and B&C DE250 over the selenium 210 screw on (smoother and more natural
). While IMO the fit and finish of the parts express bolt-on to thread-on adapters leave a bit to be desired, it does serves my purposes and also qualify as econo, I wish I could say the same about the B&C DE250.
Kegger
R.I.P. 1/12/1966 - 6/1/2017
No problem Zilch I didn't mean to have you do extra work, just wasn't sure what the above statement meant.
Spectrum77
Super Member
You may be interested in this bloke's 7Pi build-
http://www.hifiwigwam.com/view_topic.php?id=25393&forum_id=19
http://www.hifiwigwam.com/view_topic.php?id=35915&forum_id=7
I remember your Selenium vs B&C comparison and comments from much, much earlier in this thread.My subjective two cents say I can't tell anything other than improvement as result from using the bolt-on to thread-on adapter and B&C DE250 over the selenium 210 screw on (smoother and more natural
Can you see a physical gap between the driver and horn due to the adapter?
I think I remember reading somewhere Geddes stating that a seamless interface between driver and horn is crucial and that's why he doesn't use thread-on units. But his designs aren't Econo, either.
Yes. The adapter sets it out a little less than 1/2" further than the threaded 210 selenium.
Spectrum77
Super Member
Cheers, mate.
Russellc
Addicted Member
My subjective two cents say I can't tell anything other than improvement as result from using the bolt-on to thread-on adapter and B&C DE250 over the selenium 210 screw on (smoother and more natural
It may very well depend on the adapter. I have one that the driver screws flush to the surface that goes against the horn. I dont think it would have this sound difference, the driver is up against the horn as close as it can get, whether bolted or however its mounted. Zilch, are you refering to models that dont screww flush to the mounting surface, so that a little "chamber" is formed? Wayne has excellent luck using DE 250 with the Eminence H290 horn. I have tried that horn and it sounds fine substituted into my existing E'wave setup, Skywave says it needs slightly different compensation that the little 9.90 JBL waveguide.
whoops, looking at the part I see I have the "opposite" addapter. Mine is for putting a screw on driver onto a bolton horn.NEVERMIND!
Russellc
Here's a pic of the box setup and the crossover. The crossover is brass bolts through fiber board, with everything tie wrapped down and soldered to the ends of the brass bolts. First time I've done anything like this - I think a PC board will be used next time.
I double checked the crossover wiring and found I had missed a connection (not fixed in the pic - can anyone spot it?) - fixed that and the highs sound better. I really want to cut the box open and mount the horn right above the woofer, and preserve the grill as well, but I should go with mounting the horn in its own box and let it sit on top. Would anyone really care if I cut up an L55 cabinet to mount the horn on the baffle? (I know the LH people would.) Then I could add an extended bottom to the cabinet and add about 0.75 cubic feet of volume. And brace the inside - the cabinet vibrates like mad!
I measured the cabinet tuning with my WT2. With my refoamed LE14As the boxes are tuned at 41 Hz. I removed about half the area of the port by putting a pair of window caulking tubes into the ports and that drops the tuning down to 28 Hz. One tube drops it to about 38 Hz. This doesn't seem very low, but there is plenty of bass.
Listening impressions are good, but I barely have an hour or two with them so far. But I can say they play loud AND clean and are detailed without being bright. Room dispersion is very good, such that walking around or even leaving the room doesn't kill the balance too much, which is what CD is all about I guess. I have these in a very small listening area (9x12x7!) so imaging is not great no matter what I use, but these are the best so far. Perhaps a CD horn is exactly right for a small room, given that it minimizes boundary reflections? After they are more 'complete' I'll be able to try them out in a bigger room.
Zilch, thanks for getting this going! I've been curious about horns for a long time and this design really helped me get something started. These are my first DIY speakers, but now I'm wondering what a 2235 with an LE85 in an L300 style cabinet would sound like, but that's not so econo!
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Quick update! I played them loud enough to find out that the back panel on one of the cabinets is loose! It doesn't just vibrate - it rattles with a loud buzzing sound. Holding it down with my hand stops it, but I really need to brace these up. Anyone ever hear of a JBL cabinet loosing it's glue strength so that a panel becomes loose?
Junction between the resistors and the cap/inductor junction in the highpass?
Do it. Tune to 30 Hz.... :thmbsp:
