I was pleasantly surprised when I saw Kevin’s off axis measurements. Rather a lot better than expected, especially for a 2” driver. I suspect the vanes do a lot to help the horizontal response. Maybe the mixed expansion in the vertical axis effects the polar response too.
I’ll continue with that over in the other thread.
After reading most of this thread, which took me most of the afternoon, I think I'm settled on either a Behma CP755/ND or a Behma CP855/ND with the Ciare PR614's for a build. Crossed at around 700 hz. If I could find a different horn I like that would go lower, I might be able to drop the crossover point down a bit, maybe 500hz.
I might think about the Iwata 200 or 300 to get the crossover frequency lower, but I haven't found a source in the US where I can get them at a reasonable cost. I'm ok with the PR614's, they look pretty good crossed 12db/octave around 700.
I would pair these with subs, so going super low isn't a huge deal. Getting something efficient down to 80-100hz would be the goal, of course if I can get lower that would be great too. If I could achieve that in a 12" woofer, I could build something just slightly wider than the PR614's, which are 13" wide, and put the PR614's on top in a separate box or even without a box. Preference on the bass box would be bass reflex, but I might also look at some TL designs to see if I can get something in a ~15" wide design that is fairly tall so I don't need stands.
These will be for an audio/video party room, so high volume is in order! I have plenty of power, so that won't be an issue. Any thoughts and ideas on the above would be appreciated.
I might think about the Iwata 200 or 300 to get the crossover frequency lower, but I haven't found a source in the US where I can get them at a reasonable cost. I'm ok with the PR614's, they look pretty good crossed 12db/octave around 700.
I would pair these with subs, so going super low isn't a huge deal. Getting something efficient down to 80-100hz would be the goal, of course if I can get lower that would be great too. If I could achieve that in a 12" woofer, I could build something just slightly wider than the PR614's, which are 13" wide, and put the PR614's on top in a separate box or even without a box. Preference on the bass box would be bass reflex, but I might also look at some TL designs to see if I can get something in a ~15" wide design that is fairly tall so I don't need stands.
These will be for an audio/video party room, so high volume is in order! I have plenty of power, so that won't be an issue. Any thoughts and ideas on the above would be appreciated.
Seems like a small horn for 700Hz, but it doesn’t hurt to try!
What are you looking for help on. The bass cabinet?
What are you looking for help on. The bass cabinet?
It is close to a TH-4001 clone.
And as has been suggested several times by Dr. Bruce Edgar and other experts in old threads. The original TAD horns have "built in EQ" to tame the peaking up top from the TD 4001, and to smooth out the mid band bump 2-5k, making it sound much more pleasant with no need big need for passive components to tame correct the response. Which was more important back then, vs today where most just go active and EQ everything flat.
Added the traditional JBL 2440/4001 graphs from the JBL tech sheets, where you see the behavior mentioned in the 4001s, that I'm sure many are familiar with already.
Attachments
Meh, not really looking for a lot of help. Just throwing it out there in case someone says, "are you crazy?" Or maybe someone says "10" or 12" driver X" would be perfect for that situation. Or "have you looked at this TL project?"
Sometimes it saves you a lot of effort because other people have done similar projects and looked at some of the options.
Thanks.
Haha, I "meh" just about everything! 🙂 I'll start with one horn and a driver and do some measurements. If it's not what I want, I'll ship it back. In the meantime, I'll stay tuned here and other places reading what people like. I think that CD is pretty good so it's a matter of getting a horn with it that I like. I should look a bit harder to see if I can find an iwata horn, I've never played with one of those but others have spoken pretty highly of them.
All in due time, it's always a process.
All in due time, it's always a process.
The 755ND TI/Al is the cleanest, and best suited for home use of those, unless you need the power handling.
The PR614, is a 60x40 horn, that means you will have to cross that 12" fairly high up in frequency if you want a good directivity match and power response at XO. Depending on the cone shape etc, but likely more then double your intended 700hz cutoff, and not many 12"s behave well up there and further.
The PR614 is intended for a 10 degree exit angle compression driver.
Thanks, yea I might have to go with a bigger horn. There are a bunch of nice horn options on horns-diy.pl website, but I can't find prices nor any way to purchase them. Finding horns seems to be a difficult endeavor these days.
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You can see some more modern polar plots of simulated horns based on the A290 documents that I made here
https://www.diyaudio.com/community/...ifications-and-bem-simulation-results.382115/
There is a set of images further down that show some measurements from a Japanese publication, useful but not comprehensive.
With some reasonably subtle changes to the horizontal expansion and fin arrangements, improvements can be made and altogether better results can be had. This is alluded to in the A290 documents that are around.
The radial horn with fins approach has merit, the directivity can be very consistent. The vertical is too small to constrain the directivity in both planes to the same frequency. Often this results in waistbanding which the basic A290 curve is susceptible to, this is not a fixed quantity of all similar horns and with care in selecting the profiles it can be improved.
The TAD has an asymmetric rectangular throat entrance and trapezoid like fins, so it is quite different in some ways that might not be obvious looking at it.
The PR614 worked well to 800hz when I last tested it with a 12" midbass. Sounded better than crossing at 1.5k.
Sounds promising, another option would be the 18 sound XT1464. Per arez above, he doesn't think the PR matches well with the CP755. What 12" midbass did you use? I was looking at the Faital 12PR320 as an option.
Thanks.
Thanks.
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Please do NOT quote the entire post just above yours. The software had been tweaked to make this difficult, don't work around it.That peak at ~17kHz is the half-roll Be surround resonance. Hardly audible by most - and when so, it adds "air" and "sparkle", it is NOT perceived as "peaking" in the treble (which would be 2-6 kHz, typically).
The JBL "diamond" surround spread out the surround resonance over a wider bandwith, but it had issues of its own (which obviously JBL decided to gloss over in their marketing blurb...)
As for the "mid band bump" at ~2 kHz, that is NOT an artifact of the TAD driver, but instead of the TD-4001 horn, which, when used in ALL TAD studio monitors, was in fact passively equalised via a parallel RLC notch.
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Yes.
The asymmetrical rectangular throat entrance (fed by a short, zero-expansion throat adapter that squishes the wavefront vertically, from 50 mm round to 40(H)x50(W) mm rectangular, is intended to better force the wavefront to adhere to the horizontal horn walls, and feed the five horn cells equally.
The straight-sided trapezoid fins are somewhat crude (vs. the more rounded ones in the Yuichi horn), but they get the job done ;-)
In a true 2-way with a large(r) LF driver for home use the horn Fc better be 500Hz or less and the cutoff ~800 Hz max. Anything above that and the whole concept changes. The requirements for success are rather stringent. That has been my experience. 😎
I think you mean crossover freq. ~800 Hz max. In which case I would agree.
("cutoff" is technically the same as Fc)
Here are some comparisons folks might find interesting. First is the Faital HF140 with LTH142 horn THD peaks around .25%. Second a JBL 2431 on 5006815 guide, THD peaks around .25. Third is DE250 on RCF horn, THD peaks around .9%. Forth is the 18 sound 6ND430 with Wavecor TW030WA11 THD peaks around .3% .
IMO the JBL is brutally clear sounding and can be difficult on some recordings superb on others, Faital a bit dark but 60 degree horns don't work so well in my room, the DE250 and 18/wave have a great all around sound on most recordings. Each one can easily be made into great systems depending on rooms and tastes. I like the 18/wave actively crossed to the AE TD15S at 300 best.
All of the horns are without EQ and I used them without EQ. The faital might like a small high boost.
IMO the JBL is brutally clear sounding and can be difficult on some recordings superb on others, Faital a bit dark but 60 degree horns don't work so well in my room, the DE250 and 18/wave have a great all around sound on most recordings. Each one can easily be made into great systems depending on rooms and tastes. I like the 18/wave actively crossed to the AE TD15S at 300 best.
All of the horns are without EQ and I used them without EQ. The faital might like a small high boost.
