That is very interesting indeed….
I may have to grab a set just to try it….
The fir seems easy enough… and yeah that makes perfect sense…. Thank you
Nice to hear that , nice to have a CD nearly flat 400 to 20K with little 3 order distorsions must be incredible in the right horn and small corrections .
perhaps this one would make a nice combo
http://horns-diy.pl/horns/k-horn/
Well, let's take a deep breath here. One of the not-so-good things I've found about on-line forums is the tendency to jump to conclusions without perhaps proper due process. I think that the original horn he used was one that he thought was his "baseline" to judge all others. I think we're all guilty of thinking like this--on other subjects, at least from time to time.
So I give the man the benefit of the doubt, and also thank him for bringing to our attention IMD measurements for compression drivers and horns (using ARTA, in this case). Perhaps that he didn't get what others have gotten in terms of measurements shouldn't negate his original intent to illuminate the domain of interest more. I don't fault him for that. If no one is investigating and posting their results, it gets to be a very lonely subject area, indeed. I do think we can ask questions to further understand what was done, and perhaps why it was done. We can then agree to disagree, if necessary.
I do think there are a lot of guys on a learning curve with respect to this particular subject (IMD) including myself. So I'll continue to look to his measurements and others' measurements and their subjective assessments to see if there is something there that I can use. I do think that we should all be careful to fasten ourselves to any unsupported or poorly supported statements (and this is an often found tendency on this forum), and even measurements, but to continue to be inviting to all that can lend a light in the darkness, even if we don't necessarily think all the measurements or decisions are the ones that we'd make ourselves.
Chris
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wih the Celestion Axi some show mesures with big fall of past 6K and others with low natural fall till 20K . who's right who's wrong i don't care i will try one myself one day but multiples informations is always good too hear 🙂
I've been running mine from 200hz-20khz actually... The only thing that would please me more is to be able to run it lower. I was looking at some of my HornResp simulations yesterday.
There was an instance where I wanted to discover the limits of horns via compression drivers. Compression drivers are not unlike Woofers. Where ever the unhorned F is, I guess it could be called free air F? This will directly relate to the performance on a horn and what is possible regardless how big of a horn you use. (A major difference between the Horn vent and a subwoofer vent is the Q of the resonate note created, with the compression drivers you do not get a small area with an excursion null, that energy is spread out much more, a trait of a transmission with a large expansion @GM correct me if I'm wrong))
The free air F of my Axi was something around 200hz? Like 216hz? I'll have to load up the windows side of my laptop to see it. Mind you, I have tried to be strict in my judgement. In that spirit I have kept a 115db/1m expectation. This is for headroom. The Axi plus large 36" long Horn with a 150hz f6, 160hz f3, has allowed me to achieve this with a 200hz 48lr high pass. The main aspect that allowed to achieve this is the high output compression drivers are designed for. While listening at 80db true peak may reach 95db, so even my transients will have low distortion. I so use to my philosophy of design that I forgot to mention these numbers are all based around one horn... With 2 horns in stereo, there is no strain for sure
The natural response is like others have suggested(horn dependant)... This is why I said, In another thread, that maybe there is too much work to do here for passive? I dunno, I subscribed to active crossovers, so I don't know the challenges of passive filtering.
The end result is what matters to me, and this is the result with a few minimum phase filters done within a matter of seconds to minutes.....Theres some problems past 7khz but this the caveat of 2" drivers is it not? Matter of fact, this is pretty good for a 2" from what I've gathered.
I've taken some decent measurements inside my untreated living room at something like 50" away, which is where I seemed to like to sit with this "system", I put system in parentheses cause i've never set up in stereo 🤣 ...This is with a little more time spent on voicing but I never really tried to go "all out" because who cares. When I get Audiolense or Accourate, I'll set a target curve, let the dsp software do its thing and I'm sure the response will be as good as it can be.
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It is ok compared to a lot of 2" drivers out there, but that is not because of the exit diameter, but rather that larger phase plugs will have increasingly more and more modes towards higher frequencies, and in 2 inch exit phase plugs, these modes are spread over a larger area, causing more distortion to the wavefront.
A driver with 2" exit and a phase plug without modes in the audible range, and with absolute control over the wave front shape, would not have these issues.
I would ask for an example of better but unless you have examples of the same horn and different drivers it wouldn't really matter.... Below is the Axi next to the ND4015Be... I'd not give either driver the "win" per say but the large peak at 18khz is not helping voicing for the 18sounds driver.
These are 2 of the best 2" drivers available...
These are 2 of the best 2" drivers available...
JBL's "Coherent Wave" phase plug, introduced with the 2450 2" compression driver in - IIRC - 1989, pretty much solved that issue... when the 2450 is equipped with a Truextent Beryllium diaphragm that does not go into break-up until well past 20kHz, the wavefront stays tidy all the way to the top.
I had to do a fair amount of tweaking to get the details to show but the JBL 2450 with Be diaphragm aint pretty either....On second thought, this is better than the 2 above...or is it.... I'd put them all in the same ballpark, how about that? If you start talking numbers, as in money, will it make sense?
The decay does look pretty clean, gotta give it that...
But its not like I don't like what I see from the Axi
I came for the one of the best midranges in the world.... I wouldn't sweat slight differences in twinklies over 10khz on a 2" driver... once it gets about 16khz my ears check out any way 🤣
I've said it before, and I'll say it again, with these drivers we are at the top of the food chain, You aren't loosing with just about any of these drivers!!! Radian950 and what ever else top shelf driver, used properly, you are winning. Its just fun to chop up the details I guess but if anyone is losing sleep over it, I'd say they have lost focus.
You could also, if you care that much about >10khz, simply use a driver with a smaller exit!
I
The decay does look pretty clean, gotta give it that...
But its not like I don't like what I see from the Axi
I came for the one of the best midranges in the world.... I wouldn't sweat slight differences in twinklies over 10khz on a 2" driver... once it gets about 16khz my ears check out any way 🤣
I've said it before, and I'll say it again, with these drivers we are at the top of the food chain, You aren't loosing with just about any of these drivers!!! Radian950 and what ever else top shelf driver, used properly, you are winning. Its just fun to chop up the details I guess but if anyone is losing sleep over it, I'd say they have lost focus.
You could also, if you care that much about >10khz, simply use a driver with a smaller exit!
I
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I can't remember that I gave you the permission to publish my data that have been send over a private line. Furthermore, the data data beyond 10k are absolutely meaningless in this setup.
Unfortunately, those measurements in Hobby HiFi were for an early batch of Truextent dia's that had some issues.
This has been reported on the Lansing Heritage Forums, but I cannot locate the exact post now.
I am not aware of more recent, equally detailed measurements for the same driver+diaphragm combination.
FWIW, my own "amateurish" frequency and impulse response measurements, done with calibrated Beyerdynamic mic and HolmImpulse software and with the driver mounted onto the Arai A320FL horn, look very clean and free from obvious resonances or break-up all the way past 20kHz.
Not to intrude, but those plots don't look like they contain any state secret to me, but hey, it's your data and sure, you tecnically "own" it.
That touchy tone again, though... tsk tsk
The member POS also measured 2450 + Be.
https://www.audioheritage.org/vbulletin/showthread.php?31657-Truextent-diaphragms-measurements
I like my 2450 SL (Aquaplas). My friend is using 16 ohm Aquaplas w/2450, and he prefers it to stock 8 ohm one, but it's discontinued...
Words have no "tone". The interpretation is on your side. Btw, what about "tsk tsk"...?
To publish data given on a private communication channel that is not your own, not naming the source, no setup is known and then do an Interpretation that is quite meaningless. If you don't like my posts then sfair there is an ignore function but please spare me from lecturing me.
As well, I apologiez, I was not sure where these measurements came from, if these are the ones you sent, that was about 2 years ago, I just have a folder full of measurements that I've accumulated with no mention of source... again I did not mean to expose this, obviously sensitive, data, without your permission.
- mic at ~40cm from the horn mouth
-No smoothing per se. It is a gated response, around 600Hz, so the response gets more precise as precision rises.
- PTF-95HF horn (no really usable under 1khz, so only the HF response can really be compared)
-No smoothing per se. It is a gated response, around 600Hz, so the response gets more precise as precision rises.
- PTF-95HF horn (no really usable under 1khz, so only the HF response can really be compared)
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You can simply buy the JBL 2451-SL 16 ohm diaphragm, then you have a 16 ohm, Aquaplas, 2450 diaphragm, the only real difference is the model number.
You could even buy a 2450 16 ohm Diaphragm, contact and send it to Upland loudspeaker service, Ken will Aquaplas your JBL diaphragms for a price, but is not cost efficient in this case. There are also a few others that will do that on request.
Current model: D16R2451SL
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Yes except for the fact that the ND4015BE is a 1,5" exit driver, with a 4" diaphragm.
The ND3s looks better behaved, also the nitride coating seems to do a much better job in the N versions.
I have been looking for this, but as far as I know it was discontinued several years ago...
Do you know where I can get a pair?
https://reconingspeakers.com/products-page/jbl-d16r2451sl-diaphragm/