Been there, done that and there's a reason that Altec only marketed one version with the original large tweeter horn/1 kHz XO [best overall point for a 15" coax], which was a commercial flop. Made a great small school PA speaker though [with/without stage riser]: http://www.voiceofthetheatre.com/images/vottcatt1945.10.jpg
Rather surprising/interesting what replaced it though: http://greatplainsaudio.com/wp-content/uploads/2016/06/A6.early_.jpg
These variants OTOH could work with a bit of DSP, but unfortunately are almost never seen 'in the wild' as they move from owner to owner in privacy and not just because they're rare, especially the last one:
9864
9894
A700
GM
The link at the bottom is a review of several types of horns in detail. If anyone has links to more studies that are detail like this one, covering various horns, please share.
What I find interesting is that with the 321hz la cleache horn, it uses a Tad 2001. From what I could find out, the Tad 2001 has a 2" diaphragm, 1" exit, yet on the measurements, it appears to play from about 300hz on up, pretty fine. Group delay is 1.2ms at that 300hz I think. I understand that for bass, group delay can be higher than I expected with trivial consequence but, in the midrange I don't know the acceptable range. So I pulled up a scan speak 12MU/4731T00, in winisd, to find that, in a sealed box, at 300hz, group delay was .5ms and at 200hz, the group delay was 1.1ms. (between ~120hz-550hz the AEtDM sealed is tighter than a 4" scan speak!?)
I'm getting the impression that the freq range spec'd on compression drivers are modest when the driver is used for spl on their lower side, kind of governed by efficiency, pwt performance, and horn used. I'm wondering if a the jbl 4" diaphram in a 350hz jmlc, is capable of going as low with good results.
A lot of details seem to be missing, like xmax information and some type of specs modeling, in order to be able to tell what type of performance would be had at different bandwidth/spl/horn combinations. It does seem like anything above the horn cut off is acceptable for non PA, as long as the driver behind the horn is up for it.
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True, but with no clue what the markup basis would be it becomes what the market will bear, which of course with this type vintage gear is all out of proportion to reality nowadays.
I get really ill when I notice that some relatively inexpensive [used] motorcycle or car I've owned is now going for > what I made in a 30 yr career, with some even after tacking on my entire retirement portfolio.
Admittedly, some were better than average bargains and was pretty sure they would at least ~keep up with inflation, which was good enough for my long term needs, but up to 1400+ times! Never [obviously] in my wildest/greediest dreams. GM
Likely because they have the potential to carry carry everything above the XO point and nobody wants a XO in the middle of the midrange. No different than using a Coaxial dynamic driver crossed to a woofer at 200-300hz. The midrange is the most important band, having this band sourced from just one driver, gives the signal a high coherency, and removes the negatives of an xo from this crucial area that things like vocals, tend to dominate.
Xover points don't affect when a horn or waveguide or woofer loose directivity, size does.
A generalization would be that most horns are ~47.1239 in circumference....and most horn/woofer combos are crossing to a woofer with ~47.1239 circumference....no matter where you cross, you are going to get the same approximate polar detail.....oh wait! This is not the case with constant directivity horns/waveguides....I keep forgetting that...I'm not using a constant directivity horns/waveguides so I guess those problems are not ones that I consider. I thought you made the comment that constant directivity horns or wave guides available don't perform low enough to even consider crossing that low, so if you are using that type of hardware you couldn't even take advantage of that design philosophy to begin with....
Someones going to have to explain this in detail cause at 300hz the polar of a horn of any type (unless big enough to have direcitivty at 300hz and lower, which is gigantic btw) crossing to a woofer of similar circumference is going to have matching polars. If you are matching horns and woofers that vary greatly in size, you have already started to limit the range of successful xo points or made it impossible, for a matching polar.
A generalization would be that most horns are ~47.1239 in circumference....and most horn/woofer combos are crossing to a woofer with ~47.1239 circumference....no matter where you cross, you are going to get the same approximate polar detail.....oh wait! This is not the case with constant directivity horns/waveguides....I keep forgetting that...I'm not using a constant directivity horns/waveguides so I guess those problems are not ones that I consider. I thought you made the comment that constant directivity horns or wave guides available don't perform low enough to even consider crossing that low, so if you are using that type of hardware you couldn't even take advantage of that design philosophy to begin with....
Someones going to have to explain this in detail cause at 300hz the polar of a horn of any type (unless big enough to have direcitivty at 300hz and lower, which is gigantic btw) crossing to a woofer of similar circumference is going to have matching polars. If you are matching horns and woofers that vary greatly in size, you have already started to limit the range of successful xo points or made it impossible, for a matching polar.
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I've wondered about the push for CDs to reach lower too.
I get the desire for them to reach down to where a cone begins to lose pistonic control.
I've heard for a 12", that's 700-900Hz depending. So for a CD to get to 600-700Hz solves that.
And if someone wants to use a 15", I can see they would want the CD to reach a bit lower still.
I'm also beginning to intuit the directivity pass-off between CD and cone, but that seems to be size-of-horn related vs cone diameter, more than anything else.
And it seem like it takes a really big *** horn to utilize the newer CD's push into lower territory... Horn's that are too expensive to make according to B&C's sales manager...
So why the push lower? I sure dunno, unless it's about the whole point-source extension, acoustic center co-location thing.
Cause for example, I've been learning firsthand that synergies have issues...throat to horn matching, and straight sided conical wall problems....but still, the acoustic co-location lets them sound really good.
Maybe the extended range CD's will help acoustic location.
I don't think the push lower is about xover in the vocal range. There's still gonna be one in there no matter what the CD can do...
I get the desire for them to reach down to where a cone begins to lose pistonic control.
I've heard for a 12", that's 700-900Hz depending. So for a CD to get to 600-700Hz solves that.
And if someone wants to use a 15", I can see they would want the CD to reach a bit lower still.
I'm also beginning to intuit the directivity pass-off between CD and cone, but that seems to be size-of-horn related vs cone diameter, more than anything else.
And it seem like it takes a really big *** horn to utilize the newer CD's push into lower territory... Horn's that are too expensive to make according to B&C's sales manager...
So why the push lower? I sure dunno, unless it's about the whole point-source extension, acoustic center co-location thing.
Cause for example, I've been learning firsthand that synergies have issues...throat to horn matching, and straight sided conical wall problems....but still, the acoustic co-location lets them sound really good.
Maybe the extended range CD's will help acoustic location.
I don't think the push lower is about xover in the vocal range. There's still gonna be one in there no matter what the CD can do...
True, but with no clue what the markup basis would be it becomes what the market will bear, which of course with this type vintage gear is all out of proportion to reality nowadays.
I get really ill when I notice that some relatively inexpensive [used] motorcycle or car I've owned is now going for > what I made in a 30 yr career, with some even after tacking on my entire retirement portfolio.
GM
There's a small but steady market for vintage Audio gear and a bigger market for classic cars and motorcycles, but for how long?
Hypes and trends do exist here as well.
Most of the exotic stuff - e.g. 50s and 60s Ferrari's, is primarily bought by investors,
Prices of aircooled 911s that skyrocketed until recently, appear to stabilize or even drop.
Well I mean no one wants that, but like I stated earlier "I'm getting the impression that the freq range spec'd on compression drivers are modest when the driver is used for spl on their lower side, kind of governed by efficiency, pwt performance, and horn used. I'm wondering if a the jbl 4" diaphram in a 350hz jmlc, is capable of going as low with good results."
I'm speculating of course but in particular, by using horns that load quite low, it appears that you can get performance closer to what you see on the PWT measurements, probably limited by final excursion requirements vs spl goals...which its hard to say what drivers can do what since we don't actually have full thiele specs on compression driver diaphragms
And that is true because the full vocal range actually goes slightly than 200hz? but, maybe there's a trend for distortion in the lower register to be less perceived? Lower frequencies have less definition in location perception? I think its the co-location as you word it, getting as much bandwidth out of one source, a long with an aim for the mid range for obvious reasons.
Does anyone have the Le Cleac'h spreadsheet....GM I'm looking at you....lol, no seriously I can't find it so far...
I have it on an HD 'somewhere', though fear it's the one damaged when my 2K Pro machine literally melted down.
At one time though, lots of folks had it/used it, though would probably have better luck on the HE forum or one of the bigger French ones.
That said, download this and tell us if it works. I don't have Excel loaded [is the 'x' on the end removed?]: Dropbox - JMLC_horn_v2.xlsx - Simplify your life
GM
At one time though, lots of folks had it/used it, though would probably have better luck on the HE forum or one of the bigger French ones.
That said, download this and tell us if it works. I don't have Excel loaded [is the 'x' on the end removed?]: Dropbox - JMLC_horn_v2.xlsx - Simplify your life
GM
Thanks GM I also just found it here Rectangular Throat Horn Calculator / Spreadsheet for Le cleac'h and Oblate Spheroid
Just a wee bit lower
: https://www.guinnessworldrecords.co..._comment_id=1001835863163719_1860547197292577 Silliness aside and while there's folks with higher and lower voices, 100-8 kHz is the average AFAIK and of that, only from ~ 250 Hz where the female voice starts out to ~5 kHz where our hearing acuity is at ~the same amplitude as at ~250 Hz need be on one driver/horn and preferably there would be an octave each side for the XOs.
Way back when it was a man's 'world' it started at 100 Hz and no doubt in my mind that the 100-5 kHz chosen for the AM radio BW was for this reason.
Ditto when W.E.chose a 50-10 kHz BW, nominally flat from 100-5 kHz for its 'full range' cinema horn.
Like I said, finally starting to get back to our roots.
Re LF 'definition', close your eyes, cup your ears with fingers spread apart a bit to roll off the lows and hear how 'bright' the world becomes and decide for yourself if you need the LF to help locate sounds.
Another way to make you lose interest in LF 'clarity' per se is to listen to a really 'sweet' sounding [super wide BW] 15" [like you ordered] XO'd at up to even the Altec 604's 1.6 kHz. I've heard washing machines with more 'clarity'.
Of course we need as much as we can get since it's degrading the HF's clarity in the XO BW, so better to push it down as low as practical [< 100 Hz] where at higher SPLs our hearing acuity has ~flattened out: https://cdn.surfacedstudio.com/2010/10/fletcher-munson-curves.gif
GM
Done! Thanks!
GM
OK, now got three locations for Google to choose from.
GM