Is this the adapter you are using? (The one in the photograph.)Originally Posted by norealtalent
Here is a drawing of the TAD 4002 driver. It is sold as a 1.5" version without adapter and as a 2" version with the adapter. If the adapter you are using mimics this exponential expansion, I imagine you are correct and it will very closely mimic a proper 2" driver being mounted on the horn.
Widget
[quote=Mr. Widget]" I imagine you are correct and it will very closely mimic a proper 2" driver being mounted on the horn."
Well...., what do you know? Who says you have No real talent ?
The advice about using a baffle on the 2397 is great. I just tested this and got a noticeable improvement in sound quality with my 2397/2441 combo. I don't have any measuring equipment, but the difference is not subtle at all.
I'd love to read an explanation of why this works.
BTW, didn't I read that the proper aspect ratio of the horn height to diaphragm dia. is .5 ? 2435/435Be. = 3", 2397 = 1.5" Is that correct?
Do yer Smiths have LIPS?
JBL recommends them:
http://www.jblpro.com/pub/obsolete/2397.pdf
"Vertical dispersion is largely dependent upon the baffling; with the recommended cylindrical baffle extending at least 76 cm (3 in) above and below the mouth, a nominal 60° vertical beamwidth is achieved."
The original Smith design paper is posted somewhere in these forums with design details.
Ya know, I used 6" of foam on top of mine. less like a reflective type baffle and more of a sound absorbing one. The bottom of the horns have the side by side L222/220's below them. Whatever is going on, it sure smoothed the sound out. I must have a reflection problem. Does the recommended baffle extension help the horn achieve 800hz, or does it matter? That's how I read subwoof's advice. I thought the horn would go down to 800hz regardless
That certainly looks like a similar designed adapter. May very well be identical.
Even a stopped clock is correct twice a day.
Well...., what do you know? Who says you have No real talent ?
Who said we don't have a sense of humor on this site?
Widget
My point was that if the expansion is continuous like it is on this TAD example then you will indeed be mimicking a traditional 2" driver. The 2328 and the 2397 "Smith" horn were designed to work with that type of driver. All of the traditional 2" drivers from JBL and TAD and others are based on the original geometry of the Western Electric 594 2" exit driver. These drivers have a throat that has a ~300Hz cutoff and the expansion of the throat is an exponential horn of that rate.
I don't think the initial expansion within the 243X series of drivers is of this rate so even applying an extension that is of the proper rate will exactly duplicate a 2" exit driver like this TAD example does, but the discontinuity may be slight enough that the results are quite acceptable.
You have compared the 2435 using your adapter with the 2441 and found it to be more than acceptable so I would assume you have lucked into an adapter with geometry that seems to suffice. I posted the photo of that adapter in an attempt to clarify which adapter you are using so that others may give it a shot and see if they have similar results. The photo I posted was from the Cannon Sound (Australia) website. I believe the adapter pictured is a P-Audio model. Could you tell us where you sourced your adapters and if there are any markings on them?
Thanks,
Widget
Tractrix horn from : Stereo-Lab.de
425 Euro for a pair.
mats
P-Audio PC5038, perhaps?
No dimensioned drawing on the website:
http://www.paacoustic.com/pdf/ACCESS...C-ADAPTORS.pdf
Re WE594 and it's children:
"By our calculations, the initial flare rate in the older
driver design was approximately 160 Hz, reflecting the
need to drive the very large horns that were used in
early motion picture systems. Today, we can double or
quadruple that flare rate, inasmuch as many horns are
now intended for nominal crossover at 800 Hz."
So here's what I get out of it:
Pattern control appears to be the primary benefactor of increasing
the driver's flare rate, but the comparison of distortion levels, especially
between 2450/2380 and 2451/2352 combinations would seem to indicate
an additional benefit of the wide flare/Optimized Aperature horn pairing.
As good as the 2435/adapter/2397 may sound (indeed, one of the options I'm
considering myself), I can't help but think there may be some benefit in
using a much shorter/abrupt transition adapter (understanding that the smith
horn itself may be the limiting factor in pattern control in this instance).
I suppose the 2435/adapter/2397 may also just be one of those happy
circumstances, but it does seem as though some optimization for the
2435 might be in order (all already mentioned: flare rate matching, horn
scaling, etc...).
I'm certainly enjoying and interested in listening to all
of your experiences and ideas (so thanks for that).
Cheers,
-grumpy
I'm not sure if the 160Hz vs. 300Hz is a function of my fuzzy brain or if I was mixing up usable frequency vs. cut off frequency... as in our tractrix discussion earlier.
In any event, yes pattern control does seem to be much more of an issue in today's designs. I think it is primarily due to the fact that contemporary horn design is almost exclusively in the pro audio domain and most modern sound systems use arrays of speakers that need to work in concert (no pun intended) and not create the lobing and other problems stacking a pile of A-7s or vintage JBL's would create.
All that aside, what will sound best in a home environment is the issue at hand. I have a strong personal bias against the JBL Biradial horns. I have never heard any system using them that sounded as good in terms of imaging or smooth frequency response as a tractrix or some of the other horns including the trusty old exponential radial horns.
Widget
The adapters I use are from Cannon Sound, they look just like the picture but have no identifying marks. They stopped offering them for a while but I have been told they are available once again. The 2435 mounting holes must be drilled and I put them in the lathe to match the driver and adapter perfectly.
The 2435 uses a quite different expansion to the throat than a typical phase plug. There is no tapered expansion as the cross section shows the TAD is designed. All tapered expansion is horn or adapter dependent. The driver itself terminates flush with the phasing components.
It is a very happy combination. Whether by chance or intent I cannot say but I have yet to find anything that does it better. The 2441's are wonderful and have their own qualities but I cannot say they are all around better.
YYYep. That's why I hang around here listenin' ...All that aside, what will sound best in a home environment is the issue at hand.
(mostly)
-grumpy
[quote=Mr. Widget]Even a stopped clock is correct twice a day.
You could look at it that way, or it just may be that you finally recognize what time it is.
243x drivers use a two-stage phase plug terminating at the mounting face consistent with OA design guidelines. After considerable effort, I was able to secure an answer from JBL Pro (Button?) that they were indeed "compatible" with OA horns, though some (235x, for example) would require mounting flange modifications. Clearly, PT Waveguides are also "rapid flare" designs.
In question here is whether this phase plug (below) is "backward compatible" via throat extension with earlier horn designs as is apparently the case with 245x drivers. Are the phase plugs different in the 1.5" vs. 2.0" versions of those large format drivers?
What about Harman Consumer's use of 243x drivers? Do we consider H9800 and Array Series horns to be rapid flare?
Edit: Rob's pic of the diaphragm side of 2431 phase plug, bottom. I'm not seeing what's "two-stage" about it - the initial (~0.25") straight section before the flare? Looks like the outer ring might have a shorter path length due to the angular offset....
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