Not a clue. Don't see many people parting those out, but the 2404 phase plug looks pretty similar. Maybe somebody can compare those.
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Not a clue. Don't see many people parting those out, but the 2404 phase plug looks pretty similar. Maybe somebody can compare those.
Hi Jeff, we did exactly that. There are plenty of those parts on eBay right now, just look for '2404H horn throat and phase plug'.
Problem is that even if the cone and the first part of the horn are shared between 2403H and 2404H, the elliptical end section of the cateye horn is difficult to get.
eBay had quite a few of them listed in previous months ... same seller as the one that has the buttcheek phase plugs.
Or buy some cheap ferrite tweeters (no matter which type) with challenged cosmetics, if alnico is difficult to get right now.
Ralph
Measurement distance was 1m, mic and preamp were Behringer. Speakers were fixed to baffle openenig by sqeezing in some pieces of cardboard alongside the horn throat.
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Here's a few shots that show the setup and help to put the Bode traces with / without baffle into a clearer context :
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Following in the next posts are the Bode plots corresponding to the pictured ferrite/alnico JBL tweeters and some non-JBL types.
First, the 2405 (#1 sample) mounted on a small baffle as per the picture in the previous post
Second, the same 2405 sample, but naked on top of box aligned with front face of that speaker
Third, #2 sample of 2405
Fourth, fifth -- the 2404H pair without a baffle -- a meas. with baffle was not done for 2404H
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Here's five rings, some original some with slot (2405) fram.
When viewing watch sample variation, but also keep in mind that the 2405 fram sounded much better than the std. fram despite nice response graphs from all :
First a standard 2402H (sample #1)
Second, std. 2402H (sample #2)
Third we have alnico 2402 with 2405 diaphragm (#1)
Fourth, another sample of the above
Fifth, a ferrite 2402H with 2405 disphragm ex-factory. Metal parts are a wee bit differently machined (see elesewhere) to accomodate the 2405 fram into the ring radiator design.
No difference due to magnet type was found from any of the plots.
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Some non-JBL types were measured and listened to also. The HH was also sold under the Multicell brand in Europe; the sample later turned out to have quite some damage to it's diaphragm, but sounded and measured very good nevertheless. Wonder how good that thing gets when reconed. Perhaps the best value in the field ...
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Also very good, but a bit tame at times was the Goto tweeter type SG16. This is the smallest magnet Goto offers for their super lightweight aluminium supertweeter coil/membrane. Larger magnets with this diaphragm are reported to sound and measure very similar to the SG16. The agile moving parts have very fine resolution as a result. Perhaps resolution will increase with larger magnet size even more.
The larger magnets are also available with Beryllium diaphragm. Deep-pocket territory ...
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A very finely resolving slot tweeter is available in the unusual hemisherical design of the Fostex T825. The fram is quite small and perhaps because of this, resolution and dynamis are similar to the Goto tweeter. Very wide dispersion as in 2405, while neutrality was also really nice. Below is an overlay of the on-axis and 30° plot.
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And here a tweeter from category unobtanium - a mint sample of Coral H100. Quite a bit more dynamic sounding than the small Goto, and at the same time offering the highest resolution of the whole field. This tweeter is so ruthlessly revealing that we tried a different source after first listening resulted in the panel not liking it all that much despite the wealth of detail and examplary neutrality. It simply tended to sound a wee bit hard-edged, even harsh before the change of source.
Only recommended for top-notch setups, go for cateyes or slots otherwise and enjoy a more forgiving sound with nevertheless same or better subjective dynamics at slightly reduced resolution if your setup isn't in the super-league.
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Here we're back in Lansingland with two samples of Don Keele's babies in standard (D8R2405-equipped) configuration :
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What remains to be done?
Well, first, there's the need to retry a quick experiment we did with using a slot tweeter fram in a 2403/076 motor. During the tests it became more and more clear that larger magnets coupled to smaller frams are the best combination in tweeters unless you want them from 2 or 3 kHz up. Given the info i read earlier in this thread namely that all JBL models of a given period had identical magnets, it seems safe to assume the cateye as the most balanced sounding JBL expansion would benefit from using 077 instead of the heavier/wider 076 frams.
And then, there is the surprise tweeter from TOA ... in the listening comparison it already scored well, but although we might have guessed it, its tiny slot must be coupled to a baffle just like a 2405 -- but little did we know that the HF371 cannot do without a 2.5 kHz trap: listening was before measurement, hence needs to be repeated.
(last pic shows response with a rudimentery baffle to the sides, not at top/bottom of exit; watch how the usable range smoothens out and the peak at 2.5kHz up even more)
Should be fun comparing the two.
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Great Thread !
Lots of wonderful contributions in here!
Thanks!
:)