2446H and Truextent on the Yuichi A-290, a 290hz with a hyperbolic flare - it's a clone of the TAD TH-4001
2446H and Truextent on the Yuichi A-290, a 290hz with a hyperbolic flare - it's a clone of the TAD TH-4001
2445 core
2311 /2308 / baffled
D16R2441
D16R2445
Truextent
2445 core
350hz Edgarhorn (tractrix flare)
D16R2441
D16R2445
Truextent
2445 core
Yuichi A-290, a 290hz with a hyperbolic flare - it's a clone of the TAD TH-4001
D16R2441
D16R2445
Truextent
These were taken a few nights earlier using a 2441 core with a D16R2441 diaphragm. The 2446H plot shown here was taken at that time too. That was when I ran into trouble. The D16R2445 diaphragm wouldn't fit right in the 2441 core and when I went to take a Truextent diaphragm out of a 2445 to put in the 2441 there were mold issues (#51) in the 2445 due to the Arlene's glue that was used to adhere the felt pad to the back cap. I called it a night.
Compared to the others, the Truextent diaphragms do not appear to have any special FR extension in the 14K to 20K range.
The Yuichi and Edgar do not differ as much as I expected. This is all on-axis, right? Both are pretty well-behaved.
THANKS for doing this and sharing it!
deHavilland Aries SE 845; UltraFi Monaco SE 845
Tannoy GRF-R, DMT15; '52 Jensen Imperials+JBL 2441, LE15B; TAD 2402 clones
I'm surprised that there are acutually less HF extension with the Be diaphragm than with the original Ti's.
Any idea why?
2213 + 2435HPL w/aquaplas + H9800 (Matsj edition)
Here is a link to Yuichi's own measurement.
http://www.geocities.jp/arai401204/H.../A290-S90.html
I dont have a 2445 / 2446 core to compare but my own measurements of the 4001 confirm the HF extension.
With a simple two stage passive EQ / impedance circuit per Tads design its quite easy to get a flat response and impedance from 600 hertz response to 18 khertz.
Controlling or should I say damping the impedance has a marked effect on sound quality.
I expect the Tad diaphgram surround and the 4001 phase plug play a big part on how it performs on paper. As to subjective impressions its a matter of taste.
They are nice horns. Yes, this is all on-axis. I did a few off-axis shots just to see where the horns started dropping off. I was especially curious as to how tight a sweet spot the Edgar might have.
Thanks Ian. That link was helpful. I know nothing about these Yuichi horns. They look and measure nice. I'll have to hear a pair someday.
It looks like he got a bit more extension from his 2441 than I get from either of mine. I tried both on the Yuichi and determined that they were probably a wee bit low on flux density. That's why I pulled their diaphragms and put them in the 2445 core.
I'd like to see a schematic of the Tad circuit.
It does. The Truextent uses less beryllium as well as the soft surround (as compared to the 476Be diaphragm) with the result being reduced extension. The Truextent also has a bit higher distortion according to JBL's measurements.
The titanium and aluminum diaphragms can't really compete with the sound quality of the berylliums. The Tad and JBL four-inch beryllium compression drivers are very expensive (and in the case of the JBL, nearly impossible to get). These aftermarket beryllium diaphragms offer excellent cost/performance.
You're welcome. I really don't enjoy handling other people's beryllium diaphragms and swapping them around in various cores. Everytime one is exposed I get real nervous.
When I ran the impedance curve on the second 2445 with the Truextent installed I didn't like the way it sounded. There were unwanted resonances. I opened it up, cleaned out the little bit of mold on the felt in the backcap and then cleaned the gap out (there were a few metal particles in the gap) and then reassembled it. That fixed the problem. I'll check the first 2445 (the one with the mold) today so Dan can get two fully functional drivers back. Don't use Arlene's glue in these back caps guys. I used the Moyen recone glue in my 2445J's and there weren't any issues.
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