Amen to that. Mine keeps asking why I don't implement a proper gain structure with the bi-amping, and questions my use of damper diodes for a preamp power supply. She still loves me though, and I'm saving some 5AR4's for her for Mother's Day.
More on topic, maybe, how would I ascertain if my TADs have tired diaphragms? The point was made above that most of us only get to hear TD-4001's that have been through the pro sound wringer. I don't *think* mine have been abused, but how would I know? Would this show up on FR response, or maybe it's a hard-to-measure transient response thing?
I'm not curious enough to buy a new pair.
C.P. Moyen Co. Inc. offers a comprehensive "Industrial Adhesives, Epoxies, and coatings, printed catalog titled: "Product Selector guide" describing specific applications on "metal, paper, foam & cloth" in loud speaker Assembly, including identification of each Moyen Adhesive solvent system, aka: Toluene, Methy Ethyl Ketone, Toluene, or water, each solvent depending on the speaker component to be cemented.
Call C, P. Moyen Co., Customer Service at 1-847-67-6866, for the "Product Selector Guide."
Cheers, herki the cat
The last time I glued in foam pads I used a hot glue gun. I opened them up a couple years later and saw no issues. I think white glue is made with floorer and that would mold.
The Arlene's glue is definitely the culprit.
An interesting JBL driver candidate for diaphragm replacement with Be would be the 2450. This driver was originally developed to accommodate a Be diaphragm as JBL was considering going head to head with TAD with that design. It was the reason for the development of the "Coherent Wave" phase plug. It allows for output from the diaphragm to be recombined in-phase at the driver throat in comparison to the out-of-phase output from a traditional phasing plug with variable length paths. According to JBL, it really only works with a Be diaphragm. The Al and Ti diaphragms are in breakup mode over most of their bandwidth, and as one designer said, are so "phasey" that there is limited benefit from the "Coherent Wave". However, a Be diaphragm, being pistonic for most of its bandwidth, would theoretically benefit the most.
This theoretically in-phase output would be a unique driver attribute compared to the TAD drivers and even JBL's current Be drivers. It would be interesting to have feedback if this two decade old technology actually results in a superior driver with a Be diaphragm.
Regards
Don McRitchie
Should also be applicable to the (20lb heavier) 2446 motor/phase-plug, no?
back to that. OK, I have 1.5 and 2.0" PWT's started in the garage...
of course they'd only be good for comparisons on -those- PWT units, but
impetus to finish them to a usable state is a good thing.
After exchanging emails with Truextant and perusing their web pages,
I see the curves they represent their product with is on a 2446J body
(using the 16 ohm dia) and 2386 horn (flat front, 40x20 CD horn) ...
which -sort of- answers the question about the worthwhile-ness of using
a 2446 or 2450 with the CW phase plug.
I'm using a pair of JBL 2446 bodies with the Tru-extent Be diaphrams on 350hz round Edgarhorns.
I don't know how different things would be with other horns or CD's, but I do know that I'm spoiled with what I have. I can't think of using Al or Ti diaphrams anymore as none of them play as "smooth and/or detailed".
I also am running a 2-way w/JBL 2226 on the bottom end. Some may need a tweeter, but for my ears it does just fine without tweeters.
Just my 2 cents worth of course!
Regards, Ron
JBL Pro for home use!
Hello Ronbut I do know that I'm spoiled with what I have.
Yes the Beryllium sure sounds nice. It's a nice upgrade.
Rob
"I could be arguing in my spare time"
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