New Project with JBL's 4647 and 2445

Have you posted a pic of your system in this thread? I'm sure Michael and others would like to see what you have done with your 2507 boxes....[/QUOTE]

Yes, Ron. Would you kindly please post pictures of your system. Zilch is right saying I'd, along with others, be interested in seeing them. Please do. I do listen carefully to what Zilch says act wisely on it aswell. Many thanks for the advice.
Thanks.

Hey guys,

I don't have a digital camera, but I'll try with my 35 mm. Would that work?

Ron

Sure...if you have access to a scanner... even a crappy one.

Or get digital copies at the developer....

...And Ron this is me at the moment :bouncy: Thank you so much...it will bring needed inspiration.

2425J on 2370A with UHF drivers requires 6 dB attenuation on the midrange driver (white resistors between red and black wires) to balance with 2235H as woofer in 2507 box.

Crossovers are 3110 and 3105, NIB. 3110 MF output set to "Min" to allow 2235H bass to dominate for these plots, but there's plenty of MF output available at "Mid" or "Max." 3105 is set to "about" the middle of the available range.

RTA said both MF and UHF drivers want to be out of phase with the woofer in this setup. Don't generalize from that tho; every physical arrangement is different. The "hole" at 160 Hz is room stuff. Ignore it.

NIB 2402H (top) and 2404H-1 with 2402 diaphragm (bottom). These particular tweeters are documented in the Ring Radiator study elsewhere in these forums.

I'll do the two-way study with 3110A next....

Today's testing confirms my dislike for these tweeters in this system: hissy, harsh, whistley.

OTOH, 2407H on OASR or PT-F95 is actually listenable.

AND, it goes well out beyond 20 kHz, for those who can hear anything out there.

See here: http://www.jblpro.com/ae/pdf/spec_shts/AM4200_95.pdf

Also wants some attenuation to balance with 2235H. Here, the same 6 dB. MF at "Min," HF boost at "Mid."

I don't see a down side to doing this. Impedance remains the same, and damping's not an issue with M/H compression drivers, I don't believe; there's already other stuff in the path.

Bottom RTA plot is with no attenuation, same crossover settings. Perhaps that's how some might like it. Me, I wanna hear that lovely woofer do its thing.... ;)

Thank's Zilch. I'm not sure that I want to give up what my neighbor calls, "That exciting sound" my present system offers. Padding down the 2425 may leave me without that factor. It needs more study before proceeding. The 2235H in the 4507 alters the over all sound too much.

Ron

Hi, Ron.

Well, at least we know what the options are.

Specs say there's a 4 dB difference.

If you happen across some 2235's, give it a try.

Or build B380 boxes for them and augment your system with them as subs.

Gonna try the 2446/2380A with 2403H and 2407H now....

Hey Zilch,

Thanks for your time. It's tempting. Perhaps Mike will try it first.

Ron

Quote:

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Originally Posted by jbl

Hey Zilch,

Thanks for your time. It's tempting. Perhaps Mike will try it first.

Ron

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Frankly, I would not mind trying it. My only problem is space and limited funds. The system that Zilch et. all is helping me put together is being tested, the only thing I get to do is physically put the components together. This is the case, at least for now. At some point in time, I hope to explore a whole lot more. But after been in uni for a year, funds are tight at the moment for explorations.

There is no doubt that my present plan cries out for a pair of 2235, be they reconed or original. When I do get them, I'd put them in my 4647 and follow Zilch's porting suggestions. If they don't work out to my ears, and provided I'd kept the 2225s, I'd put them back on and as Zilch suggests to you, use them as sub. Though that may mean getting a different network if and when I do so. I would wish not, especially at this time. I'm, like youself, in the hunt for 2235H. But more for other much need components than them.

Zilch's recent posts are very revealing, in that they show the extent to which we could tweak and rework our systems. For that, I cannot personally thank him enough. The only wish here is that of money, and lots of it. But that's ok, none of us are going anywhere, anytime soon.

...are we getting those pictures Ron? No pressure. Just dying to see 'em.

Michael

Hi there:
I recall a while back that some of you wanted to see pics of the horns I thought were 2380a. So, afer triying for days to get these in the right sizes but could not, I made them into PDF formats to be able to post. They are matter of fact on sale.
Here are some measurements:
The 2445 sat comfortably where you see the holes.
Length: 2ft 7inches
Width (From left to right at the front of the horn) 2ft
Height (on the same position) 1foot 2inches

If anyone can help to identify these, that would be great. As that was the reason suggested of me to gather and post this information.
Thanks all!
Michael

....Ok. I thought I'd post this one. I just tried a tool that works great and very easy. So I'll post this one that I tried it with...

Hurry Twisted! You might become a Senior Member before the powers that be bust you!

:p