Treble drivers in 4345

[johnaec]

What's needed to help move this forward in a fair manner - more $upport?
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Really, what exactly are we talking about here - lets bring it out in the open, eh?

Heather - I initially wrote a long reply with my perspective on the situation, (while I don't have the electronics knowledge to design crossovers, I do design and build cabinets), but then decided it boils down to the fact that researching, designing, and testing things takes substantially more time that most people realize, and if you're doing it primarily for others' benefit, it's only fair to expect some kind of payback, otherwise, 'might as well just go fishin', or do a regular job that likely pays more in return...

If I'm doing a job that also includes the resulting "product" for me, then I'm definitely willing to absorb part of the expense, (as I think most others here do also). But I still like to think the rest gets spread around fairly, as I'm sure others do.

'Only speaking for myself here - others may have different ideas...

John

[Chas]

Heather, I haven't actually seen a 4344 or a 4343 in the flesh but as a 4345 owner, I think the smaller ones may in fact be slightly better with respect to cabinet panel rigidity. My '45's have very large side and back panels that are nowhere near as solid as my much smaller 4430's. They're well made and braced, but with panels as big as they are, it's difficult to maintain the same degree of inert properties.


Giskard, I would be very interested in any tidbits you choose to share here. Key words being you choose. Heck, If you just want to share the basics but keep certain proprietory information for paying clients, I wouldn't blame you a bit.

[4313B]

Room size is a constraint for me, so I'll have to do it with a 15 and the smaller box that it allows, rather than the nearly double size box needed for the 18s of the 4345s. For me - the 4343 sounds like a good compromise - or, as Ian mentioned - the 4344 Mkll type design (a bit more up-to-date) - but from what I've read in the forums of folks who've heard or own them, I want more the bottom of the American speakers rather than the Japanese sound.

I think you may mean the 2235H/2122H-based 4344 as opposed to the 2231/2121-based 4343? It might also be cool to see someone do a 4 cu ft LE14H-x version. I consider the 4344 MkII out of scope as is the 4348. Those models are JBL Consumer and not JBL Professional Series and really aren't of the same genre to be fair.

'Only speaking for myself here - others may have different ideas...

Nice post John. I deleted my first draft after reading yours.

Giskard, I would be very interested in any tidbits you choose to share here.

I'm kind of leaning towards a "forum project" wherein more than one or two people get stuck doing the R&D. I'm still pondering the ramifications of that.

If you think it worthwhile, after I pull these you can borrow them.

If you think they are worth checking out then we should at least get an impedance curve and SPL/phase curve on them.

A number of people, myself included, are sitting on pairs of 2435's.

Ok, maybe an impedance and SPL/phase curve on them as well.

If someone with a lathe wants to try laying out a tractrix/ram's horns style of horn with a 1.5" throat, that will install in the 434x hole for the exponential "foghorns"--that could be the solution for that.

Anyone?

My new 2421B diaphragms are sitting here waiting to be installed. After I've done that I'll have a perspective on the stock configuration.

Ok.

I still think beryllium offers the ultimate in fine detail.

Ok.

I think the next steps needed are: A network option for the 2450 aquaplased and a horn solution and network for the 1.5" berylliums.

Ok. I guess send them over when you are done with them and I'll ask subwoof again to send his 1.5-inchers.

It may be that Lansing Heritage Forums needs an R & D budget.

I'd really like to have a private conversation with Don about that before anything more is said about it.

[Guido]

I think the next steps needed are: A network option for the 2450 aquaplased and a horn solution and network for the 1.5" berylliums.

I second this!
Let's go this way Giskard

[John W]

I can turn a couple horns for a 1.5 in drivers. The lathe is all ready to go.
I would need someone to come up with a good profile, though.

[andresohc]

I am interested in these circuits also. I only need the top half (2122H, 2307/2308/2425, 2405). I have built a center channel box (without a crossover) but not tested it. It has two 2122s. I hope to build a pair of front channel speakers next spring or summer with the latest equivalent circuit . I have to sell off some more of my JBL bookshelf speakers to fund it, but would be very interested in the latest design of the 3145, primarily above the 2245s. As I have posted before I plan on trying to drive the 2122s down to the upper range of the SUB1500s. I will have a pair in sealed boxes. If you see 4313As and L112s in the market place thats why.
I have all the components for the 4345s plus a pair of sub1500s awaiting crossovers, money, and time. I will contribute what I can toward the new design. Thanks for all the help either way Giskard and Ian.

[Ian Mackenzie]

If anyone is intertested I am going to look at designing a diffraction wedge wave guide system for a customised HF and UHF elements of the 4345.

Using customised wave guide techniques it is possible to overcome some of the major shortcomings of the original design:

Time alignment of acoustic centres.
True acoustic impediance matching of drivers at crossover point.
Control of early reflections.
Significantly reduced distortion.

I have not determined what the drivers will be but the use of wave guides frees up the use of very high performance direct radiators is such an arrangement.

Ian

[X_X]

Ian,

Count my hand.

I seem to recall you mentioned using different HF and UHF drivers in another thread and I can't seem to find it now. What were the (other) drivers you were thinking on?

I might lend a hand with your project. I am not as technical, but I'll wake to make a contribution before it goes a over t. Perhaps the first thing would be to find suitable drivers, hmm?


Nate.


**** I already reconed- didn't see your 2245 core offer until it was too late. Thanks anyway, mate. Swan is wonderful. I was a bit bargy. Cheers.

[Ian Mackenzie]

Nate,

Hi over there. I will keep you in the loop. It will be a long term project

This a nothing new, Duntech used a similar approach in their designs.

The thing about it is looking at amplitude response and power response is a very one dimensional view of what a loudspeaker does when you start to serious model the system as a whole. By apply some clever concepts you can realise a more ideal system.

I a not suggesting anyone hack into their 4345's or that it is a has been system.

Far from it but for the diy speaker builder there are some wonderful opportunities. You just have to open you eyes!