Building the 4345/4344

[Tom Loizeaux]

Ian,
Thanks for a nice overview of the 43XX monitors. These broader looks increase our understanding and appreciation of these classics.
From my limited knowledge and from what I learned from the Heritage Site, I see the 4343, not the 4344, as the "junior" version of the 4350/55. A number of catalogues show the 4345 and 4343 as options to the "flagship" 4350/55, but no where do I see the 4344 shown, listed, or even mentioned! I feel the 4343 should be used as the "15 inch" equivalent of the 4345. I suspect that the 4343 was the most prolific, with the 18" 4345 comming in next. My guess is that there simply weren't very many 4344s made. I've heard that the 4344 is a slightly "improved" version of the 4343 because it uses ceramic drivers and has a slightly "improved" crossover (adding bypass caps, if nothing else). I suspect that, because the 4344 didn't have to work in the "rotatable top panel", the 4344 may have placed the drivers in a slightly more optimum position ? In the lineage of JBL studio monitor development, the 4343 was the design that added the 10" mid-bass driver, used the shorter, 1200Hz 2307 horn, and established the "narrow bandwidth" idea over it's predecessor - the 4333.
It's interesting to hear you, as well as many others, say that the 4-way design using a combination of a quality woofer, 10" mid-bass, compression driver, short horn w/ lens, and slot tweeter was one of the best designs to come from JBL.

I am curious to hear the 4344s, but I'm happy enough with my 4343s that I don't know if the 4344s will be a significant enough improvement.

Tom "cautiously seeking sonic perfection"

[4313B]

"I feel the 4343 should be used as the "15 inch" equivalent of the 4345."

Well that's not even debatable; the 4344 is the 15-inch equivalent of the 4345.

Given the recent awareness of how the stock 4344 was constructed though, I would strongly urge using the 4343 enclosure as a basis to build a "4344" clone. The ONLY component differences between the 4344 and 4345 are the 15-inch 2235H in place of the 18-inch 2245H and the two different foilcals. The 2235H in the 4344 is an evolution of the 2231H in the 4343 and the 2122H in the 4344 and 4345 is an evolution of the 2121 in the 4343. The newer 3144/3145 filter of the 4344/4345 is also argueably a better design than the 3143 in the 4343.

"the 4344 may have placed the drivers in a slightly more optimum position"

I wouldn't bet on it. The network in the 4344 is IDENTICAL to the network in the 4345 and nothing was done to compensate for the decrease in baffle width or the different arrangement of all the transducers with respect to the baffle edges. Again, I would use the 4343 enclosure and transducer arrangement to build a 4344. Oh wait... I already did that... numerous times... and it freakin' works.

"I am curious to hear the 4344s, but I'm happy enough with my 4343s that I don't know if the 4344s will be a significant enough improvement."

Cool! Whatever floats your boat. The 4343 is no slouch at all. It's just a natural "evolution" to upgrade the 4343 to the 4344's 15-inch driver, 10-inch driver, and crossover network. No different than upgrading other systems such as the L250 to the 250Ti. Been there, done that, bought the T-shirt and used it to oil the black walnut veneer. The really cool thing is one can recone both the ferrite 2121H and the ferrite 136H/2231H as the newer drivers and be done with that part of it, in fact one doesn't even have a choice as far as the 136H/2231H goes.

[speakerdave]

"used the shorter, 1200Hz 2307 horn"

Couple of questions--

Do you think this was done for a sonic improvement or to accommodate cabinet dimensions?

Are the crossovers for these speakers (4343,4345,4344) specific to that horn? That is, if the horn were changed to the 2312/H92 (JBL describes it as having a "smoother performance and is preferred if enclosure depth is adequate for mounting") and the drivers and frequency division kept the same, would an adjustment in the crossover be necessary?

Thanks,

David

Addendum: Drew Daniels says that transition from a cone to a horn is better if the horn is "well-behaved" below cut-off. I'm thinking he means crossover frequency? That would be one reason for me considering this change. The H92 is good to 800, crossed over at 1200--wouldn't that contribute to smooth transition? My proposed cabinet design would accommodate the depth.

[4313B]

The HL91/2307 came first. The HL92/2312 was developed because the HL91/2307 doesn't do real well when forced to go down to 800 Hz to meet a 15-inch LF transducer. The shorter HL91/2307 is the better choice in systems like the 4343, 4344, and 4345 where it is crossed over higher.

The HL93/2311 is arguably the best choice of the "fog horns" (JBL engineering term) and one worth examining. A perfectionist would probably tweek any filter to make up for the change in horn depth. The HL92/2312 has an ass load of delay, the HL93/2311 has the least amount.

If you are building all this from scratch you are immediately freed from various constraints. You can forge ahead and make all new mistakes, you can remain true to the past and live with the same old mistakes, or you can go with something in between. It's your time and your money

I'd be real inclined to do a 4343 enclosure and the 4344/4345 components/filters. I'd also try to work in the 375/HL93 in place of the LE85/HL91 and see what happened.

[speakerdave]

Thank you for that.

David

[Ian Mackenzie]

Giskard and I talked about the pros/cons of both the 4343 and 4344 enclosures today.

I will publish a cabinet design soon enough. This will be derived from the 4343 cabinet dimensions but with best practise design/construction for forum members. The baffle layout will have offset drivers like the latter 4344, but the woofer will also be offset and the ports next to it, this being a better engineerig solution.

The 4343 is an excellent system, perhaps the virtue of the 4344 is the offset driver configuration offering arguably better imaging and smoother response where the cabinet is not sofit, or flush mounted as is often the case in a studio.

Those of you who are lucky enough to be proud 4343 owners may therefore opt for an enclosure upgrade and perhaps a recone of the 2131A and upgrade to the 2122 if you can arrange this, along with the 4345 network.

The rest of you will have an open choice, the offering will be the best of the best.....

On that note I will stress in the following posts the use of the highest quality film foil capacitors such as Hovlands in the crossover network, metalised polypropolyene are inferior and will Not extract the full transparency and clarity of the 2307/2308 exponential horn or the Slot Radiator.

If you really seek to further impress your ears and enjoy the golden years they have left, I may be enouraged to offer a very high performance active crossover and a balanced SE class A amplifer exclusively to forum members. (in a private thread)

The synergy of this amplification and the inherent design concept of these 4 way monitors is pure JBL Nirvana at the highest level...but more about that later.

bye for now

Ian

[boputnam]

Originally posted by Giskard
If you are building all this from scratch you are immediately freed from various constraints. You can forge ahead and make all new mistakes, you can remain true to the past and live with the same old mistakes, or you can go with something in between.

It occurs to me we need a special thread to archive this invaluable wisdom...

[4313B]

Sure we do .....

[subwoof]

I just built a pair of new frames to replace the ( now destroyed ) particle board originals...

Here are a few pics:

[Ian Mackenzie]

Sorry for the delay, I will post the drawings tomorrow.

I have been trying to use a drawing package (Visio Pro), but as a newby to this package its more trouble than its worth.

So the drawings will be accurate, but not of architectual scale...forgive me.....Some of you who are dab hands with a Cad package may wish to tart up the pfds, we can then archive them into secure place on the forums.

More later.

Ian

[boputnam]

Hey...

I've got AutoCAD 2004, but cannot profess to be proficient at (with) it. But, Giskard has done some dandy work, the Widget too. Maybe a suitable bribe could be arranged...

Vegemite?

NOT!!

[Ian Mackenzie]

Vegemite....


Yep I wil be bring a few jars with me..thats a given.

Do what you have to do I say

Ian

[ngccglp]

Ian,

I am also interested to learn how to build my own speakers. But I don't think I will ever manage to build a cross-over. I am thinking of getting a electronic crossover to solve this problem. I can then get used power amps to drive the drivers actively.

Is that possible?

David

[Ian Mackenzie]

I am also interested to learn how to build my own speakers. But I don't think I will ever manage to build a cross-over. I am thinking of getting a electronic crossover to solve this problem. I can then get used power amps to drive the drivers actively.

Is that possible?

What........? Balls......they are not hard to make.

Some simple skills in the case of the 3145 ..a factory design, careful selection of components and you are home. If you are plan a to build up this project or another JBL vintage design we are here to help you....just ask.

This system can be bi amplified to improve dynamic capability under hi drive conditions but it does involved a bunch of extra amplifiers, cables etc and often is difficult to control hum and noise unless care is taken.

If you are starting a raw design from scratch talk to one of our knowledgeable members about your plans...I am sure they would be happy to assist where they can.

Ian

[ngccglp]

Alright then, I'll start by keeping a close track to this thread and learn whatever technical lingo there is to learn about cross-over.
Thanks.

David.