Building the 4345/4344

[TimG]

Alex:

I found out the hard way that the E130/E140 use a stronger magnet than the 2225/2235 and thus result in a hybrid driver if reconed as a 2235. You would have to measure one to determine how it would change the cabinet tuning and response. It would probably make the high frequencies slightly more efficient and reduce low end response slightly.

[Alex Lancaster]

You are right, 1.35T vs 1.2T, but I have done it, and could not hear any difference, it probably would come out with lab measurements, but I still would do it.

Alex.

[Ian Mackenzie]

Just to help focus the newby's, I was referring the search function in the technical forum s, there are oodles of threads talking about how to building up either the 2235 or 2212H.

Regards the compression driver the 2421 is available SH occassionaly but the 2425/2426 can be used.

Neither the 4344 or the 4345 will perform as stated without the true driver set. I said above there is no need to put in alternatives, if you do the final response will vary from the original. This will require complex network re design, again there are some threads that talk about this but it hardly seems worth while building a hack version unless you already have alternatives on hand and want to use them

The recones are available for both fom JBL, if you ask nicely Giskard maybe able to assist you.

Ian

[Guido]

Hi David!

What about the 4435?

The drivers are much easier to get as the 2426 is still available and the 2234 could be reconed from several transducers ...... do a search.

The 2344 might be a problem but there is a copy out there from P-Audio (PH316).
Or you choose the new Waveguide which I will do in my 4435 project.
see http://www.audioheritage.org/vbullet...&threadid=1730

[boputnam]

I am a dope. I have now confirmed that every batch after the original is botched. Completely Somehow, a component (the secret one...) was omitted. Throw the shit away. The moronic Paint Master cannot replicate his batch even with his formulae, in his handwriting. Imagine my displeasure...

So, in the words of Paul McCartney*, "we start again". I will drag the 4301B's back down to the toothless one, and give it another go. If this fails, or even if not, I may banish myself, forever...

* - Paul McCartney, Unplugged (the official bootleg), 1991, MPL (EMI), UK release of the MTV session, Limehouse Studios, Wembley, 25 Jan., 1991.

[Ian Mackenzie]

Bo,

don't get too stressed,

Ian

[boputnam]

I'm REALLY pissed. I made special effort, and even TIPPED the dope! He was too chatty - I shoulda recognized the increased risk with increased chatty. Obvious, now...

[Mr. Widget]

I thought the color problem was similar to the toilets running backwards down under.

JBL Blue MUST be applied in the Northern Hemisphere and preferably in California.

[Ian Mackenzie]

Ha Ha Ha

No no Widget, you are getting confused with flushmatic clearner...hospital grade.

Bo....My advise is tell this F&^%$#g C%$T his balls will be dark blue back if he does not deliver (demand a full refund or rippem right off..his balls )

Ian

[boputnam]

Even better, my friend, will be to curse him to eating Vegemite forever - afterall, that IS the color he produced, afterall...

[herve M]

Tim G "4355 hybrid
Woofers: (2) 2235H $326 each or (2) 1500FE $510 each
Midbass: 2012H or 2020H about $250 each or 2251J ?$600?
Compression Driver: 2430 $275 2332 horn $50 or S4800 horn ?
Supertweeter: 045Ti ?

4348 hybrid
Woofer 1500Fe
Midbass 2012H
Compression driver 2430
Super tweeter 045Ti
:

Tim G, Where can to buy 1500Fe and 045Ti ????

HerveM"

[Ian Mackenzie]

Just to avoid potentiai off topic threads end trails here, can we perhaps start a new thread for those thinking along the lines of 4435/4350/4355's.

There is certainly plenty of virtues in these particular monitors but it would be better to offer depth of coverage of the 4344 & 4345 for those that are keen to construct such traditional "Precision JBL Monitors"

Ian

[Ian Mackenzie]

As an intermediate step between outlining the thread and actual construction plans I thought it would be useful to post some information/details about what to expect from the JBL 4344/4345 project and also examine the question of which project should I build.

No doubt some of you have longed to buy/ or make such a design but never heard one actually go.

Okay, there are a whole string of JBL 43xx series monitors and the best source of detailed data is a our very own Heritage Library.

Its worth reading though the brochures to get a feel for what the monitors are about and also the product/people profiles of Greg Timbers.

My take is the 4344/4345 was the last of the sophisticated medium format 4 way monitors JBL manufactured which were more refined versions of the earlier 4341/4343/4343B monitors.

The basic idea of these designs was to offer most of the benefits of the larger flagship 4350 model but in a medium format for less large studios of that time. The concept revolved around deliberately limiting the operating bandwidth of the individual drivers, thus maximising the optimum benefits of the drivers in terms of transient response, clarity and power handling.

The trick was to blend the drivers perfectly in such a way as to provide a smooth response and coherent sound stage. But up until this time that was not thought possible.

However, JBL's Greg Timbers developed a rare talent for the blending of these multi driver systems to the point of it becoming an art form. The JBL L250/Ti is another notable multi driver system designed by Greg Timbers from the JBL Consumer Series. (see the Heritage Library for references)

Obviously the crossover network is a key ingredient in the overall system and I will devote detailed discussion of its construction later on in the thread.

So we have this snazzy multi driver monitor using now vintage components. But what does it deliver?

For a moderate outlay in S/H or reconed drivers you will have something pretty special and a timeless classic JBL monitor.

The 4344 is a big step up in accuracy from the popular 3 way 4333/A with the added 10 inch 2122H mid cone. The 4344 also uses an advanced crossover network & a shorter 1200 hertz high frequency horn, together they provide transient definition and instrumental clarity that beyond comprehension.

The larger 4345 monitor sports an 18 inch 2245H woofer in a 9 cubic ft enclosure and has 2 db more sensitivity (95 db) than the 4344 and slightly more bass extension.

For comparison with other systems...

Earlier in my audio career I built the classic 4 way 4343* (circ 1980), then in more recent years a 3 way Lansing / JBL system with the large 2397 Smith Horn & 2405 Slot Radiator, and later added the 10 inch 2122H JBL mid cone to make a 4 way system.

The improvement in adding more drivers in a properly blended system was remarkable.

I then changed out the 2397 and 2405 for the 2344 Bi Radial Horn and it was again a 3 way design with reduce time alignment issues (20 inches ) between the Horn and Slot.

On hearing in comparison the original 4343 system some 23 years on, I immediately scoured the world for the 2307/2308 Horn Lens assembly and a Slot Radiator so that I could re create that special something that the classic 4 way JBL monitor delivers.

The current state of art in crossover component quality now further advance the Legacy of the Classic 4 way JBL Monitor to a new levels of precision.

Some of you will be weighing up whether to build up the simpler contemporary 2 way 4430/4435 monitor or the more complex JBL 4344/4345 classic 4 way precision monitor.

That is a personal decision that you alone will have to make.

I will continue with posts of the box design in the next few days.

Ian



*In 1980 I felt it was necessary to have a decent hifi for my 21st birthday and on seeing the brochure I fell in love with the 4343 and decided to build a pair. They now reside with my brother and are affectionately referred to "The wife".

[mikebake]

Originally posted by TimG
Alex:

I found out the hard way that the E130/E140 use a stronger magnet than the 2225/2235 and thus result in a hybrid driver if reconed as a 2235. You would have to measure one to determine how it would change the cabinet tuning and response. It would probably make the high frequencies slightly more efficient and reduce low end response slightly.

That is exactly one of the pairs that I have; E130's with 2225 paper. I've thought of having Giskard analyze the result, but your prediction seems accurate.

[Ian Mackenzie]

A status update.

At the moment I am researching the original construction techniques used in this series of monitors.

So far, looking at available information kindly submitted by subwoofer...on the 4343, the type of side/bottom joint construction...a combination 45 angle mitre with locking sleeve and some other issues appear inappropriate and probably unattractive to would be project participants.

So we are looking at alternatives hence the hold on publishing any blue prints for the moment.

The most likely approach given most of us have a router (you would need to buy one for the baffle cutouts and it is an indispensible tool) is the attached image showing a basic sketch of the simple rebated butt lock joint.

The other red line drawing is a side elevation of the baffle rebate inset into the sides. The welded glue joint with additional cleats would make a very rigid enclosure. The top,sides , front and rear would be assembled together, there being a rear boot panel for service access.

Assuming some reasonably precise cutting and routering with uniform panel dimensions, the enclosure would be squared and trim at assembly and make the assembly straight forward.

Additional cleats can be used and of course would be necessary if you were to use the simple butt joint.

No doubt many of the experienced cabinet makers on the forums can devise some fancy and perhaps more sophistication joint construction but at the end of the day it has to be something the average diy speaker guy can put together.

I hope to have this sorted in a few days.

As I mentioned earlier..feel free to comment...this is a community Project

regards

Ian