In the other thread Authenticate a 4343 the poster wants authenticity period.Originally Posted by macaroonie
In the other thread Authenticate a 4343 the poster wants authenticity period.
I am trying to hit authenticity where possible - I know there are easier, and even better materials to choose from, but in the end, I want my clone to be a JBL 4343 reproduction, not something that looks like it.
The first hurdle is going from imperial to metric measurements in available sheet thinknesses.
From what I have been able to gather from seeing pictures of 4343 baffles, it seems the baffle is also made of particle board, at least the square upper part, together with the mid-box.
The back is also Particle board.
The bracing seems to be pine or Birch bracing, based on the pictures alone.
I'll need to verify baffle, back and side thicknesses before I can order sheets.
i have been looking at the parts list from Solen - Wowza, that is a hefty price tag!
and then more than 300 in shipping alone + import taxes.
Been looking at local Jantzen components instead, but some values are impossible to find (take for example 160uF caps) - is it crucial for the crossover, that we are hitting exact values here?
What is the rule for combining caps and resistors to match the values in the diagram?
and do anyone have good input on somewhere in Europe, from where I can order this stuff?
Okay
I will try and frame this area with some economic rationalism.
Imagine you were in production like Jbl.
What they did was evaluate alternatives.
The parts in that list are the ideal choices and because it’s charge coupled you need four times as many capacitors so it’s not an inexpensive aspect of the project
Secondly, you can Biamp which avoids building the woofer filter and some parts of the 2122 filter
Biamping is where a high level active filter splits the frequency range into two halves after the preamp so you have low and high outputs that go into a a power amp then the woofer (low) and the mid+horn+slot (high)
In general terms it’s the preferred way to run this kind of loudspeaker
You will need an active crossover and two Stereo power amps.
Looking at the parts some areas there options in terms of capacitors.
For example in the very early systems Jbl used Mylar capacitors (green caps these days).
What Jbl did in the last iteration of this system the 4344mk11 was to select some cost effective alternatives to expensive polypropylene capacitors in key areas which made a lot of sense. The woofer filter capacitors are non polarised electrolytes types (NPE) bypassed with small value polypropylene capacitors like 0.01. The woofer filter was not charge coupled in production.
So you can save a heap of money there.
Next the 2122 high pass mid filter capacitors Jbl selected non polarised electrolyte (NPE) bypassed with small value polypropylene capacitors like 0.01. These capacitors are charge coupled.
The low pass section of the 2122 filter and the high and uhf filters use polypropylene charge coupled capacitors. Basically all the capacitors in red on that list could be non polarised electrolyte (NPE). The rational is cost. You will probably not use this aspect of the crossover once you Biamp and after that you probably won’t go back to full passive operation.
Don’t worry about working out a list right now. I am just relaying you an approach
It will do exactly what the other list does but in a far more cost effective manner.
I can draw it up for you if you like.
In the diy space of course people don’t have cost limitations only the depth of their pockets.
To get you up and going the above is being smart. Later on once you sort out the drivers you can go for broke if that’s your plan.
Send me a PM and l will go through it in more detail.
In the diy space crossovers and in particular capacitors attracts a lot of conversations so beware
Finally, check out Parts Express. Their shipping cost might be lower
Edited for clarity 5.14 pm ESAT
Thank you Ian
I would like to go full passive first time around, but you idea about making a more budget filter, that is still in line with JBL thought, sounds really nice!
I would like to take you up on your offer for a revised filter!
One of the things iv'e noticed, is that some of the crossover values needed for the original filter, are not available here in DK.
As if there are some standard values, and some values are not? or am I just stuck on the wrong side of the ocean?
an example is the 160uF capacitor - the available models are 120uF, 150uF, and 220uF - I guess I could just parallel a 150uF and a 10uF?
Let me get back to you in a couple of days with the solution
No, there are plenty capable companies in europe.
One of the things iv'e noticed, is that some of the crossover values needed for the original filter, are not available here in DK.
As if there are some standard values, and some values are not? or am I just stuck on the wrong side of the ocean?
You allready named Jantzen in Denmark, I believe Duelund is somewhere in scandinavia too but in my opionion a little bit on the voodoo side. So beware as Ian said, no need to pay 500€ for a single capacitor.
But I have experienced Mundorf (in germany) to be very helpful. You can order your individual values there. Even for a single part!
What exact values for the inductors are you looking for?
Yes. Parrallel 150uf with 10uf results in 160uf total value. Put them in series and it will be the opposite way...
Hi Ian,
I think more important applying bi-amp-ing (with active LF, HI filter round 300~500Hz) is that it would be avoided interaction of the large coil inductance with the speaker characteristic so mid-bass emphasis would be avoided . Such things has been more elaborated by the G.Timbers when he has been talking about JBL4345 network and possible improvements of such great speakers (even there he has not mentioned, may be 2420&2307 has to be exchanged with 2441&2311, as MY PERSONAL opinion too).
regards
ivica
I am well aware of that
Please re read my earlier post(s)
People are at times polarised or obsessed on a single quest like having the best.
That’s fine if that is the focus but it’s not here.
From the outset users focus has been about authenticity of the original design
The users desire is to use full passive at least for now so l am offering assistance within that scope
Hi all
The reason I want to use full passive (would be nice with the possibility to add a biamp-switch, at some point) is that I also collect vintage amplifiers - for example I use the Marantz model 16 as my main driver right now - I have a couple of other amps from Marants and Luxman as well, and a Marantz model 250 is going to drive the 4343 when they are done - but I don't really want to be dependent on having 2 amps in function all the time, as they are constantly rotating in and out of service, maintenance and storage
That makes perfect sense
Okay - a tiny update:
I bought two original 3145 crossovers, per Ian's recommendation, And I've ordered some speakers and are sourcing the last parts.
Status today:
Bought:
Pair of 3145 Crossovers
Pair of JBL LE85 + H91 + Lenses
Pair of 2231A with 2235 cones
Pair of L136A with 2231 cones.
Pair of C8R2122H recone kits
Tomorrow I am visiting a guy who has listed the following for sale:
pair of 2123 baskets only
Pair of 2405A (without diapraghms, but he might have an original pair lying around)
All in all, I think I have a good basis for the project - once all the drivers are either ordered or in-house, I'll start working on the enclosure... I hope tonight, that I can start building a CAD drawing from the measurements I have.
There’s no stopping you now
I have an enclosure question:
Basen on the JBL pro 4343 publications (http://www.jblpro.com/pub/obsolete/4343b.pdf) it says the following in terms of enclosure materials:
"To eliminate resonance, the enclosure isconstructed of dense 19 mm (0.75 in) and 25 mm (1 in)stock with a 15-ply baffle panel"
first off - what dimensions are used where? - 19mm particleboard on the sides and 25mm on the back-panel or opposite?
Furthermore, the plywood baffle text, is a bit of a surprise as pictures in this thread: (for example) http://www.audioheritage.org/vbullet...-along-the-way
Clearly shows the use of particle board on the baffle, both for the upper section and the LF baffle portion...
Can anyone shed some light here?
Another thread here
http://www.audioheritage.org/vbullet...3-repair-story
The one inch is the outer walls
3/4 is the dog box
On the baffle we have all read the flyer
I suggest the flyer copy from marketing preceded the actual production run.
The prototype from their custom shop might have been plywood baffle.
I would personally use ply for the upper baffle if you intend to remove and rotate it like the original at particle board or mdf is easily chipped
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