Discussion Thread JBL 4343 to 4344 upgrade

[saeman]

Rick,

That was an exotic approach to contruction and not absolutely necessary.

You need to decide on the drivers, then the crossover and so on.

The active crossover is an anciliary device best placed near your pre amplifier and power amps.



Ian

Am glad to hear that the massive array in the pic was on the exotic side of the arena. As a beginner that approach is somewhere in the future for me I would guess.

Driver compliment for my 4344's will hopefully be 2235H's (have two) 2122H's (am researching cone kit availability now), 2425 or 2420/275ND mids (have the horns and lenses) and 2405 (have two). That leaves the x-overs !!! Giskard offered one of his charge coupled systems some time ago and that approach looks to be the best. Will have to leave the physical configuration to him. I'm sure that there will be enough room to accomodate them. Passive/internal with this system is my intent. I have used the JBL 5234's, SAE 4000 and others with my 4350's and have some experience with the active approach (not as extensive as many of you guys out there) but a start non the less.

Thanx for taking the time to reply. Rick

[Lancer]

Does anyone have a picture that shows the end product, of a custom built x-over project, for a 4343, 4344,4350 type system - Thanx in advance Rick

I guess I could send you a picture when I'm done building yours...

[saeman]

I guess I could send you a picture when I'm done building yours...

Ah Lancer - you are still out there. On the subject of the x-overs we discussed for my JBL-NOT 4351 project - I need to respond to your request for the 3107 bolt pattern and this post has just remined me of that - will get it shortly. I was unable to PM you so tried regular email. Has your email address changed??? Rick

[Lancer]

I just answered your emails briefly. I'll look at your emails more closely tomorrow night and answer them more fully.

[Ian Mackenzie]

Thanks Zilchster,

Perhaps Rick can be guided by one of a experienced crossover builders...Ummm.

Please note, If you decide to make a full passive network, this will cost at least 50% more due to the large capacitors for the woofer and midrange filter. This will also add to the physical size of the network.

What I am proposing is a neato active solution for the 4344 project with passive charge coupled crossover for the mid- horn, horn-uhf transitions. IMHO and based on my recent experiements this will give very impressive results without breaking the bank.

The crossover is the heart of any loudspeaker and the results at the end of the day are a careful balance of design, implementation and cost.

Ian

[Ian Mackenzie]

I guess I could send you a picture when I'm done building yours...

Agreed,

Ian

[Ian Mackenzie]

Rick,

How are those boxes going?

Ian

[saeman]

Rick,

How are those boxes going?

Ian

Hi Ian

Have one baffle complete with mid-base box mounted and all holes cut. Need more 1" P.B. and have it ordered. In 10-14 days I should have a prototype cabinet done and ready for veneer. Here's a revised dwg. I moved the rear panel recessed area down towards the center. Plan "A" left a real tight clearance between the mid driver and the cabinet back, with the recessed area at the top of the cabinet.

The recessed area is 15" high, 23" wide and 3" deep. This should be enough room to mount x-over components/boards. I'll bounce this off Lancer before I cut any wood to final dimensions.

My best to you as always - Rick

[saeman]

Please note, If you decide to make a full passive network, this will cost at least 50% more due to the large capacitors for the woofer and midrange filter. This will also add to the physical size of the network.Ian

I really don't have the choice of not going full passive on the networks for my 4344 project. The only room I have in the house that has electronics to support a bi-amped/active x-over system is my family room (my turf) and that room is home to my 4350's currently and eventually the 4351's. Going full passive on the 4344's will allow me to put them in any room without needing the extra space for support electronics. To this date the WAF factor has never been an issue. Moving a big full blown system into the living room (her turf) could very well knock a hole in the dike!! Rick

[Ian Mackenzie]

Ah Ha...now I see sez I...the waf factor....

Ian

[Ian Mackenzie]

While deemed the obvious we should also do a section on setup and placement.

There is some confusion about the slot being on the ineer and outer edge?

I was having a good listen last nigh before going out on the turps (Saturday night) and it is crucial to this style of monitor that they be palced correctly to ensure not only good imaging, but that the system sounds balanced.

The latter issue is that if toed in too much, you loose the imaging in the extreme highs and the horns can become too prominant.

Ed,

Have you had an opportunity to update the MS Word dcoument yet.

Also, I have requested Unwound (aka Edgewound ~Ken) prepare some posts on driver maintenance, perhaps Techbot will also offer some information of a techincal nature as this is the first topic on the agenda.

If possible I would like to see this posted in the design forum in this month ((September) and we can then rollover the other topic progressively.

Ian

[Ian Mackenzie]

Rick,

Have you thought of installing a couple of plate amps on the rear and bi amping
(or just bolting a stero power amp to the rear......given the cost of power amps (Parts Express) I image the full passive would be perhaps more so.

The active crossover an be anything ...a small black box....

Only one mains cable and one signal cable and your on cloud Nine.

So much more for so much less (done right of course..I would help you with that!)

I revisited this as I am so pleased with the most recent advances I have made in bi amping that passive mode now seems far less attractive.

Ian

[Tom Loizeaux]

After thinking about Ian's mention of correct slot tweeter placement, I pulled the grille frames off my 4343s and noticed that the nameplate is positioned directly over the upper half of the 2405s! These aluminum plates span the width of the grille frame and are positioned to completely block the upper half of the slots vertical horn! How could this meet JBL's approval?
I think I'm going to have to remove these nameplates...at least until I'm convinced that this was either intentional...or that it really doesn't matter!
But really, why do we worry about toe-in or tweeter height relative to listening postion when the 2405s are partially blocked?
How could JBL allow this? I'm puzzled.

Tom

[Robh3606]

"But really, why do we worry about toe-in or tweeter height relative to listening postion when there are largly blocked?
How could JBL allow this? I'm puzzled."

That's odd to say the least that they are blocked by the name plate?!! I run my clones naked with no grills and toe in and height do indeed make a difference. Why they are blocked??? Any doubt dump the grills and see for yourself.

Rob

[Ian Mackenzie]

Ha,

A lot of engineering effort went into the position of those name plates...LOL.

I doubt if many people use them with the grills on.

Tom this is an interesting issue....have you tried with the grills on/off to verify any change ?

Ian