Discussion Thread JBL 4343 to 4344 upgrade

[Rolf]

Hi folks.

So, I have finally used an RTA on my 4343B's after Ian's instructions.

As I said earlier I adjusted the speakers by listening. This is how the L-Pads where with my ears: UHF: -2, HF: -2, MF: -1. Believe it or not, the only change after the RTA was adjusting HF from -2 to -3 on the L-Pads. I also had to lover the gain a little bit on the electronic crossover on the left channel, and I believe this is due to furniture in our livingroom.

How does this look comparing to your settings?? Please let me know!!!!!!!!!

Thanks to Ian and everybody else (the list is to long to thank everybody by name) who got me going with this. Now the sound stage is crystal clear, and I believe the need for an eq is gone. I recommend everybody with large size monitors to try this.

I wonder what will be the next issue.....

Rolf

[Ian Mackenzie]

Great news.

Happy listening


Ian

[Rolf]

Great news.

Happy listening


Ian

Thanks Ian. I am enjoying? it. How do you compare the settings of the L-Pads in your experiance?

Rolf

[Ian Mackenzie]

Thanks Ian. I am enjoying? it. How do you compare the settings of the L-Pads in your experiance?

Rolf

Rolf,

My understanding is you have a stock JBL 4343 system.

My reference system is a JBL 4345. The 4345 has identifcal drivers and crossover network to the 4344 except the woofer. The 4344 crossover (3145) is different to the 4343 crossover (3143) and therefore the calibration is different. My L Pads are in "O" position.

In anycase if you have measured with your RTA the levels of the drivers to be flat then that is what matters and the subjective result will be obvious as you will forget about the speaker and start enjoying the music!

Ian

[Rolf]

Rolf,

My understanding is you have a stock JBL 4343 system.

Yes, the 4343B. 2235H, 2121H, 2420 (alnico) and 2405 (alnico)

In anycase if you have measured with your RTA the levels of the drivers to be flat then that is what matters and the subjective result will be obvious as you will forget about the speaker and start enjoying the music!

Ian

Jippiaoitayey!!!! I DO, MORE THAN EVER! (And I am over 50)

Regards

Rolf

[Ian Mackenzie]

For those interested in tackling some of the upgrades here are images taken of the project in development.

The origins of the signal driving the loudspeaker start long before the passive crossover.

We found during the course of the project development that the active crossover was a significant contributor of tonal accuracy, dynamics and resolving power of the loudspeaker system.

A new active crossover was designed and tuned to the application of biamping the 4343-4344-4345.

We also found that the capacitor coupling the (52 uf) midrange in the 4343 passive crossover had a direct impact on the midrange and hi frequency performance.

After various trials it was also determined that upgrading the drivers and the passive crossover to the 4344 specifications for biamping provided the maximum performance potential from the loudspeaker system.

An external passive crossover using audiophile grade components was build and tested using the Giskard equivalent 3145 crossover design.

Other refinements including the use of high quality terminations played a significant part in attaining the maximum resolution of the loudspeaker system.

Below are some images of the project reference components . A protective film covers the front panel of the passive crossover for shipping.

This is a diy project, not a commercial product and it was built by hand.

No doubt a better finish could have been arranged with a CNC lathe and other production tools, but would not have been half as much fun!

I would like to thank Ed for the opportunity to be involved in his project and for being so patient. This project was Ed's idea, its been a great pleasure working with you Ed...enjoy. I would also like to thank Giskard for his technical input and also Don for being able to share this on the Lansing Heritage Forums.

Ian

[porschedpm]

I'm thinking the photos are arranged as follows (top to bottom):


Photo 1- Active crossover-innards
Photo 2- Active crossover-back panel
Photo 3- Passive crossover-front panel
Photo 4- Passive crossover-rear panel showing 8 pole Speakon connector
Photo 5- Baffle modified to 4344 specs

I'm continually amazed at the level of expertise demonstrated by Ian and a select few of the other members that make up brain trust here on the LH Forum. Thanks for inspiring the rest of us.

[Ian Mackenzie]

I'm thinking the photos are arranged as follows (top to bottom):


Photo 1- Active crossover-innards
Photo 2- Active crossover-back panel
Photo 3- Passive crossover-front panel
Photo 4- Passive crossover-rear panel showing 8 pole Speakon connector
Photo 5- Baffle modified to 4344 specs

I'm continually amazed at the level of expertise demonstrated by Ian and a select few of the other members that make up brain trust here on the LH Forum. Thanks for inspiring the rest of us.

Thanks Ed,

Please note these are snap shots.

I need to label the active crossover front and rear panels.

Ian

[sa660]

Ian,

Very good work,
I am always wondering about the recommendation for low frequency enclosure and the need to rigidify the cabinet.
For example could we extend the bottom wall of the mid cabinet to link with the side wall and back wall. This will increase the rigidity of the box and because of the asymetric position will help reducing the vibration of the resonance zone for the wall cabinet. Other means using 2x2" beans internaly will help.
Looking iniside the 4435 I beleive JBL did a lot of work on improving the rigidity and the energy from both 2234 is very well absord.

[Ian Mackenzie]

Ian,

Very good work,
I am always wondering about the recommendation for low frequency enclosure and the need to rigidify the cabinet.
For example could we extend the bottom wall of the mid cabinet to link with the side wall and back wall. This will increase the rigidity of the box and because of the asymetric position will help reducing the vibration of the resonance zone for the wall cabinet. Other means using 2x2" beans internaly will help.
Looking iniside the 4435 I beleive JBL did a lot of work on improving the rigidity and the energy from both 2234 is very well absord.

I will post some images of the internal bracing of the 4343 in day or so.

One point to remember is that as a result of isolation of the mid and low frequency transducers in their respective chambers, the control of panel resonances and internal damping can tailored to meet the respective requirements.

As a result, the approach taken in a design such as the multi 4 way monitor can and would be different to a 2 way system such as the 4430/4435 where the enclosure is no doubt treated to control the bass and a large portion of the mid band frequencies.

Ian

[Ian Mackenzie]

Positioning

Today I re arrnaged my system to arrive at a configuration to has less architectual constraints like doorways and windows.

The set up is now more like the graphic in the 4344Mk11 OM.

Prior to this I had to allow for a glass window opening b/n the louspeakers which restricted the distance b/n the loudspeakers. I now have what more closely resembles equi-distant positioning while my listening postion is further out from the rear wall.

The improvements are quite noticable.

Ian

[Robh3606]

Hello Ian

I like that positioning guide. My second system is set up along those lines with some space off the rear wall and side walls. When you get the spacing close too or at that magic triangle it really is amazing what a difference in can make. I am a little close to mine set-up that way but it sure sounds good.
Rob

[sfellini]

Hi -

I can't find this manual on either the JBL
support site or the Tech Ref section of this
forum. Could someone post it?

Thanks,
Steve.

[Lancer]

http://www.harman-japan.co.jp/suppor...al/4344Mk2.pdf

[Ian Mackenzie]

Attached a diagram from the English version of the 4344Mk11 manual: