JBL 4343 rebuild and configuration project

[Steve Gonzales]

Thanks Dave, also for your contribution. Black is beautiful too.

These would require 3145 networks for the only club I know of - wouldn't they?

Doesn't that sound like a winter project?

We'll see.

No, the 4343 is a four way. That seems to be the flavor of the day here, and rightly so. I shipped Dave a pair from California a couple of years ago. Damn near broke my a** moving, packing and shipping them. Majestic to witness in person. Enjoy your dream fulfilled, they deserve to be owned by someone like you. Regards, Steve G.

[Rolf]

Rolf,
their position is >3,5m or 11,5ft away from each other, in a room having around 30qm. I get a better stereo image from the usual listening position with the slots in the inner mounting holes.

THAT I do not understand. You have about the same room as I have, and I have tried both ways. I am sure you have a good stereo image with the 2405 on the inner side, but if you follow Ian's recommendations (as I did, but can't find the thread ... Somebody help??) you will get a much wider and deeper sound perspective. In my room the 2121 is adjusted to -1, the 2420 to -2, and the 2405 to -1. The network, the 5235 is set on level 7. All these adjustments is done with a SPL meter using specific frequencies for the different transducers. If you do this I can almost guarantee a big difference. Of course it also matters what is in your room regarding furniture, carpets and so on.

Try it, and good luck.

[Fangio]

You have about the same room as I have, and I have tried both ways. I am sure you have a good stereo image with the 2405 on the inner side, but if you follow Ian's recommendations (as I did, but can't find the thread ... Somebody help??) you will get a much wider and deeper sound perspective. In my room the 2121 is adjusted to -1, the 2420 to -2, and the 2405 to -1. The network, the 5235 is set on level 7.

Didn't find that specific recommendation also.

Well, the position for critical listening is ca. 4-4,5m away. With the 2405 on the outer sides I would get an almost equilateral triangle to them.

Ok, I'll just swap the boxes tonight (*groan*) and give it another whirl.

Also I'm awaiting a 5234 with the appropriate 4343 card soon, and have a 2nd power amp for a first Q&D biamp setup. Will report.

[Chas]

Ok, I'll just swap the boxes tonight (*groan*) and give it another whirl.
.

It could be worse, Dude....you could have 4345's

[Fangio]

It could be worse, Dude....you could have 4345's

Indeed. One 4343 weighs more already than I do (~75kg).

No, the 4343 is a four way.

That wasn't meant too serious, more a little joke. Referred to the fact that this (4345) club, and also the 4344's upgraders all use 3145(-based) xovers. We'll see if these could once be counted to that elected group.

[norealtalent]

Hey now! Forget the 4345's. Since you haven't bi-amped those 43's then you still haven't a clue what they really sound like. If I'd had bi-amped my first pair I'd probably never gone any further.

[Ducatista47]

UHF inside is a long standing, very subjective method for "linking" the tweeters. I use it myself. In the past some have felt doing so was necessary for good listening. I am currently doing it myself, but I can't defend it. I just prefer it.

Clark in Peoria

[Chas]

Hey now! Forget the 4345's. Since you haven't bi-amped those 43's then you still haven't a clue what they really sound like. If I'd had bi-amped my first pair I'd probably never gone any further.

I couldn't agree more.

[Rolf]

Ok, I'll just swap the boxes tonight (*groan*) and give it another whirl.

I forgot: about 10 deg angle against center. don't you have your speakers on wheels? I made 2 "shelf's" with wheels on them. Easy to move when my wife "have to get under or beneath them".

[yggdrasil]

I was thinking about this slot-placement. You stated that your room was 30sqm, 3,5m between the speakers and 4+m from speakers to the listening position.

Does that mean that
a) there are a very short distance from the speaker to the side wall?
b) you sit very near the back wall?

If any of the assumptions above is true you will have lots of early reflections affecting you.

Just a thought.

[Rolf]

If any of the assumptions above is true you will have lots of early reflections affecting you.

Just a thought.

Not if you have the right stuff on the wall Johnny. Agreed?

[Fangio]

Clark, thanks. Thats what I thought too - if it sounds good, why bother.

The first setup with the tweets in the outer holes wasn't a fair test though, electronics-wise. Since there are different opinions here I gave it a second try. From my other mirror-imaged speakers, the 4312's I learned that the tweeters on the inner position may help for better, deeper stereo imaging when speakers are far apart (and vise versa), and thats indeed what is audible with the 4343's again.

Rolf, Johnny, yes since the speakers are near the corners of the room, at least one, I angled both a bit to the center to avoid parallel reflections. The opposite wall in the back is almost completely covered by a huge book shelf. Maybe not optimal - well, this is a living/working area, not dedicated to perfect audio performance only.

Right now they are on wheels, or dollys again (see driver set pic). I consider the combination very handy but the look of this ones isn't that great. The 4343's seem to float with them, or to have wheels screwed directly into the bottom. Will either have to find nicer ones, or to hide them behind bezels.

[yggdrasil]

Not if you have the right stuff on the wall Johnny. Agreed?

I have not been granted permission by my wife for that kind of fun. So there is no first hand experience in that field.

Rolf, Johnny, yes since the speakers are near the corners of the room, at least one, I angled both a bit to the center to avoid parallel reflections. The opposite wall in the back is almost completely covered by a huge book shelf. Maybe not optimal - well, this is a living/working area, not dedicated to perfect audio performance only.

I suppose that would be a normal situation for most of us.

A while back I had my 4-ways in a 4m x 7m room, with the speakers on the 4m wall. When sitting in the couch at the rear wall the sound stage was blurred. In a chair with 2-3m to the rear wall the sound stage was much more defined.

[Fangio]

...since you haven't bi-amped those 43's then you still haven't a clue what they really sound like. If I'd had bi-amped my first pair I'd probably never gone any further.

OK, lets see.

An active xover arrived here last weekend. It's a JBL 5234, and afaik it has been in more than one forum members hands. The cards inside are stamped with #51340.

This thread lists some of the 5234/5234A/5235 differences, in post #3 and #4:
http://www.audioheritage.org/vbullet...ht=5234+bypass

The notes on the right side in the pic below indicate that this 5234 has been upgraded with some features of the later 5234A and 5235:

1/4 jacks and bypass caps added
C1, C2, C3, C5
C101, C102, C103, C105
0.1uF
5-16-04


I got it from Triumph Don (thanks), the modifications were done before he got it. My little hope was, perhaps the fellow who did that is still a forum member, recognizes his work and could answer some questions, as I'm quite new to these units. :dont-know

- caps type used
- are the cards 12db or 18db

And from the pic, is there any other addition desirable, from todays point of view. Anyway, I appreciate the jacks.

[Tom Loizeaux]

... In my room the 2121 is adjusted to -1, the 2420 to -2, and the 2405 to -1. The network, the 5235 is set on level 7. ...

Since you are bi-amping your 4343s, you could turn the L-pad pots all the way up and not waste power from your high frequency amp. Set the 2121 to max, the 2420 to +3, and the 2405 to max. Then you could turn down either your crossover levels or turn down you power amp feeding the high frequency section to get the balance you want without burning off power with your L-pads.

Tom