JBL 4430 and 4435 Cheat Sheet

Zonker92

All shiny and chrome
Over the past couple of years I've posted a lot of thoughts and threads on the JBL 4430 and 4435 large-format studio monitors. Since people sometimes PM me for advice or with questions, I thought I'd post up this cheat sheet summarizing many of my observations and mods. (Do not let this thread stop you from PMing me with questions or comments, but do please check this thread first, as it covers a lot of ground.)

Take all these ideas with a grain of salt; I'm just an amateur enthusiast. In some of the threads you will see people correcting some of my mistakes and erroneous assumptions.

Restoration/veneer/baffle paint/stain/finish/crossovers/damping material--see thread here: http://www.audiokarma.org/forums/showthread.php?t=654301

Finishes--see thread here: http://mail.audiokarma.net/forums/showthread.php?t=588281

Stands--see thread here: http://www.audiokarma.org/forums/showthread.php?t=561749

Baffle paint--see thread here: http://mail.audiokarma.net/forums/showthread.php?t=636991&page=6

Cabinet dimensions--see threads here: http://www.audioheritage.org/vbulletin/showthread.php?1075-Measurements-at-4430-Cabinet and http://www.audioheritage.org/vbulletin/showthread.php?2676-the-4430-DIY-thread and http://www.audioheritage.org/vbulletin/showthread.php?2355-4435-Diy

Damping--see thread here: http://www.audiokarma.org/forums/showthread.php?t=646389

Active crossovers--not really my area, but see thread here for at least some insights: http://www.audioheritage.org/vbulletin/showthread.php?6542-4430-X-Over

Ports--see thread here: http://www.audiokarma.org/forums/showthread.php?t=538592

Positioning--see thread here: http://www.audiokarma.org/forums/showthread.php?t=560092

Passive biamping--see thread here: http://www.audiokarma.org/forums/showthread.php?t=640456

Grills--see threads here: http://www.audiokarma.org/forums/showthread.php?t=672621 and here http://www.audioheritage.org/vbulletin/showthread.php?2520-4430-Diy

Internal wiring: Leave alone, I say. I think it's fine. You certainly can hard-solder all the wires to the PCBs. It would make for more stable long-term connections. I did not do it because it make it a lot harder to remove the PCBs for future work; I just cleaned up the connectors. I have tested my connections and the DCR is all basically zero, so I'm not too worried about it.

Rotary switch--see thread here: http://www.audiokarma.org/forums/showthread.php?t=537606 (more details and photos in the later pages of that thread).

L pads and rheostats: I would not bypass the L pads or rheostats, just because you lose some adjustment that way. If you do it, you will need to find your preferred position, measure the DCR on each of the two "pairs" of L-pad legs, and then replace each circuit with a separate resistor; see: http://www.audiokarma.org/forums/showthread.php?t=622331. Also, replace the rheostat with a resistor matching the DCR of the preferred setting. I'd use at least 12-watt resistors in each case.

Binding posts: I have used binding posts like these before (http://www.parts-express.com/dayton-audio-bpa-38sn-hd-binding-post-pair-satin-nickel--091-1247), but it is better with shorter threaded shafts, since the plastic back panels are thin. You might cut off the excess lengths of the shafts. And you will probably need to enlarge the holes for them. I wound up instead going with spring types like these, just because they're more OEM and they don't loosen with vibration: http://www.parts-express.com/spring-loaded-speaker-terminal-pair-nickel-13-16-tab--091-1142 (removed from their included panels).

Charge-coupled crossovers--see thread here: http://www.audiokarma.org/forums/showthread.php?t=636991. To delete the battery, see thread here: http://www.audiokarma.org/forums/showthread.php?t=532863

Coils and resistors--see thread here: http://www.audiokarma.org/forums/showthread.php?t=523597

Literature and specs--see here: http://www.audioheritage.org/html/profiles/jbl/4430-35.htm, and http://www.jblpro.com/pub/obsolete/443035.pdf and http://www.jblproservice.com/pdf/studio monitor series/4430lr.pdf

Compression driver diaphragms--see my review here: http://www.parts-express.com/radian-1225-8-diaphragm-fits-most-jbl-1-8-ohm--294-720

Recapping and bypass caps--see thread here: http://www.audioheritage.org/vbulletin/showthread.php?34407-Recapping-4430s I really can't recommend any particular caps, or using bypass caps, as I've not conducted any scientific listening tests. Personally, I use Audiocap Thetas for the smaller values and Jantzen Standards or Crosscaps for really large values, with Audiocap Theta bypass caps, but I make my choices based upon gut feelings, not science. Also, Zilch liked to use Dayton film caps with Audiocap Theta bypasses.

Eric

PS I think every thread should start with at least one photo, so:

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If you got the spec go all the way with the Big Mother, 4435. Neither one take big power to create live levels accurately and that's what its all about. Getting the correct balance by adjusting seating position and speaker location relative to the room can be a tiring process. But if and when all the nasties have been over come you will love the sound. And you really don't need the super tweeter of the DD series. It might be fon to upgrade the woofers some day if the enclosure design will allow, but I would bi-amp with an external electronic crossover and a parametric EQ to voice the speaker in the room correctly.
 
Thanks, kica! Twii, using an external active crossover, how tough is it to do the CD EQ on the horns?
 
Thanks, kica! Twii, using an external active crossover, how tough is it to do the CD EQ on the horns?


Some have a CD switch that gives whatever curve the designer decided on. The passive curve on the 4430 sounds a lot better than most active XO CD curves. JBL actually used the passive compensation when bi-amping the 4430. The main benefit is directly connecting the woofer and gaining the more precise control that that gives anyway. You still need to have a capacitor in series with the tweeter, and IMO the difference you might hear with a correctly CD compensated direct amp on the tweeter and going through the JBL pre-comp filter would not be worth it. I mean exactly replicating the drive curve of the passive circuit, which is not a simple slope by any means. Especially once you consider the L-Pads that let you dial in a preferred response...

I have a DCX2496 that does not have a setting for CD at all, but if you know what is going on it's not to hard to dial in a 6dB slope at the top of the pass band with it.

In other words, set up the tweeter with the HP filter at say 5KHz, with whatever slope you need, then add a 6dB per octave high pass to the same output, set to 20KHz. End result is a band that rises from 5K to 20K @ 6dB per octave. Gain settings are a bit higher than without the 20K filter. This works OK with my 2385 flat fronts, but the passive 3110A sounds better. I finally reworked all the opamps in a JBL XO so I could use the JBL Flat Front EX XO cards, that pretty much matches the passive sound...

Thanks Zonker for the links. Great idea.
 
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Zonk,

Nice job. I really like threads like this that take the time out of searching for the subject matter.
 
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