4430/4435 Upgrade Summary

[grumpy]

After searching the forums a bit I found the following suggestions (sorry if I missed
some), and in no particular order other than the top two factory configurations:

1) Leave them the heck alone.
2) Use 5235 with 4430/4435 specific cards.
3) Bypass caps with high quality units.
4) Build up a clone network with presumably better parts, adjusting for inductor DC resistance.
5) Build up a charge-coupled network.
6) Build up a passive line-level network (high-pass specifically?) presumably in lieu of 5235.
7) Replace the 20uF protection cap with a higher quality unit.
8) Find a 2421 (aluminum) diaphragm (vs Ti).
9) Go apeshit and design your own active crossover using stock network voltage curves as a guide or as the law.
10) Add a negative impedance amplifier or EQ to the horn electrical path in an attempt to address 2-3dB of ripple on the low end.

So far, I can offer up experience with the first two (old/stock passive, and biamp using 5235+cards).
Both were capable of making me just sit and listen with disregard for the time.
Amps were JBL/UREI 6260's (one per side in biamp-mode).
No adjustments to L-pads were made (all set to 0). 5235 HF adj was set to 8.5 and flat bass (no bump or high pass).

Initial reaction to biamp was YUCK... then I flipped the polarity on the horn input on
both sides... now we're talkin. I guess I'm one of the few that like this configuration as
well or better than passive...May take extended listening to notice finer details.
With this post, I'm trolling for other's experiences with the care and
feeding of these very nice professional tools, uh, er, speakers. Right now, I'm content
to work on cosmetics and enjoy them for what they are, but thought it might be helpful
to get 4430/4435 work re-condensed in a new thread.

Cheers,

-grumpy

[ thanks to all for the specific responses that followed ...
no need for more schematics, almost everything mentioned is well within my capability,
I have most of the parts required, and can be evaluated in steps ... nice! ]

[4313B]

Build a bi-amp only, biased high pass passive filter for the 2344A/2421A/2425H/2426H. (3134 for 4430 and 3135 for 4435. Do I really need to draw and post the partial filters?)

Build a 6 dB/octave line level passive high pass that goes between your preamp and power amp. It helps if you use an ampifier with it's own gain. Bias this circuit if desired.

Use the low pass of a 4430/4435 card in a 5235 or bypassed 5234A (bypass the electrolytic coupling caps with film and foils). Better yet, build your own active low pass that emulates the 4430 low pass or 4435 low pass depending on which system you are playing with.

A great off the shelf unit to handle both high and low pass is the DX-1 if you're lucky enough to have one. The high pass is easily biased in that unit.

Tune the 4430 down lower to around 30 Hz.

Use D8R2425 titanium diaphragms coated with aquaplas.

[Chas]

Glad to hear you are enjoying them. I haven't tried biamping mine yet, too busy with my 43XX monster project in the two channel room. Good idea you have to consolidate things into a 4430 specific area.

[Robh3606]

Hello Grumpy

I use the 2344 in a triamp set-up with the 4435 compensation charge coupled. I really like the 2344 and I felt charge coupling definately helped things out for the better. If I had stock 4430/4435's biamped I would leave them alone and build the passive compensation part of the network as an outside box and run the biamp Hi Freq output amplifer output through it. You could use higher quality caps or just charge couple it. Nice fun project, not that difficult to do. Not alot of parts either.

Rob:)

[Zilch]

Use the low pass of a 4430/4435 card in a 5235 or bypassed 5234A (bypass the electrolytic coupling caps with film and foils).I was probing around in a 5235 last night. There's no room to replace those four 100 uF electrolytic output coupling capacitors with metalized polypropylenes, for example. Is it worth replacing the 0.01 uF bypass caps with like Thetas? Any other suggestions for that area?

Tune the 4430 down lower to around 30 Hz.Closing one port takes it a little lower than that, if I recall. Is that good enough (it's easily accomplished)? I can measure Fmin with WT2, if that will help....

Use D8R2425 titanium diaphragms coated with aquaplas.And these we (us forum members) might obtain where? ;)

[Zilch]

So far, I can offer up experience with the first two (old/stock passive, and biamp using 5235+cards):

Both were capable of making me just sit and listen with disregard for the time.

Right now, I'm content to work on cosmetics and enjoy them for what they are....

Gonna be keepers, sounds like.... :D

[4313B]

I was probing around in a 5235 last night. There's no room to replace those four 100 uF electrolytic output coupling capacitors with metalized polypropylenes, for example. Is it worth replacing the 0.01 uF bypass caps with like Thetas?http://www.audioheritage.org/vbulletin/showpost.php?p=3159
Closing one port takes it a little lower than that, if I recall. Is that good enough (it's easily accomplished)?No, that's if you want to use a bump filter at 26 Hz. Blocking one and shortening the other to 4-1/8" does the trick. Vent velocity isn't too great for most home use (ends up similar to L300/4331/4333 vent velocity). Most people would balk at cutting length off a stock port. So remove it and replace it with a shorter one.
And these we (us forum members) might obtain where? ;)I'm not sure yet if I want to start doing it for other people. If Ian and Rob say "go" then maybe I will consider it.

[Guido]

If Ian and Rob say "go" then maybe I will consider it.

I'm not asked here and I do not know the background of this remark... But I say GO please ;)