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wlk
01-25-2012, 08:52 PM
Over the last five years with the help of information posted on the Lansing Heritage wesite I have built two pairs of 4430s and one pair of 4333s. All three pairs of speakers were built using the driver and horn components specified on the JBL tech sheets. All crossovers were hand built from high quality components as specified in the JBL tech sheets. I made the cabinets slightly larger at 6.6 to 6.8 cubic feet and tuned them to 30 HZ. I made the cabinets for the 4430s more of a tower design because I use them as the front speakers for my home theater.
I use the 4333s with mono block tube amplifiers that I built for listening to music.

I perfer the sound of the 4333s because I like the extra high end that the 2405 slot tweeter adds (I am an old retired guy and my high frequency hearing is beginning to fail).

I have some extra pairs of 2404 and 2405 tweeters and as an experiment I would like to add a pair of these tweeters to one pair of my 4430s.

Would anyone have any suggestions how to modify the stock 4430 crossover design to accommodate these tweeters.

Robh3606
01-26-2012, 07:41 AM
Hello wlk

I wouldn’t mess with the crossover unless you have the tools to measure and redesign it. Instead you might want to just turn the upper range all the way down. Then just use a low value series capacitor like 1uF with a 2405 and an L-Pad to adjust the level. You might be able get it to work.

Rob:)

Mr. Widget
01-26-2012, 09:27 AM
I agree... both about not messing with the primary crossovers and also in using the 2405s. I'd experiment using different caps between 1 and 2uF. The larger the cap the lower the -3dB point and more HF energy you will hear. I would center the 2405 over the horn... you may also want to experiment with placement.


Widget

grumpy
01-26-2012, 10:51 AM
Yeah, I'd stick to 1uF followed by the L-pad. That should put the -3dB point
at roughly 13KHz, where the 4430 should still have plenty of output.

A single cap doesn't do much in the way of attenuation as the
frequencies go lower; no point in tempting fate with your 2405 diaphragm.

Ensure that the 2405 is vertically pointed at the listening height of your ears...
they don't have a lot of dispersion in the up/down direction.

Mannermusic
01-27-2012, 05:48 AM
Yeah, I'd stick to 1uF followed by the L-pad. That should put the -3dB point
at roughly 13KHz, where the 4430 should still have plenty of output.

A single cap doesn't do much in the way of attenuation as the
frequencies go lower; no point in tempting fate with your 2405 diaphragm.

Ensure that the 2405 is vertically pointed at the listening height of your ears...
they don't have a lot of dispersion in the up/down direction.

All the above plus try adding the parallel inductance of .2 -.3 mH (12 db/octave high pass). I find this usually sounds smoother and reduces (eliminates, most likely), any risk to the diaphragm. Without the added parallel inductance there is too much UHF, in my experience. By the way, 1.0uF is usually the MOST I ever find useable. You have to "hook it" - I normally start with .5uF and work larger in .5 increments. When it's correct, you won't even hear the transition - a seamless blend.

wlk
01-27-2012, 11:54 AM
Gentlemen
Thank you very much for your simple but eloquent solution for adding a 2405 tweeter to my 4430s.
Last night I built simple crossovers using 8 ohm L-pads and Solen 0.1 uf caps bypassed with Wima 0.02 uf caps and it worked quit well.
Over the next few days as suggested I will experiment with different values of caps and add inductors in parrallel with the tweeters.
Would a tweeter circuit similar to the tweeter circuit in the 4333 or L300 crossover work for this application?
Would the values of the caps, inductor and the Zobel resistor have to be changed?