4435+2404H

[Squirrel]

I suppose a few 4435 owners have experienced adding 2404H tweeters. What is the best location ? inside the cabinet ( and where) or in a small box over the top, so as they 'll be vertcally aligned with the 2426?
I'll have no problems with the crossovers as I have a couple of 5 way Rane AC 23 active crossovers with time delay adjustment and several amplifiers, so I can shunt the original crossovers for the experiment.
Thanks for your reply.
Squirrel

[Zilch]

A couple of people have tried it. It's not a commonly installed modification.

Why? It messes up a good design.

Your Rane's not going to get it.

If you were talking DEQX, then, maybe.

Let it be....

[Robh3606]

Zilch has some good points but if want to try it. It's not a simple modification. If you look at the voltage drives you can see why. I used the CD compensation from the passive network in an active set-up, it yeilded the best performance no contest. I tried running the 2344 with CD compensation from an active crossover and it didn't cut it. Too much roll off above 10K. You could use that to your advantage incorporating a tweeter. Part of the problem is the transition between the woofer and the compression driver is not symetrical and then you have the horn compensation complicated with tweeter integration. If you tried it I would go 3 way active, shift around the crossover a bit between the woofer and compression driver for smoothest response, use CD comp on the compression driver and try an 8-10K crossover on the 2404. Voltage drives courtesy of Giskard.

Rob:)

[Guido]

And you should make sure your 2404's use the lightweight D16R2405 diaphragms!

[Squirrel]

HI Rob, ZILCH and GUIDO
Thanks for your infos, I did not answer immediately because it took me time to do the experiment.I give you my firts results in the thread " 4435+ Active crossovers.
Thanks and best regards.
squirrel

[Squirrel]

And you should make sure your 2404's use the lightweight D16R2405 diaphragms!

Hi Guido
How can I know the reference of the diaphragm mounted inside the 2404H?

[Squirrel]

Hi Robb
Could you give me some precision about the CD compensation process?
I read in the rane pro audio reference that it was an equalisation applied to avoid an upward tilted emission lobe;Thanks for your reply
Squirrel

[Guido]

Hi Guido
How can I know the reference of the diaphragm mounted inside the 2404H?

Honestly I don't know.
What I know is that some 2404 versions use the D8R075 diaphragm which handles more power but has less extension above 16 kHz.

[Zilch]

If your UHF response is falling above 18 kHz, chances are it's 2402 diaphragm.

The FR differences are documented in several threads in these forums.

Try "Ring Radiator Comparisons" for starters, also "Mini DIY."

[Robh3606]

Hi Robb
Could you give me some precision about the CD compensation process?


Hello Squirrel

If you look at a compression driver measured on a plane wave tube the response falls off above the mass break point at about 6dB per octave. Traditional horns like an exponential as an example have a directivity that increases with frequency. What that does is raise the on axis level at a rate that complements the natural rolloff of the driver. The higher in frequency you go the higher the directivity is. With that type of horn the directivity equalizes the on axis response so it measures flat. With a Constant Directivity horn like the 2344 this does not happen. The horn is designed to have Constant Directivity over the operating frequency range so the response on axis looks just like the plain wave tube measurement. With that type of horn you need to use the crossover to perform the compensation. That is the CD compensation I was taking about. With the 2344 the basic EQ was done rather elegantly by using a simple series cap. What the cap does is trade off the lower mid band effciency to level out the response on the horn. Since the cap acts as 6db per octave high pass filter the resultant curve goes a long was to acheive the desired response.

Read the profile on the 4430 and the Improvements in Monitors documents on the site:

http://audioheritage.csdco.com/vbulletin/showthread.php?p=76021#post76021

http://www.audioheritage.org/html/profiles/jbl/4430-35.htm

Rob:)

[Squirrel]

Hello Robh,
Thank you for your precise explanations and for the documents' references. They are very interesting for me, as you may have guessed, I' m not a specialist in speaker systems.
Best regards
Squirrel