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Thread: 4435+ Active Crossovers

  1. #1
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    4435+ Active Crossovers

    Here is the results of my first experiments with active crossovers. (Rane AC 23 B, five way) with 2404H added to my 4435
    I set the high crossover frequency at 7 Khz( it's the highest possible on the Rane), put a measurement microphone at 1 ft from the the front baffle, midway from the center of the two horns ( the 2404h was positionned on the top of the cabinet, insulated with acoustic foam and aligned vertically with the 2344A.
    The rane crossover comes without CD compensation (it can be done internally), and I don't Know if this compensation is done by a slight parametric equalisation or othewise. Thanks to Robb if he Knows what it is exactly.
    The measurement microphone was connected to a real time analyser, emitting pink noise (1/3 octave filtered)
    The level produced by each driver separately was set at 80dB Spl at 1 Ft.
    Whith the two drivers emitting, I got +3 db Spl with a slight adjustment of the delay control of the 2404 H on the Rane crossover.
    I got the same level with no delay on the crossover, simply by moving the 2404H slightly backward. The frequency response curve displayed on the RTA (resolution 1dB was flat(+or - 1dB) between 2Khz and 18kHz with a slight rolloff after 18 kHz(which can be compensated by adjusting the level of the 2404H, not necessary in my opinion).
    I proceeded in the same way with the 2426H and the medium 2234H .
    No delay adjustment needed as they are aligned by construction. I only had to adjust the level of the 2234H.
    Now between the two 2234H, the delay adjustment is inoperative to compensate differences in response level as they are horizontally positionned. Anyway, when using an amplifier for each 2235 (one from 30 Hz to 100Hz) and the other from 100Hz to 1kHz doesnt not co rrespond to the original setting, where both drivers starts at around 30 Hz. And with the Rane crossover it is not possible to have such a setting.
    The result was a losss inlevel in the bottom end.
    I then added a Velodyne HGS 18 sub( from 20Hz to 70hz), under the 4435 and set the crossover frequency of the low 2234 at 70 Hz) The overall result was a flat response curve from 20Hz to 18500 Hz) The 4435 are mounted at 3 feet high, in order to have the have the drivers emitting over my recording console.
    Now at ten feet from the monitors, atears'height behind my console the frequency response curve is nearly flat,at 80dB Spl level, but I have still a lot of work to do to improve the acoustics of my control room.At higher levels, the things are different I think that there are several things to experiment, as the Rane crossover are Linkwitz Riley type with 24dB/Octave slopes. I'll try the same experiment using Behringer DCX 2496 or BSS FDS 366 crossovers, on which it is possible to choose the filter type ( Linkwitz, Butterworth, Bessel) and slopes from 6dB/octave to 24dB/Octave. If any member has already done the job, I would be glad to know which type of filter suits the best.
    Thanks to everybody
    Squirrel

  2. #2
    Senior Member remusr's Avatar
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    Squirrel,
    So how does it sound? I have a pair each of 4430 & 4435 and also was thinking of doing something to give them some top end & smoothness. Your method seems like a research project! Couldn't I just add a 2404 or 2405 with a cap to top up the response from 10k up?

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    Senior Member Don Mascali's Avatar
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    I use a 2425H on an Everest horn and added a 2404H and 2405H in parallel with a 2.0 MFD capacitor in series with the + lead.. (At different times of course). Each sounds nice but have their own character. I would like to have the volume control that an active X-over and another amp would provide to help integrate it..

    I run my 2425H straight. If you have a 4430 or 4435 there is CD horn compensation built into the internal X-over. This would be a problem for the simple addition of a 2405H unless you disconnected or modified it.

    According to Zilch and many others you would just screw up a "Perfect" design and the utter simplicity of the 2 way system. I tend to agree. A little tweek with an equalizer may do the trick.
    4406, 4412A, L100, L100t3 (3 pair), L1, L7, 4645C, 4660A, 4695B, SR4735 and various DIY JBL Pro loaded systems.

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    With the 4435 you will not gain anything in running the two 2234 woofers at different frequency band passes. They share the same internal cabinet and the woofer operating in the 30hz to 100hz range will be driving the other woofer you have operating in the 100hz to 1000hz range like a passive radiator resulting in reduced low frequency output. What you could try is a slightly different take on what you are doing now by only operating one of the woofers up to 100hz and taking the other woofer up to the crossover point where you go into the 2426 driver. Many double 15 cabinets do that to help reduce comb filtering from the two woofers reproducing the mid range and upper midrange frequencies. That way you still get the benefit of the two 15 speakers for the low frequencies. I would use the woofer directly under the horn for the high crossover point. Without going to a more complex analog crossover or getting another analog crossover you will not be able to do it with the Rane that you have. The analog BSS FDS318 would do the four way stereo output required for this type of set up. The BSS 366 will only do stereo three way. Running the system active three way would not really be bad at all just operating the woofers in parallel. As for CD horn EQ that curve varies from manufacture of horns and crossovers but it is generally around a 6db per octave boost starting around 3500hz to 4000hz.

    Mike Caldwell

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    Quote Originally Posted by Mike Caldwell View Post
    With the 4435 you will not gain anything in running the two 2234 woofers at different frequency band passes. They share the same internal cabinet and the woofer operating in the 30hz to 100hz range will be driving the other woofer you have operating in the 100hz to 1000hz range like a passive radiator resulting in reduced low frequency output.

    Mike Caldwell
    I picked up a pair of 4435's down in Texas a few weeks ago and there is a wall in that cabinet separating the 2234's into there own chambers.???

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    Hello
    Thanks for catching my bad! I did not notice that in the specs. After reading them closer it does confirm that one woofer operates up to the 1000hz crossover frequency and the other only operates up to 100hz. To fully emulate what the internal passive crossover is doing plus the additional tweeter using a fully active system will require a stereo four crossover system ( analog or digital) that will allow the overlapping of crossover frequencies and parametric EQ points that would need to be inserted. The 4435 is set up to bi-amp, after looking at the cross schematic even when bi amping it leaves the low pass filter in place for the second woofer and the impedance /EQ portion for the 2425 driver.

    Mike Caldwell

  7. #7
    Super Moderator Hofmannhp's Avatar
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    sepate or not is the question

    Quote Originally Posted by Mike Caldwell View Post
    ........ They share the same internal cabinet and the woofer operating in the 30hz to 100hz range will be driving the other woofer you have operating in the 100hz to 1000hz range like a passive radiator .........
    Mike Caldwell
    Hi Mike,

    my 4435 have also separate chambers for the woofers, but you are right in some way. There are early 4435 where the woofer chamber is NOT separate.

    HP
    Please help us save more info about the vintage systems. Let us register your speakers and drivers.

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    Exclamation 4435 versions

    Quote Originally Posted by Hofmannhp View Post
    Hi Mike,

    my 4435 have also separate chambers for the woofers, but you are right in some way. There are early 4435 where the woofer chamber is NOT separate.

    HP
    Hi Hofmann
    I now own two pairs of 4435. the older one have no separation wall between the two 2234H, the 2344A (+2425J) is positionned at 140 mm from the lateral side of the cab, and the crossover hole is on the center of the backwall.
    On the other ones, there is a separation wall between the two 2234H, the 2344A (+2426H) is at 102 mm from the sidewall, and the crossover is fitted in the woofer chamber.
    They sound very similar, the separation wall avoids the cab's sidewall vibrations i noticed at 40Hz on the older model. So , on some records, the acoustic double bass or the kick drums are more precise, but the difference is not tremendous.
    Concerning the differences in stereo image which may result from the respective horns positions, I am unable to tell which is best as it is impossible to have them at the exact same location in my control room. Once they are fitted on stands 3 feet high from the floor, I need some help to move them ( they are so heavy!!)and my friends are not interested in spending time and muscular efforts for listening comparisons!

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    4435 with Rane AC 23S..

    tried the active three way method..observing JBL polarity..12 gauge cable..NL 8 connectors..Crown amps..the whole bit..sounds like Hammerd you know what..!!….no lo end..phased out mids..distant sounding..2404s..like an after thought....HELP...

  10. #10
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by loopya1234 View Post
    tried the active three way method..observing JBL polarity..12 gauge cable..NL 8 connectors..Crown amps..the whole bit..sounds like Hammerd you know what..!!….no lo end..phased out mids..distant sounding..2404s..like an after thought....HELP...
    Are your speakers factory built 4435s with all drivers and the network intact? If yes, how does it sound with one amp set up conventionally?


    Widget

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    Quote Originally Posted by Mr. Widget View Post
    Are your speakers factory built 4435s with all drivers and the network intact? If yes, how does it sound with one amp set up conventionally?


    Widget
    my 4430s are factory originals...very light bass...tried the switch bypass in the second cab...not much different....my 4435s did not have the factory x over...were empty .did install 2234s and 2426 drivers...that's why I went the Rane solution...

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    Quote Originally Posted by loopya1234 View Post
    my 4430s are factory originals...very light bass...tried the switch bypass in the second cab...not much different....my 4435s did not have the factory x over...were empty .did install 2234s and 2426 drivers...that's why I went the Rane solution...
    ​4430:
    If your 2235H woofers have original JBL kits installed then you should be getting plenty of bass from your 4430 speaker system ( assuming your woofers voice-coil gaps haven't been gummed up by a disintegrating internal foam filter ) .

    If gummed up ( coil movement will be quite restricted reducing bass output ), you'll need a pro reconer to deal with cleaning out the VC gaps.

    Here's a pic that shows ( at least to the trained eye ) foam that's stuck in the VC gap of a le14H-1 woofer ( the foam filter has completely disentigrated ).
    - The dustcap has been removed to allow the visual inspection.

    Name:  CloseUp-a_foam-in-gap_.jpg
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Size:  88.9 KB

    It might be prudent to send ( at least ) one of your 2235H woofers in for inspection to a pro reconer ( One; to check for JBL kit authenticity and Two; to check for the problem that I've just outlined above ).

    Here's a collage of pics of a 2235H showing a healthy foam filter ( top row > middle pic );





    4435;
    The combo of using that Rane 3-way crossover ( as a 3-way instead of as a 2.5 way ) when combined with usage of 2234H woofers that might be sporting aftermarket cone kits ( with cones that are too light ) > would nicely fit your description of inferior bass performance and a system that is ( excuse my english ) phase-phucked ( just saying ).


  13. #13
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by loopya1234 View Post
    my 4430s are factory originals...very light bass...tried the switch bypass in the second cab...not much different....my 4435s did not have the factory x over...were empty .did install 2234s and 2426 drivers...that's why I went the Rane solution...
    The bass of 4430s can be very thin or pretty good based on the room and room placement. Since the 4435s are not original, you really need to buy or build NOS or accurate clones of the original crossovers as the crossovers are absolutely necessary for a speaker as complex as the 4435 to work properly. Once you get them restored I think you’ll be impressed with their bass response.

    In my opinion those speakers will never be fully satisfying as a multi-amped speaker without the correct networks. Yes, someone with the skills of Greg Timbers could pull it off, but precious few people fall into that group.


    Widget

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    I've never heard 4435s in a studio setting but I have heard them sitting in free space (living room) and much like the UREI monitors sitting in free space, they didn't have good bass response.

    You can see in the JBL document linked, both these large format monitor types (4435 and UREI 813c) were designed with 2pi soffit mounting in mind, or 1/4 space (against front wall, side wall, ceiling). You can see the frequency response of both monitor types is flat to about 60hz in 2pi.
    http://www.audioheritage.org/vbullet...me-1-Number-15

    Compare that to the UREI pdf below. On the last couple pages you'll see frequency response of the same 813c in free space is only flat to about 100hz. I couldn't find a free space response for the 4435, but would assume it's similar. Also, many studios of that time added eq to the bottom, especially if they didn't soffit mount.
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