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Thread: My JBL 4355 Homecinema Soundbar build

  1. #31
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    I assume that the intention is to put a monitor on top of this cabinet (you too bldozer).

    Have you checked to see if your monitor is suseptable to stray magnetic fields?

    Don't belive the crap that AlNiCo JBLs do not affect CRTs. This is why when you look at my center channel speaker, all of the components were originally mounted at the bottom with the ports at the top.

    But even just with a couple 130As, a 175/potato masher, and an 075 mounted low in the cabinet, the Mitsubishi 40" table top (CRT) would be subject to distortion/purpling toward the bottom of the screen. When I went to front projection with a Stewert screen, this was no longer a problem and the horn was raised in the cabinet to replace the center port and this port was put at the bottom. This also allowed me to put a tweeter on top of the cabinet.


  2. #32
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    Who still uses crt's ? I don't know anyone .

  3. #33
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    Quote Originally Posted by dezmond View Post
    Who still uses crt's ? I don't know anyone .




    So are you saying that NONE of the modern monitors can be affected by a stray magnetic field in any way? I don't know that I would take that bet, which is why I cautioned the OP to check it out.

  4. #34
    Senior Member bldozier's Avatar
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    Thanks um I will remember that for a future build

  5. #35
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    Excellent build thread and design. Although in a space limited area, have you had the opportunity to "stretch its legs" with say 200+ watts of power and some great music? The compression drivers being extremely efficient will always dominate the sound field without padding them down considerably.

    Do do you have a crossover schematic that you worked from?

    eventually, you may want to review again the 4345 commentary from Greg Timbers and consider going fully active tri-amp or quad-amping with less passive crossover components, but that is a huge proposition unless using a lot of DSP correction and compensation.

    very nice build effort, and if this is your test box, love to see what you have in mind for a final design.

    I'd suggest a model number of 4358-C, the 435x following the double woofer systems, the 8 referring to 18" woofers,Mandy the C for a center channel "soundbar".
    When faced with another JBL find, Good mech986 says , JBL Fan mech986 says

  6. #36
    Junior Member music2u's Avatar
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    Thank you so much "mech986". After "a long journey" it is nice to see, that you guys understand why one is doing these things and understand the rationale behind it. I will experiment with amps (also tubes) and as this is in my own house, I have "some flexibility" to listen to "higher volumes" ;-)

    I took the crossover schematic from GT as documented in this forum, charge coupled (diode method). If I look at all the inductors, my first idea was to go fully active. I consider to go in a two way design per satellite speaker and add the 2405 with a simple 6db highpass filter as a super tweeter (the center will remain passive). I plan to do that in the analog domain, i.e. without any DSP.

    Before I settle on the final enclosure and crossover, I plan to try alternatives to the compression driver section. The 2440 and the Radian dia's sound somewhat "soft" in my opinion. The 2245 and 2202 section will stay. And the concept with 2" compression drivers. Although I like the tribute to the 4355, I would love to compare the setup with larger horns like Yuichi's.

    @bldozier: Crossover build is only technical. With some discipline and patience you will make it. Development of a crossover is more like an art.
    @toddalin: I don't have any probs with my Sony LCD screen.

  7. #37
    Senior Member JuniorJBL's Avatar
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    HA!!

    Soundbar!!

    That's just plain cool!! Definitely a one-off.


    Excellent job Stefan.
    Always fun learning more.......

  8. #38
    Senior Member berga12's Avatar
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    Forget about running the 2405 at 6db slope.... it will be destroyed.
    minimum 12khz above 7-8khz is the minimum (some say 12db at 6khz....I still consider only 18db above 8khz...)

    yuichi is a wonderful chioce if you decrease crossover point of 2440, then you'll not listen anymore to a studio monitor,but something different.

  9. #39
    Junior Member music2u's Avatar
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    Thanks "Junior"... I see you enjoy it

    @Luca: OK, I will take care of my 2405. Currently, I try different setups for the mid-high section.

    eventually, you may want to review again the 4345 commentary from Greg Timbers and consider going fully active tri-amp or quad-amping with less passive crossover components, but that is a huge proposition unless using a lot of DSP correction and compensation.
    I am very interested but I couldn't find it. Does anyone remember where it is?

  10. #40
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    Soundbar, LOL
    Respect!
    What is the weight of this thing?

  11. #41
    Junior Member Betiuxs's Avatar
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    JBL 5739 Tuning for 2235H

    Name:  s-l1600.jpg
Views: 1816
Size:  99.0 KBHello! can someone help me on this ? I have 2 JBL 5739 dual 15" cabinets that I would like to use with 2235H's
    can someone tell me if they can be tuned to match the JBL 4355 Low frequency? these are the enclosure dimensions
    PHYSICAL SPECIFICATIONS:
    • Enclosure Dimensions: 1219 x 762 x 450 mm D(48.0 x 30.0 x 17.8 in. D)




    Thanks

  12. #42
    Senior Member ivica's Avatar
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    Quote Originally Posted by Betiuxs View Post
    Hello! can someone help me on this ? I have 2 JBL 5739 dual 15" cabinets that I would like to use with 2235H's
    can someone tell me if they can be tuned to match the JBL 4355 Low frequency? these are the enclosure dimensions
    PHYSICAL SPECIFICATIONS:
    • Enclosure Dimensions: 1219 x 762 x 450 mm D(48.0 x 30.0 x 17.8 in. D)




    Thanks
    Hi Betiuxs,

    About 95mm each if port diameter about 105mm
    or 157mm if diameter is about 125mm.
    ivica

  13. #43
    Junior Member Betiuxs's Avatar
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    Quote Originally Posted by ivica View Post
    Hi Betiuxs,

    About 95mm each if port diameter about 105mm
    or 157mm if diameter is about 125mm.
    ivica
    sorry but still don't get it can you explain a little more Thank you so much

  14. #44
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    Quote Originally Posted by Betiuxs View Post
    sorry but still don't get it can you explain a little more Thank you so much
    Ivica gave you the port lengths for a given port inner diameter. These dimensions give the volume and mass of air contained in the port which affects the port tuning that defines how the cabinet interacts with a given woofer.

    since your cabinet is a lot smaller than the 4355 cabinet, the internal volume is also a lot smaller, and requires tuning with the ports to achieve the same relative tuning with the much larger 4355 cabinet. One can also tune lower or higher and introduce artificial electronic EQ to extend the response lower if needed at the expense of power, a bit more complexity, and potential overexcursion of woofers in question.
    When faced with another JBL find, Good mech986 says , JBL Fan mech986 says

  15. #45
    Junior Member Betiuxs's Avatar
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    Quote Originally Posted by mech986 View Post
    Ivica gave you the port lengths for a given port inner diameter. These dimensions give the volume and mass of air contained in the port which affects the port tuning that defines how the cabinet interacts with a given woofer.

    since your cabinet is a lot smaller than the 4355 cabinet, the internal volume is also a lot smaller, and requires tuning with the ports to achieve the same relative tuning with the much larger 4355 cabinet. One can also tune lower or higher and introduce artificial electronic EQ to extend the response lower if needed at the expense of power, a bit more complexity, and potential overexcursion of woofers in question.
    got it guys thank you very much

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