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Thread: Jbl Tcb 4688

  1. #1
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    Jbl Tcb 4688

    Excuse for my poor English.


    I have a TCB 4688 with 2 X 2240, if I add another TCB, but with 2 X 2241.
    That causes a problem? For the answer in frequency and the same deep bass?
    Am I going to win at it by adding it the second TCB a lot?
    Is the TCB conceived to install two 2241 there?

    Are there people who already have to test two TCB?

    thanks

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  3. #3
    RE: Member when? subwoof's Avatar
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    same but...

    I have used both the 2240 and 2241 versions and they are interchangeable. Other that the maximum output difference, they can be used together but I think your compatibility problem will be with the people who live near you..:o)

    sub

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    Tcb (4688) normally should be placed horizontally, but if I put the tcb standing (vertically), is what I can damage the speakers?

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  6. #6
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    Quote Originally Posted by alnico View Post
    Tcb (4688) normally should be placed horizontally, but if I put the tcb standing (vertically), is what I can damage the speakers?
    Oupss
    after all these years I repeat the question
    I am faced with the problem of space
    is it that I can damage the speakers if I stand up?
    or it can affect the performance?

    thanks

  7. #7
    Senior Member grumpy's Avatar
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    Opinion:

    In a very general sense, over a long period of time there is the possibility
    of the suspension (spider/surround) permanently shifting from gravity.
    In the short term, that same shift puts the voice coil off center and adds
    adds an asymmetry to the suspension response, potentially causing additional
    harmonic distortion.

    Will it really hurt anything? Probably not, unless you're pushing it to the point
    of unlistenability in a home environment. Will it hurt performance? Probably
    not much audibly other than the potential change in boundary reinforcement...
    you might want to re-EQ the system after such a move.

  8. #8
    Senior Member martin2395's Avatar
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    I wonder how it compares to the latest single '18 Synthesis sub for HT duty. I heard the whole system some time ago and it was astounding, when you think that 'that's it' they suddenly hit you even harder

  9. #9
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    Think Symmetry

    I refer to Technical Notes Volume I, Number 19. This is a paper about the TCB technology.

    Look at figure 2, the thing is completely symmetric.

    Imagine (thought experiment) you divide chamber 2 into two halves using a sheet of carton. The pressure on both sides of the sheet would be the same. It will not bend, why should it? Now cut the box into two halves along the line of symmetry. Close the half chamber two of two halves using some rigid sheet of wood. Voila! now You've got two boxes using DCB Technology.

    It is left as an exercise to the reader what 'DCB' means. Of course, you would build the two DCBs from scratch.

    Does somebody have a suited box calculator software?

    Ruediger

  10. #10
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    Quote Originally Posted by grumpy View Post
    Opinion:

    In a very general sense, over a long period of time there is the possibility
    of the suspension (spider/surround) permanently shifting from gravity.
    In the short term, that same shift puts the voice coil off center and adds
    adds an asymmetry to the suspension response, potentially causing additional
    harmonic distortion.

    Will it really hurt anything? Probably not, unless you're pushing it to the point
    of unlistenability in a home environment. Will it hurt performance? Probably
    not much audibly other than the potential change in boundary reinforcement...
    you might want to re-EQ the system after such a move.
    thanks

  11. #11
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    Amplification recommended for 2 JBL tcb 4688

    Hello, I come back with another question about TCB 4688

    With 2 JBL TCB 4688 and 2240H 8ohms each ,
    What a very strong amplifier you recommend me? Taking into account having only one amplifier,
    And who would be able to deliver a very good power in 4ohms each channel.

    Each of the channels of the amplifier would feed a tcb and its 2 x 2240h = Therefore 4 ohms per tcb.

    Presently I have 4 x Harman Kardon Citation 16A bridged mono = 500w on each of the 18 inches 2240, With only one very powerful amplifier, would I have a better significant result, power, damping factor etc ....

    thanks

  12. #12
    Junior Member Bassdabob's Avatar
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    Quote Originally Posted by alnico View Post
    Hello, I come back with another question about TCB 4688

    With 2 JBL TCB 4688 and 2240H 8ohms each ,
    What a very strong amplifier you recommend me? Taking into account having only one amplifier,
    And who would be able to deliver a very good power in 4ohms each channel.

    Each of the channels of the amplifier would feed a tcb and its 2 x 2240h = Therefore 4 ohms per tcb.

    Presently I have 4 x Harman Kardon Citation 16A bridged mono = 500w on each of the 18 inches 2240, With only one very powerful amplifier, would I have a better significant result, power, damping factor etc ....

    thanks
    Best amps so far for Home usage with 2240 was the crown macro reference. for PA duty i would highly recommend itech 5000 HD with proper settings
    CROWN+JBL+18SOUND = Fun

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