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Thread: 4333 / S300 / L300 equivalent bandbass circuit

  1. #1
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    Lightbulb 4333/S300/L300 equivalent bandbass circuit

    I have managed to come up with an equivalent bandpass circuit for the 4333/S300/L300 which negates the need to use the very expensive and hard to find tapped autotransformer.

    If anyone is interested I will post the schematic.

    Has anyone thought of using charge coupled technology in their 4333/S300/L300's?

    If anyone is interested I will post that schematic as well.

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    Smile I am

    Hi Giskard

    I'm always interested in seeing these circuits, especially transformed/equivalent types .

    regards <. Earl K

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    Re: 4333/S300/L300 equivalent bandbass circuit

    Here is the schematic.

    It's voltage drive is a dead ringer for the original voltage drive as measured on December 16th, 1975.

    Most of the components are available from Parts Express. The LF inductor is the 14 gauge perfect layer wound air core. For those who like the signature JBL bass hump at ~ 30 Hz you may need to tune the enclosure up a couple of Hz. All the MF inductors are the 18 gauge perfect layer wound air cores.
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    4333/S300/L300 with charge coupled tech

    4333/S300/L300 with charge coupled technology
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    Moderator / Treasurer/Marketplace Czar boputnam's Avatar
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    Beauty!
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    Senior Member Jan Daugaard's Avatar
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    Charge coupled cirquitry for the S3100

    I'm the happy owner of four S3100, but nevertheless on the look-out for improvements, so I would like so see the charge coupled cirquitry for this model.

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    Thanks Rob !

    <. Earl K

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    Re: Charge coupled cirquitry for the S3100

    Alrighty then!
    Here's the stock schematic.
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    Last edited by 4313B; 05-15-2003 at 05:37 AM.

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    Re: Charge coupled cirquitry for the S3100

    Let us know what you think if you decide to give it a try. I wouldn't mess up your stock networks, I'd build from scratch.
    Use all polypropylene if you can instead of any NPE's.

    For those who care, I believe the S3100 MK II is already charge coupled...
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    Senior Member Jan Daugaard's Avatar
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    Thanks, Giskard, for the charge coupled version of the NS3100.

    One of my S3100 has a problem with static, so I may kill two birds with one stone by building the charge coupled version of the cross-over cirquitry: Getting rid of the static (which is probably due to a defective capacitor) and getting better sound.

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    Senior Member GordonW's Avatar
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    Whoa, man, Giskard... is that big HF notch filter/impedence "compensation" network connected to the input terminals of the cabinet there? What exactly does that do for the effective impedence of the whole cabinet?

    Regards,
    Gordon.

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    I've never seen nor run an impedance curve on an S3100 so I don't know.

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    autotransformer

    I tried to find the -6db point of an air core inductance(for example, 1.5mh) which its -6db point isn't exact the .75mh and then tried to make a line-out from the -6db point. It seems it works like a taped autotransformer. But I found its frequency response droped several dbs as attached picture. And the small load resistance the more it drops. And I also found the higher inductance was and the less it droped.

    Who knows the frequency response curve and could show it here? then we can try to make taped autoformer ourselves.

    The attached is freq response with 8ohm load.

    Please give some good advice for the drop.

    Thanks.

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    Another picture with 16ohm load.

    sorry for this large picture. It's the first time to load a picture.

  15. #15
    Senior Member Jan Daugaard's Avatar
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    S3100 impedance curve

    Originally posted by Giskard
    I've never seen nor run an impedance curve on an S3100 so I don't know.

    JBL has published an impedance curve for the S2600 in the owner's manual for the S2600/S3100. The former has a 12" woofer and 92 dB/W sensitivity, whereas the latter has a 15" woofer and 95 dB/W sensitivity, but they are otherwise identical. I can't attach the entire owner's manual as it exceeds the 160 KB limit on this forum.

    First, the scale must be wrong -- the impedance can't be between 2 and 3 ohms over most of the frequency range.

    Second -- and this is not apparent from the attached file --, the cross-over cirquitry in the S3100 mk II is not only charge-coupled, it also has a resistor in parallel with the woofer with a higher resistance than the resistor in parallel with the woofer in the S3100. What is the consequence of this other than a lower sensitivity in the latter case?
    Last edited by Jan Daugaard; 05-22-2003 at 12:28 AM.

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