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Thread: Giskard Charge-coupled 3145 crossover network iron core inductor source

  1. #16
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    Quote Originally Posted by tjm001 View Post
    Thanks. This helps. I'm beginning to get the picture. I need to bone up on the equipment that goes before the amps now. Any suggestions?

    Tom
    My suggestion is to read all the older threads ( spread throughout this great site ) about the 4345 ( & bookmark them all / if you haven't already ).
    - They do offer a very good road-map in moving forward ( quality > listening wise, IMO ).

    The standard crossovers ( mentioned in those threads ) are all quite acceptable electrically ( from this guys perspective ).
    - The analogue types mentioned, were models from Bryston & Ashly ( & to a much lesser extent , the ancient JBL 5235 variants ).



    PS; If you decide to put a separate amp on the UHF, I believe GT was talking about a tiny classD GainClone of sorts ( preceded by its own dedicated HiPass ). This could easily be something from miniDSP ( out of China ).

  2. #17
    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by Earl K View Post
    PS; If you decide to put a separate amp on the UHF, I believe GT was talking about a tiny classD GainClone of sorts ( preceded by its own dedicated HiPass ). This could easily be something from miniDSP ( out of China ).
    I'd considered doing this on the 4345, some day. I don't find any inadequacies in the current setup using the bi-amp version of the crossover design here, but figured it's a simple mod easily undone, after satisfying my curiosity. I've set aside a couple of Crown D45s for this purpose, figuring to also bi-amp the 030 system one-day—just for fun—with a pair of Crown VFX-2A crossover I've had sitting around for years. Just never enough time for all the plans.
    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

  3. #18
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    Falcon Acoustics out of England also produces iron core, sintered ferrite core, and air core inductors for speaker crossovers. The favorable exchange rate is nice as is the custom specification of value, tolerance, and core type. Falcon have served the British speaker industry for 4 decades.

    http://www.falconacoustics.co.uk/aud...st.html?cat=60

    http://www.falconacoustics.co.uk/aud...st.html?cat=61
    When faced with another JBL find, Good mech986 says , JBL Fan mech986 says

  4. #19
    Senior Member Ian Mackenzie's Avatar
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    Quote Originally Posted by tjm001 View Post
    OK I've been studying the old posts http://www.audioheritage.org/vbullet...upgrade/page14 and http://www.audioheritage.org/vbullet...-modifications for several days now. These are excruciating detailed and drawn out communications over a long period of time back in 2005 between mainly a French guy in Canada (BandKMan) and others mostly (Ian Mackenzie) and others about crossovers for 434x systems with 4313B. I am enlightened and much more informed after reading these strings. I also think I now better understand 4313B's reaction to my post last year questioning Charge Coupled Crossover Networks. Sorry I stumbled into this about 10 or more years after the fact! But I am not a troll. I was and still am an innocent and honest bystander at the wrong place at the wrong time when I questioned Charge-coupled crossovers.

    It seems obvious to me from reading all this is that the way to go on a 4345 DIY crossover is the bi-amp option. My problem is I'm from the old school of what electronics were back in the 1960's. I studied and was well versed with all the Capacitor/Inductor stuff back then, but my career path led me in an entirely different direction (Air Traffic Control and Law Enforcement). Other than the Nelson Pass crossovers I built for my L300s last year, I haven't fooled with this stuff since the late 1960s. I'm still into the Amp, pre-amp and passive crossover mode. So I'm a little shaky on the bi-amping.

    I am confident I can build Cross-coupled crossovers for my 4345 project with minimal advice. My question at this point is, if I go bi-amp or even tri-amp as Greg Timbers recommends for the 2405, do I just follow the schematic eliminating the LF and UHF legs of the schematic? My instinct tells me there is more to it.
    It's a learning curve and early on we were still discovering historically how these filters worked.

    This was the equivalent 3145 schematic charge coupled

    The differences are in the mid and uhf filters compared to the stock schematic and the original filter that GT designed.

    The voltage drives in all cases are almost identical.

    The most recent charge coupled filter used a diode to create the screen voltage from the signal instead of the battery.

    Try and use the closest dcr values for the coils.

    The filters should be separated by "air" and not in close proximity to each other or any ferris metal.

    As mentioned just do biamp and feed the mid filter without the series capacitor and shunt inductor.

    Be careful wiring up the crossover to observe the polarity of the drivers.

    The factory crossover had a number of compromises and eliminating the biamp switch improved it a lot.

    The adjustment of the Lpads requires care and l have covered this in a post elsewhere

    These systems has a live character and I f you can get your hands on some of the acquaplas, dusted diaphragms are an improvement.

    Links to most of these points can be found in the 4345 reference thread.

  5. #20
    Senior Member tjm001's Avatar
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    Quote Originally Posted by Ian Mackenzie View Post
    It's a learning curve and early on we were still discovering historically how these filters worked.

    This was the equivalent 3145 schematic charge coupled

    The differences are in the mid and uhf filters compared to the stock schematic and the original filter that GT designed.

    The voltage drives in all cases are almost identical.

    The most recent charge coupled filter used a diode to create the screen voltage from the signal instead of the battery.

    Try and use the closest dcr values for the coils.

    The filters should be separated by "air" and not in close proximity to each other or any ferris metal.

    As mentioned just do biamp and feed the mid filter without the series capacitor and shunt inductor.

    Be careful wiring up the crossover to observe the polarity of the drivers.

    The factory crossover had a number of compromises and eliminating the biamp switch improved it a lot.

    The adjustment of the Lpads requires care and l have covered this in a post elsewhere

    These systems has a live character and I f you can get your hands on some of the acquaplas, dusted diaphragms are an improvement.

    Links to most of these points can be found in the 4345 reference thread.
    Thanks! I've decided to do the triamp thing as GT described with the little amp for the 2405. So the crossover construction should be fairly straightforward since there will only be three air core inductors.

    Tom

  6. #21
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    final schematic in 2011.

    hi.
    as i am in the same state with my JBL 4345 i have found another (different) schematic for the 4345 here in the threads.
    it was mentioned it is an final schematic with slightly different values.

    would anybody recommend this schematic over the "old" one?

    http://www.audioheritage.org/vbullet...esigner-s-Post
    post #4 (PDF)

    thanky a lot for your input here.

    regards from vienna
    slavko

  7. #22
    Senior Member Ian Mackenzie's Avatar
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    The schematic on the right in the PDF will work fine.

  8. #23
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    can you please just explain to an non-pro, what difference the two schematics (differnence in values of the Cīs, Līs and Rīs) have?

  9. #24
    Senior Member Ian Mackenzie's Avatar
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    No Lpads and standard component values


    The end result is the same

  10. #25
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    Quote Originally Posted by Ian Mackenzie View Post
    No Lpads and standard component values


    The end result is the same
    R44+45+46 is the subsitute schematic for the L-pad. thatīs how i understand it. (i will put L-pads instead of R44+45+46)
    (also R35+36+37 and R29+30+31)

    but i would like to know why the values changed slightly over time?

    i am taking clarity sa caps instead of solen caps, because they are not so common and available here in austria.

    thx

    regards

  11. #26
    Senior Member Ian Mackenzie's Avatar
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    Not wanting to damp your curiosity

    You wanted a non pro response

    The values are based on the load values in each specific schematic

    An Lpad is not an ideal constant impedance attenuator, that is why the fixed network is used

    Do not change anything

    The voltage drives are set up specifically for those specific parts

    If you want to use Lpads then use the other equivalent 3145 schematic

  12. #27
    Senior Member quindecima's Avatar
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    Ian,

    Do you have a link to the schematic with the diode instead of the battery? I looked for one but couldn't find it.

  13. #28
    Senior Member Ian Mackenzie's Avatar
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    Quote Originally Posted by tjm001 View Post
    Thanks! I've decided to do the triamp thing as GT described with the little amp for the 2405. So the crossover construction should be fairly straightforward since there will only be three air core inductors.

    Tom

    Any progress on this yet?

  14. #29
    Senior Member tjm001's Avatar
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    Quote Originally Posted by Ian Mackenzie View Post
    Any progress on this yet?
    Thanks. Still trying to gather all the components. I just built the L300s last year so I'm still enjoying them. Not sure if I should leave them intact and sell them, or pirate the LE85s and 2405s to use in the 4345 project. Probably makes sense to leave the L300s intact and get different mid and high frequency drivers. I regret selling those short horns last year on eBay. I'll probably start building the boxes after I get back from my Florida trip next month. I'm in no rush. I will start a new thread about the construction when it gets underway.

    Tom

  15. #30
    Senior Member Hoerninger's Avatar
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    Quote Originally Posted by quindecima View Post
    Ian,

    Do you have a link to the schematic with the diode instead of the battery? I looked for one but couldn't find it.
    Look here
    http://www.audioheritage.org/vbullet...9&d=1425751189

    Enjoy
    ____________
    Peter

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