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Thread: 18" bass bin design for hi fi

  1. #16
    Senior Member RMC's Avatar
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    With the drivers you have you are somewhat condemned to vented box use.

    The LE15A EBP is 91 and the EVM 18B EBP is 88, so both close to 100 which normally indicates a vented box is pretty much written in the sky...

    Drivers with an EBP around 50 are usually more appropriate for a sealed box.

  2. #17
    Administrator Mr. Widget's Avatar
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    As a point of reference, I have owned Klipsch LaScalas, I built DIY clones of Belle Klipsch speakers and used both Klipsch 15" woofers and JBL 2220s in them (the Klipsch sounded better), I have built EV Eliminators (see drawing), and have owned Klipsch Heresys, Cornwalls, and Klipschorns. You can say I have been around the block on this topic. I have not kept any of these as I have moved up the food chain as it were and my needs and interests have changed.

    That said, of this group the Cornwalls and the Klipschorns sounded the best. In general a well designed reflex system will sound better than a seriously compromised horn system. In the right room, the Klipschorn is quite remarkable, but it is very difficult to build and almost more difficult to place in most rooms.

    As far as the LE15A woofers you have, it sounds like they are also blown and need to be rebuilt. There is so much more to the design of a woofer than matching the impedance of the woofer. The LE15A has an edge wound coil that is fairly short so that in operation it doesn't move out of the 3/4" gap... this is not a run of the mill woofer. You can very likely get it to play again, but you won't have an LE15A. My suggestion is that you sell your blown 18" EV woofers and your blown JBLs and put the money towards properly working woofers, any of the JBLs listed on the list in the JBL enclosure guide that is attached below will work well if you follow the guide.


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  3. #18
    Administrator Mr. Widget's Avatar
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    FWIW: I had forgotten that I actually tried to give my Klipsch Belle clones away here back in 2007. I ended up on the Klipsch Forum and found a happy match.

    http://www.audioheritage.org/vbullet...ipsch-Wantabes


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  4. #19
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    thanks a lot for your answers, very ilustrative

    EBP IS stiff suspension and sensitive ?, with diferent suspensions the ebp change ?

    then, vented enclosure is almost win

    3115 crossover is not popular

    just wondering
    on biamp , electronic crossover can I keep 3105 crossover to handle the tweeter ?


  5. #20
    Senior Member RMC's Avatar
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    EBP = Efficiency Bandwidth Product

    This was invented by speaker Engineer R.H. Small as a way to address the suitability issue of a low frequency driver VS the type of system or box to be used: vented, sealed or horn loaded. Easy to calculate: driver Fs/Qes= EBP. Suspension alone doesn't make the woofer, and different suspensions would also change Vas parameter. Many things are involved.

    Qes refers to driver's electrical aspect of suspension. EBP is a good rule of thumb, however driver Qts should also be considered as part of the picture. Other aspects can also be taken into consideration, as an example, remember the mention of a foam surround larger excursion driver, where in a horn cab the cone may strike the horn's throat, etc.

    Vented enclosure is often a win, to use your own word, JBL considers this as the best compromise among box types. Nevertheless, some drivers are still best used in a sealed sub-box.

    From this site, Qes:

    "The driver's Q at resonance (Fs), due to electrical losses; dimensionless. "A measurement of the control coming from the speaker's electrical suspension system (the voice coil and magnet). Opposing forces from the mechanical and electrical suspensions act to absorb shock."

  6. #21
    Junior Member retromick's Avatar
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    DIY subs

    My new diy subs
    2269h in 9.5 cuft enclosurs
    ports 2 x 4” x 9.5”
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  7. #22
    Senior Member grumpy's Avatar
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    Nice details!

    Your dentist and drywall person should love it

  8. #23
    Junior Member retromick's Avatar
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    Quote Originally Posted by grumpy View Post
    Nice details!

    Your dentist and drywall person should love it
    Not sure about them, but I’m stoked! Taken me a long time and lots of cash t find my nirvana😎😎😎

  9. #24
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    They Look Great !!

    Very Pro !!


  10. #25
    Senior Member Anti K's Avatar
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    Right!

    That's the right thing! Bass 15'', better 2 of them. Sub 18'' (better 2 of them )

    How You drive them?

    Try what happens closing tubes of upper cabs (15'' sealed then) and active crossing between Upper Cab and Sub around 90...70Hz.
    Should make low end very concrete.

  11. #26
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    Name:  WhatsApp Image 2021-08-07 at 03.25.35.jpeg
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    Some advance
    building 4530
    2 18” 16 ohm
    2 075 16 ohm
    2 2446J with 2350 horns
    crossover 3115 and 3105
    The idea is to go biamp using only 3105 and dbx electronic crossover 500HZ

    do I need to install a filter to protect the 2446 ? Or I only need to coonecto from the electronic crossover to amp to 3105 diectly to 2446 ?

  12. #27
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    The EVM-18B was used in the SH1810L-ER bass cab, a "SubScoop" design. It has useable response to -10dB at about 34 hz. I have a pair of the mid/hi cabs that were part of this system.


    https://www.google.com/url?sa=t&sour...eFA-MzHXmM6eSP

  13. #28
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    Quote Originally Posted by short_circutz2 View Post
    The EVM-18B was used in the SH1810L-ER bass cab, a "SubScoop" design. It has useable response to -10dB at about 34 hz. I have a pair of the mid/hi cabs that were part of this system.


    https://www.google.com/url?sa=t&sour...eFA-MzHXmM6eSP
    thanks
    I already builT the 4530, those on the photo are mine.

  14. #29
    Senior Member RMC's Avatar
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    Hi Eduardo,

    Its generally a good idea to put a protection capacitor in series with the compression driver in case of electronic crossover mishandling or malfunction for example.

    You didn't mention which 18" woofer you're actually using, but since you previously mentioned the EVM18B S2, I'm assuming here this is the one.

    The 12 db/oct 500hz xo in 2446 specs is indicated as minimum. I would crossover a little higher to make some meaningful room for the protection capacitor. Below 700hz the compression driver's response falls rapidly anyway. Since the woofer is a musical instrument driver it has rising response which you can take advantage of by crossing over just a little higher such as 700-800hz. The 2446 sure won't mind.

    The rule of thumb for blocking capacitors is to locate it about an octave below crossover frequency to minimize interactions, so moving xo a little higher you can now put a good quality blocking capacitor for 400hz roll-off.

    Btw, as i recall JBL never made an 18" woofer version of the 4530. To my knowledge there isn't a JBL blessing on such design. They could easily have done one if they wanted to having the 2240, K151 and E155 drivers, all three suitable for horn loading as per JBL. But they didn't.

    I remember reading years ago in one of the Pro Audio magazines a reader question asking about scaling up or down the 4530 cab. The Engineer who replied (maybe from JBL) said it wouldn't be proper. There would be issues with the horn's throat and/or mouth making it less than optimal. Possibly why JBL never made one...

    I know many guys have made some of their own brew anyway. But that doesn't make it an approved design per JBL engineering standards. No doubt it will still produce sound, then you can enjoy it, however i'd suggest to avoid beating on it too hard. A 4530 type box doesn't go deep, its rather made for bumped up bass around 60-100hz...

    Note the EVM woofer has Qts of 0.36, this is very high compared to drivers JBL suggested for use in such rear loaded folded horn, having Qts of 0.17 to 0.21 (maybe stretchable a little). My guess is that the higher Qts EVM may further increase the cab's bumping bass by design, which may not be that bad here when looking at woofer response curve showing LF level being lower than the rest. Indirectly might be sort of a "balancing act" then.

    Richard

    TO Short Circutz2

    Simply a precision, the EV SH... cab you mention uses the EVM 18B Pro-line rated 400W, whereas the poster here has indicated using the EVM 18B Series 2 rated 200W. Just don't want him to think that he can go 400W...

  15. #30
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    Quote Originally Posted by RMC View Post
    Hi Eduardo,

    Its generally a good idea to put a protection capacitor in series with the compression driver in case of electronic crossover mishandling or malfunction for example.

    You didn't mention which 18" woofer you're actually using, but since you previously mentioned the EVM18B S2, I'm assuming here this is the one.

    The 12 db/oct 500hz xo in 2446 specs is indicated as minimum. I would crossover a little higher to make some meaningful room for the protection capacitor. Below 700hz the compression driver's response falls rapidly anyway. Since the woofer is a musical instrument driver it has rising response which you can take advantage of by crossing over just a little higher such as 700-800hz. The 2446 sure won't mind.

    The rule of thumb for blocking capacitors is to locate it about an octave below crossover frequency to minimize interactions, so moving xo a little higher you can now put a good quality blocking capacitor for 400hz roll-off.

    Btw, as i recall JBL never made an 18" woofer version of the 4530. To my knowledge there isn't a JBL blessing on such design. They could easily have done one if they wanted to having the 2240, K151 and E155 drivers, all three suitable for horn loading as per JBL. But they didn't.

    I remember reading years ago in one of the Pro Audio magazines a reader question asking about scaling up or down the 4530 cab. The Engineer who replied (maybe from JBL) said it wouldn't be proper. There would be issues with the horn's throat and/or mouth making it less than optimal. Possibly why JBL never made one...

    I know many guys have made some of their own brew anyway. But that doesn't make it an approved design per JBL engineering standards. No doubt it will still produce sound, then you can enjoy it, however i'd suggest to avoid beating on it too hard. A 4530 type box doesn't go deep, its rather made for bumped up bass around 60-100hz...

    Note the EVM woofer has Qts of 0.36, this is very high compared to drivers JBL suggested for use in such rear loaded folded horn, having Qts of 0.17 to 0.21 (maybe stretchable a little). My guess is that the higher Qts EVM may further increase the cab's bumping bass by design, which may not be that bad here when looking at woofer response curve showing LF level being lower than the rest. Indirectly might be sort of a "balancing act" then.

    Richard

    TO Short Circutz2

    Simply a precision, the EV SH... cab you mention uses the EVM 18B Pro-line rated 400W, whereas the poster here has indicated using the EVM 18B Series 2 rated 200W. Just don't want him to think that he can go 400W...
    Thanks for the clarification 😁

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