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Thread: Request K130/K140 Bolt Hole Circle Dimension

  1. #1
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    Request K130/K140 Bolt Hole Circle Dimension

    Halloo,

    Does anyone have JBL published bolt hole circle spec for the K130 or K140 drivers? Looking online I have only found the more general K series pages , which don't give those specific mechanical details for each of the drivers in the series.

    Dropping in a couple of 1/4" bolts, getting them as close to straight in as I can and measuring across I believe the distance is 14 9/16" which is very close to the D130's 14 5/8" but not exact.

    The D130 spec sheet gives the hole size as 3/16" but the ones on the K130 basket are a generous 1/4" so I think the circles could be different as well.

    Splitting hairs maybe but I can't guarantee my measurement was with the bolts 100% straight in and I'm eager not to do anything to distort the rim when it gets tightened down.

    My first post , I'd rather be contributing than asking for help, but perhaps when the project is done I'll have something worth showing.

    Thanks !

  2. #2
    Senior Member RMC's Avatar
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    Hi G.A,

    Welcome aboard the Lansing Heritage.

    This is what i have for the E series 130 and 140 woofers, not the K series though. Such data presumably the same?

    "Frame mounting screw drill size: 7 mm or 9/32"

    "T-nut drill size: 6 mm, # 1 "

    Quoted as it is from a JBL publication.

    You decide if that info meets your needs. Hopefully this helps you.

    Richard
    POWERED BY: QSC, Ashly, Tascam, Rolls Mosfet, NAD, and Crest Audio

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    Senior Member edgewound's Avatar
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    Quote Originally Posted by G.A. View Post
    Halloo,

    Does anyone have JBL published bolt hole circle spec for the K130 or K140 drivers? Looking online I have only found the more general K series pages , which don't give those specific mechanical details for each of the drivers in the series.

    Dropping in a couple of 1/4" bolts, getting them as close to straight in as I can and measuring across I believe the distance is 14 9/16" which is very close to the D130's 14 5/8" but not exact.

    The D130 spec sheet gives the hole size as 3/16" but the ones on the K130 basket are a generous 1/4" so I think the circles could be different as well.

    Splitting hairs maybe but I can't guarantee my measurement was with the bolts 100% straight in and I'm eager not to do anything to distort the rim when it gets tightened down.

    My first post , I'd rather be contributing than asking for help, but perhaps when the project is done I'll have something worth showing.

    Thanks !
    The front mount hole for all the JBL 15" drivers is 13 31/32". It's a very exact fit for the frame with very little...almost none...slack in the frame fit. Drop the frame in place and center punch the frame mounting holes before drilling the holes. The factory mounting hardware for the 15" frame is (8) 10/32 fillister head machine screws with matching T-nuts. The O.D. of the 10-32 T-nut is .24", so the drill size would be 1/4".
    Edgewound...JBL Pro Authorized...since 1988
    Upland Loudspeaker Service, Upland, CA

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    Thank you both for your replies. Those details will help me a lot .

    One question about the flange design. There's a small shallow channel cut into the back of the flange just before it becomes the basket wall turning up toward the magnet. Any idea why it's there? Something to do with the casting process or was it for some sort of gasket material? Just curious.

    Anyway, the dimension info is much appreciated. Thanks again!

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    That channel was for a tubular gasket which really only worked on machine cut baffle holes cut to JBL specs and even then on many JBL made speaker systems the gaskets didn't seat properly. Use flat gaskets on the back of the mounting ring.

    Quote Originally Posted by G.A. View Post
    Thank you both for your replies. Those details will help me a lot .

    One question about the flange design. There's a small shallow channel cut into the back of the flange just before it becomes the basket wall turning up toward the magnet. Any idea why it's there? Something to do with the casting process or was it for some sort of gasket material? Just curious.

    Anyway, the dimension info is much appreciated. Thanks again!

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    Ahaa! It's such a fine shallow groove. I can understand why it could be difficult to get anything to hold on there. Flat gasket it will be, eventually.

    Eager to try out the K130, I have a cabinet I built years ago for an Altec 15. It's pretty big, probably about 10cuft. I'm pondering a quick way to make an adapter for it. A ring of some sort. . . . . .

    Thanks Riley !
    G.A.

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    For what it's worth I use cap head allen screws to mount just about all of my speakers in their enclosures,
    either 10/32 or 1/4-20.

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    Thanks for the suggestion. Yes, I like those too. 1/4-20 is what I used for the Altec years ago.

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    Quote Originally Posted by G.A. View Post
    Thanks for the suggestion. Yes, I like those too. 1/4-20 is what I used for the Altec years ago.
    The heads on those don't strip out as easy and the chance of slipping with the screwdriver and punching the cone is all but eliminated!!

    For gasket sealing Parts Express sells some thin weather stripping type material.
    Most of the hardware store stuff is too thick.

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    Senior Member edgewound's Avatar
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    Quote Originally Posted by G.A. View Post
    Thank you both for your replies. Those details will help me a lot .

    One question about the flange design. There's a small shallow channel cut into the back of the flange just before it becomes the basket wall turning up toward the magnet. Any idea why it's there? Something to do with the casting process or was it for some sort of gasket material? Just curious.

    Anyway, the dimension info is much appreciated. Thanks again!
    It's for an O-ring that is supplied with every driver installed in factory enclosures, and retail packaged units.
    Edgewound...JBL Pro Authorized...since 1988
    Upland Loudspeaker Service, Upland, CA

  11. #11
    Senior Member RMC's Avatar
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    G.A.,

    RE Eager to try out the K130, I have a cabinet I built years ago for an Altec 15. It's pretty big, probably about 10cuft.

    This cab size is way too large for a K130. JBL recommended size is 2-4 cu.ft. for the E130 (closest thing to K130). Moreover, in their Enclosure Guide JBL suggested 3 cu.ft. tuned to 40 hz (for E130), so right in the middle of the box size range above.

    Since the K version of the driver has somewhat higher Qts parameter than E version, you MIGHT be able to use a 4 cu.ft. box (subject to speaker software modeling), but this is probably the largest it should go.

    Having a previous cab for an Altec 15" doesn't mean it is suitable for another woofer (i.e. K130). Each case must be examined carefully. Btw the 10 cu.ft. cab would also be too large for proper use with the K140.

    Another issue is that a too large box will "mandate" the driver to go very low bass wise, but on the other hand the K130 has next to no cone travel capability to reproduce very low frequencies. With some output you risk bottoming or damaging the driver.

    Richard

    P.S. I'm listing below a few driver parameters from JBL in case they're needed later. Just a reminder for me.

    K130: Fs 40 hz, Qts 0.25, Vas 297 L, Xmax 0.76 mm
    E130: Fs 40 hz, Qts 0.19, Vas 297 L, Xmax 2.54 mm
    POWERED BY: QSC, Ashly, Tascam, Rolls Mosfet, NAD, and Crest Audio

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    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by G.A. View Post
    Eager to try out the K130, I have a cabinet I built years ago for an Altec 15. It's pretty big, probably about 10cuft. I'm pondering a quick way to make an adapter for it. A ring of some sort. . . . . .
    What will you be using the K130s for? Guitar, PA, or home hi-fi?

    Decades ago when the K130s were a current product I used them in a hi-fi scenario in 3-3.5 cu ft cabinets with questionable tuning (meaning I used an outdated guide and don’t remember the details) With a bit of LF boost they worked quite well.


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    Wow, What's all this ? I had no idea so many bright lights would show up to help. I figured one or two quick, "Bolt circle is xx inches" and I could save saying anything until the project is worth reporting, (or not).

    So, thanks for all your generous inputs. I'll try to get away with a simple . . . . Uhh , they're not really K130's. Just in K130 baskets with a BBPro estimated optimum cab volume of 6.9 cu.ft. based on some pretty rudimentary T/S numbers. I do pledge to come back with some more useful (or not) stuff once I've had a chance to hook them up. So far , I haven't heard a peep from them but having them in a workshop with lots of metal and other dust around, I don't want to expose the motors to anything but the inside of a cabinet.

  14. #14
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by G.A. View Post
    Uhh , they're not really K130's. Just in K130 baskets with a BBPro estimated optimum cab volume of 6.9 cu.ft. based on some pretty rudimentary T/S numbers.
    If you don't already know, the K130 basket and motor structure is the same as JBL used in most of the alnico era 15" woofers. You can recone it with a wide range of kits to create many different JBLs, even alnico 2235s.

    That said, it sounds like you have aftermarket frankenwoofer kits in there and are well on your way.


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    I thought the measurements for the D130 would apply but found that the bolt hole measurements didn't agree with those on the K130 basket. Looking further I couldn't find a detailed sheet anywhere for the K130/140 dims.

    A friend says he's going to 'whip up' an adapter (he talks like that - generous understatement) from a few layers of thin sheet Al and so I'm especially keen to get the hole circle right on. Measuring across the front from outside of one hole to inside of the other gives a C to C distance. Hopefully I've got it close enough in spite of the cork gasket's overhang making it a bit fudgey.

    Incidentally, I did draw up an adapter ring in Front Panel Express. 16" outside, 13 15/16ths" inside , smooth holes for the Altec circle and threaded for the JBL. Hit the price button = 1400 Bonitos! Ay, Chihuahua! Not even colour anodized.
    I guess I could see it being worth something in that direction if a machinist had to draw it all out and cut and drill manually - a technical work of precision art, but when you know that a laser is going to blast it into existence before morning coffee break it's a little over the top. Well, I thought so anyway.

    Thanks !

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