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Lab 15 Subwoofer Build - New Guy - Advise Appreciated

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  • Wolf
    replied
    Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

    Originally posted by Beau View Post
    There is a dual driver enclosure for the web-special Lab 15 on AVS.

    http://www.avsforum.com/forum/155-di...g1x-build.html
    Looks like a Menace!
    Wolf

    Leave a comment:


  • donradick
    replied
    Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

    Probably should start my own thread, but the OP may be interested in what I can get going.

    Question about Boundary modeling - I'm basically planning to put this in a corner, so I get a lot
    of help. Jeff's Diffraction Boundary Simulator shows about +9 dB gain at 20 Hz, falling to +2 at about 100 Hz.
    Click image for larger version

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    So I was on the borderline - at 100 watts I slightly exceed xmax at 20Hz
    Click image for larger version

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    but that's giving 109 dB, which should be enough for most music for me.

    But combined with boundary reinforcement, won't the actual load on the speaker
    look more like this?
    Click image for larger version

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    IOW, 10 dB less strain on the driver from 20 hZ to 80 Hz ?

    Leave a comment:


  • isaeagle4031
    replied
    Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

    Yes these were built for an OEM that backed out on the total number of drivers being built. So they sold off the lot and charged back the OEM for the remainder per Jerry. I don't know for sure if they used a stock coil. I can't think of another driver in their line that would use the same coil.

    Leave a comment:


  • billfitzmaurice
    replied
    Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

    Originally posted by matt996 View Post
    The driver does have funny specs... I wonder what was the intended application for the 4-ohm Lab15s.
    Since they never appeared in the Eminence catalog they were likely OEM, created at the request of a manufacturer who wanted a 4 ohm driver instead of 6. The problem is that when you do that is that, unless you're placing an order for 10,000 units, Eminence creates the OEM using stock off-the-shelf components. Jerry McNutt probably couldn't find an on-hand 4 ohm coil of the correct dimensions that would retain close to the original specs, so that's why they ended up so far off. Despite that the driver still models very well in a horn of the right size, but the very low Vas that makes it best suited for a horn also makes it not the best choice in a direct radiating alignment.

    Leave a comment:


  • matt996
    replied
    Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

    The driver does have funny specs... I wonder what was the intended application for the 4-ohm Lab15s.

    Although sealed is clearly a mismatch from optimal, the driver is a reasonable candidate for a Linkwitz Transform sub -- being a 15" driver with healthy xmax, and good power handling. Many people are happy with lesser subs in such a configuration. You have the driver and box, so all you need is an amp with DSP and you can see if it will meet your needs. Keep in mind you will get some boundary reinforcement when used in a room, so 100 dB at 20 Hz may not be as bad as it sounds. It all depends on how much SPL you actually need, in your room.

    Some background and a circuit that does the LT (but it's more common to just use DSP at this point)
    http://www.sound.westhost.com/project71.htm

    And a recent build employing the principle: http://techtalk.parts-express.com/sh...of-8-quot-fury!

    Leave a comment:


  • Beau
    replied
    Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

    Originally posted by donradick View Post
    Tom, I feel for you! I may be selling my pair if I can't make them work, and 3 cf is the max I can do.

    Here's a thought - by using both woofers "face to face", you can make the box appear to be 2X the volume that it actually is.
    http://www.jlaudio.com/header/Suppor...amshell/498114

    Assuming I have the correct numbers in Unixbox :D
    Process - I took 3 cf X 28.3 which gave 85 Liters. For Isobaric, I doubled the volume model to 170 Liters.
    Excursion looks pretty good at 100W, with 109dB, and I'll get a boost with corner placement.
    This gives a pretty good F3 (If I didn't mess it up again !!)
    [ATTACH=CONFIG]52937[/ATTACH]
    There is a dual driver enclosure for the web-special Lab 15 on AVS.

    http://www.avsforum.com/forum/155-di...g1x-build.html

    Leave a comment:


  • billfitzmaurice
    replied
    Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

    Originally posted by donradick View Post
    Here's a thought - by using both woofers "face to face", you can make the box appear to be 2X the volume that it actually is.
    With isobaric the box volume is net, not including the size of the plenum chamber that connects the two drivers. With the size of the LAB 15 that chamber size would be considerable, so the gross box volume reduction wouldn't approach 1/2. And since only one cone is radiating the dB output isn't that of two drivers, it's that of one.
    If one is going to use these drivers there's only one logical route, and that's to put them in cabs that will actually work well with them.

    Leave a comment:


  • donradick
    replied
    Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

    Originally posted by tomsassurance View Post
    OK Don and isagle4031 you know the scoop...I'm a completely lost. Is there a way to make the 3cf box work 19.25x19.25x20? The box was designed for the DVC Dayton 15 and they indicated using accustafill. Any "Hail Mary" passes accepted. Thanks guys.
    Tom, I feel for you! I may be selling my pair if I can't make them work, and 3 cf is the max I can do.

    Here's a thought - by using both woofers "face to face", you can make the box appear to be 2X the volume that it actually is.
    http://www.jlaudio.com/header/Suppor...amshell/498114

    Assuming I have the correct numbers in Unixbox :D
    Process - I took 3 cf X 28.3 which gave 85 Liters. For Isobaric, I doubled the volume model to 170 Liters.
    Excursion looks pretty good at 100W, with 109dB, and I'll get a boost with corner placement.
    This gives a pretty good F3 (If I didn't mess it up again !!)
    Click image for larger version

Name:	isobaric-3cf.png
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    Leave a comment:


  • Chris Roemer
    replied
    Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

    The "high Q" driver (that Tom apparently has) won't reach 40Hz in 3 vented cu.ft.

    Leave a comment:


  • Jay1
    replied
    Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

    It still works in 3 ft3, it just doesn't have great extension. The "high Q hump" is less then 1 db at 70 hz, and goes away completely with a low pass filter.

    Leave a comment:


  • Chris Roemer
    replied
    Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

    TOM! - (I HATE using !s, AND CAPS!) the "standard" (low Q) Lab15 is the one that'll work OK in 3 cf. Unfortunately, the guys here are pretty sure that you've got the "high Q" (4 ohm) version which will NOT like a 3 cf box.

    Leave a comment:


  • Jay1
    replied
    Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

    Use a pair of the 3" x 17" aero port kits. Just trim the length so the inside port opening is 3" from the internal cabinet wall. Again the EP4000 with a 30hz HPF will be a perfect match for max output usage.

    Leave a comment:


  • tomsassurance
    replied
    Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

    OK Don and isagle4031 you know the scoop...I'm a completely lost. Is there a way to make the 3cf box work 19.25x19.25x20? The box was designed for the DVC Dayton 15 and they indicated using accustafill. Any "Hail Mary" passes accepted. Thanks guys.

    Leave a comment:


  • jhollander
    replied
    Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

    If any one wants to do 26 cubes we could do a tapped horn. I can fold it, but it will a bit of free time.
    Attached Files

    Leave a comment:


  • isaeagle4031
    replied
    Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

    Originally posted by donradick View Post
    sheesh <strikes forehead with hand> I was using <ahem> a different constant..... Thanks. Things don't look quite so rosy now!
    LOL. Got your back my friend

    Leave a comment:

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