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Advice needed on DIY Kappalite 3015 3-way

Discussion in 'Amps and Cabs [BG]' started by zac2944, Mar 14, 2008.


  1. zac2944

    zac2944

    Dec 28, 2004
    Rochester, NY
    I’m planning a 3-way cab design as part of an experimental build using composite material. The main focus of my build is to produce a lightweight and sufficiently durable cab, but I also want it to sound good.

    I’ve modeled the 3015 in WinISD to look at box size and port tuning. That seams pretty straight forward. Where I get lost is the crossover and matching drivers. I’ve read through the info on lalena.com, and a few other website, but I’m still not too confident. I've even read through parts I & II of the "Boutique 3-way" thread. Any input you guys could offer you be much appreciated.

    Here are the components I’m considering:


    Opinions on this speaker combination?

    Do the crossover points look good? I don’t have any info on the order (1st - 6 db/octave, 2nd - 12 db/octave, etc.) of the crossover, but I emailed Carvin and hope to get a response.

    What about beaming, phase shift, and stuff like that?


    parts.
     
  2. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    That appears to be a 4 ohm crossover, which is not going to work right with an 8 ohm woofer. Look at the 1503 model instead. PM me, I have one of those here at the moment and can fill you in on it. Personally, I'd at least go with the Peavey crossover that Greenboy mentioned in the megathread.

    I'd like to hear about your composite build too.
     
  3. zac2944

    zac2944

    Dec 28, 2004
    Rochester, NY
    Thanks for the heads up on the crossover. I made a bad assumption there that if it could handle 800W @ 4ohm then it would work for ~450W @ 8ohm. I didn't know crossovers were ohm-specific, I thought they just needed to be able to handle the power you send through them without overheating. PM on its way.

    I'll post more about the composite build when I get there. I've been doing some calculations to estimate weight and looking at the pros and cons of fiberglass/foam composite and wood/foam composite (ala Flite cabs).

    Considering only the drivers (16.1 lbs) and cabinet, I'm calculating weights of 30-35 pounds total depending on which type of composite I use and how they are built. I'm going to do some testing and mock ups before I commit to a full build.
     
  4. asad137

    asad137

    Jan 18, 2007
    Minneapolis
    Physicist
    I'm interested in this as well. I've been thinking of ideas to make a box from a wood/foam composite -- something like 1/8" outer plywood sheets bonded to 1/2" thick foam. It should easily be as stiff as 1/2" solid ply. As I'm sure you're aware, the trick is in attaching panels together. Haven't figured out a good, not-too-labor-intensive solution to that.

    Asad
     
  5. zac2944

    zac2944

    Dec 28, 2004
    Rochester, NY
    I hear ya. I'm thinking that epoxy on rabbet joints for the edges of the pannels, with interior battens or supports epoxied as well. I don't mind the labor, but I want to test the strength of this type of joint before I build a full cab. I have a local plywood distributer that carries 1/8 for boat building. I might be able to start experimenting this weekend.

    I'm also considering epoxy/fiberglass over foam. The down side there is the cost; $80-$120 for the epoxy/glass.
     
  6. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    If you're doing this for fun all well and good. Commercially speaking ultra-light constructions are expensive, witness JBL Vertec 4880s that go for $11,000, and carbon fiber hi-fi cabs that go for over $20,000. Even if you halve a cab's weight there are few willing to pay double or more for it.
     
  7. Blues Bass 2

    Blues Bass 2 Supporting Member

    Oct 3, 2001
    Davenport Iowa
    Your components look very good but for about 6 dollars more you could get a Selenium D 210Ti compression driver that would screw right on that horn instead of the DT150 tweeter.They are on sale now at Parts Express and are a very nice driver,a step up from the tweeter.They weigh a little more but have a larger voice coil and a wider bandwidth than the DT150.I have them in a pair of monitors I built and they are very smooth.
     
  8. zac2944

    zac2944

    Dec 28, 2004
    Rochester, NY
    Yes, I'm only doing this for fun. But still, my composite construction cab (if it actually works) will run $325-$400 depending on which construction method I go with. IMO, not too bad. It could also end up as a $400 pile of junk.

    The labor involved is what makes something like this so expensive. It just doesn't lend itself to mass production. If I was to use carbon instead of fiberglass or wood then add on another $200-$300 for the carbon fabric. That stuff is very expensive.
     
  9. Why are you using 3015 instead of 3015LF? It does run in a smaller cabinet than 3015LF, but does not get down as low. F3 is about 58 Hz, best case.

    LA6-CBMR has a steep rolloff right at the crossover frequency of 500 Hz. This is certainly less than optimal, as a gentle slope crossover assumes linear response an octave below the crossover point. This driver also has a ragged top end response. There are better choices if you are willing to skip the sealed basket and make your own subchamber.

    The LA6-CBMR has a declining high end above 500 Hz. Its response drops to 95 SPL, where the 3015 driver has a flat 100 SPL. The combination gives a warm bottom, somewhat muted mids, then a harsh top where the 108 SPL compression driver kicks in.

    The DT150 compression driver data sheet recommends a minimum crossover of 4,000 Hz. Eminence makes a 3-way at 500 and 5000 Hz that would do the job at 8 ohms. It is an internal-only type, without a level control on the tweeter.

    The optimal mids solution with Eminence drivers is a pair of Delta Pro 8B (16-ohm) wired in parallel. Due to the higher impedance, each will accept 56v maximum, which is right in keeping with the maximum applied to the 3015. The parallel pair makes 8 ohms to keep the crossover happy, and the combined output matches the 3015 and compression driver.

    The problem with 8B is nobody is stocking them yet. My wholesaler (Parts Express) requires a 100 unit minimum order. I could set up another account directly with Eminence, but I have to buy a minimum unit/dollar amount. I'm buying two 8B through a dealer friend by piggy-backing on his next order, so I can have a pair for prototyping. You might contact Bernie at www.bltsound.com to see if he can get 8Bs.

    IMO, with the above choices, you will indeed wind up with a $400 pile of less than optimal parts.
     
  10. zac2944

    zac2944

    Dec 28, 2004
    Rochester, NY
    Thanks for the input. I see your point about the LF version. It does seem to work better in a 3-way design. One thing I haven't mentioned yet is that I would like to build this cab in stages. At first I'll run just the 3015 in a sealed cab. Then I'll add the ports and tune. Then I'll make the cutout and add the tweeter. At this point I'll run the cab bi-amped from a GK 1001RB-II. I sends 480W to the 3015 and 50W to the DT150, with a crossover point of 5kHz, and both outputs are adjustable. If I want to keep experimenting at this point it would be to add a mid and 3-way internal passive crossover. Buy adding to the system and evaluating at every step my ears will have a chance to learn what the calculations and conventional wisdom say I should be hearing.

    Unfortunately, according to your post the closed back mid won't work out very well. If a separate enclosure is required for the mid then adding one late in the game will not be as easy as cutting a hole. Hmmmm.

    Since the focus of this build it on the construction, I don't want to get into adding a mid enclosure. Just making a box will be tough enough.
     
  11. These pieces are not suitable for staging. Build all, or none. The 3015LF will be a dull and lifeless driver without another driver to pick up the highs.
     
  12. zac2944

    zac2944

    Dec 28, 2004
    Rochester, NY
    Suitable or not, I'm going to do it that way so that I can hear what the different pieces of the system add. In the end they will all be there. I want to hear what the ports will add to the low end, and compare what I hear with the results shown from WinISD.

    I'm glad I'm not using then 3015LF then.
     
  13. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Big mistake. Aside from the issues of extension the LF will take over twice the power that the 3015 will before exceeding xmax. Bruce has been around the block more than a few times. Dismissing his advise is unadvised.
     
  14. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    Just to play devils advocate, you can find this out with EQ.
     
  15. Kindness

    Kindness

    Oct 1, 2003
    Chicago
    Somewhat on topic, can anyone weigh in on whether there is ever a time that it is better to use the non-LF in a two way bass cab having a midrange driver?
     
  16. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    I modeled the 3015 and 3015LF in equal boxes ranging from 80 to 120 liters, leaving the port tuning constant at 45 Hz. The curves are practically on top of one another. So, if you are planning on having a midrange anyway, the main difference seems to be how much cone excursion is enough. The LF is unconditionally fart proof, which IMHO makes it a really DIY friendly driver.

    Edit: I should have said: "The curves are practically on top of one another below 250 Hz."
     
  17. zac2944

    zac2944

    Dec 28, 2004
    Rochester, NY
    I'm by no means dismissing Bruce's advice. I'm sure he knows his stuff and I'm grateful for his advice. My apologies to the man if I didn't come across that way.
     
  18. zac2944

    zac2944

    Dec 28, 2004
    Rochester, NY
    So it sounds like the 3015LF is the way to go insted of the 3015, but are there any drivers for the mids that match up well? Bgavin's recommended mids are not available.

    How much power would a suitable mid driver need to be able to handle? Whould it have to match the ability of the 3015LF?

    Could two 4ohm drivers wired in series be used? Would there be a 3dB gain by using two drivers?
     
  19. zac2944

    zac2944

    Dec 28, 2004
    Rochester, NY
    Maybe the 3015LF and a 18sound 6ND410 6" mid would be a better match up.

    I've got to go back to the drawing board.

    I'm looking forward to building a cab, but picking out drivers is a drag!
     
  20. BBMS

    BBMS

    Jun 29, 2005
    Since you have committed to spending around $400.00 for a 3 way cabinet, and you want a 15", , why not build an Omni15/ TallBoy15 (by Fitzmaurice)? I built two, and they are much nicer than the JBL 4700 series 3 way cabinets I've been using. They are also nice bass cabinets. Why not go with something that works, than one that may/may not work? You still get to spend lots of time building a cabinet. MY
     

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