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Need some x-over suggestions for cab building

Discussion in 'Amps and Cabs [BG]' started by Magneto, Mar 3, 2004.


  1. Does anyone know what types of crossovers are used in some of the bass cabinets that have a single 15" driver and a tweeter (horn-loaded hi-freq transducer) ? Some of the ones I've been looking at are the Hartke cabs, such as the VX115, although I've seen numerous other cabs that have this type of setup. I am thinking this type of setup would work well for me, because I like the idea of having the tweeter handling the extreme highs.
    Any ideas, opinions, or suggestions would be very helpful to me.

    Thanks for your help with this..

    Mag..
     
  2. jdombrow

    jdombrow Supporting Member

    Jan 16, 2002
    Colorado Springs, CO
    Designing crossovers is an art, and they not typically something you buy off the shelf or copy from another cabinet. The crossover is designed to work with the parameters of the specific drivers, as well as the cabinet size. It may also make a difference if the box is sealed or ported.

    If you're planning on building a cabinet, read everything you can on speaker cabinet design before you start buying drivers and cutting wood.
     
  3. The preferred solution is an active crossover and bi-amping.

    The active device is immune to the wide impedance variations inherent in loudspeakers. When the impedance does not match the design parameter of a passive crossover, it sounds lousy because it does not cross over smoothly.

    If your project requires passive crossovers, buy one from Eminence. The cost of winding your own will be higher than buying one. Get it from www.partsexpress.com for a good price.

    If you are asking these questions at all, this demonstrates insufficient knowledge to build one. This is not an attack, only a statement of fact. Don't do your own dental work, either.

    :D

    Over the years, I've been down the road of rolling my own crossovers... and will never do it again. My active units (Rane MX22) are so far superior to passive units in every way. The crossover slope is 24dB, which is MUCH higher and has less phasing issues that lower slope passives. A passive unit similar to my Rane would be enormously expensive to build. Get 'em used on eBay for $50 or so.
     
  4. jdombrow

    jdombrow Supporting Member

    Jan 16, 2002
    Colorado Springs, CO
    He was only asking about a crossover for a single 15" with a tweeter. Wouldn't a bi-amp rig with active crossover be overkill in this situation?
     
  5. Yes.

    But, I saw your words 'design' and 'build', and responded to that.

    Many (cheap) tweeters use a single capacitor in series with the unit. The really cheap piezo tweeters don't even need this.

    This is a (high pass) filter, and not a crossover. IMO, this is a sloppy situation, because a filter allows the woofer to waste power by attempting to produce high frequency notes, which it cannot do.

    A single component filter (capacitor) is a 6dB/octave slope, which means it has to cross over pretty high up the scale to keep the low frequency energy out of the tweeter.

    I have the Eminence Crossover Catalog on my web site. Eminence offers both crossovers and high-pass filters for a modest sum.

    The problem arises by not knowing the upper limits of the woofer. If the woofer is only good to 1200 Hz, and the tweeter cuts in at 5,000 Hz, there is a huge hole in the response. Ideally, the next driver (midrange, tweeter, etc) should crossover one full octave below the out-of-gas point for the woofer. In the example above, it should cross over at 600 Hz, if the woofer is only good to 1200 Hz.

    Tweeters don't work at 600 Hz... they blow up.
     
  6. Thanks for the very informative replies. I am an inexperienced builder, but we all have to start somewhere. I am rebuilding my setup after many years of not playing bass.
    I have built some nice cabinets in the years past, but those utilized full range 15"s, 12"s, or 10"s, with no crossovers. I do know a bit about designing a cab to work with a certain speaker's specs, and I like to build.
    There's alot of technical data that I need to be concerned with, but I'm learning as I go.
    I have had a couple of car sub cabinets (in the past)that had the hi-pass filters on the tweeters as mentioned, but I didn't figure that the bass cabs I was referring to would use a setup that cheap.

    I'll probably have more questions to ask later, but thanks alot of helping..

    Mag...
     
  7. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    Chicago
    Some companies use a simple 6 dB/octave crossover (aka a single cap in series with the tweeter) some probably use a 12 dB/octave, etc.

    Avatar goes the 6 dB/octave route, SWR uses a 18 dB/octave crossover involving two caps and a coil. If you can find an old Bass Player article with the 2x10 shoot out, you can see the SWR crossover complete with component values...

    More complex crossovers like SWR (and Eden) also include a automotive light bulb current limiter in series with the tweeter to absorb excess energy during really loud passages.

    Avatar, SWR and Eden all include an L pad attenuator between the crossover network and the tweeter to control the level.

    Have fun!
     
  8. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
  9. More great information! Thanks alot people for the ideas. The information at the passive crossover link is very helpful. I'll be doing more searching and reading before I start making choices. I rarely rush into anything.

    Mag...