Getting started with active crossovers

Discussion in 'Home Theater Projects' started by AlexKunec, Aug 3, 2004.

  1. AlexKunec

    AlexKunec Stunt Coordinator

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    Hi,

    The latest active crossovers thread inspired me to build some myself. I went to this website and thought that would be perfect for me. $75 for all the parts I need to build and test 2 3 way speakers. However, I emailed the author, and he hasn't responded. So I was gonna put together a kit myself. I want to order everything at once.... from digikey.

    What should i get?
    Also, what kind of power supply do i need, or can i build that myself too?

    Thanks
    Alex
     
  2. ThomasW

    ThomasW Cinematographer

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    That's a very stale webpage. Last time I heard, the kit was no longer available. Now that situation may have changed, but don't order anything from DigiKey until you hear one way or the other from John,
     
  3. Mitch N

    Mitch N Stunt Coordinator

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    www.diyaudio.net always has some cool projects going on and many times DIY kits that are relatively low cost and very capable. The guys there are hard core tweakers and never stop working on projects
     
  4. AlexKunec

    AlexKunec Stunt Coordinator

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    I cant access that website, r u sure its not diyaudio.com?
     
  5. Mitch N

    Mitch N Stunt Coordinator

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    My mistake it is .com
     
  6. Mike Keith

    Mike Keith Second Unit

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    Marchand sells board kits for single channel active crossovers that have all the parts, I hear there quite good. Just use 2 boards and a power supply in your own enclosure, add jacks and a gain control and you should have a good 2-ch crossover for under $100.

    http://marchandelec.com/xm1.html
     
  7. Bob K

    Bob K Stunt Coordinator

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  8. Mitch N

    Mitch N Stunt Coordinator

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  9. Bob K

    Bob K Stunt Coordinator

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    Mitch,

    I've never heard the Behringer, but it seems to get decent marks. If you're going to get a pro item, I'd suggest looking at zzounds.com . I ordered a pro amp -- a Behringer EP1500 -- from there last Monday and it arrived on Wednesday with free shipping.

    Let us know what you do and post a review!

    Crossovers from zzounds.com: http://www.zzounds.com/prodsearch?fo...=16&submit.y=9
     
  10. Dave Milne

    Dave Milne Supporting Actor

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    I'm not a big fan of the Behringer crossover, or any other digital-domain crossover for that matter... at least for higher-end audio and theater systems. The extra A/D and D/A conversions aren't good for sound quality. Digital crossovers are very handy for trying out a bunch of frequencies and slopes. When done fiddling, I'd recommend implementing with a good analog crossover, like the venerable Sallen-Key topology with premium op-amps, tight-tolerance film resistors and poly or teflon caps. This stuff is all relatively cheap from Newark, Avnet, Digi-key, etc.
     
  11. Bob K

    Bob K Stunt Coordinator

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    Dave,

    I could be wrong, but I was under the impression that the CX2310 and the CX3400 were analog crossovers, while the DCX2496 was a digital crossover.
     
  12. Ethan Winer

    Ethan Winer Stunt Coordinator

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    Alex,

    > I was gonna put together a kit myself. I want to order everything at once.... from digikey. <

    The active crossover schematic at that site is not a good design. The biggest problem is it uses two separate filters for the high and low outputs. This means that any component value deviations will give a different crossover frequency for each output. You'll find a much better design on my Articles page:

    www.ethanwiner.com/articles.html

    Look for "Spectrum analyzer and equalizer design" halfway down the list. The active crossover is about 2/3 of the way into the article.

    --Ethan
     
  13. alan halvorson

    alan halvorson Cinematographer

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    Anyone have opionions on Rane electronic crossovers, specifically the AC 22B or the AC 23B? I have a pet speaker project that I've been hemming and hawing on for many years that requires an electronic crossover with adjustable delays. These seem to fit the bill.
     
  14. ThomasW

    ThomasW Cinematographer

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    Rane makes good stuff. And they use 24dB/octave L/R slopes most people prefer. :wink:

    A fundamental problem with analog units like that, is that they are a terror to adjust. The little knobs are basically impossible to set accurately without test equipment.
     
  15. alan halvorson

    alan halvorson Cinematographer

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    Thomas: Are there any digital equivalents to the Rane, with delays?
     
  16. Ethan Winer

    Ethan Winer Stunt Coordinator

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    Alan,

    > Anyone have opionions on Rane electronic crossovers, specifically the AC 22B or the AC 23B? <

    I have an older Rane AC 22 and it's great.

    --Ethan
     
  17. Dennis XYZ

    Dennis XYZ Stunt Coordinator

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    Don't forget Linkwitz's general purpose circuit boards. Using them, along with his circuit examples, you can build a crossover with time alignment, baffle step compensation etc., not just a plain vanilla textbook crossover which is only marginally useful in most cases.

    PCB order page

    Active filters page
     
  18. Michael R Price

    Michael R Price Screenwriter

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    Alex,

    Here's what I would do. Buy the basic components you need for the power supply (usually a regulated +/-15v supply), and a breadboard and some opamps. Pick two capacitor values that are not multiples of each other, I used 6.8nf and 15nf, and buy a bunch (big bunch) of resistors around the values you would expect to need. If you give me a little while I can try to find the Digikey order listing for my crossovers, but it's a little different since I did not use opamps.
     
  19. AlexKunec

    AlexKunec Stunt Coordinator

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    What op amp should I use?
    Also what is biasing? Does it only apply when I only have a single polarity p/s?
     
  20. ThomasW

    ThomasW Cinematographer

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    My vote for best op-amps are the Burr-Brown OPA-2604 :wink:
     

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