5-Way Crossover

Discussion in 'DIY Corner - Tips & Techniques' started by Polygon, Jan 29, 2008.

  1. Polygon Audioholic

    Polygon
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    I have an old set of DBX Soundfield V speakers. They are a 5-way speaker and I love how well they throw sound around and they have very good tight bass but the highs aren't all that clear. I've checked Parts Express and I couldn't find anything. Do you guys know of any good 5-way crossovers?

    The speakers are composed of:

    1" tweeter
    3" tweeter
    3" ribbon tweeter
    8" midrange
    15" driver (bi-ampable)
  2. jaxvon Audioholic Ninja

    jaxvon
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    The unclear highs are probably due to a rolled off response from the tweeter, not a modified curve from the crossover. I doubt a new crossover will fix this. If I were you, I would invest in better speakers. however, if you are intent on "fixing" your old ones, you will first need data on the response of the individual drivers to properly integrate them with a crossover. If you have the measurement tools to do this, or have access to the original measurements from DBX, then you can go about designing a new crossover. I would personally recommend that you go the active route, using two Behringer DCX2496 units (one for each speaker) and enough amplification (5 channels per speaker).
  3. Polygon Audioholic

    Polygon
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    So, are you suggesting replacing the tweeters and the midrange or are you suggesting dumping the DBX for something better?
  4. TLS Guy Audioholic Overlord

    TLS Guy
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    If you have to ask the question you can't mod these speakers. That would be a huge task. eBay, someone will take them off your hands.
  5. Mudcat Senior Audioholic

    Mudcat
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    I have the these speakers too. They are most definitely not 5-way. They have five speakers, but they are three way. On the top, pointing straight up are a 1 inch tweeter and a three or five inch mid range. On the beveled face is a 3 ingh long ribbon tweeter and an 8 inch mid range. On the vertical face is the 15 inch woofer
  6. j_garcia Audioholic Jedi

    j_garcia
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    A 5-way crossover is highly unlikely. Most speakers are 2, 2 1/2 or 3 way, regardless of the number of drivers, as 5 way would have each driver operating in far to narrow of a band to yield the benefits of any of them. If you have never built a crossover before, I would say this is not a good place to start. Without the ability to measure the response and make adjustments to the crossover correspondingly as Jaxvon mentioned, you have no chance of improving the speakers.
    Last edited: Jan 29, 2008
  7. Polygon Audioholic

    Polygon
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    Well, I've already looked into that with speakers from parts express and replacing the tweeters and mids would be cheaper than anything I would replace them with. I'm just wondering if that will reallt give me the sound quality I want. I wouldn't replace the driver as it does what is't supposed to do perfectly. Not to mention, these speakers are in new condition. Like I said, they throw the sound very well. That's why I like them so much.

    Regardless, I don't plant to get rid of them. I would just use them in another rig. So I want to improve the sound anyhow.

    Yep, those be the ones. That's interesting to hear. So, how are the crossovers wired? I'm sure one frequency is going to the driver, one to the midranges, and one to the tweeters?

    So, I could just get a good pair of 3-way crossovers? I really do want to keep the low end of the drivers.
  8. sparky77 Full Audioholic

    sparky77
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    Its possible that the capacitors in the crossover are no longer their intended value if these are older speakers, replacing the capacitors with new higher quality components of the same values, you may get back the high frequency response back. The most obvious way to determine if the capacitors are failing is if one speaker seems to have different response compared to the other one.
  9. Polygon Audioholic

    Polygon
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    I never thought to check the caps. I've never seen the crossovers obviously. However, they are old. They were bought by my father in 1984 and he sold them to me in 1997. I can't see a difference in sound between the speakers. The effect I'm hearing is almost muffled highs.

    The main reason I ask this question is because I've replaced the crossovers in two other pairs of old speakers and improved the sound dramatically. They were exhibiting the same effect these DBX speakers are.

    Sadly, I've never built and type of circuite. I've always bought the crossovers. I also don't know what these sounded like when now, so I have no experience to compare them with.

    So, Parts Express, sells a 3-way crossover. I'm wondering if that would work as I assume two pairs of speakers are operating on the same frequencies. This would also be a cheap option. If it doesn't work I could always use them in a DIY build and sell them.
  10. sparky77 Full Audioholic

    sparky77
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    The crossovers from PE most like wouldn't work properly in those speakers, the crossover points and cuttoff slopes wouldn't be close enough to what the speakers need to sound right. There is more likely a rather complex crossover network to account for the impedences and sensitivities of all the drivers in the cabinet, but simply replacing the capacitors would not change the crossover, just repair it, and often times if electrolytics are used, the cripsness in the highs can be brought back by replacing them with metalized poly caps.

    Do you have any soldering skills?
  11. Polygon Audioholic

    Polygon
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    I've had to solder new caps in my cars ECU, so that would be familiar.
  12. TLS Guy Audioholic Overlord

    TLS Guy
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    I did not remember that speaker, but I see it had a ribbon tweeter. Now ribbons of that date were a piece of foil in a magnetic field at the mouth of a horn. The units were driven by a transformer as the impedance of the foil ribbon was so low. The problem with those designs was stretching of the ribbon over time, especially when driven hard. When that happens you get the problem exactly you describe. I would bet that is the problem with your speakers. If you use generic crossovers, if the ribbons are ruined now they will be.

    The first ribbon tweeter was produced by Peter Walker of Quad in 1949. This was replaced by the first full range electrostatic in 1956/7.

    The ribbon was further developed by Stan Kelley at Decca. I used a couple of these tweeters years ago. Despite using steep order crossover, ribbon replacement was periodically required. Fortunately the ribbons were cheap and easy to replace.

    Here is a link to the Decca of Stan Kelley.

    http://www.soundfountain.com/amb/ribbon.html

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