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Crossover construction help needed

Discussion in 'Home Theater Projects' started by Jonathan T, Mar 30, 2005.

  1. Jonathan T

    Jonathan T Well-Known Member

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    I'm attempting to build the Crossover for a Kit81M and I'm running into trouble. The drivers (I'm testing them free air with a small amount of power from my my reciever.) are producing high distorted sound, especially from the tweeter as it's playing the baseline. I built the crossovers by taking the leads of the components and twisting them together so I could test it and change anything if I ran into problems. Now, I don't think the twisted connections are bad, I double and triple checked them and everythign seems to be making good contact. I hooked every up on a piece of wood and I'm using 14 gauge wire as the manual says I should.

    I have 1 question though, the schematic shows that multiple parts in many different place need to be connected to the same wire in parallel but at different places. Do I have to connect them in different places or can I just twist the leads all together in one place?

    Also, I'm only using the left channel of my reciever as I only built one crossover at this time, I don't think that should make a difference though.
     
  2. Patrick Sun

    Patrick Sun Moderator
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    Tweeters shouldn't be playing the bassline if the filter is doing its job.
     
  3. Jonathan T

    Jonathan T Well-Known Member

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    Um, not to be rude but......duh.

    I took it apart and rewired everything exactly as what's in the schematic. testing now.
     
  4. Eric Ha

    Eric Ha Well-Known Member

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    They can be all together. As Patrick said, if the tweeter is playing the baseline, something's not right of course. Check your schematic again, and again.[​IMG] After that I would guess check components.
     
  5. Jonathan T

    Jonathan T Well-Known Member

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    I checked every connection and even rewired some, again. It's just getting worse. I only have a multimeter that can measure amperage, direct and alternating current and resistance. The resistors are good, but I have no way of checking the inductors or the capacitors. This is quite frustrating.
     
  6. Allen Ross

    Allen Ross Well-Known Member

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    can you show us a pic of what you have so far, see if we can see anything that you are missing?
     
  7. Jonathan T

    Jonathan T Well-Known Member

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    Sure, I will provide a picture.
     
  8. Patrick Sun

    Patrick Sun Moderator
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    The schematic doesn't look too tough to wire up. The bottom portion is the 'return' or the negative leg of the circuit, and they all represent the same point electrically, so tie them up where possible (L1, L2, R2, and positive terminal of the tweeter). Make sure you are using the correct valued components as listed on the schematic, reversing the component values could move the filter break point from the 2KHz range down to the 500-1000Hz range, which could explain the bassline playing through the tweeter.
     
  9. Jonathan T

    Jonathan T Well-Known Member

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    I'm using the correct values for every component. I took everything apart so I'll wire it up again and if it still doesn't work I will post a picture.
     
  10. Jonathan T

    Jonathan T Well-Known Member

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    Hmm, rebuilt everything and the results are the same. I don't think it's the joints I made either, everything it twisted tightly. This time, I just the suggested layout that was printed in Adire's manual and I noticed some problems. The layout and the schematic have different tweeter networks on them. The Schematic shows that the 4.3uF capacitor is jointed to the positive amp rail which connects to the negative terminal of the tweeter. The layout depicts that the 4.3uF capacitor is connected to the negative amp rail which connects to the positive terminal of the tweeter.

    I'm beginning to think the schematic is incorrect.
     
  11. Jonathan T

    Jonathan T Well-Known Member

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    [​IMG]
    [​IMG]
    [​IMG]
     
  12. Jonathan T

    Jonathan T Well-Known Member

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    I changed the layout to what was on the paper shown in the picture. The tweeter isn't quite as distorted but the woofer is playing intermittenly. Bad connection?
     
  13. Jonathan T

    Jonathan T Well-Known Member

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    Emailed adire, got this back

     
  14. Dan Wesnor

    Dan Wesnor Well-Known Member

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    First of all, make sure it's not turned up too loud. There will be no bass from the woofer when it's sitting on the floor, so there's a tendancy to turn it up until the sound fills out, which in this case would overdrive the tweeter.

    I don't think it's inductor coupling. Inductor coupling is not really that strong. But I would still build the two halves of the crossovers separately just so you can see things better.

    It looks to me like there's a capacitor missing from the tweeter side, and a capacitor where a resistor should be. That's what I see from looking at the diagram under the components, so I could be wrong.
     
  15. Jonathan T

    Jonathan T Well-Known Member

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    That capacitor is the third one at the top, I moved it because the layout on the schematic was different than the one in the manual and I just changed everything to match the schematic.

    It isn't turned up too loud. First think I checked was the tweeter seeing as it's more sensative and less tolerant of music outside of it's operating range than the woofer. I held the tweeter right up to my ear everything I tested it and only turned it up so that I could barely hear it.

    I seperated the networks and rewired everything and I'm getting better results already.
     
  16. Jonathan T

    Jonathan T Well-Known Member

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    I wired the 2 networks up, 6 feet apart from each other, still the same situation as before. I tried the woofer network alone and the sound comming from it was intermitten. Sometimes it would sound like ok, but if I turn the volume up slightly, it would cut out, then back in with a large amount of distortion.
     
  17. Jonathan T

    Jonathan T Well-Known Member

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    Ok, like I said before, the woofer crossover (and just that, I did not have the tweeter connected) works for a while and then stops. Just now, for 5 minutes, everything was working fine, I then stoped the song and started it again and the distortion started up, I did not touch anything, nor did I move myself. Could a bad part or a bad connection cause this?
     
  18. Jonathan T

    Jonathan T Well-Known Member

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    hm, everything seems to be working now, and I didn't change anything. The tweet is quite syllibant and there is a very noticable hiss though.
     
  19. Eric Ha

    Eric Ha Well-Known Member

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    The tweeters are harsh for a while, but calm down after use. Mine took weeks to totally lose the harshness. If they're wired out of phase this exacerbates it.
     
  20. Allen Ross

    Allen Ross Well-Known Member

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    what are you powering it with? this sounds like either bad connection or you are activating some protection circuitry.
     

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