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Thread: Urei 809 crossover rebuild

  1. #1
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    Urei 809 crossover rebuild

    The other day I replaced the foam woofer surrounds on my Urei 809's and since doing so they sound a LOT better. I have to believe the disintegrating rubber, though it looked intact, must have had thousands and tiny pinholes and thus ruined the sound.

    Now that they are sounding better I think I should go for broke and replace some of the ancient parts in the crossover - yes, these are 100% original crossovers. I assume all I have to do is pull out the crossover, note the values of all the bits and pieces, purchase replacements, and replace each - one at a time.

    I am quite handy with a soldering iron, so I am not worried about that.

    I dont want to over simplify it nor over complicate it. My google-fu has yet to yield any useful information.

    Help is much appreciated.

  2. #2
    Senior Member grumpy's Avatar
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    I hesitate to encourage this as it certainly devalues the crossovers down the road, but these are the custom cab units (?), so maybe it's no longer a consideration. 2) you've essentially got the right idea, but understand you may also prefer them as they were, so be gentle when extracting the old bits. 3) why not go nuts and DC-bias the caps while you're in there... Instructions and examples abound... 9v battery or diode (to rectify the audio for a floating "DC" bias). Have fun!

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    I'm not to precious about retaining value but I do attempt to preserve the integrity (physics/engineering) of the original design. Yes, I made custom cabinets for a couple reasons:
    - they were butt ugly and I didn't like the looks of them in the living room.
    - the originals were damaged and weakened (major cabinet vibration)
    - the new cabinets are identical in volume, construction methods and bracing with the exception of using furniture grade, no void, walnut plywood.
    - original fiberglass was used to fill the cabinets.
    - acoustically transparent grills made from vintage reproduction grill cloth.

    As I write this I am wrecking my house listening to Daft Punk but the two pheasant sculptures sitting on top of the right speaker have not moved an inch - however the rattling window is making me crazy.

    So about the crossovers - I've googled a bit and yet to find anything actionable aside from "do it". Maybe I am not looking in the right places or with the right words.

  4. #4
    Senior Member grumpy's Avatar
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    Typically, one would leave the resistors and inductors alone and just replace the capacitors, using whatever kind of capacitor floats your boat: foil & film, metallized polypropylene, motor starter caps... Takes all kinds... I've done ok with SonicCaps (sp?) and Solen. Working voltages over 50v is probably ok if you're not serenading the neighbors (might find ratings and values on the existing caps). Also probably a good idea to get a copy of the network schematic if you don't have one already.

    Didn't intend to sound like I was knocking the cabs ... They look quite nice.
    just didn't remember which were yours.

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    I didn't take it as an insult and do understand how somebody may be bothered by it; I was attempting to show I respect the original design and intent.

    I may have a copy of the schematic around here somewhere - if I do its been 10 years since I've seen it.

    Since my last post I have found a few posts on crossovers, just recap the things and call it good - it seems. As for all your fancy 9v battery stuff, I have no idea what you are talking about. I would like to know but maybe better off now knowing.

  6. #6
    Senior Member grumpy's Avatar
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    Here's a start. Not in 100% agreement, but it'll do:

    http://www.enjoythemusic.com/diy/091...crossovers.htm

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    A couple of friends of mine bought expensive crossovers from Germany with autoformers instead of resistors. One pair is for Altec Valencia. The other pair is for Altec 604 speakers. I can find out the name and contact information to this guy if you want.

    Mårten

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    Part of me wants to say yes to the crossover information but I think I will just tune up the existing circuitry with fresh parts and call it good.

    "At the Deerfield Inn" (Keith Jarret, Gary Peacock, Paul Motian) sounds pretty fantastic right now. I think the folks at Urei knew what they were doing.

    Unfortunately, I am looking at some of these 4355 builds I fear I may go off the deep end.

  9. #9
    Heather [Senorita member] hjames's Avatar
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    Quote Originally Posted by Urei809 View Post
    Part of me wants to say yes to the crossover information but I think I will just tune up the existing circuitry with fresh parts and call it good.

    "At the Deerfield Inn" (Keith Jarret, Gary Peacock, Paul Motian) sounds pretty fantastic right now. I think the folks at Urei knew what they were doing.

    Unfortunately, I am looking at some of these 4355 builds I fear I may go off the deep end.
    Well, rather than 4355s, there are a pair of big ol' 413B UREIs near me for sale ...
    15" coaxial with a 15" Eminence helper woofer in the cab ...
    God awful heavy - but if you are already that far down the UREI path ...

    [I have no info for the 809 crossover rebuilds ...]
    2ch: Oppo, Acurus RL-11, JBL 240ti, Heath AS101, Carver TFM-25,Von Schweikert VR4
    7: Oppo BDP103D, B&K, UREI 809A, JBL B460,

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