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    Crossover refurbish for B&W Matrix 803

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    Kentley

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    Age : 64
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    Crossover refurbish for B&W Matrix 803

    Post by Kentley on Tue Mar 31, 2015 9:35 pm

    As this is out of the purview of a tube forum, please respond by PM, unless you consider it good general info.
    I bought B&W Matrix 803 used six months ago These are the original model with one 7" woofer, date of manufacture 1990. I had to replace a burnt tweeter, so I did both successfully, and I love these with the ST-120 in a very cozy room. I think I hear slight variation in response, however.
    I know from research that the crossover design is pretty simple, but that B&W perhaps used inferior components i.e. cheap electrolytics. I have all the values for the parts - two or three chokes and two or three caps. I am considering upgrading these components. Seems like a fairly easy project. Any suggestions???? And is it in fact the case that these crossover elements can degrade over 25 years???

    corndog71

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    Re: Crossover refurbish for B&W Matrix 803

    Post by corndog71 on Wed Apr 01, 2015 10:01 am

    I don't think B&W skimps on parts but you never know until you break them out. The main ones to replace would be any caps in the signal path. Particularly in the tweeter circuit.

    Kentley

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    Re: Crossover refurbish for B&W Matrix 803

    Post by Kentley on Wed Apr 01, 2015 10:22 am

    corndog71 wrote:I don't think B&W skimps on parts but you never know until you break them out.  The main ones to replace would be any caps in the signal path.  Particularly in the tweeter circuit.

    I doubt as well that B&W has deliberately cheapified anything, particularly since the speakers under discussion were made during their "Golden Age" when the company was the cat's meow. But I wonder, since there seems to be a slight mis-match in the responsiveness of the crossover frequencies, if the apparently long inactivity when these were in storage somewhere has altered the capacitance values enough to be heard. I guess it's worth a try, since even Mundorf replacements are well within my budget. You inspire me to give it a go.

    j4570

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    Re: Crossover refurbish for B&W Matrix 803

    Post by j4570 on Wed Apr 01, 2015 10:41 am

    I'm one that usually takes a measured approach. I'd replaces the caps (all of them though) and then listen. I would doubt the chokes would be improved upon unless one got physically damaged and is broken.

    Kentley

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    Re: Crossover refurbish for B&W Matrix 803

    Post by Kentley on Wed Apr 01, 2015 10:48 am

    j4570 wrote:I'm one that usually takes a measured approach.  I'd replaces the caps (all of them though) and then listen.  I would doubt the chokes would be improved upon unless one got physically damaged and is broken.

    That is exactly the conclusion I have come to. I simply wished to receive confirmation from someone more saavy than I, a relative toddler in this realm. Thanks! flower

    deepee99

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    Re: Crossover refurbish for B&W Matrix 803

    Post by deepee99 on Sun Apr 05, 2015 1:42 pm

    Just my two bits' worth, but a lot of high-end speaker builders cut corners in the x-over department, because it's the one component you can't see on the showroom floor.
    Electrolytic caps in particular go out of value if not regularly powered. Let your speaks sit idle in the garage or a back bedroom for a year, they're likely toast.
    Modern replacement caps will require a burn-in time, but the break-in is not painful. Kinda like starting with a new tube. Don't go overboard on the spendiness. Anything above $10 per cap for a crossover is wasted money, IMHO.



    Kentley

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    Re: Crossover refurbish for B&W Matrix 803

    Post by Kentley on Sun Apr 05, 2015 2:03 pm

    deepee99 wrote:Just my two bits' worth, but a lot of high-end speaker builders cut corners in the x-over department, because it's the one component you can't see on the showroom floor.
    Electrolytic caps in particular go out of value if not regularly powered. Let your speaks sit idle in the garage or a back bedroom for a year, they're likely toast.
    Modern replacement caps will require a burn-in time, but the break-in is not painful. Kinda like starting with a new tube. Don't go overboard on the spendiness. Anything above $10 per cap for a crossover is wasted money, IMHO.


    Yes deepee - I do believe all of this applies here. The speeks were stored somewhere for Dog knows how long. The cabs are in great shape, but one tweeter coil was toast, so I replaced coil/diaphragms in both. There is the slightest mismatch in Xover freq. - nothing most ears would register, but.... The present caps are indeed electrolytic - not because B&W was being cheap as much as that everyone was using them in 1990. Anyone have any fave brands? Oh - in looking for replacements, I found that few companies made the correct values. What's my tolerance factor here? If I just matched BOTH SIDES L&R with the closest I could come would this suffice? I'll look up the data again - I know I wrote it down somewhere. Where's that bloody notebook......?

    deepee99

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    Re: Crossover refurbish for B&W Matrix 803

    Post by deepee99 on Sun Apr 05, 2015 2:13 pm

    At the risk of getting flamed here, my experience is that there's a fair degree of "slop factor" in cross-over caps. In other words, if the specs call for 5uF you can get away with 8. The voltage rating is more important. I'm not familiar with B&Ws but probably 200 volts would be minimum spec.
    Parts Connexion would be a good place to look. Just get some $10 polys and call it a night.
    Happy Easter,
    -d-

    peterh

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    Re: Crossover refurbish for B&W Matrix 803

    Post by peterh on Sun Apr 05, 2015 2:37 pm

    deepee99 wrote:At the risk of getting flamed here, my experience is that there's a fair degree of "slop factor" in cross-over caps. In other words, if the specs call for 5uF you can get away with 8. The voltage rating is more important. I'm not familiar with B&Ws but probably 200 volts would be minimum spec.
    Parts Connexion would be a good place to look. Just get some $10 polys and call it a night.
    Happy Easter,
    -d-
    It's very unlikely that a speaker crossover will be exposed to more then 25V. Make a safety factor 2
    and 50V is ample margin.
    But avoiding electrolytic's is a good advise.

    Kentley

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    Re: Crossover refurbish for B&W Matrix 803

    Post by Kentley on Sun Apr 05, 2015 3:03 pm

    I guess I oughtta take a look-see at the caps before I rush into anything. There is also the size factor - I've seen pix of the two boards and there ain't much room down there.
    Taking things one step at a time has always been difficult for me.
    Thanks, guys. I'll report back when the fruit is riper. pirat

    corndog71

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    Re: Crossover refurbish for B&W Matrix 803

    Post by corndog71 on Sun Apr 05, 2015 7:12 pm

    I would try to stay as close to the stock value as possible. The voltage rating doesn't matter in speakers. On the cheap side I would recommend ERSE Pulse X caps. They aren't the most resolving but they'll get the job done. Being that these are B&W though maybe consider sonicaps or mundorf. Some places will even match the caps for you. Some may say don't bother but for a couple more bucks why not get them matched? Oh and if they don't fit on the board then consider hardwiring the crossover without the board.

    Like this:

    Kentley

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    Join date : 2015-03-06
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    Re: Crossover refurbish for B&W Matrix 803

    Post by Kentley on Sun Apr 05, 2015 7:52 pm

    Now THAT is elegant!
    I certainly don't mind spending even $200 on this project, though I doubt it could conceivably run to that unless I choose custom V-Caps and contract the work to Brunei. At my age I have been approaching the building of my system with a "get what will satisfy for 40 years" (as I plan to live to 102 Laughing ).
    Since this is not an urgent matter, I will continue to look for the "perfect AND elegant solution". Thank you, Mr. Dog - and the rest, again.

    Kentley

    Posts : 300
    Join date : 2015-03-06
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    Location : Worcester, MA

    Re: Crossover refurbish for B&W Matrix 803

    Post by Kentley on Sun Apr 05, 2015 8:31 pm

    I couldn't resist looking for the "perfect" replacement caps now. I can get a complete set of SoniCap Gen1 at the exact values specified for less than $90. Over and out.

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