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B&W 803D crossover caps

I am considering an upgrade of the crossover capacitors in by B&W 803Ds, particularly the mid and HF coupling caps.

I took out the top bass driver to find out what caps were installed. It looks like for the diamond tweeter B&W uses a Mundorf Supreme silver/gold, 4.7 mfd 1200V. For the mid driver there are two; a 47 mfd Mundorf MKP 400V series coupling cap (in series with the driver) and a 10 mfd Mundorf Supreme siver/gold bypassing cap (parallel to the driver).

I was thinking about changing out all three, but have a few concerns.

I was going to replace the 10 mfd, 4.7 mfd Supreme silver/gold with Supreme silver/gold/oil. Would there be enough of a difference in these two types to justify the cost? I also do not want to make the upper end any brighter.

I am also concerned about the long term reliability of oil filled caps, as some failures have been reported in warmer environments. I wonder if B&W did not use the silver/gold/oils for that reason.

The biggest impact I suspect will come from the replacement of that series 47 mfd MKP. I would probably use either the Mundorf MCap EVO (Al metalization), MCap EVO oil (Al/oil), or the MCap EVO silver/gold/oil. All three are the same size for 47 mfd, and will fit to replace the MKP. Barring the issues about oil, which might be the best sounding? Again, I want to avoid too much enhancement of the upper midrange.
dhl93449

Showing 4 responses by ptss

ptss
1,964 posts
 
Thanks DH for the link. I found it interesting but did not see any post mods pics?
ptss
1,964 posts
 
I don't wish to sound to basic here but I believe more bypass caps may be the only sensible thing. Have you asked B&W-- or an authorized repair center? Are you up on any crossover design changes for the newest series? ?Have you spoken to Mundorf? And lastly,seriously, have you had a lot of success modifying crossover in other comparably high quality intelligently deigned speakers
ptss
1,964 posts
 
Hello again DH. I simply asked questions-that I thought may be helpful to you or others thinking of such mods. Re B&W; JBL Engineering was very (in fact surprisingly so) helpful re my 1985 250Ti's many years ago; even to provide me new ideas that they had come up with and would be implementing! I respect the investment B&W has in it's business and goodwill so anticipate good PR; why shouldn't you approach them? Are you perhaps doing a bit of 'assuming'? I believe Mundorf are technically expert. I could not find your post re the Spectral DMC 10 in the WhatsBestForum but am interested as I enjoy a DMC 20 with phono in my system. Might authorized repair centers have knowledgeable techs-perhaps with real interest in what they do?
ptss
1,964 posts
 
Dhl I did move the huge crossover in my 1985 JBL 250Ti's outboard to great effect. Perhaps you can consider ways of isolating your XO within the boxes, although I feel B&W are respectful of this benefit as previously they advertized the benefit of having the XO in the bases of top speakers. By the way what are your feelings re: bypass caps?
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