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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
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edwyun
244 posts
 
Um, why not go to active crossovers and get the most control of the drivers and how they sound?  A lot easier than the "black arts" of trial and error using different caps.
dhl93449 OP
455 posts
 
edwyun

Because that route is fraught with just as many variables and complexities. I was going to do that with another previous set of speakers and ended up buying the B&Ws instead.

To do what you suggest  first you need 3 to six power amps, depending on if you use stereo or mono amps. You need to adjust the output levels of each amp with each driver, so you need an RTA/pink noise setup to do it right. Then you need a decent XO setup. Anyone know of discrete component class A XOs that have three XO points? And a choice of first, second, or third order slopes? No? Me neither.  There are XOs out there, but most are op-amp based which is unacceptable to me. Finally, if you are using B&W drivers, you have to have impedance and parameter data for the drivers which is unobtanium unless you measure it yourself.

As I stated I considered building my own speakers prior to buying the B&Ws, and was going to go the full active route. But I could never get over the compromises and costs, plus I cannot design a cabinet like B&W does. 

mark_nz
48 posts
 
Thank you for sharing your crossover upgrade experiences - I previously owned the 803D and 803 Diamond speakers - great value high tech speakers with timeless industrial design.
dhl93449 OP
455 posts
 
Mark:

You're welcome. They are sounding exceptional right now. That 47 mFd EVO SGO midrange coupling cap is really making a difference.
mj1958werner's avatar
mj1958werner
4 posts
 
Hi guys,

I just took my midrange crossover out and replaced it with the midrange crossover of the 800D.
The bass and treble crossover are the same  in the 803D as in the 800D.
I owned the 800D years ago and always liked the sound of its midrange.
The sound wasn’t coming from the midrange but was like hanging around the speaker. (Maybe reversed polarity? )
I owned and tweaked lots of B&W speakers. The silver signature is one of my reference speakers and are recaped with mundorf silver gold in hi frequency and mundorf silver gold oil in midrange.
The sound is really transparent, lots of resolution, silky and no harshness. (Tweeter is also operating in reversed polarity here!)


There is some place in the bottem of the 803D cabinet.
Remove the bass crossover and install the 800D midrange crossover in theen same compartment, but upside down on the matrix internal structure.
Afterwards the 803D sounded
BEAUTIFUL.
The emphasis of the tweeter disappeared.
I wouldn’t put the silver oil, silvergold in oil in the tweeter or midrange because personal I found them to be a bit too detailed.
The 800D was the most natural sounding speaker of the whole 800D series. (800D, 800 Diamond )
The crossover cares 2× mundorf supreme and 1 silver gold (no oil).

Cheers Werner.


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