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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
erik_squires
16,412 posts
 
The issue of Mundorf vs. Copper film:
Mundorf Supreme caps have their very own house sound. To me it is like a disney / Fuji film sheen with hypersaturated colors. Scintillation is also a good way to describe it.

This is what Magico and B&W like to use in their top end.

If you bought your speakers for that, stick with the capacitor and speaker brand.
If you are getting into swapping to copper film caps, which are my choice, you maybe need different speakers altogether, because they are not going to sound the same and you are going to end up in a lot of expensive upgrades before you realize that.
A good cost effective compromise IMHO is to use Clarity's top end with copper film bypass caps for anything over 5uF
dhl93449 OP
455 posts
 
Erik S:

Last time I checked, a few years ago, Jupiter did not make a copper film cap in 47 uFd to replace that critical midrange coupling cap. Clarity cap makes one in their CSA line, but that is metallized poly pro. It is 62 mm diameter (much larger than the 50 mm diam EVO and the 42 mm MKP), so it may not fit on the MR CO board. Plus, I doubt if those CSA versions are any better than an OIL or SGO Mundorf. In general copper film caps are too large to fit or are not available in high enough capacitance. And of course, we dare not parallel smaller values for fear of the dreaded "phasey" smearing effect.

I also need to say that in general, with 90% of the music I listen to, the modded B&W 803D I have sound wonderful. There is some material, mainly compressed rock (like in my case Genesis Trick of the Tail/CD ,not vinyl), that sounds harsh. I do not ascribe to your description of these speakers whatsoever, and I have had numerous friends and strangers listen and they find the results impressive (some are musicians). So I am happy with them for the most part, but continue to look for ways to improve them if I can.  
grannyring's avatar
grannyring
6,544 posts
 
Jantzen Alumen Z. Just combine/paralell for needed total by using as close to equal values as possible. I think the Clarity CSA is a better sounding cap on the mids then the Evo line and should fit using good DIY skills.

You can paralell caps of the same brand at near the same value with no problem at all. In fact, this method is used my some very high end builders for the best sound.

I don’t doubt that your upgraded B&W sound wonderful and better than stock. More than one way to audio bliss! 
georgehifi's avatar
georgehifi
10,312 posts
 
You can paralell caps of the same brand at near the same value with no problem at all. In fact, this method is used my some very high end builders for the best sound.
Yes this is the only time to do that with caps in the signal path as I said previously.
And yes it "can" even be beneficial as  2 3 or 4 paralleled caps will have a lower esr than one cap of the same make and value. BUT!! the lower esr means that driver will have a slightly louder presentation due to the lowering of series resistance. So the voicing of that driver will change to what the manufacturer designed it to be and this should be taken into account.

Cheers George
arty_vandelay
28 posts
 
I've done some work on my 800D2 crossover, which makes the mid-treble response smoother and more "seamless".

The FST driver exhibits a slight peak at 3.5 kHz, which can be fixed with a RLC (2mH + 6R+ 1uF) network in shunt with the driver, and by soldering a 0.67mH inductor in parallel with the tweeter, the tweeter's response conforms more closely to ideal, and the improved phase relationship reduces the dip around 2kHz.

Ideally, the tweeter series cap should be 4.3uF. 

I've confirmed before / after with comprehensive measurements. 
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