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.

I have 803D first series since 2009, I won't change them with D2 or D3 series since (expecially the D3 with only 2 woofers) I find them leaner than the original D series.

The 803D are the best speakers (in my very well tuned system, with Purepower 3000 and two isolation trasformers added in series, one for Luxman 509u integrated amplifier, one for Accuphase DP 700 SACD player, Cardas Clear series cables - Beyond XL for isolation trasformers, Beyond and standard Clear power for amp and source, Beyond XLR interconnects-, except for speakers -where I have still the old Golden Reference, 2 pairs biwiring-) I have ever heard in their price range, they are complete speakers and can play all kind of music, with satisfying bass response (no other speaker have that punch) and great clarity and imaging.

803D obiouvsly have faults:

- in the highs, sometimes harsh/hard/highlighted  (I could never make Genesis' "Selling England By The Pound" sound without harsh metallic highs, since lots of albums sound great and smooth, maybe it's a matter of recordings)
 - in the midrange, lacking of warmht and richness, sometimes hard in jazz music (horns dynamic peaks sometimes are strident)
- in the bass, sometimes fat in the mid-bass (covering the lower midrange) and not so well articulated and "vibrant"

After reading your experiences, "merging" both, I am considering to replace caps, sticking with Mundorf, trying to respect as much as possible the original project:

- the Supreme SG on the tweeter, with a Supreme SGO; I hate silver sound signature, but I want to respect the project only adding "warmht" and refinement an oil cap can bring to the table

- the MKP coupling cap on the midrange (the bigger weak point!) with a Supreme EVO Oil; I started thinking about a Supreme Classic, but it seems it does not fit :/ ; Stoni said his 803D2 now sound better than the Sonus Faber in the midrange using Supreme Evo Oil !
I don't want to add silver at this point, where the original project had no silver caps, and I don't want to highlight upper midrange giving an unwanted "silver signature"

- the Supreme SG bypassing cap on the midrange with a Supreme SGO (same as tweeter thoughts : I hate silver, but I don't want a revolution, only a step up in warmht and refinement)

- the woofers MKP caps, with ... ???
Maybe every other cap I will put will be better than the MKP, so I would not have to worry about!
As I told before, keeping punch and richness, I would like to improve bass articulation making it more "vibrant".
I am thinking about Supreme Silver Gold, without oil (maybe could I "recycle" caps I put out of tweeter and midrange?) ...
There was no silver in the original project here, but I think it could be useful making bass faster. On the other hand, I don't want it to become lean.

Any comment or suggestion (keeping in mind I want to use only Mundorf capacitors and I don't want to change too much the speakers, but only to improve where they have weak points) is welcome, many thanks if you do

There is nothing wrong with this xover in the quality of it’s parts, look elsewhere for your upper midrange brightness.

As for the suggestion of by-pass caps, don’t! The only time to use by-pass caps is with power supply caps (decoupling), never with a cap in series with the signal or in xovers (coupling), as the two different time constants of the caps will have a smearing effect in that region that they are working in and actually degrade the sound, always use one good quality cap, and that is what B&W have done here.


Cheers George
I don't want to bypass caps ;) , I read the cheap 47nF MKP is in series (a "coupling cap") with the midrange driver, while the 10nF Supreme Silver Gold Oil (in the D2, without oil in the D series) is in parallel (a "bypassing cap") with the driver.

My project is to put a 47nF Supreme EVO Oil instead of the MKP and a 10nF Supreme Silver Gold Oil instead of the same model but without oil in mounted in the 803D, and to replace the 4.7nF Supreme Silver Gold in series with the tweeter with a 4.7nF Supreme Silver Gold Oil.

I read above 803D2 have a 51nF (instead of 47nF) Supreme Silver Gold Oil on the tweeter, maybe that's why D2 series is smoother than the D (which tweeter cap is without oil), but even more forward in the treble range.

There's no cheap caps on the mid xover I just linked to, Mundorf and M-Cap!!! and no 47nF there is a very good quality 47uF.
One good cap of the correct value that B&W worked out that's it, if you look at the 802D MkII photo I linked to of the mid, they have already used very good caps, I have no doubt the tweeter would be just as good if not better. 

Cheers George

I don't think I suggested there is a quality issue with the parts in the crossover, but a cheaper MKP version will not sound the same as a Silver/Gold/Oil. That is why they make the SGO in the first place. Do you even have 803Ds or have listened to them?

Replacing that MKP 47 uFd with a SGO did make a significant difference in sound quality. Neither capacitor sounds "bad", but the SGO sounds better, and isn't that what we all strive for? If every manufacturer had the tuning of their product perfect out of the box, then there would be no upgrade market then, would there?

Since my original post I have added a few more mods. I now believe the upper midrange harshness that sometimes is present is sourced from the FST midrange driver. There is a mod that the 800/802 series had (a heavy cast iron weight attached to the back of the FST driver) that is absent from the 803 series. When I asked B&W tech support why the 800s have this but the 803D does not, they told me the weight will not fit in the 803 cabinet, but it will fit in the marlan cabinet on the 800/802. So not entirely believing their story, I ordered two to see if I could fit them. I had to remove a small pc of 1" of foam at the back of the cabinet (so tech support was correct) and the drivers and weights fit fine. You have to make another threaded tension rod (I used 6mm stainless threaded rod) and obtain a couple of 6mm SS nylok nuts; one set to attached the rod to the FST driver, and another set to hold the weight snugly against the back of the driver. Don't forget there is a rubber gasket placed between the weight and driver. You may also need loktite between the threaded rod and the FST driver to keep things tight and to prevent loosening. This mod also worked quite well in smoothing the upper midrange even further.

What I would really like to get a hold of next is the latest version D3 midrange driver. They are completely different from the older FST and from what I understand, have addressed many of the problems of the earlier version. But, they are not available on the B&W parts website yet (maybe the never will be).