B&W 803D crossover caps

ptss

Do not worry. I have plenty of experience modding equipment. If you doubt it, see my post on mods for the Spectral DMC-10 in the WhatsBest forum.

BTW, my version is just the "803D". I have it on good authority that the later version "803 Diamond" uses only the Supreme Oil, not the SG or the SGO. This info was provided by looking at a replacement crossover for the Diamond version. Seems like that is a big step back, according to the only review I have found to rank all three Mundorf Supremes (humblehomemadehifi).

Call B&W regarding crossover caps? Are you kidding?

A simple swap out of a crossover caps is not rocket science. It will not damage the speaker or destroy my amplifiers. At this level of performance, the results will probably be very subtle, but that does not mean they are not worth doing.

Manufacturers often make design decisions based on cost as well as performance. We have an opportunity to re-evaluate that decision and remove cost from the equation, up to certain limits.

John:

Thank you for your thoughtful comments.

My goal is to remove a bit of upper midrange brightness without effecting resolution in bells, symbols, vocal microphonics. The speakers are not at all bad as they are, but could stand a bit of improvement in these areas. I well know from my experience modding amplifiers that improvements in certain components can improve the sound in seemingly small but still significant fashions. I have no hard and fast goal for the end result, but will probably know an improvement when I hear it.

A few other parameters. The replacements need to fit on the existing pc board without kluges or modifications. No running feet of extra wire from a remotely mounted component to the board. They cannot reduce the reliability of the speaker by leakage of oil or wax. And finally there is cost. Given the value of the 803Ds I don't feel like spending $5000 on caps.

I was using the extensive review of humblehomemadehifi for initial evaluations. That review does not place the Clarity MR above the Supreme SG, but I realize there is probably a degree of subjectivity (to each his own). The Jupiter caps are highly regarded, perhaps above the Mundorf line.

As I posted above, it looks like B&W may have stepped back in SQ for the later Diamond series. They may have had a reason for using Supreme Oils (Al metallization) instead of the more expensive SG as in my D version, but I suspect it may have been more cost driven than SQ driven.

Regarding the other components, from my BOM documents on the 803D, the resistors are part number RNP50s, which are 100W, 5% power film resistors (TO247 package) that are clipped in to heatsinks on the CO board. They are made by MB Electronics in Germany. The resistor in series with the diamond tweeter is either 0.5 or 1.0 ohm (there is a contradiction between the value on the BOM and the schematic). The resistor in series with the midrange FTF is 100W 2.0 ohm RNP50s. My suggested replacement would be a Caddock MP900 power film resistor, which has a tighter tolerance and better tc, same TO247 package.

The inductors look like nothing special. Air core, conventional wire wound, wire gauge 1.2 mm (not flat ribbon).

It seems to me the most important cap is the 47 mFd midrange FTF coupling cap. But here we are limited severely by that capacitance. Mundorf has a Supreme EVO SGO that is 47 mFd, but it costs $700-800 and is too large to fit. The next closest are the EVOs I cited above. Bypassing is possible, but probably not that effective as this driver is crossed over at 4KHz, and a bypass would be kluge at best.

The next is probably the diamond tweeter coupling cap at 4.7 mFd. The Jupiter will fit as well as perhaps the Clarity

And yes, I considered re-wiring as well. But not for now, as that requires a complete strip down of all the drivers, and I want to avoid removing that FTF midrange if at all possible.

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:
Sorry if I misinterpreted your comments. Mine were based on an experience I had a few years back with B&W regarding a delamination problem I had with some 804s speakers I had. The finish on the top of the speaker (Cherry) was splitting and cracking and I felt this was a manufacturing defect but B&W would not agree. They were arrogant and condescending which left a bad taste in my mouth. They also tend to believe that their engineers have the last word in innovation and if they did not think of it, well then it will not be an improvement. Ergo I would be loath to contact them about any potential component replacement as I can pretty much predict their response.

You mention JBL and I was going to point out that I also re-built the crossovers in my JBL L212's, as well as the power amp in the sub. I did not use crazy audiophile components (just good Dayton polypro caps and air core inductors) and the sonic results were amazing. I had previously modded these by mounting the drivers on solid walnut plates to time align them. That mod is documented on the JBL Lansing Heritage site (under DHL or DHL93449 no sure which) a few years back.

http://www.audioheritage.org/vbulletin/showthread.php?32862-Modded-and-restored-JBL-L212-speaker-system

http://www.audioheritage.org/vbulletin/showthread.php?33993-L212-Sub-amp-rebuild

The post on the WB forum is under the Spectral Manufacturer's section of the forum.

http://www.whatsbestforum.com/showthread.php?18147-Spectral-DMC-10-mods

DHL,

I wanted to thank you as well for your thoughtful reply. I will be interested to learn how your project goes and hope that you will post updates to this thread.

I wanted to make one more comment about the capacitors I discussed which were in a bit of disagreement with Tony Gee's observation. For me the Mundorf S/G/O tilted things upward too much whereas I found the Clarity MR to be very well balanced. In my system the latter was the superior performer and based on that experience I would not recommend the former to anyone wanting to avoid adding emphasis to the high frequencies. Face's and/or Undertow's comments on this topic a few years back on the Capacitor Log thread make for good reading as well. I agree with you too that it'll ultimately come down to system synergies and personal preferences, I simply wanted to relate my experience for your consideration.

All the best,

John