B&W 803D crossover caps

George:

Regarding parallel caps. I agree in general, except when there is no or limited choice. For example, when an Al electrolytic is used as a coupling cap at the output of an amplifier driving low impedance loads. A polypro or film cap may not be available or practical to use in that application if DC offset from the amp is an issue. Adding a parallel poly pro film cap will definitely improve the sound over just an electrolytic alone. 
I believe one reason that parallel caps are not a panacea is that certain properties (like poor dielectric adsorption) cannot be compensated for by placing caps in parallel. 
One practitioner of massively paralleling film caps (John Curl of Parasound) has recently commented that that practice (seen in many early Parasound power amps) may not be best. He cites resonance effects between these parallel stacks at extremely high frequencies (100's of Megahertz) as the issue. Those early power amps still sound pretty good though.

For example, when an Al electrolytic is used as a coupling cap at the output of an amplifier driving low impedance loads.

This kind of amp cap coupled output is very rare to have. I take it it’s tube with no output transformer, but with capacitor coupling instead, I would just get an OTL myself but??

For and 8 ohm speaker you would need at least 2000uF for the coupling cap to see low fr limit of -3db at 10hz.
One or a couple paralleled depending what polarizing output voltage this amp has of these would fine great with NO! bypass cap.

https://hfc-fs.s3-eu-west-1.amazonaws.com/s3fs-public/audio-note-electrolytic-update-051217_0.pdf
or you could get cheaper Black gates instead.
https://www.hificollective.co.uk/components/black_gate_n_type.html

Cheers George

@dhl93449

I found here http://www.audiokit.it/it/30951-condensatori-mundorf (I am from Italy) there is a 47uF Supreme EVO Oil, which measures 76x67 mm.

The 47uF standard M-Cap EVO Oil measures 50x50 mm, the same as your EVO Silver Gold Oil.

Do you think the extra 26mm thickness of the Supreme Evo can make it not fit in?

Maybe if Stoni (see the 12-09-2015 10:27pm post) could use the Supreme EVO Oil into his 803D2 the same could happen in our 803D ...

The M-Cap Evo Oil is available at 100uF, so if I use the EVO Oil in series with the midrange maybe I could put woofer and midrange (coupling) caps of the same type (like in the original project!) even if you told me woofer caps don’t make significant difference in sound, but there would be a theorical coherency between bass and mids, both with EVO Oil instead of MKP, and the same thing would happen between mid (bypassing) cap and tweeter (coupling) cap, both with Supreme SGO instead of Supreme SG.

I am also thinking of removing all silver from my speakers, and "downgrade" from the Supreme SG to the standard Supreme for coupling tw cap and bypassing mid cap: warmer, richer and more natural sound, with absolutely no emphasys on the treble and upper midrange.

Maybe If I do, I would transform the B&Ws in other speakers and I don’t want to, but I would be happier.

Hard choice

B&W itself did "downgrade" from Supreme Silver Gold to an "inedited" Supreme Oil, without silver, and the general consensus is the 803 D2 sounds much better in the treble range than the D, much smoother (and still not enough...maybe the problem is Mundorf?).

I don’t know if replacing a silver cap with another silver cap, but with oil, is worth the money an the work; @dhl93449 please, I ask you to tell me the changes you had in hf so I can have some elements to make my decision easier (better to say less hard).

@stoni chaged the B&W custom 51uF Supreme Oil in his 803D2 with SGO, then he had to make another work to change tw cap again (with a Jensen Duelund if I remember well), it is clear he was not satisfied from the upgrade (iscit a real upgrade, with these diamond tweeters?) from an (aluminium?) oil cap to a silver gold oil cap, since the latter highlights high frequencies and may mask the other parts of the spectrum.

In a well tuned and high quality system (in mine, electricity and source are near to state-of-the-art, with a power regenerator followed by isolation trasformers for each machine and a divine Accuphase DP700 SACD player, cables are near to the best Cardas ever made, Luxman 509u integrated is not the best amp in the world but if you read Uday Reddy’s Soundstage! 2009 review maybe you may hurry to find an used one, or to buy the new 509x) a SGO capacitor could sound without harshness afterall.

Don’t misunderstand me: I don’t listen now with harshness in the highs (only some selected albums make me struggle, for example Genesis’ "Selling England by the pound" or Joe Satriani’s "The Extremist", and I know even these albums could sound better, and all the music with them), I have simply reached speakers limits and I want to go on in my audiophile journey of (personal and equipment’s) improvement.

Another idea could be to use the Supreme EVO Oil in all positions: 4.7uF tw coupling, 47uF mr coupling and 10uF mr bypassing, and EVO Oil on the woofers.

Or 4.7uF Supreme Evo Oil in tw coupling and 10uF in mr bypassing, Evo Oil both in mr coupling (47uF) and in woofer caps (2x100), to make something similar to the original project of both D and D2.

The only truth is one should have to try, not reasoning "on the paper" ... !

I had a change in my system I did not tell you until now...
A (deplorable in my opinion) technician repaired my Purepower putting inside it Claritycap SA caps instead of the original taiwanese Fu-Jack caps (they seem Panasonic or Vishay clones) without telling me before, maybe because he had that caps in stock, without need for ordering a 10uF 500V (for the power stage, right after power inlet) Panasonic and a 2uF 600V (for battery recharge system) Vishay caps.
Now I have the impression of a tonal shift towards mid-highs.

The Humble Honemade Hifi comparison tells the Claritycap make sound shift towards clarity, since Panasonic is the most neutral cap in its range, it does not highlight anything.

Do you think I have to make another technician replace the Claritycap SA in my regenerator with Panasonic and Vishay (since there is no Panasonic cap under 10uF), and only after that to think at speakers recapping?

Many thanks

" This kind of amp cap coupled output is very rare to have. I take it it’s tube with no output transformer, but with capacitor coupling instead, I would just get an OTL myself but??"

Not as rare as you think. Did you know the Bryston BDA-1/2/3 all have Al electrolytic (surface mount) coupling caps in their outputs? Along with I think their preamps, even current production. Their engineers are concerned with the small amount of DC offset their class A discrete amps produce (10 - 20 mV), ergo the caps. Using a 10-30 uFd film coupling cap is out of the question for them, as it's size and cost would be prohibitive.

Bryston does not parallel a film cap with these Al Elct caps in the output stages, due to the lack of compact surface mount film versions (poly pro are very rare in surface mount), and NPO ceramics are outrageously expensive. 

In my new BDA-3, I removed the Elect caps and put in a surface mount shorting bar. The small DC offset is easily handled by my Parasound JC2 preamp and its DC offset servo controllers. Made a significant difference in sound quality. I have been in contact with Bryston Eningineering and urged them to put in DIP switches so that users have the option of shorting out those caps if they have downstream circuitry that can handle the offsets.