Hi Michael and Volleyguy,
I know Jimmy's site and I know he loves his Cast Duelunds. Especially the silverfoil ones. Well for the small capital he invested in these caps he really should love them!!
The Duelunds are his number one caps, I believe he then prefers the paper tube Jensens, a bit similar to Volleyguy I guess. In the end Jimmy preferred the paper tube Jensens over the mylar AudioNotes and the copper tube Jensens.
The system in which the Cast Duelunds, tinfoil V-caps, Jensen Alu tube and Jensen paper tube were tested consists of a heavy modified CEC transport coupled to the Audiomagic DAC (same league as the AN 5.1 Signature) and a very fine all tubed preamp and all tubed poweramps, both created by Peter, driving AN speakers (not sure about the model). Though it can't produce very high SPL's, is limitated in the low domain and is way less revealing than my modified Apogee Scintilla's, it is quite a good system (without any plastic cap in the signal path). More important for me was to have the caps tested by a guy I know that is very experienced, has very good ears and puts most interest in tonality (!) in his designs and modifications.
You're so right Volleyguy, about PIO copperfoil caps sounding good right out of the box. Both Jensens and the Cast Duelunds showed this clearly.
I was surprised that the Duelunds didn't show the big difference (even not after hundreds of hours playing) that other people, like you, experienced. But maybe it had something to do with these Cast caps belonging to the very first 630V caps produced by Duelund. I'm interested to hear Frederiks opinion on this. After a very long time the Cast Duelunds outperformed the Jensen in alu cap, but only by a small margin, whereas the paper tube Jensens outperformed the alu tube Jensens right out of the box.
I've not been able yet to listen to Duelunds (VSF nor Cast) in a passive speaker xover. However, the caps in the passive xover of the Scintilla are relatively high values: 240 uF in front of the midribbon and 10 uF in front of the tweeter ribbon. I bought Obbligato caps for my new (nowadays outboard) xover, but I might try out the Duelunds or Jensens in the end for the tweeter ribbon.
I actually would have liked it A LOT when I would have been able to skip the entire passive speaker xover and have it replaced by a linelevel xover. In theory I would be able to do this as I have three stereo poweramps and the Scintilla is a three way all ribbon magnetostatic speaker. There is very good software available that is able to copy the behaviour of the passive speaker xover exactly. The "problem" in my situation that makes me not do this is a small DC voltage on the outputs of the poweramps that is not easily taken away (without affecting the poweramps performance). So I need the caps in front of the delicate foil-only mid- and tweeter ribbons to prevent the DC voltage damages these ribbons.
The two inductors in the original passive speaker xover however are skipped and have been replaced by a linelevel solution. The bass ribbon (kapton backed alufoil) for instance will be connected to the poweramps output directly.
Have you ever thought about going all linelevel xover?
Cheers,
Kees