Duelund Capacitors??

Does anyone know what the sonic differences are between the copper foil capacitors and the aluminum foil capacitors.
The copper caps are twice the price. are you getting twice the sonic benefit by using copper over aluminum foil caps?
Hello the difference of the 2 is much with Copper the detail is more fleshed out and harmonics a little richer , the Silver may be even a little better,for sure the Copper is the best value for a expensive cap and the most natural
on the planet .Some may like the pio paper in oil that is a little more rich perhaps a bit to much .the Copper VSF is the way to go, and for sure their carbon resistors for they are the best I have ever used just clear and open.
P.s "The caps are 200v", Not as a few others stated 100.
Agreed. Based on our experience with Jensen aluminum vs. Jensen copper (Jensen is the OEM for Duelund), copper foil is the way to go.

We have, in fact used the Duelund VSF copper foil and can highly recommend it. If you're on a budget, forget the Duelund aluminum and just use the regular Mundorf MCap Supreme (not the silver/gold/oil versions), which is almost as good as the VSF in copper.
Are you using them in crossovers or as couling capacitors in amps?
The Duelund VSF Copper is currently used as part of a loudspeaker x-over. It's the only cap that's directly in the signal path, making it very easy to evaluate.

The Jensens were tried in several circuits, including as coupling caps in a tubed phono preamp, output caps in a tubed active line stage, and as a driver tube's cathode to ground bypass in a 300B SET amplifier. I can't remember if we ever tried them in the x-over.

The Jensen aluminums made the components almost unlistenable. By contrast, the copper Jensens were reasonably smooth and pleasant. In the electronics, we ultimately preferred the VCap TFTF Teflon.

Based on that experience, we didn't bother with the Duelund aluminum and went straight for the copper.
The copper foil is well worth the extra cost, the Duelund's are exceptional components, the resistors being a no brainer best buy for sure.

The caps may seem a little costly but once you compare them to others and understand the type of Machinery and time necessary to make these, they are well worth every dollar.
I have the Duelund caps installed in the tweeter high pass xovers of my speakers. I did not do lots of analysis or comparison, but Tony Gee has done an enormous amount. Look at his web page, humblehomemadehifi.com under the 'cap test' heading. He ultimately preferred the copper VSFs over dozens of others he's tested.

One other thing to note, and this is directly from Tony - to get the 'sound' of a capacitor, you only need 10-20% of the total value to be the 'good' cap. Example - you need a 5 uF cap for a HPF. Use a 4.5 uF Clarity Cap and a 0.5 uF VSF copper, and it's almost identical to the sound of a 5 uF VSF, and you've spent significantly less.

Happy listening.
"One other thing to note, and this is directly from Tony - to get the 'sound' of a capacitor, you only need 10-20% of the total value to be the 'good' cap. Example - you need a 5 uF cap for a HPF. Use a 4.5 uF Clarity Cap and a 0.5 uF VSF copper, and it's almost identical to the sound of a 5 uF VSF, and you've spent significantly less."

For output coupling, should the 2 caps as above be used in series or parallel?

Steven, the bypass high-quality cap is connected in paralell with the larger, less expensive cap.
Their values add. In the example above, 4.5 uF + .5 uF = 5 uF. The combo replaces a 5 uF cap in the crossover.
Thank you Casouza :)

Out of curiousity, if they were connected in series, what would that do to the total value?


Steve, the resulting value is defined by the formula C1 x C2/C1+C2 , in this case about 0.45uf. BTW this is the same formula for resistors in parallel.
Hi Atmasphere,

Great, thank you for the education, I should read more about these things!

Always use a bypass cap in parallel with your other cap. In series, the total capacitance will always be lower than the smallest value cap.

For example, if you put a 1uF cap in series with a 100uF cap, the measured value of both of them would be around .99 uF.

Back to the Duelunds ; I compared an Aluminum Duelund to a BAT cap to see if there was an improvement. BAT uses a very similar cap to the Jensen Copper foil in oil. The BAT caps have copper leads, whereas Jensen uses silver leads.

The BAT caps were the best, followed by the Copper foil Jensens, then the Aluminum Duelunds. The Duelunds were too bright and not as tonally correct.

These test were done on signal level and not speaker level. I mention this because speakers normally sound better with the brighter caps, rather than those which are darker and richer, which to me, are preferable on line level and signal coupling.

So I leave it open for the Duelund Aluminum on speakers. But based on all that I have read, the Aluminum Duelunds have never outperformed the Copper.

For what it's worth, I replaced the Mundorf silver/gold/oil (s/g/o) capacitors in my speakers (Silverline SR17.5) with Duelund VSF copper (I had replaced the stock caps with the s/g/o).

Some brief notes:

- The slight upward tilt of the s/g/o that Tony Gee mentioned was too much for me after several months of listening.

- The VSF copper caps are indeed much better harmonically balanced as Tony Gee noted. They are also richer and faster than the s/g/o in my application.
Just FYI, I've listed my Duelund Silver Wax/Oil 0.047 caps on e-bay. :)


The new Duelund Jam caps are a great bargain 40% off retail, introductory 
Lot price tinned Copper, in oil great combo rich but also open and detailed 
I use to complement my one big cap in my speakers 68uf these Big 2.2 if caps 
Are over 2inches by 2inches just for s 2uf cap can you say Huge .630v can go anywhere if you have the space . Metal can recommend electrical tape if near anything conductive.  I  am not positive if non conductive.
The New Duelund Jam  caps use Tin -Copper foil in oil cap , they have several
Different case types depending on size. Which give a slightly different character.
These are s step up from the  Jensen from my experirnce could be too because of the paper case in Jensen vs my caps  metalcase,vs paper giving paper  bit softer balance on the leading edge .
Sorry, need to clarify something I read.

Jensen is NOT "the OEM" for Duelund. Jensen makes one line within their pretty broad spectrum of capacitors for them.



Has anyone compared the Dueland JAM or the Jensen VSF with the Audyn Pure copper capacitors in general, or in the 0.1uf or 2.2uf values, in particular? I know there's a significant price difference but I'm more curious about the sonic differences.

The specific application is in a tube preamp cathode follower signal path.


The crossover caps inside these boxes are said to be the new world's best crossover caps for speakers!