Nov 182017

Inspired by the praise and enthusiastic response from Duelund Coherent Audio customers around the world to the Duelund DCA line of tinned-copper cables, Frederik Carøe did something amazing, he applied the same creativity he used in developing the Duelund DCA cables to new lines of Duelund tinned-copper foil paper-In-oil capacitors.

Prototype 0.22uF Duelund CAST tinned-copper capacitor.

I compared the prototype Duelund CAST 0.22uF tinned-copper capacitors in my vintage MX110Z tuner-preamplifier’s first stage cathode follower of the high level input, where I replaced two key pairs of 0.1uF capacitors at C93 & C95 and C94 & C96, with various pairs of desirable vintage and current production high-performance 0.22 uF capacitors.

It was perhaps the most dramatic “slap down” I have ever heard.

The prototype Duelund CAST tinned-copper-foil paper-in-oil capacitors were at a performance level both musically & sonically so far above any of the other capacitors I’ve tried I was stunned by the result.

It wasn’t like the Duelund’s were a little bit better, they were more like an order of magnitude better, and the result in my MX110Z was breathtaking!

The only caveat with the hand-crafted Duelund CAST tinned-copper PIO’s is that they are physically large in size, which limits where you can fit them in a circuit.

The prototype Duelund tinned-copper PIO’s were a tight squeeze under the hood of my MX110Z, and had I not been able to get them inside, I would have surface mounted them on the outside, as the performance improvement was so dramatic I couldn’t have done without them.

I get quite a few emails asking for recommendations of capacitors for “hot rod” modifications to audio electronics, and my recommendation is always to use the Duelund tinned-copper PIO’s because of their remarkable level of performance.

For my musical and sonic preferences, there’s nothing in my experience that even comes close to the Duelund’s.

A pair of prototype 0.22uF Duelund CAST Sn-Cu capacitors that I’ve soldered into my vintage MX110Z McIntosh tuner-preamplifier.

I also tried the prototype Duelund CAST tinned-copper foil PIO’s in the breadboard crossovers I had built for my vintage Altec A5 Voice of the Theatre loudspeakers, with the same dramatic results.

I have come to the conclusion that the Duelund CAST tinned-copper foil PIO capacitors represent the single biggest audio capacitor advancement … perhaps ever!

Duelund 0.22uF JAM tinned-copper capacitor.

The extensive labor that goes into the handmade (and essentially custom order) Duelund CAST tinned-copper PIO’s makes them very expensive, which puts them out of reach of a lot of enthusiasts, so Frederik created a more budget oriented line of Duelund tinned-copper foil paper-in-oil capacitors called Jam.

The new Duelund 0.1uF JAM tinned-copper PIO capacitor!

I haven’t yet tried the Duelund Jam line of tinned-copper foil PIO’s yet, but if they are anything like the Duelund CAST’s, they could be the high-performance bargain of the century.

I reported earlier that Frederik had sent me a set of four of his new Duelund 0.01 uF tinned-copper bypass capacitors to experiment with.

Duelund 0.01 uF tinned-copper bypass capacitors.

If you’ve been reading along for awhile, you might remember that I compared the Duelund CAST silver-copper hybrid capacitors (with their built in pure silver foil PIO CAST bypass capacitor), to their pure silver foil and pure copper foil CAST counterparts in the C1 positions of the Duelund CAST external crossovers for my Tannoy Westminster Royal SE loudspeakers.

External Duelund CAST crossovers for my Westminster Royal SE loudspeakers.

I thought the Duelund CAST silver-copper hybrid capacitors sounded a lot like the ultra-expensive pure silver foil paper-in-oil Duelund CAST capacitors (that I prefer to use in my WRSE crossovers C1 position) from the mid-range on up, and like the pure copper foil paper-in-oil Duelund CAST capacitors from the midrange on down.

It was an impressive display of the voicing power that a Duelund CAST silver bypass capacitor could exert on the already impressive pure copper foil paper-in-oil Duelund CAST capacitor.

Duelund CAST 6.8uF copper-silver hybrid capacitors (left), Duelund CAST 6.8uF pure copper foil capacitors right.

Duelund pure silver CAST 6.8uF capacitors.

As I reported earlier, I tried the new Duelund CAST tinned-copper bypass capacitors in the crossovers of my Altec A5 Voice of the Theatre loudspeakers with impressive results.

If fact I really didn’t want to take them out for other trials as I was so satisfied with the positive results they brought to my A5’s crossovers.

But I wanted to repeat the C1 experiment in my Duelund-WRSE crossovers using the Duelund tinned-copper bypass capacitors combined with the pure copper foil Duelund CAST capacitors.

Duelund CAST pure silver foil PIO in C1 (lower left).

Currently I’m using the pure silver foil Duelund CAST capacitors (above) in the C1 position and they are absolutely amazing. Nothing has been able to displace them as my favorite capacitors in C1.

How will the Duelund CAST tinned-copper hybrid capacitors compare in C1 to the Duelund CAST silver-copper hybrid capacitors, the pure copper foil Duelund CAST capacitors, and the exotic pure silver foil Duelund CAST capacitors?


First I decided I would put together a pair of Duelund CAST tinned-copper “hybrid” capacitors using the 6.8uF Duelund CAST pure copper foil capacitors and the 0.01uF Duelund CAST tinned-copper bypass capacitors.

Duelund 6.8uF CAST Sn-Cu “hybrid” (bottom) and 6.8uF Duelund CAST pure silver foil (top) capacitors for C1.

The leads for the Duelund bypass capacitors aren’t quite long enough to span the distance between the jumbo-sized 6.8uF Duelund CAST pure copper foil capacitors, so I used a short length of Duelund DCA26GA wire to bridge the gap.

Duelund CAST “hybrid” Sn-Cu caps installed into C1.

Below is the Duelund CAST crossover for one Westminster Royal SE, with the Duelund CAST Sn-Cu “hybrid” in the upper left-hand corner of the crossover.

Duelund hybrid Sn-Cu caps installed into C1 (upper left in crossover).

Before I do any comparative listening between capacitors at C1, I want to give the 6.8uF Duelund Sn-Cu “hybrid” a listen for a while to get a feel for its general presentation, overall musicality, and sonics.

The Harrow & The Harvest

I put on Gillian Welch’s The Harrow & The Harvest to start my listening, and even though I just said I wasn’t comparing the Duelund CAST hybrid Sn-Cu caps to the Duelund CAST pure silver caps I have been happily listening to in C1, I couldn’t help but be caught by surprise how dramatically different the two capacitors sound in C1.

My immediate impression of the Duelund CAST “hybrid” Sn-Cu caps in C1 is that they are vivid, colorful, dramatic, visceral, and exciting to listen to music with.

They do a beautiful job of portraying tempos, dynamic nuance, melodic flow, and the “touch” of Gillian and David upon their instruments in The Harrow & The Harvest.

Duelund CAST “hybrid” Sn-Cu capacitor in C1 of the HF circuit of the WRSE crossover.

The Duelund CAST “hybrid” Sn-Cu caps also unravel harmonies extremely well, so I could easily hear the contributions of David’s harmony to Gillian’s vocals, which sometimes can be difficult to do because they blend together so seamlessly.

For those of you who have been enchanted with using Duelund DCA tinned-copper cables, you’ll hear a lot of familiar tinned-copper conductor characteristics from adding a Duelund tinned-copper coupling cap.

It’ll take a while for Duelund CAST “hybrid” Sn-Cu caps to settle in properly to the crossover’s C1 position, but I’ll report back.


It’s early Sunday morning, and I let the Duelund CAST “hybrid” Sn-Cu caps play music all day Saturday in the WRSE’s crossovers’ C1 positions.

The Tannoy Westminster Royal SE’s high-frequency horns are extremely sensitive to system changes, and provide an “x-ray vision” level of transparency into the effects of even subtle system changes, making them very useful for reviewing.

At the end of the day yesterday my aural observations about the Duelund CAST “hybrid” Sn-Cu capacitors in C1 were almost identically analogous to my first listening sessions way back when with the Duelund DCA16GA tinned-copper cable (or WE16GA).

Duelund CAST “hybrid” Sn-Cu capacitor in C1 of the HF circuit of the WRSE crossover.

For example, with the Duelund CAST “hybrid” Sn-Cu capacitors in C1, I would say that the timbre of instruments sounds more accurate and ‘real’ to me, with lots of meaningful natural nuance resolved.

There is also that remarkable tinned-copper resolution of tone color, those chordal variations resulting from adding additional pitches to three tone triads, that give different styles of music their ‘sound’ and emotional feel.

The Duelund CAST “hybrid” Sn-Cu capacitors in C1 are transparent and resolving, much like the Duelund CAST pure silver foil capacitors, but with more vivid timbral textures, a greater sense of the recorded space, and there is an information rich nuance to the presentation of the music both harmonically and dynamically that sounds very realistic and satisfying.

I think that the Duelund CAST “hybrid” Sn-Cu capacitors provide a very large serving of the sound, feel, and emotional impact of live music, in terms of timbre, melody, harmony, rhythm, dynamics, tempo, tone color, beat, and the ability to play naturally at live-like volume levels, which makes exciting, emotionally engaging, and very satisfying to listen to music with.

Duelund CAST pure silver foil PIO in the C1 position of the HF crossover circuit.

I put the Duelund CAST pure silver foil capacitors back into C1 this Sunday morning for a little more listening.

The Duelund CAST pure silver foil capacitors I have been listening to in C1 have four years of listening time on them now, and sound amazing both musically and sonically.

The Duelund CAST pure silver foil capacitors are smoother and more refined sounding, there’s less sibilance on Gillian’s vocals in The Harrow & The Harvest, for example, than with the Duelund CAST “hybrid” Sn-Cu capacitors.

The Duelund CAST pure silver foil capacitors display a relaxed natural musicality that allows me to to immerse myself into the music nicely.

They also put me as a listener a few “rows” further back from the musicians than the Duelund CAST “hybrid” Sn-Cu capacitors do. At identical volume settings the Duelund CAST “hybrid” Sn-Cu capacitors sounded louder to me than the Duelund CAST pure silver foil capacitors.

The Duelund CAST “hybrid” Sn-Cu capacitors sound more direct and forward in comparison to the Duelund CAST pure silver foil capacitors, and have a little bit of that initial “acoustic roughness” that I heard with the Duelund DCA16GA and Western Electric WE16GA cables before they were fully run-in, yet overall they have a very beguiling and enchanting presentation musically & sonically.

I’m thinking that the Duelund CAST “hybrid” Sn-Cu capacitors might benefit from a little voltage-only conditioning in the same way that the 16GA tinned-copper cables do, so I’ll report back on that after I try it.

What’s remarkable to me is how much audible influence that tiny 0.01uF Duelund CAST tinned-copper coupling capacitor exerts on the performance Duelund CAST pure copper foil PIO capacitors.

If I were blindfolded and had listened to the Duelund CAST “hybrid” Sn-Cu capacitors followed by the Duelund CAST pure copper foil PIO capacitors, I would not have suspected that they had anything in common, the transformation is that dramatic.

Certainly the tiny 0.01uF Duelund CAST tinned-copper coupling capacitors are an intriguing voicing option, and the Duelund CAST “hybrid” Sn-Cu capacitors that I made using them combined with the Duelund CAST pure copper foil PIO capacitors are elevated to a new level by using them.

Before, when I compared the Duelund CAST pure copper foil PIO capacitors and the Duelund CAST pure silver foil PIO capacitors, for my tastes it was a dramatic “no contest” comparison.

While both the Duelund CAST copper and silver capacitors are amazing performers, the Duelund CAST silver capacitors pretty significantly showed the Duelund CAST copper capacitors their heels musically & sonically.

0.01 uF Duelund tinned-copper bypass capacitors.

The big performance disparity between the Duelund CAST pure copper foil PIO capacitors and the Duelund CAST pure silver foil PIO capacitors in C1 pretty much vanishes with the Duelund CAST “hybrid” Sn-Cu capacitors.

That’s pretty amazing to me when I think about the fact that the addition of the 0.01uF Duelund CAST tinned-copper coupling capacitors had that dramatic of an effect on the overall performance I was hearing.

In fact, if the bit of acoustic roughness I hear with the Duelund CAST “hybrid” Sn-Cu capacitors smooths out a bit, I may actually prefer the combination to the Duelund CAST pure silver foil PIO capacitors.

I’m not quite ready to declare that yet, but the fact that I’m even thinking about that is pretty shocking to me given how much I preferred the Duelund CAST pure silver foil PIO capacitors in C1 previously.

I’m still really early in this comparison of the Duelund CAST pure silver foil PIO capacitors and the Duelund CAST “hybrid” Sn-Cu capacitors in C1, so I’ve got a lot of varied music to listen to yet to make sure I understand what is happening across the broader musical & sonic spectrum.

The initial implications of the tiny 0.01uF Duelund CAST tinned-copper coupling capacitors are rather staggering, which may turn out to be very good news for those of us who can’t afford the ultra-expensive & ultra-performing Duelund CAST pure silver foil PIO capacitors.

Duelund 0.01 uF tinned-copper bypass capacitors.

Many thanks to Frederik for sending these tiny 0.01uF Duelund CAST tinned-copper coupling capacitors for me to experiment with, they are illuminating!


The Alternate Blues

I’ve been listening to The Alternate Blues to check out how well the Duelund CAST “hybrid” Sn-Cu capacitors handle muted trumpet, a tough instrument to get just right, and the Duelund’s acquitted themselves excellently, sounding piquantly natural, just like they should. A happy result!

I’ve also noticed that the Duelund CAST “hybrid” Sn-Cu capacitors are continuing to settle down, losing some of that initial tinned-copper acoustic roughness, so I might not even need to run them in with a little voltage-only conditioning. I’ll see how they continue to progress and then decide about the voltage-only conditioning.

Anouar Brahem’s “Blue Maqams” double LP set.

After the muted trumpet reality check, next I put on my new double LP set of Tunisian jazz oudist Anouar Brahem’s Blue Maqams.

Blue Maqams is both impressive music and beautifully recorded, and it sounds gorgeous with the Duelund CAST “hybrid” Sn-Cu capacitors.

Anouar Brahem is joined by Dave Holland (double bass), Jack DeJohnette (drums), and Django Bates (piano), with the result being a sensational album. You’ll definitely want to get a copy of this one!

Stay tuned for more!


Check back throughout the weekend as I continue to explore and report on the results of the Duelund CAST “hybrid” Sn-Cu capacitors in C1!

As always, thanks for stopping by, and may the tone be with you!

 Posted by at 6:28 am

  7 Responses to “A Weekend Adventure with the new Duelund tinned-copper paper-in-oil 0.01uF bypass capacitors! Updates.”

  1. This is exciting I look forward to this. I’m glad your gonna compare it to the exotic silver caps as well. I hope they become available soon.



    • Hi Bill,

      As you’ll read in the updates, the change wrought by the addition of the tiny 0.01uF Duelund tinned-copper coupling capacitors to the Duelund CAST pure copper foil PIO capacitors puts the combination on a roughly equivalent musical & sonic performance level with the Duelund CAST pure silver foil PIO capacitors, although they do sound completely different.

      I’ve still got a lot of listening to do, but the results so far are very promising!

      Kind regards,


      • Jeff,

        Thanks for the updates. Nice write up. I’ve been torn between these an the silver bypass caps. Although I don’t think these are available yet. Just been waiting and thinking it out. I love everything about the tinned explanation, but also like how the silver sounded in your observations with it being more laid back few rolls back. Before I installed my Cast tin caps I ran them in current mode for a week straight. Not sure what it did as I didn’t hear them prior to that, but they sounded great and still do. I just have one position left and it happens to be close to what your experimenting with.



        P.S. in my experience the voltage mode adds the warmth, width, texture things like that. The Current mode smooths out the core sound gets rid of the core gruffness.

        • Hi Bill,

          I’d recommend you hold off and get the tinned-copper bypass caps when they become available.

          My comments applies to the full silver Duelund CAST caps in the post, not the silver bypass ones, which don’t sound the same.

          I just checked Parts Connexion to see if they were in stock yet (nope), and the same for HiFi Collective in the UK (nope).

          Hopefully it will not be too much longer.

          Kind regards,


  2. Hi Jeff

    This is off topic, but I enjoying the delights of tinned copper speaker wire.

    I purchased some Supra tinned copper speaker cable. I installed it yesterday, and listening today I can only say wow.

    The music was so engaging. I was really moved by the music, in a way I have not experienced before.

    I really can’t explain it, the sound is so addictive, rich and beautiful, the experience can only be described as magnificent.

    I went for the Supra because it is such good value for money, I couldn’t resist trying it.

    The dueland tinned copper cable in the Uk retails for about £9 per metre, and as you need a double run for right and left connections, it was going to get rather costly. The supra was a bargain in comparison.

    I think tinned copper speaker cable is slowly creating a mini revolution in audio playback.

    All the best

    Chris . . . .

    • Hi Chris,

      Thanks for telling me about your experience with Supra tinned-copper speaker cables, and I’m pleased to hear you’re enjoying them so much!

      I know just what you mean about tinned-copper, it has a uniquely musical presentation, and once heard it is hard to go back to conventional copper or silver cables.

      Kind regards,


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