A little while back Frederik Carøe - the founder of Duelund Coherent Audio - asked me if I would like to try a set of his exotic Duelund Coherent Audio CAST Silver Capacitors in the Duelund-Westminster Royal SE High-Frequency Crossover, and of course I said yes!

Frederik asked me which of the capacitor positions in the WRSE high-frequency crossover would be the best choice for giving the CAST silver capacitors a workout, and I recommended the C1 position 6.8uF capacitor (below on the left of the schematic), as it connects directly to the incoming signal on HF+ and the autotransformer, which influences everything that occurs in the high-frequency crossover.

In the photo below of the Duelund-WRSE CAST crossover, you can see the copper 6.8uF CAST capacitor in the lower left of the photo, with one lead (with the yellow tape) connected directly to the HF+ input using the binding post bypass method, clamping it directly to the spade connector of the Sablon Audio Panatela component speaker cable for the best possible connection.

As you can see in the photo below, the other lead of the copper 6.8uF CAST capacitor inserts directly into the setscrew lug that connects the autotransformer. Not only do the binding post bypass method and setscrew lugs provide the best possible connection without signal degrading solder, they also make it a breeze to insert a new set of capacitors!

Frederik said he would get started on making up a pair of silver 6.8uF Duelund CAST capacitors for the C1 positions in the Duelund-WRSE high-frequency crossovers. I know quite a number of you have been asking me about the Duelund silver CAST components, but I haven't really been able to say much because I haven't tried them, so this is going to be exciting giving them a try and telling you about the result.

I also asked Frederik if he would take a few photos of the process of crafting the capacitors - without giving away any secrets - so you could get a feel for what goes into making a set of Duelund silver CAST capacitors. The first photo of building the silver CAST capacitors from Frederik is below, showing the preliminary winding of the raw silver foils.

In the Duelund CAST silver capacitors Frederik uses only pure annealed soft silver foil in natural paper and oil, along with resonance control both inside and outside the capacitor. A capacitor is made using two foils with paper between the foils, which results in capacitance being created in the electric field between them. Each Duelund CAST capacitor is completely hand made in an incredibly labor intensive process.

As a refresher on the crafting of the silver Duelund CAST capacitors, the first step is to make foils of pure silver that have been initially wound with paper to a certain value that is a good deal over the 6.8uF capacitance needed in the C1 position of the Duelund-WRSE HF crossover.

These initial silver foils are then placed under vacuum pressure in an oil tank at high temperature for about a week, so that everything inside the winding undergoes vacuum impregnation and is permeated by oil.

When this process is done, the resulting foil is wound by hand in a humidity and temperature-controlled room to an exact specification, and then it is placed back into the oil.

Immediately after this process the winding is sealed by the use of a special lacquer, which is also used in the yacht industry to seal against moisture. This takes another week. During this process a ring of vacuum impregnated paper has been readied with a base of CAST material.

I'll keep you posted as Frederik sends more photos, and ultimately I'll write a full article about them along with my listening impressions.

Stay tuned for this exciting developing story!