3.3uF Duelund CAST Tinned Copper (Cu/Sn) Speaker Capacitor

Duelund CAST Copper Loudspeaker Capacitor (100Vac / 200Vdc) The CAST series is Duelund Coherent Audio's flagship — the no-compromise reference capacitor that sits at the apex of their entire range. Built around the proven Virtual Stack Foil construction and elevated through a proprietary multi-day casting and impregnation process, the CAST Copper has been recognised for over a decade as one of the finest crossover capacitors ever produced, regardless of price. For builders pursuing the absolute best, it remains the benchmark by which all other capacitors are measured. Construction The CAST takes the foundation of Duelund's Virtual Stack Foil design — pure copper foil and high-density paper in a flat, low-inductance geometry — and subjects it to a proprietary WPIO (Wax-Paper Impregnated in Oil) treatment. The capacitor body is impregnated under high pressure over several days, producing a finished form with mechanical damping properties unmatched in conventional capacitor construction. Microphony, internal resonance, and parasitic vibration — three of the most insidious sources of distortion in passive components — are reduced to a degree that has to be heard to be appreciated. A final ring of hard-pressed paper is added around the cast body, further reinforcing the damping and giving the CAST its characteristic cylindrical form factor. The result is a capacitor that behaves more like a solid mechanical block than a wound component, with the signal passing through it unaffected by structural vibration from the surrounding speaker cabinet or amplifier chassis. Lead-outs are 1mm tinned copper. The outer lead is connected to the outer foil and should be oriented toward the lowest-impedance path to ground in your crossover for optimal noise rejection. Sonic Character The CAST Copper is celebrated for a presentation that listeners consistently describe as "calm" and "serene" — an unusually quiet acoustic background against which musical detail emerges with extraordinary clarity. Instrument separation, soundstage stability, and the localisation of individual voices and instruments are reproduced with a precision that lesser capacitors simply cannot match. Strings carry their natural texture without harshness; brass retains its metallic sheen and dynamic snap without stridency; vocals are presented with breath, body, and emotional immediacy. What separates the CAST from the VSF Black and other premium designs is the sense of mechanical stillness behind the music — a quality that becomes increasingly apparent on complex passages, dense orchestration, and at higher listening levels where lesser capacitors begin to compress and congeal. A burn-in period of 50–100 hours is recommended before critical evaluation, though many builders report continued refinement well beyond this point. Applications The CAST Copper is intended for the most exposed positions in serious crossover work — series and parallel placements in tweeter and midrange networks, full-range and single-driver loudspeaker designs, and any application where one capacitor carries the entire signal in or out of a critical driver. Equally suited to high-efficiency horn-loaded systems, where its low noise floor and resolution are most clearly heard, and to revealing modern multi-way designs where every gain in transparency is directly audible. Often combined with Duelund CAST inductors and resistors to create a fully matched signal path — an approach that maximises the sonic synergy of the range. Specifications

Construction: Virtual Stack Foil (VSF) with proprietary WPIO casting process Conductor: Pure copper foil Dielectric: High-density paper, wax-paper impregnated in oil (WPIO), high-pressure impregnated Outer treatment: Hard-pressed paper damping ring Voltage rating: 100 VAC / 200 VDC Tolerance: ±2% Lead-outs: 1.0 mm tinned copper Country of origin: Denmark (handmade)