Air core coils are the best possible solution. To ensure a capacitive coupling only to neighbouring and not all turns, Mundorf manufactures an oxygen free copper foil coil (OFC copper). The coil shows a consistent performance even beyond 100 kHz. The large surface reduces the skin effect (higher frequencies are carried on the copper surface).
Additionally, the coil has a tough, yet elastic isolation made from polypropylene foil ensuring a high mechanical stability and, therefore, suppressing vibrations efficiently.
A lab test carried out by Hobby HiFi (4/2000, starting at page 66) confirms both points: this coil is far better than vacuum impregnated round wire coils or baked varnish coils (and obviously standard coils) and is clearly superior to TRITEC coils and foil coils by CFAG (vibration, microphonics).
Mundorf is certain that these characteristics cause a considerable improvement in dynamics, attention to detail and three-dimensionality. This type of CFC coils you'll find e.g. in the Magnat Vintage 990 setting you back some 40.000 EUR (ref. Stereoplay 12/2001 page 12). Mundorf CFC Cupferfolien-Spule Mundorf CFC Air Core Coil In the picture you'll notice the tightly wound coil and above the wide foil connectors that can be shortened to the required length.
Cross section of the foil coils
11.5 x 0.07mm = 0.81mm² · AWG 18 (like wire with 1.02 mm diameter)
17.0 x 0.07mm = 1.19mm² · AWG 16 (like wire with 1.23 mm diameter)
22.0 x 0.07mm = 1.54mm² · AWG 15 (like wire with 1.4 mm diameter)
28.0 x 0.07mm = 1.96mm² · AWG 14 (like wire with 1.58 mm diameter)
44.0 x 0.07mm = 3.08mm² · AWG 12 (like wire with 1.98 mm diameter)
70.0 x 0.07mm = 4.90mm² · AWG 10 (like wire with 2.5 mm diameter)
70.0 x 0.10mm = 7.00mm² · AWG 9 (like wire with 2.99 mmdiameter)
70.0 x 0.15mm = 10.50mm² · AWG 7 (like wire with 3.7 mm diameter)
L denotes inductance, R the DC resistance, D the diameter, Le the length, Wire-W the width of the wire, DxH the diameter and the height.
MCoil SFC silverfoil coils have been developed for uncompromising state-of-the-art audio applications focused on absolutely flawless and a holographic 3D-like performance at utmost dynamics providing a considerably increased range of vivid. subtle timbres and precision.
Due to changing raw material prices, the prices of the coils are on request.
According to Mundorf the outstanding sound characteristics of the SFC series can be further enhanced by the addition of 1% gold of the highest purity.