Capacitor FAQ's
How can one choose the right capacitor for the job?
For many applications, such as woofer low pass shunt circuits and impedance equalization traps, one need not spend a fortune on capacitors and can usually get by with a single Zen cap. In most cases, bypassing with a Harmony or Crescendo cap will improve performance, but it is not always necessary.
For tweeter applications, it is imperative that one use the best combination of capacitors one can afford, and we strongly recommend Cascade Bypassing whenever possible. See our Bypassing section for more information. It is not uncommon in high performance systems for the tweeter network to cost more than the tweeter.
What is the difference between a metallized capacitor and a film-and-foil capacitor?
The difference is in the conductor layers. A metallized capacitor has a layer of aluminum conductor vapor deposited on a dielectric film. This metallization layer is very thin - on the order of Angstroms. Two layers of the metallized film are then wound together, so the cathode conductor is separated from the anode conductor by a layer of film on either side. The metallized capacitor has the advantages of size, simplicity, and price. Its disadvantages are a slight loss of transparency (due to the thinness of the conductor) and a slight intrinsic noise (due to inadequate internal damping). Metallized capacitors also tend to be strongly directional.
Film and foil capacitors are constructed of two layers of film and two layers of foil (the cathode and anode foil). Again, when they are wound, the cathode foil is separated from the anode foil by a layer of film on each side. Film and foil capacitors have the advantage of excellent transparency (due to the enormous conductor volume) and very low intrinsic noise ( due to the high internal damping). The disadvantages are size and price; for the same capacitance value and voltage rating, a film-and-foil capacitor has nearly four times the volume and three times the price. Film-and-foil capacitors also tend to be less directional than metallized film caps.
Does this mean that film-and-foil capacitors always sound better than metallized caps? No. The quality of the film, winding tensions, end termination and lead material all play roles in the overall sound of the capacitor. But we have found that when using the same film, the film-and-foil cap does always outperform its metallized cousin.
If the required value is not listed, how does one make it?
Wire several capacitors in parallel. Capacitors in parallel add; i.e. a 1.0µF in parallel with a 3.0µF is equivalent to a 4.0µF.
Are Capacitors Directional?
Yes. Most capacitors do have a preferred orientation due to their winding configuration. All North Creek capacitors are designed to give their best performance with the gray lead as the input and the white lead as the output.
Is it O.K. to mix brands of capacitors?
Yes, and in some cases it is almost necessary. We feel that most film-and-foil capacitors and many metallized film caps have a sonic signature that is a little inhomogeneous and with an over-emphasized or ragged treble. For most of these caps, bypassing with a 600 Volt Crescendo cap will do wonders for the combination's harmonic balance. Capacitors with an overly soft treble (such as polyester film or low frequency polypropylene film caps) will benefit from a 1µF Harmony bypass cap, and can be further upgraded with the addition of a 0.10µF Crescendo cap.