AN COPPER FOIL / MYLAR CAPACITORS
Why did we move to oil filled Mylar from oil impregnated paper?
When truth be told we have been experiencing increasing problems with the failure rate of our paper in oil capacitors over the past 3 to 4 years, and despite a major research program into the causes of this increasing break down rate we have really come up with a blank. We suspect that the cause has to do with subtle changes in the chemistry of the paper, the oil or some other key part of the caps, possibly due to new environmental requirements imposed on the production of the paper, but who knows? Anyway, when it became obvious that we were unable to fully establish and rectify the cause, we decided to try Mylar. The initial experiments with oil impregnated Mylar were not sonically satisfactory, so we experimented with changing the construction to oil filled, the materials sealing the capacitor and the way we connect the foil ends to the lead out wires and voila! After some running in, the new Mylar/oil filled capacitors actually sound better in most respects than the previous generation of paper signal caps, the only real drawback is that they take nearly twice as long to run in and sound quite a bit worse than the old paper/oil type when they are new. So there you are, you don't get something for nothing!
As you can see from the above pictures, each of our signal capacitors is marked with a line on the right; this marks the start of the foil. It is our experience that the Audio Note (UK)™ capacitors perform best when the start of the foil is "facing" the incoming signal.
Our own production audio signal capacitor range is now complete with the addition of the 0.39uf/630 volt capacitor. This is without question the best and most competitive range of audio signal capacitors available by some considerable margin.
The new copper and silver foil signal capacitors are available in a range that is specifically targeted at the single-ended triode amplifier market, although most values will also be excellent for other types of audio application.
Apart from the considerable improvement in price, the fact that the new copper foil capacitors are considerably better sounding than anything else - including the previous Jensen-made copper signal caps - makes them even better sonic value. The improvement is due to the use of greatly improved materials, better production methods and tighter production tolerances, plus the fact that the new caps are encased in copper instead of aluminium, glass or plastic.