valve amplifiers and high efficiency speakers

Rebuilding a capacitor (1)

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This modification comes originally from Kees Pel & Olaf Biessen, as you can read here. The way in modifying is made better by Cees Piet. The following report is a modification by Cees, and as a result of this, his hand are seen on many of the following pictures. Thanks Cees! My system sounds better again....
Attention! This is "only" meant as a guide! Although all modified capacitors so far are functioning without any defects, this is no guarantee! You can achieve a major improvement in sound if the following is done accurately:

Here we have the original Elna, Elna without its plastic insulation and the new wooden enclosure. The inner diameter of the wooden enclosure is the same size as the outer diameter of the original elco. The best kind of wood for this, is tropical wood, like bankirai. These kind of woods are oily and thus less porous as pine or spruce. Porous kinds of wood may be used, but make sure that inner- and outersides are well lacquered to ensure good preservation of the capacitor.

First of all, the new housing is made to measure. To do this, take the height of the elco plus 5mm. This is done because the elco has to be submerged in beeswax, later on...

Removing the plastic insulation. Remember which one of the leads is the negative one! (with new capacitors, the short lead is negative).

Cut it at the top, then peel it down. This is the easiest way...

The metal housing is clamped firmly into a vice. Not too firm!, just enough to keep it in place while filing.

The filing: Slowly file a groove, that can be used as a guide when filing through the metal.

Carefully filing until you can see through the groove into the capacitor. Do not file longer as neccesary!, the capacitor is just below the metal... At the neck the housing is squeezed in, so carefully file a bit deeper.

Now the capacitor is turned 180 degrees to file the second groove..

Carefully open up the capacitor. This is done by holding the file in the groove, and jerking it fore and aft, using the top as rotating point. Do this at both sides.

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