Just to be clear, the usual handling of a Teflon cap required to install it has not resulting in a change in value in the 20 years we've been using them (prior to using V-Caps we had Teflon caps made for us). So this is far less of an issue than I probably made it look.
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I apologize for the late reply. Atmasphere is correct, as it relates to many capacitors that used 'teflon' film… before V-Caps were introduced in 2004.
The TFTF or CuTF series V-Caps don’t change capacitance, and aren't deformed or damaged with normal handling. I've tested both smaller values as well as larger values (up to 3.3 uF) as if squeezing a lemon, or pinching a grape, while measuring on a Quadtech LCR 1920, Quadtech 7600+, and GenRad 1689M. The capacitance measurements, as well as the DF and ESR measurements don't change beyond the testing equipment’s +/- accuracy range.
Where you MAY run into a problem (with any film capacitor) is when an installer gets overly aggressive with a nylon cinch tie. A great deal of force can be exerted over a very small area, and the square 'box' portion of the nylon cinch can make contact with the central body of the cap. The square corners of this box can penetrate the skin of a capacitor, and cause a short. Also, I've seen instances where small material on the surface of the cap gets driven through the outer skin...
I recommend cinch ties be used at each end of a capacitor winding, where penetration of the cinch tie of the outer skin isn't likely to cause a short, because it is at the cap's ‘margin’.
The reason V-Caps are wrapped in bubble wrap, is to:
1) protect from shipping damage. Anyone who’s done business with VH Audio, knows I have a tendency to ‘overpack’ ; -) 2) protect the solid core leads from getting bent acutely 3) prevent a sharp edge from one of the cap's solid core leads from penetrating the winding of another cap, during drop-kick exercise by UPS: https://www.youtube.com/watch?v=slk6zeM4Of8 4) I use bubble wrap to help ‘pair’ caps when customers and OEM’s want matched pairs.
I'd also like to mention that a true ‘hermetically sealed’ cap is encased in a (usually) metal/glass/ceramic enclosure and must use a special hermetic seal with bare (uninsulated) metal lead material. No other type of capacitor is truly hermetically sealed, in the strictest sense, which would also protect against immersion in liquid. The OIMP V-Cap series is a truly hermetically sealed capacitor. However, in a practical sense, modern capacitors are usually 'sealed' quite well...
Long term changes due to Atmospheric pressure is not likely. I have copper and tin capacitor standards/prototypes that were built >13 years ago, and the capacitance, DF and ESR hasn't changed for those samples, at least not within the tolerance of my measuring equipment, which is far more accurate than typical equipment used in most capacitor production facilities...
Lastly, regarding mechanically dampening and securing caps to the board, there are many methods that can be successfully used for this, including 3M double sided tape, nylon cinch ties (when used correctly, and not overtightened), and nylon cable clamps (like this: https://www.waytekwire.com/products/1378/Nylon-Cable-Clamps/). To provide additional mechanical dampening, you can use silicone stretch seal tape (found at any Home Depot) to provide a nice ‘bed’ for the capacitor, and protect it from sharp edges that might be found on underside of circuit boards. Best regards,
Chris VenHaus |
I upgraded the coupling caps on my NOS ARC VS110 (I believe they were WonderCaps) with TRT DynamiCaps. It took a good 200, maybe 400 hours for the new caps to fully settle in but I am very happy with the improvement. Are the TRT's the best to be had-without a doubt not, but the prices of the best caps don't make sense when you're looking to upgrade a $2,500-$5,000 amp IMHO. I doubt most non-engineer audiophiles understand what coupling caps do in a tube-amp. Peter of Symposium once gave me a long detailed explanation. I will post it here later. |
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