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Old 13th Oct 2017, 5:25 pm   #141
GrimJosef
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Join Date: Sep 2007
Location: Oxfordshire, UK.
Posts: 4,310
Default Re: Audiophoolery. 'Cable Break In' - I never knew that!

I once had a scientific glassblower make me a very nice rare-gas discharge calibration lamp for a spectrometer I was using. We spent a little while discussing glass-to-metal seals and how tricky it could be getting them to work over a wide range of temperatures without the materials' different thermal expansion coefficients causing the seal to micro-crack. The best results involved tuning the glass's and metal's compositions to work optimally over the device's operating temperature range. I'll bet the seals in valve bases were optimised for, say a range of 0C to 150C or so. Military spec valves might be rated to work from lower temps (high-altitude aircraft) to higher (badly ventilated kit inside hot parts of tanks or ships). But surely they weren't designed to go down to genuine cryo temperatures. I wouldn't want anyone to come crying to me if their precious Mullards faded away after a few years due to cathode degradation by low-level gas ingress. Of course if I had a stock of them and I needed a way of making sure that my customers kept coming back for more then I might well be more enthusiastic .

Cheers,

GJ
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