Questions about tubes and gear that glows. FAQ
In Reply to: Why do my tubes keep blowing? posted by occ on December 7, 2006 at 01:51:54:
When you say you have had the voltage checked, what exactly do you mean? Was monitoring equipment connected to the mains to measure voltage value range over a period of time, say, a day, or a week, a fortnight? Or, was a simple â€˜snap shotâ€™ of mains voltage values taken? And, by whom? I think, given own experience of mains supply voltage values, here in the East Midlands, value range of voltage supplied needs to be ascertained.
Secondly, is the mains transformer for the power amplifier rated for 240v? I own a Canary CA-601MkII valve/tube pre-amplifier made in the US but supplied to the UK. It has a 220v rated mains transformer. Fine for, say, the French market, but not too great for the UK. I operate the unit with an isolation transformer that also cuts the voltage supplied to the unit. Internal voltages are then of a value appropriate to the valves utilized. Without, given the voltage supplied to home, which conforms to EU harmonization of voltage supplied to domestic consumers, but yet allows UK suppliers to supply at a value above the nominal 230v, the voltages seen by the valves would significantly stress the valves, many of which are difficult-to-come-by and expensive NOS. Depending on the operating conditions of the design, which might operate the valves at the upper limit, a high mains voltage, from own experience, might push the valves to fail. I might add that I use isolation transformers, from British Audio online, for all the audio equipment operated. The main unit utilized has voltage reduction and I run all items, whether rated 230v or 240v â€” the Border Patrol SE300B PSU is rated nominally 230v while the Audio Note DAC2.1x Balanced is rated nominally 240v â€” from isolation transformers. I routinely suffer high voltages close to the upper limit permitted by EU harmonization.
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