dngl
He'd rather show hisbuns than wear fur.
- Joined
- Jun 22, 2001
- Posts
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- 15
yeah man, Melos amps are for lazy people because they have three inputs and don't require much maintenance. They do chew up tubes, I hear...
Originally posted by Morse Hi Calanctus! In my honest opinion you should look at the issue of valve lifespans in terms of hours of operation, rather than asking for a set figure ("Need I replace them every x number of years?"). Also, it really depends on how you use your hifi. Here are some examples of good ways to kill your valves quickly (i.e. if you want your valves to last, DO NOT DO THESE THINGS). 1. Short cycling - if you like to turn your hifi on and off many times during the day, you will wear out your valves much faster. This is because the high voltage peak hitting the cold valve will wear away at the thin outer coating on the cathode. Eventually the coating on the cathode will be damaged to the point that the valves emissions drop, and it's time for a new valve. 2. Tapping on a hot valve - some people like to tap on their valves while they're running to test for "microphonics". DON'T DO IT! You can easily induce microphonics (and other damage) in a healthy valve by doing this since valves are more delicate when hot. 3. 24/7 operation. This is the opposite of valve killing strategy number 1; some people go overboard and like to run their amps continuously. Go check the data sheets for various valves; frequently a manufacturer will have 2 sets of specs, CCS ("Constant Commercial Service") and ICAS ("Intermittent Commercial and Amatuer Service"). The CCS specs for allowable voltages and currents will always be lower than the ICAS spec, as will the lifespan (if rated). Thus, if you run a hifi that was designed around ICAS standards in a CCS manner, you can expect to dramatically shorten the lifespans of your valves. As far as an hour figure for valves, it can be anywhere from DOA to 100,000 hours (that would be for the creme de la creme of 12AX7's - the Telefunken, under ideal conditions). Figure around 2,000 to 3,000 hours of operation for output valves and a bit more for the small signal valves, and you probably won't be too disappointed. The last valve I had die an ugly death on me was a cheapie Chinese EL34 that died somewhere around 800 hours of operation. As far as your question about sourcing replacement valves, you can buy valves from many different places online; you could start looking at Parts Express at http://www.partsexpress.com/ and Triode Electronics at http://store.yahoo.com/triodeel/index.html For whatever it's worth, I've bought quite a few things from both those places with no problems yet (knock on wood...). Anyway, good luck and Enjoy Your Music! Morse |
Originally posted by Morse Currently I'm working on a doctorate, thus I occasionally teach (and bore!) roomfuls of people at a time to earn my keep. |