|
Tubes Asylum Questions about tubes and gear that glows. FAQ |
|
|
|
Tubes Asylum Questions about tubes and gear that glows. FAQ |
|
In Reply to: Tube life considerations. tt verses oxide posted by amnesiac on August 7, 2017 at 05:17:49:
A lot depends on the circuit.
Tube life depends a lot on how hard the tube is run, which is circuit dependent. As a general rule, the harder a tube is run, the shorter its life span. For example, preamp tubes usually are not pushed hard, e.g. 50% of plate dissipation or less, so they may last 10,000 hours or more. OTOH, power output tubes are often run at 75-80% of plate dissipation in order to get that last watt out, and therefore may only last 2000 hours.
Another factor is filament voltage. Tubes that are run with 10% lower filament voltage have somewhat less emission, but also last significantly longer - David Berning, for example, has routinely run his filament voltage at around 5.5 volts for 6.3 volt rated tubes, and claims 10-20,000 hours life span.. Turn on and turn off cycling can also decrease filament life - with incandescent bulbs, that was a significant failure mode.
Finally, is tube construction. NOS tubes were frequently built in the days when tubes were the primary amplifying device, and were engineered to be reliable and long lasting, by giant corporations (GE, RCA, Sylvania, Telefunken,etc.) with lots of resources for research. Competition pushed them to improve reliability - if a company was to get a reputation for unreliability, there were other companies ready to replace them. Modern tubes have come a long way but are built by relatively small factories (compared to the "good old days"). They may have more modern metallurgy but quality control may not be as strict.
All the above are generalizations and no doubt individual exceptions occur.
This post is made possible by the generous support of people like you and our sponsors:
Follow Ups
- RE: Tube life considerations. tt verses oxide - JimL 10:14:50 08/07/17 (0)
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2024, Audio Asylum, all rights reserved ]
