We all love valve or tube gear don’t we? We love the warmth and character that those Vacuum Tubes impart into our carefully crafted audio. But what happens when one of those valves gets old, starts to show signs of overuse and eventually fails? It turns out that troubleshooting your own valve gear is not as tricky as it first might seem.
Valves Versus Solid State
In the solid-state world of transistor-based circuits if a component fails it’s normally a binary thing, it either works or it doesn’t. In the tube world, things can be a lot more “grey”. When a valve gets past its best it normally dies in a very slow gentle fashion. A valve will very rarely just blow like a fuse. It’s a much more drawn-out affair. A valve that is slowly failing will often still work but cause the signal to degrade and more noise may be created by the amplifier, compressor or EQ. Basically it will hiss.
The other common type of valve failure is whats called a microphonic valve. This is where some of the inner components of the valve become detached allowing to vibrate or rattle. This can sound like a ping or bell sound coming from the device. It can sound like a mechanical noise but it is actually in the audio signal path.
In the video, filmed at Studioszene 2019 from Cologne Germany, Technical Editor James Ivey talks to John Petersen from Tube-Tech about noisy and microphonic valves and how to replace them and it’s not as scary as you might think.