Written by Don Stick on behalf of Bands for Hire.
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Most guitarists are fairly fanatical about the tube amp. There is something about the glow of hot glass and the imposing sight of weighty
Written by Don Stick on behalf of Bands for Hire.
Most guitarists are fairly fanatical about the tube amp. There is something about the glow of hot glass and the imposing sight of weighty iron through the grille that seems to sum up so much of what's cool about the electric guitar.
Some of the tube amp designs of the last 60 to 70 years have oozed so much aural and visual mojo that it's difficult to imagine the course of electric guitar playing's evolution without them. Many of these designs have been refined and re-packaged by now in a bewildering number of (often complex) formats; but the heart of a tube amp and the circuits on which it is based have actually changed very little.
Now, I'm not suggesting that the untrained electrician or the DIY hero should consider going elbows-deep in circuits that can contain upwards of 500 volts.
An open tube amp may have the potential to kill you even when switched off; and even if you have the knowledge, the best tube amps are far too exquisitely engineered under the hood to be messed about with by just anybody.
As with most things though, there is a lot that can be achieved with just a basic level of knowledge—and if nothing else you might save yourself a trip to the amp tech!
Preamp Tubes
These are the smaller tubes that you can see on your amp's chassis. They are often—but not always—hidden behind metal sheaths that are there primarily to reduce microphonics. Most modern amps are designed around 12AX7 preamp tubes, which have a very high gain factor, and generally the brands that tend to be fitted at the factory (common ones include JJ, Ruby, Sovtek and Shuguang)