Guide to getting and playing better gigs
Tranny Amps
There's no doubt, over the last thirty years, solid-state guitar amplification has had to play second fiddle to the mighty valve at almost every step in its development. But times they are a-changin', and some of the latest designs are so good at delivering the right vibes that even experienced ears have trouble telling Stork from butter, if you know what I mean...
The beginnings of solid-state spelt the end for many western valve manufacturers -guitar amplification only represents a tiny proportion of the worldwide semiconductor market, and when cheap discrete transistors started to roll off the production lines all western valve manufacturing plants closed within a very short space of time. Whilst many amp builders turned to the eastern bloc for continued valve supply, there was also an impetus to use transistors and develop technology to make the new breed of semiconductor produce all the warm guitar friendly tones of it's predecessor.
But this was not, as it turned out, a particularly easy thing to do. The very first combo amps were general purpose public address derivatives (anyone old enough to remember the Linear Concord?) which really weren't specifically designed for guitars, and it took a while for manufacturers to catch on that we guitarists still wanted our distortion.
Eventually proper solid-state guitar amps began to appear, and to woo us away from our glass bottles, we were told by every maker that only their circuits captured the 'unique overload characteristics of real valves'.
One of the first was H&H, with their truly crap-sounding Valvesound circuit , but despite decent build quality and a snazzy fluorescent control panel the range never lived up to it's promise. Some of the worst aberrations of the time came from established valve names such as Marshall, Fender and Vox, whose transistorised reincarnation of the AC30 was a universal turn-off.
Unlike valves, whose designs have remained unaltered since the 40's, the transistor has been continually improved over the years, original discrete devices such as the AC128 which was fitted to Arbiter's Fuzz Face have now been almost entirely been superseded by dual op-amps such as the ubiquitous TLO72.
These have improved power handling and faster slew rates, which make it easier for designers to approximate valve power curves, and many power devices also include built-in protection against overheating and short circuits, boosting the important reliability factor.
The latest trend in trannies is 'current feedback' which was first properly exploited by Marshall with their highly popular Valvestate series, and many makers have since used current feedback to good effect.
At the top of the current feedback amp heap you'll find Peavey's latest Transtube range, and the Hughes & Kettner Attax series, with Marshall set to introduce a revamped Valvestate in the very near future.
Like any guitar amp, a solid-state design incorporates a preamp which shapes the guitars sound and applies distortion, combined with a power stage to drive the loudspeaker, however, unlike a pure valve amp where the power stage is often considered to be the most important tonal element the preamp is king in tranny designs.
The tone control stack is often much more complex than its valve equivalent, some designers will stick to the traditional passive layout which only cuts frequency bands, but you're just as likely to find active controls which have enhanced range and can boost as well as cut.
A different but equally valid approach can be found in some Hughes & Kettner amps, such as the all-conquering Attax series, which combines traditional passive tone controls with highly active 'voicing' knobs that boost mids and cut treble and bass, or vice-versa depending which way the knob is turned.
Modern valve amps are not as pure as you might think, many designs are actually hybrids, incorporating solid-state devices at strategic points to do things that are just, well, easier to do with silicon, like voltage regulation, reverb driving and recovery or effects loop buffering.
And of course there's the infamous diode limiter which defined the tone of Marshall's JCM800 series, but that's another story. Amps like these are a long way removed from the totally organic and involving behaviour of their pure ancestors, but it's horses for courses at the end of the day many guitarists have never experienced the interactive nature of a simple, pure valve amp like an early Vox AC30 or a pre-CBS Fender Deluxe, and are content with the less demanding behaviour of a modern hybrid design because that's all they know.
Set such an amp alongside a state-of-the-art Hughes & Kettner which hums less, is lighter, cheaper and easier to dial in and includes the important advantage that unlike valves, op-amps don't wear out, and the dividing line blurs to invisibility in many cases. What remains important though is that the amp defines your sound to all and sundry, valve or solid-state, it's your link to your audience and if you find an amp that works for you then don't worry about valves, or the lack of them. Tone first!