AMP schoolFriday, 20 January 2012 14:36
Valves, or tubes as they are referred to in the US are the subject of much mythology. Every guitar player even remotely interested in tone generally believes that valve amps beat the pants off solid state amps any day of the week. While in most cases this is generally true, if you asked the average player WHY valve amps sound better, your likely answer would be a mixture of wildly wrong conjecture and a collection of old wives' tales about the virtues of them there glowing little bottles.
Like most people with a reasonably enquiring mind, many of these topics have fascinated me for ages, I know little bits and pieces of the theory*, and have a relatively well developed bullshit detector (ie: I can usually sort out the facts of a subject from the horseshit), but always wanted to know how all of these bits and pieces went together into making a great amp.
As a result of this, when a friend asked me if I’d be interested in doing a weekend course totally dedicated to valve amps, with the added bonus of being so hands on that you walk out of the course with a fully working little 15 watt firecracker of an amp, I jumped at the opportunity.
Enter Grant Willis – the man behind Valve Heaven. As well as being an amp tech extraordinaire, Grant runs the Amp building course, and has a somewhat interesting history in that his background is originally in more conventional electronics engineering (if you need an example of what this might mean, if you talked to, say, an audiophile amp tech about distortion, he/she would probably say that anything over .5% distortion means your amp is a piece of garbage…. Yet most guitar players, particularly pop/rock players wallow orgasmically in vast swathes of distortion every time they play!), so he has a healthy scepticism of the myths of valve tone. Yet, in his own words, a lot of what musicians believe in about components logically doesn’t make sense, yet, they can discern the difference between a 30 cent cap and a Sprague Orange Drop cap as the tone control in a Les Paul, so, in his view, if it makes you play better, there is something in it.
Valve Heaven Amp Course starts at the relatively ungodly hour of 9:00 am on a Saturday – but don’t let that put you off; Grant limits his course to ten people at any session, and he has the gift of being able to tailor the course, theory and practical, to suit a very wide range of skill levels without anyone feeling left out (we had everyone from people who had never used a soldering iron to those who’d been foolishly sticking their fingers into Marshalls and Fender amps for years in our group). His teaching is very methodical, and very clear – you go through the logical process of building your rather charmingly named Lamington from the coarse end (power supply) to the fine stuff (building the pre-amp) while being told exactly how each part works along the way. There is a logic to everything he does, and Grant is more than happy to not only discuss the logic behind what he does, but to also give a very unbiased view on what other amp makers do and why they do things their way.
Along the course of this extraordinarily enjoyable two days, participants discover practical knowledge about how a power supply works and why it needs to be that way, what a tone stack is, what push pull output stages are and why they rock, what is important about biasing, and why, contrary to almost all beliefs, the Vox AC30 is NOT a Class A amp (they still sound great, so who cares…..) – along with easy to follow answers to pretty much any other question you could ask about valve amps. Another thing Grant emphasises is that while most people see (quite correctly) valve amps as a fairly expensive, rather boutiquiey way of making amps, that, with some serious knowledge of how and why they work, with a bit of lateral thinking and an enquiring mind, you can assemble a pretty wonderful valve driven amp out of some fairly mundane (albeit unusually repurposed) components from the local electronics shop.