I’ve used a little artistic license with the title of this blog post, however be assured it is technically accurate and true – the Blackbird preamp pedal really is based on exactly the same tube circuitry and design ethos found in vintage custom tube amps that have exchanged hands for up to $50,000. These amps command hefty price tags because they’re a rare commodity, being bespoke, one-off creations built for legendary players, such as Stevie Ray Vaughan, Larry Carlton, Ry Cooder and Carlos Santana. As you can imagine, their tone is very good too, exceptionally good, being the result of many years of empirical design or ‘tweaking’ (as it’s known in the audio electronics industry) by an experienced tube amp guru. The tube amp guru I’m talking about is Alexander “Howard” Dumble.
Dumble began ‘hot-rodding’ Fender ‘Tweed’ and ‘Blackface’ guitar amps during the mid 1960s. The idea behind hot-rodding is to modify the preamplifier section of the amp by adding additional tube ‘clipping’ stages and tone-shaping circuitry to improve the amp’s playability. In practice this means tailoring the preamp to increase its gain and sensitivity making it more responsive to playing dynamics so that it sustains or sings. The guitar amp really is a musical instrument in its own right and because of this it’s vital to get the ‘sound right’ so that it works with you rather than against you. By modifying guitar tube amplifiers, Dumble was effectively setting them up in very much the same way a guitar luthier will adjust the action, intonation, etc of a guitar to best suit a guitarist’s specific playing technique.
Designing this type of tube preamp circuitry is a non-trivial task though, that is, a great deal of experience and insight are required to understand how to balance the tone and response of the amplifier. Amongst other things, this tweaking involves curtailing the bass response whilst emphasising certain high-mid frequencies to decrease ‘blocking distortion’ in the circuitry to sweeten the overdrive tone. However, you don’t want to loose too much of the bottom end otherwise this adversely affects the tone. It really is an art and frighteningly time consuming (I’m speaking from personal experience here) to optimise the circuitry to get it to sound right, but when you do get it right the tone is as smooth and rich as bourbon and honey or perhaps luxury dark chocolate is a better metaphor. Anyway, I’m sure you get the idea. What I’m trying to say is, once the preamp circuitry has been tweaked it becomes a completely different machine, more musical, responsive and playable. Inevitably word got out about this new preamp architecture and guitar amp manufacturers, such as Randall Smith (Mesa Engineering) and Mike Soldano (Soldano Custom Amplification) followed Dumbles’ lead in the 1970s and 80s with their own versions of hot-rodded tube preamp circuits.
These amps were a huge inspiration to me when I began designing my own tube pedals back in the mid 1990s. I spent a lot of time reverse engineering (er, copying) their circuits and tweaking them closer towards perfection, always pushing for more of the tone I wanted and lower noise too, which is challenging to attain in a high gain tube preamp circuit. Even after many years of tinkering with tube circuits I still can’t claim to have all the answers, but I’m convinced the development of the Effectrode ‘Tube Drive’ and ‘Blackbird’ pedals do take the art of tube amp design to higher ground. Both these pedals are real tube preamps, not a digital model, simulation, ‘profile’, etc. They’re all analogue and operate at 300V plate voltages and there’s not a single op amp in the signal path. There are also a few additional enhancements under the hood too, such as D.C. powered tube heaters for lowest possible noise operation, transformer isolated DI for recording direct, biasing options on the Blackbird and the pedals are built on custom manufactured silver-plated circuit boards. Even guitar amp manufacturers don’t do this. These pedals really are the real McCoy and you will notice the difference when you play through them – their tone is unmatched in terms of warmth and richness and they respond beautifully to playing dynamics – they’re an utter joy to play through.
You can find out more about the research and development effort that went into making the Effectrode Blackbird and Tube Drive pedals a reality in the article: The Story Behind the Tube Drive
