The Big Sky Drive pedal… technical stuff

The BSD is a unique circuit developed by DingoTone. The design is based loosely on our very successful HZD Boost pedal.

The input stage is a high-impedance common-emitter amplifier followed by an opamp booster (the “Drive” control).  The booster drives into Germanium clippers through a resistor-capacitor (“RC”) circuit that manages the clipping dynamics. Managing current flows in the circuit is critical to obtain good clipping tone – the “time-constants” in the surrounding RC networks have to be right.

By their very nature, Germanium diodes will give tube-like overdrive – the onset of clipping is mild and “rounded”, just like saturating the output stage of a tube amp. The Germanium diodes in the BSD have been carefully selected to give great tone – a lot of different clipping circuits were explored with our field-test team to find the one that sounded the most transparent.

After clipping, the signal is low-passed to flatten the EQ and it then flows through an opamp active level control circuit.  The level control circuit does not add any color and it is functionally similar to the HZD’s “boost” circuit.

The output of the level control circuit feeds the active Baxandall EQ. The EQ is high and low shelving with shelf frequencies selected to be useful to musicians. With this type of EQ it is possible to obtain “mid boost” (reducing the bass), treble boost, and many other tones.  The video demo for the HZD shows the basic function for this type of EQ.

A final opamp stage gives another level adjust and provides a low impedance output drive for the pedal.

The tone in the BSD comes primarily from two places in the circuit:
– The Germanium clippers… these give a complex and smooth overdrive tone.
– The EQ section… this circuit is essentially the same as the EQ on the HZD, which has been described as “milky smooth”.

DingoTone field-testing philosophy… DingoTone’s field-test philosophy is to ship between 6 and 10 field-test pedals at the same time to different testers around the world (DingoTone testers live in the USA, Canada, Australia, Ireland, the UK, and the Netherlands). Sending pedals to everyone at once results in almost-real-time interaction between testers. This approach is very expensive (build and ship 6 to 10 pedals for each design iteration, instead of sending a single pedal from one tester to the next), but it results in a higher quality design.