Drives in Parallel vs Drives in Series

Drives in Parallel vs Drives in Series

This video compared drives in series with drives in parallel, using two Hamilton Effects pedals built from the same underlying idea.

The setup used the Twin Boost, the first pedal I designed for Hamilton Effects, alongside the Twin Parallel, which explores the same gain stages arranged differently. Both pedals use two boost circuits, but the way those stages interact changes the character of the sound quite significantly.

Everything was recorded through a stereo reverb setup, hard-panned left and right, and then into an HX Stomp for direct recording.

Why I made this video

I made this video for two main reasons.

Firstly, I had begun overhauling several Hamilton Effects designs, and during March I was clearing the last few pedals from the previous batch. By that point the Embers had already sold out, leaving just one Twin Boost and a couple of Twin Parallels remaining.

Secondly, I wanted to demonstrate what these pedals actually do. The name Boost can sound quite utilitarian, and it can give the impression that the pedal is simply there to make the signal louder. In practice these circuits are much more about gain staging and how different gain structures interact with each other.

In that sense they function more like tools for exploring signal behaviour than traditional boost pedals.

The Twin Boost

The Twin Boost contains two independent gain stages.

One side functions primarily as a clean boost, with enough output to push an amplifier into overdrive. Any distortion heard in that configuration is coming from the amplifier being driven harder.

The other side includes a bias control, which alters the transistor bias point. This introduces more unusual textures, including slightly gated and compressed sounds that can resemble certain fuzz behaviours, but within a relatively low gain circuit.

Stacking these two stages together is where the pedal becomes more interesting.

Drives in series

When gain stages run in series, one feeds directly into the next.

The first stage shapes and clips the signal, and the second stage receives that already-processed waveform. Rather than simply increasing volume, this usually results in greater saturation, because the signal is effectively being clipped more than once.

This is the same principle that applies when stacking typical overdrive pedals on a pedalboard.

The Twin Boost follows this approach. Its two stages can also be reversed in order, allowing different interactions between the gain stages.

Drives in parallel

The Twin Parallel explores the alternative approach.

Instead of feeding one stage into the other, both circuits run in parallel and are blended together with a mix control. This means each signal path keeps its own character.

One side can remain relatively clean and fast in its response, while the other contributes additional drive or texture. Blending the two allows the sound to retain clarity and attack, while still introducing more harmonic complexity.

This can be particularly useful for rhythmic playing where definition and articulation are important.

Closing thoughts

The comparison highlights two different philosophies of gain design.

Series stacking increases saturation by pushing one stage into another.
Parallel blending allows two different gain characters to exist simultaneously and be mixed together.

Both approaches start with the same building blocks, but the structure of the circuit changes the result.