In my previous column, I took a deep dive into the elegant utility of passive electronics, describing the circuit in detail and denoting that despite their simplicity, passive electronics are capable of a surprisingly broad array of great tones. This time, we’re going to stick the battery in and talk about active electronics.
As I described last month, “active” and “passive” as applied to bass electronics refer to the presence (or lack) of an external power source. Unlike passive systems, an onboard active scheme requires the addition of electricity, typically from one or two 9-volt batteries. This means that amplifying devices like transistors can be incorporated, allowing players to boost their instrument’s output beyond what’s generated by the passive induction of current in the pickups. Power also makes it possible to have frequency-selective volume control, something we often call equalization or EQ.
The first mass-produced onboard active electronics were found in the Music Man StingRay. Other systems pre-date the StingRay (notably Alembic basses), but Music Man was the first manufacturer to offer a bass with stock active electronics in large-scale production. Since then, active systems can be found on basses from the cheapest on that rack at your local Guitar Center to bespoke custom basses costing over $10K.
A reasonable question many players have: Given how versatile and reliable passive circuits are, why bother with an active system? Active basses have a few key advantages over their passive brethren. First, almost all active basses offer preamplification, conditioning an instrument’s sound in various ways to make it suitable for the much larger amplification occurring in a rig. As a consequence of the typical preamp’s components, active preamps buffer the signal, resulting in a low output impedance. The advantage is two-fold: First, a low-impedance signal is much less vulnerable to frequency loss over long cable runs, and second, it doesn’t require a high input impedance at the amp or recording-console input to preserve fidelity.
Since active preamps have a suite of amplifiers within them, most circuits allow for substantial gain boosts and flexible EQ. In fact, it could be argued that the preamp of the average bass head is somewhat redundant with the most flexible of the available active systems. Modern onboard systems can include up to four bands of EQ, sweepable frequency centers, and an accompanying passive-style tone control, giving players the best of all worlds.
The handful of disadvantages of an active preamp include potential for increased noise, susceptibility to dead batteries, and the potential to introduce distortion as the circuit runs out of headroom. That said, most contemporary circuits are relatively immune to these shortcomings, with even battery life being on the order of months.
BASS PLAYER Senior Contributing Editor Jonathan Herrera is the magazine’s former Editor-in-Chief. An accomplished player, Jonathan is now a full-time musician and producer. His latest endeavor is Bay Area recording studio Airship Laboratories. Catch up with him at jonherrera.com and at airshiplaboratories.com.