Do I need an Onboard Preamp?

Do I need a preamp?

A preamp is just as it sounds, a pre-amplifier. It is an electronic amplifier that prepares an electronic signal for further amplification through your basses amplifier or signal processing chain through say a pedal board,mixing board, before hitting the end of the signal such as your amp or USB interface for recording. The idea of a preamp started with the need to amplify a low level signal, most likely from high impedance pickups, to line level. Preamps are used in many transducers in audio applications such as pickups and microphones. Equalisation and tone control are used in many preamps found in the music industry.

A preamp can be onboard an instrument, outboard through use of a pedal, or incorporated into the housing of the amplifier. Depending on size and fitment for onboard use, some require an outboard preamp due to lack of fitment of modules, controls, and batteries onboard the instrument. If you feel you may be in a situation where fitment is a concern for an onboard preamp please contact us:

What preamp will fit my bass?

This varies from instrument to instrument. Fitment and size restriction is always something to consider when purchasing an onboard preamp. If the instrument is equipped with a rear route, battery compartment, and has a control cavity depth greater than 1.25″, many if not all of the preamps we carry will fit just fine.

For situations like a Jazz bass or P-bass where the controls are top routed and mounted to either a control plate (Jazz Bass), or pickguard(P-bass) fitment can be slightly more difficult and we recommend consulting us for assistance on preamps outside those listed as retrofit for these style of basses.

What is the difference between 9 and 18v preamps?

This is dependent on the preamp. The option to run additional DC voltage to supply more power to the preamp is there to increase the headroom of the preamp since there would be less of a chance of the signal getting clipped due to lower or inconsistent voltages. This is not necessary for everyone and is a preference on a user to user basis. Some feel that running 18v for the additional headroom is worth the additional routing for a battery box, and some do not.

What is meant by the terms ‘active bass’?

Generally speaking, the term means that there is a battery in the bass. Most commonly, the battery is being used to power a preamp. The preamp uses a battery and thus the instrument is powered (active). Occasionally, the pickups are active; a bass with active pickups would, of course, also be considered active.

Most pickups (even in ‘active basses’) are actually passive. A bass can have an active preamp with passive pickups: This is the most common scenario.

EMG, MEC and some others have models that are active and require a battery. Sometimes these pickups are used with preamps as well, but not necessarily.

Many preamp manufacturers are designing their control harnesses with passive pickups in mind, as they are more common both as retrofit parts and for OEM use

Do I need active./passive switching?

Some instruments have a switch which changes the signal from active to passive. This switch is not changing the pickups, or how they function: the switch is not making a pickup active or passive. It is changing the signal path for the controls.

More precisely, an active passive switch is a bypass switch. When in ‘passive’ mode, the signal bypasses the active part of the preamp (which is typically the EQ section).

Do I need Active pickups to work with a preamp?

No. Most aftermarket preamps are designed with passive pickups in mind.








John East



Passive Harnesses



Trickfish Amps