A bass equipped with active pickups is a great way to give your low end rumble a good shot in the arm but in order to make the best use of all that extra power, you’re going to have to know how to use their built in EQ controls.
For those of you unfamiliar with the workings of a standard electric guitar pickup, essentially they consist of a magnet that is wrapped around thousands of times with copper wire, creating a coil around the magnet. When a string is plucked, the inherent magnetism of the vibrating metallic string (usually nickel plated) causes a modulation, or change in frequency, in the magnetic field of the coil which creates an alternating current. This means that plucking a guitar string causes a magnetic shove of sorts to the copper in the pickups which then causes the magnetism in the copper to push back a magnetic signal of its own (we’ve all played with magnets and noticed how they push back if you have them facing a certain way, same thing). That signal created is what is sent over to the amplifier through the guitar cable.
Up until the 1970s, pickup manufacturers pretty much had no way of creating more powerful pickups that wouldn’t negatively affect tone. Back then, the technique used to increase the gain consisted of increasing the magnet size or the number of winding around the magnet but this caused problems of their own. Oversized magnets affect string vibration and too many windings can pick up unwanted noise, both of which will mess with your tone.
It wasn’t until 1969 that Alembic founder Ron Wikersham discovered a method that would increase the output signal without increasing the unwanted attributes that came with the previous methods. His idea was basically creating a low-impedance bass guitar pickup by giving decreasing the windings. This yielded a pickup that had less radiation and less unwanted noise but it always meant a weaker output. In order to combat this, he built a system that included an internal preamp built inside the instrument to boost the low-gain signal. This innovations brought many advantages to the electric bass.
The Importance of EQ Controls
The problem with low-impedance pickups is that although they have a wide frequency response, they tend to lack character in their tone, which is why built-in EQ controls are included – to help shape the sound. Your average active bass will usually come with either two or three frequency bands: Low and High or Low, Mid and High, respectively. Some of the more elaborate active pickups, such as some from the guys over at EMG, also include an active EQ system, but that’s not the standard with most manufacturers. Anyways, the built-in EQ works the same as they do on an amplifier; they allow you to cur or boost certain frequency bands. Each control should have a center position that allows you to either cut (attenuate) or boost (amplify) the frequency band. Just think of that center position as the zero point.
Settings and Switches
On active bass guitars, the pickup gain is generally controlled by a master volume and a balance control instead of one single volume potentiometer per pickup. To find out, just turn the controls at random. If a single control allows you to turn the sound off, this means that you have a master volume pot.
Your bass guitar may feature one or three additional switches:
- Active/passive switch: allows you to power off the preamp to switch the instrument into passive mode. Convenient when the battery is empty, but limited if your bass has neither real passive pickups nor a passive tone control. Most of the time, active/passive bass guitars have no real passive design, so they should be used primarily in active mode. Here are the most common features:
- Pickup wiring selection: allows you to choose between serial and parallel pickup wiring. Series wiring design allows to have both pickups in the same circuit (as if you had only one pickup) to maximize output gain. The parallel design allows you to vary the sound from one pole to the other. You get less output gain but the sound is much more subtle.
- Coil selection for dual or triple-coil pickup: some bass guitars equipped with humbucking pickups give you the possibility to decide which pickup coil you want to use. This allows you to emphasize specific frequencies or maximize output gain.
- Phase invert switch: although quite rare nowadays, it can still be found on some instruments (Neuser, G&L). It allows you to switch between a full sound and a brighter but colder tone. Personally, I have never liked the out-of-phase sound.
It's not so difficult to get an active bass guitar under control. I'd even dare say that it's easier than a passive bass guitar. And that's because you're probably more used to working with EQ bands than to setting a master tone control. The workflow is more or less the same as with a passive bass guitar up to the tone setting step, which is replaced by an EQ. But before EQing, I recommend you to balance the pickups with all EQ bands set to 2/3 instead of zero. Once you find the right pickup balance tweak the mid-frequency band, which determines the dynamics of your signal depending on whether the frequency band is boosted or cut. A mid boost will work in most situations (finger picking, pick, etc.). However, for some music styles and playing techniques, cutting the mids will emphasize the bottom-end and the highs while providing sharper attacks (slap, tapping, etc.). So first you have to decide which way to go if your bass offers a mid-frequency control.
Then, you can dedicate yourself to the other frequency bands, taking the center as a starting point (to have a solid reference). Cut the lows and then increase them slowly until the sound has enough bottom. Take it easy — in most cases, when a bass sounds bad, it's because it is too dull. Now do the same with the highs until the signal is perfectly accurate and, if needed, bright. Both high and low frequency bands affect our perception of the mid range, so fine tune the latter if needed. Set the mids to match either the low or high frequency band depending on the pickup you're using and the position of your right hand.
A good EQ doesn't need extreme settings. Don't overemphasize the high and low frequency bands. I advise against cutting or boosting bands too heavily. To be effective, the EQ setting must be neither too dull, nor excessively bright nor too mid-heavy.
Like with a passive bass guitar, the goal is to find the right balance. Since low-impedance pickups have no specific sound character, only the EQ colors the signal. So set it carefully and don't forget that you must also set your amp next!