Pickups Demystified: Active vs Passive Pickups

Most guitar players are familiar with passive pickups, the original pickup design that involves thousands of winds of thin wire and produces tones from jazz to rock. However, there’s a whole other technology out there that many guitarists either love or hate, for whatever reason. I’m of course talking about active pickups, those “9v battery required” guitars. Contrary to popular belief, active pickups weren’t designed primarily for skull inlayed guitars! There are quite a few advantages to active pickups in both sound and performance that I think is worth looking into.

Key advantages of active pickups

The initial output of active pickups is quite low, but since active pickups rely on a preamp of sorts to boost the signal, some advantages spring up. Magnetic fields surrounding a traditional passive pickup are quite high, resulting in string pull that may negatively affect sustain and tone. Since active pickups are designed with weaker magnets, they will have more sustain by letting the string vibrate freely. Freakish overtones that come from placing your pickups too high will also disappear.

Have you ever noticed your humbuckers change tone when all you do is roll back the volume? Active pickups are virtually immune to this problem as stated on EMG’s site, “Unlike a traditional passive volume/tone system, the low-impedance EMG system lets you turn down the volume with very little effect on the tone, so you won’t sound muffled when you back off .” The key to this statement is LOW Impedance. Most of the benefits of active pickups revolve around the benefits of low impedance versus a traditional high impedance guitar output signal. You may already know that a Les Paul style guitar will have pots as high as 500k or a Strat style single coil guitar using 250k pots for volume and tone. But with active pickups, you will take it down to as low as 25k for EMG pickups and Duncan Blackouts for example. One reason for the low value is to keep these lightly wound pickups from sounding too trebly and to maintain a low resistance/impedance.

As a side note, I have found that you can remedy the roll back issue with passives by using a “treble bleed mod.” Just solder in a capacitor to your volume pot (usually a .001 cap) and retain more treble as you roll back the volume. But I digress, there are other benefits to Low Z pickups than just a transparent volume taper. Think about all the benefits of a quality buffer and you have your answer. Longer cables can be used without high frequency loss, especially useful on stage or with a complicated pedalboard setup. Also, active pickups are often converting to a balanced signal, which takes your guitar or bass to the same low noise environment as pro audio gear. Less hum and low radio interference make low impedance pickups ideal for pristine recording and wireless setups.

Ever notice how bass players seem to embrace active pickups more than guitarists? It may be the low noise factor but most importantly it comes from the flat, clean signal they offer. Remember the fact that actives don’t get the same amount of winds on a bobbin as passives do. As you over wind a pickup, the output is louder but the tone is darker. The excited signal produces a wider range of low, mid, and high frequencies that is amplified and sent out distortion free, a bassist dream! The snap and increased sustain that comes from active pickups as well as increased headroom is ideal for slap happy players. However, this wider frequency response provides the ideal canvas for metal guitarists. If you want to pile on the distortion, you want two things as your foundation: a low noise signal and a crystal clear tone. This way, dropped tunings and high speed shredding will remain articulate with a sharp attack as opposed to muddy and undistinguished.

Difference in construction

The classic EMG 81 uses a ceramic magnet to provide it’s sharp punch regardless of how dirty the signal. However, pickup designs such as the EMG 85 use Alnico V magnets for the same reasons as vintage pups, a warmer tone. Also, Duncan Livewires try to get closer to the sounds we know and love like the ’59 and JB by using the same resonant frequency. In theory, this gives you all the benefits of both worlds. Although I haven’t tried Livewires in anything other than the Dean Mustaine axe, they seemed promising with their vintage voicing.

Active can also come in different forms. Take for example the active midboost circuit commonly used for Clapton’s woman tone. Installing this simple battery powered preamp in a Strat let’s you boost midrange and gain for that fat humbucker like tone with the single coil spank intact. It also apparently converts the impedance from high to low, as evident by the changing of the volume pot from 250k to 50k. This seems like a nice compromise between vintage and modern to me, especially if you want to preserve those classic tones.

Active pickups do have their perks as do passive. The question is which one sounds good to you. Personally, I’m going to look into the Lace Alumitone, which I stumbled upon in my research. They are passive but have a huge frequency range and use 95% less wire than a normal pickup. Oh yeah, their output only measures 2.5k but they are loud and lightweight to boot. Confused? Yes I am.

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