Study Hall

Supported By

Twice The Fun: Further Applications & Advantages Of Double-Miking

Approaches for guitars and bass of both electric and acoustic varieties as well as piano and more.

In a previous article (here), I presented approaches and advantages in double-miking a range of percussion instruments. Let’s continue the discussion here by expanding the focus.

Acoustic guitars are another instrument that can benefit greatly by being miked from more than one position. Just as guitar pickups are usually positioned at different points along the string length of an electric guitar, placing one microphone near the bridge, and another where the neck meets the sound hole on an acoustic guitar, provides a powerful tool for pursuing a spectrum of tonalities.

It’s better if the mics are identical in order to minimize phase shift between them, but I’ve seen different models work well together such as a large diaphragm condenser mic, like an AKG C414, near the sound hole, coupled with a shotgun mic, like an AKG C568B, aimed at the bridge. You’ll want to have the time available to carefully select mic types and mic placement while in a quiet environment, but the payoff is worth the time it takes.

When simple fader movements can effectively (and naturally) alter the guitar’s tonality “on the fly” from verse to chorus, and song to song, it becomes much more inviting to employ regular shifts in tonality as the set list works its way towards bottom. The use of dual mics streamlines the process of sculpting the sonic properties to best complement each musical passage, and is much easier to implement than it is to constantly change EQ settings.

Altering The Tone
Double-miking is always a win on acoustic bass. And if the bass is often featured in solos – a format common to many jazz ensembles – you might go as far as tapping three sources; i.e., a DI from the installed pickup, if there is one; a small mic clipped to the bridge under the strings; and a large-diaphragm directional mic near one of the f-holes, or close to where the fret board ends. With three sources to work with, it becomes easy to alter the tone subtly or dramatically as the music requires.

And by employing a range of tones in the mix, you can make sure that bass passages will hold their own when the rest of the ensemble is playing, but not suddenly emerge as too harsh or too trebly when the bassist takes a solo.

Case in point: I once had a good, clean bass tone from an electric Rickenbacker 4001 using a separate DI on each of its two pickups, which the stereo 4001 is wired for. By itself the bass sounded fine, but when the rest of the band kicked in, any hope of definition was lost.

After trying tons of EQ and compression to no avail, I ended up putting the treble pickup through an MXR distortion box. Instantly it became a simple task to dynamically balance the “dirty” treble pickup against the “clean” bass pickup, thus adjusting the definition as needed for each musical segment.

Whenever the bass figures were masked by the full band playing, I’d simply jack up the treble pickup to provide clarity and stop the bass from being buried in the mix. And whenever the bass was not fighting sonic masking from the other instruments, I’d drop the treble pickup fader by a few dB. This kept the perceived tonality of the bass consistent between the crowded musical passages and the open soundscapes.

Electric basses that aren’t wired in stereo (as Rickenbacker called it) can benefit from a DI on the pickups, a DI on the speaker output of the bass amp, and a large diaphragm mic on the speaker cabinet. These three sources provide the means to achieve a range of sonic qualities that suit a wide variety of musical needs.

Remember, it’s the perceived sonic quality of the combination of instruments playing at any given moment that’s important, not what you hear through the solo bus—which will probably sound atrocious when heard out-of-context with the remaining instruments.

Degree Of Separation
Figuring out what’s what is no easy task. You’re out in front of the PA but you’re hearing the sum of the instrument’s acoustic signature (if any), whatever is coming out of the instrument amp, the contribution of the stage monitors, and of course the main PA itself. No wonder it sometimes feels like you have very little control over the mix. This is especially true in small or highly reverberant environments.

But often, altering an instruments tonality will provide a more effective way of controlling where it sits in the mix, than altering only its volume level. This is a prime reason why double-miking is such a valuable asset.

Of course it’s not just bass and guitar that can benefit. When reinforcing violins, violas, and cellos, it’s advantageous to blend contact pickups (if present) with an overhead mic that captures one, or several physically adjacent instruments in a string section.

If contact pickups are not being used, a small diameter condenser or ribbon model placed as close to the instrument as possible, combined with an overhead mic a few feet above the player, provide options to quickly tailor the timbre to fit the music.

A pair of DPA directional mics used on a grand piano. The close spacing and angular inclination minimizes phase inconsistencies. Credit: DPA

And then there’s piano. String instrument? Percussion instrument? Or just an unwieldy beast? Because of its size, a grand piano presents an entirely different set of needs and opportunities. Mics placed over the center node of the long bass strings will provide a rich, round, and powerful sound, while mics placed near the hammers or bridge will provide more complex harmonic content, making the sound brighter, clearer, and punchier.

However, there’s likely to be phasing issues when using multiple mics that are several feet distant from one another. Experiment by all means, but it’s unlikely that you’ll be able to blend widely separated mics without at least some cancellation artifacts. Still, you can use one set of mics for certain tunes, and the other set when a different sonic texture is called for. Or pair the bass section nodal mics with the treble section hammer mics. Or vice versa.

Guitar amplifiers take many forms these days, with more and more offering built-in direct outputs. As a starting point, the use of the direct output is good insurance against a possible blown speaker in the guitar amp during the show, but it may or may not provide the sound you’re seeking. So augment the direct out with a mic on the amp’s primary loudspeaker.

Two mics on a guitar amp, and at left, varying the distance between the two. Credit: Jeff Capps

Further, when circumstances permit, try two different types of mics on an amp or even on a bank of amps when that’s the situation. There are many good choices, such as an Electro-Voice RE20, Shure Beta 52A or SM57 for capturing warmth and body, coupled with a Royer R-121, Sennheiser e609 or Shure Beta 87A for a crunchier, sharper quality. You can also place these at different distances.

The use of dual mics works far better than messing with EQ over and over as the performer inevitably dials in new tones for every song segment, and/or switches guitars for different musical moods.

Impact Of The Effect
Rather than complicate things, the use of dual mics can make the effects game an easy win. By keeping one mic predominantly dry and the other fairly wet, it’s a simple task to play with reverberant content. You can accentuate the reverb tail at the end of a musical figure by bringing up the wet fader, or eliminate reverb altogether for an intimate experience during a guitar-only passage by bringing it down.

Other effects can be split among the mics, or anchored to just one. While it might take some time and practice to get used to, in the end you’ve got a super-simple means of playing with the impact of the effect without having to think about what’s routed to where.

One approach to double-miking a saxophone.

One other note: it may be advantageous to have a second operator work with you. In such cases, dual miking really comes into its own. Dual mics provide the side benefit of letting each operator adjust tonalities on “their” instruments without having to hog the single EQ section that’s common on most digital desks.

And as much as I am personally in favor of never being afraid to use extensive EQ, if that’s what’s called for, I’m an even bigger fan of dual miking. The range of tones, and the ease with which they can be achieved—and continually tweaked in real time – is a very different experience than that of using EQ, even if you were to ride the EQ controls non-stop throughout the show.

Study Hall Top Stories