How to Mic a Bass Amp?

(Last Updated On: February 27, 2021)
Bass guitar with amp combo setup on the stage.

When you watch band concerts, you would often get fascinated with the lead guitarist. But seldom would you notice the bass players. Yet, the bassist plays a critical role in the solidity of the music of a band. The bass sound, of course, is crucial to getting the right sound for the band. The bass player provides the band with a rhythmic and harmonic foundation.

If you listened to a recorded song, for example, you would notice that the bass line provides a steady pulse to the song. The bass line—being the backbone of most songs—is critical to the cohesiveness of the recordings.

There are three different techniques on how to record the bass guitar, namely: directly, through an amp, or the combination of two. Without this steady pulse supplied by the bass, the song will lack the rhythmic foundation that is very important to good music. Hence, the bass player should have a steady hand that can produce steady bass sound. Moreover, the bass player has that important responsibility to produce that steady pulse.

The bass also provides the harmonic foundation to a song recording. It is the unifying factor in music. Without the bass, the harmonies begin to pale. This is because we often hear the different notes relative to the bass sound or the lowest-sounding pitch.

Factors to Consider When Recording Bass Line

You can capture the direct signal of your bass line. You can do it by using a DI-box. But its use should depend on whether you are using active or passive pickups. If you are using an active pickup, you can directly connect the bass to your audio interface or mixing console. If you are using a passive pickup, however, you must first connect your bass to a DI-box to match the impedance levels.

If you directly record, you can capture the note definition and the low end of the bass guitar. Yet, you will never capture the sound’s body. You can only capture the sound’s body using an amp.

Yet, the best way to record the bass line is by engaging in direct recording together with the use of an amp. Bass amps will produce a better low-end response for coping with the bass guitar’s low notes. This gives the bass recording its punch. On the other hand, if you engage in the DI approach, you can avoid spills. You will also have more options for mixing later.

Different Methods for Miking Bass Amps

As mentioned above, there are three ways to mike the bass amp. You can either use a re-amping box, engage in direct input recording, or engage in DI and bass amp recording.

1) Re-amping Box

The best way to record the bass is by using a dedicated re-amping box. Of course, you can buy an inexpensive re-amping box. The re-amping box works like the DI box. But it works in reverse. It matches the DI bass signal for the amplifier. It also offers a hassle-free and flexible approach for matching both signal levels and impedance.

You can use the re-amp box by plugging your DI bass signal and inputting it to the re-amp box. You can connect a mic to the pre-amp box. Afterward, you can now overdub the amplified sound of the bass onto a distinct track.

2) Direct Input

Direct input is usually done when you want to directly mic the bass for live performance. Miking the bass directly has its advantage. The frequencies of bass, for example, tend to bleed onto other mics. This is because lower frequencies are characterized by less directionality. This means the bass frequency spreads in all directions evenly. However, you can always process later the DI signals, or you can re-amp it or record it.

Direct input also has a disadvantage. Its output, for example, is high and lack of bass depths. Thus, it is not advisable to plug it directly onto the mixer or the audio interface. The good thing is that most basses make use of passive pickups. Hence, you need to use a DI box for boosting its low signal.

3) DI and Re-amping Box Combined!

If you want to make a great recording of the bass line, you should combine the use of direct and bass amp. You could get a clear and clean sound of the bass if you combined the use of both methods. You will also get a warm low-end along with rich harmonics, especially if you utilize a valve amp.

You should use a DI box, especially if you don’t have active pickups. This will enable you to boost the low signal of the instrument.

The majority of sound engineers generally employ the hybrid approach. This approach, of course, is great for studio recording. You can mike the amp while using the DI box to record the bass line simultaneously. The result is a powerful and complex bass tone. You can also tinker with this recording to suit your taste and preference. The only disadvantage of this hybrid method is that you lose the advantage of sound isolation.

One caveat, however, when you engage in hybrid isolation is this—you should ensure that you align the two tracks. The track for the amp, of course, will exhibit a slight delay. Hence, you need to align both tracks. Aligning both tracks ensures that you don’t get a thin sound, or you get strange textures in the sound.

You can align the two tracks by dragging the 2 tracks to visually align their peaks. You can also align them by using a 2ms delay to get a powerful and punchy sound.


Bass Miking in Live & Studio Environments

You should configure the miking of your bass according to your miking environments. Your miking for studio recording and live playing, for example, should differ from each other:

1) Live Playing

Miking bass amps for live playing is different from miking bass for recording. This is because miking for live playing is more restricted. The common way to mic bass amps is by pointing a cardioid dynamic microphone toward the speaker of the amp.

The dynamic microphone used for live performance, of course, shows less sensitivity to the music’s dynamics. You should remember that bass playing is very dynamic. But when you compress the bass sound, it tends to sound very strong. Hence, if you use a dynamic mic instead, you can give the sound a natural compression.

2) Studio Miking

The setup for studio miking, however, is a bit different. If you use, for example, a bass DI, you can avoid the unwanted spill. You can also allow for a good drum take if you record the bass together with the drum. Moreover, if it is the bass line that is quite right, you can then feed the DI signal through an amplifier and miked it up. This process is referred to as “re-amping.”

At present, you can use any of the outboard recording channels (channel strips). These outboard recording channels usually come with DI inputs. Most of these outboard recording channels come with dynamics control and EQ. Moreover, the use of these onboard recording channels would produce great results without necessitating amplification.


How to Configure your Mic Setting?

If you already know the perfect configuration of the dials of the amplifier, you will still need to know how to set up well your mic on the guitar amp. This process can be tricky, especially if you’re required to do a quick setup for a live show. Hence, you should have prefigured out beforehand what mic to use and how to position it for live playing. Here are some tips on how to do it:

Choosing the Right Mics

In the hierarchy of importance, the bass amp belongs to the least prioritized in the setup. The vocal, of course, and the guitar amp mic is prioritized. Then, the leftover mic is often relegated to the bass amp.

Yet, you should choose a mic that is appropriate for the bass amp. You can use the classic AKG D112 (usually used for bass drums), for example, because it works well with guitar bass. This mic produces a low-end boost and can deal with high SPLs. But if you don’t have this mic, you can instead use the SM57. This alternative does a great job if you position it correctly.

On the other hand, if you use a cardioid mic, it does exhibit the proximity effect and will give you more bottom-end. It also has a good low-end response.

Mic Positioning

Finding the sweet spot for the mic when recording bass is not easy. Any small movement can impact the sound of the bass guitar. Hence, you should be very careful when positioning the mic. The ideal thing is to position the mic around 6-12 inches away from the speaker. You may experience bleed issues if you move the mic further than this distance.

Bass sound, of course, is better if you maintain the mic at the right distance from the amp. You should position or direct the mic at the center of the speaker’s zone if you want a brighter and punchier sound. If you want a dark and smooth tone, however, you should position the mic away from the speaker’s center.

You should at least maintain the mic at a minimum distance of 5 inches from the amplifier if you want to get a decent tone. Of course, a greater distance can be more beneficial if it is necessary or if the situation calls for it.

You should remember that miking the bass amp is different from miking the guitar amp. Guitar will sound good if its mic is very near the speaker. Yet, with the bass guitar, you need to maintain a certain distance between the mic and the bass amp.

Moreover, your choice of mic can determine the sweet spot between the mic and the bass amp. If the mic that you are using is very sensitive, you should not position it very close to the amp. However, if you are using a mic like that of the AKG D 5 or SM58, you need to position the mic closer to the amp. This is because these mics exhibit a lessened or diminished bass response. Yet, if the mic you’re using seems to exhibit overpowering bass tone, then, you should try to move the mic farther a bit from the amp.


Things You Should Refrain From Doing

When recording the bass line, you should avoid recording with the mic signal peaking at 0 dBFS or 0 decibels Full Scale. You will know that the mic signal is peaking if you would look at the track and see that the signal is already going red. This means that you are already going beyond the headroom. In a case like this, you need to lower the recording level to avoid digital clipping.

In doing so, you will have enough elbow room and dynamic range when you mix the tracks. If you don’t adjust the mic signal when it is already peaking close to 0 dBFS, you will find it hard to fix the mic signal later. It is better to fix it while you are recording to make your mixing later easier. Moreover, fixing the bass tone when mixing may lead to over-equalizing and over compression.

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