Live sound technicians at music venues generally use two main methods of running electric guitar and bass guitar through the PA system: Miking up a cabinet, or running a DI (direct injection) from the amplifier head or a dedicated DI box (or direct box). While guitar cabs are more commonly miked up and bass amps DI’ed, either method can work for both instruments depending on the situation, the style of music, and the player’s equipment. This article will give a basic rundown of both methods and help you decide which will work for you, whether you’re a soundman or on the stage performing.
Carvin Audio’s M67 instrument microphone is perfect for use with guitar cabs.
Why Mike a Cab?
Miking a guitar cabinet is a simple and reliable method that accommodates all aspects of the guitarist’s setup, from his or her guitar, to effects pedals, to the amp head, and finally, to the cabinet. The type of speakers and cabinet used (and how they work in conjunction with the amplifier and everything else in the chain) are responsible for a large part of the guitar’s overall sound. For instance, if the guitarist uses a tube amp pushed into overdrive, the speaker is instrumental in many of the harmonics and overtones present in the sound they hear on stage. This is also what the guitarist was hearing to create their sound. Distortion and overdrive tones through the speaker are rolled off by the speaker in the 3000 to 5000 Hz frequency range depending on the speakers used. The amplifier may not be rolling off at this point, so a DI (or direct out) from the amp may sound very bright and thin in comparison to the speaker cabinet. Thus the large amount of speaker emulator outputs on amps and specialty direct boxes.
Some Hints on Miking a Guitar Cabinet:
The center of the speaker is where most of the really high frequencies come from, and these are usually much louder at close miking then the mids and lows. For a more even response it is best to place the microphone off center of the speaker. Here we are talking about the actual round front of the speaker and not the whole front of the cabinet. On cabinets with more than one speaker, you can experiment with placing it between the speakers or go to one speaker and place it off center to the outside edge of that speaker. Placement will change the sound and in some cases this could be a huge change.
When to Go DI on Guitar:
That is not to say you cannot or should go direct out on guitar. If a guitarist gets most of their sound from effects pedals or other effects processing, rather than an amp and cab, a direct out setup may be suitable- just make sure to place it after all of the essential effects before you send it to the console. Also, if the guitarist is using a cabinet that just doesn’t sound good or isn’t suited for the room, or if you just can’t get the right mic placement to make this setup work, it’s worth it to try a DI. Also don’t be afraid to make some major adjustments to the DI’s console channel EQ to get a good sound. A good start is to roll off the highs above 5000Hz and maybe cut some high mids in the 900 – 1500Hz range.
To DI or Mic a Bass Cab?
DI is the preferred live sound engineer’s preference for bass guitar for numerous reasons. It is simple, helps to compensate for bad room acoustics, and accurately captures a clean, fairly neutral bass signal that is easy to adjust at the mixing board. Many bass amps, including the Carvin Audio BX1600, BX250, and B2000 come with built-in DIs with pre/post EQ switches to further shape the tone going to the board.
Bass Amp Miking:
Just like guitarists, many bassists use effects pedals and other tone shaping tools to create their signature sound, in which case miking a cab may be the better option. For instance, if the bassist has a very distinct overdrive sound created by a pedal, a DI may not accurately capture it, as much of that sound is shaped by the amp and cabinet. Attempting to put a DI right after the overdrive and send it to the board may result in a brittle sound, as the amplifier’s EQ and cabinet tend to round out bass overdrive sounds. When available it is ideal for bass to have both a DI and miked cabinet. This also helps when the bass amp is a little under powered for the band. Here the bass player maybe playing a little harder on the strings, but the cabinet and amp have rolled off much of the high frequency clicking string fret noise. The direct out would pick up all the string clicks right off the bass. Also some bass pickups are better at hitting the amp’s front end with strong mids, but may not sound as good going into a DI.
There are no hard and fast rules when choosing to go with either method. Every player is different; so take the time to really experiment with both. Leave us a comment and tell us which setup you prefer.