How to Connect Instruments to a PA System

To learn how to connect instruments to a PA system, match each instrument to the right kind of input: high-impedance instruments (electric guitar, bass, passive keys) need a DI box into an XLR mic input, while line-level gear (synths, mixers, drum machines) can go straight into a line input. Mics and acoustic-electric instruments each have their own path too. Get the input type and gain right and everything else falls into place.

This is the live counterpart to capturing a clean signal in the studio, where the same impedance and gain rules apply when you stage your gain correctly.

Know your three input types first

Every PA channel expects one of three signal types, and sending the wrong one causes weak, distorted or noisy sound:

• Mic level — the tiny signal from a microphone. Uses an XLR input and needs lots of preamp gain.
• Line level — a strong signal from synths, audio interfaces, laptops and other mixers. Uses TRS or RCA inputs and needs very little gain.
• Instrument (Hi-Z) level — the high-impedance signal from an electric guitar or bass pickup. Needs a DI box to convert it to mic level before it hits the PA.

If you are fuzzy on the cable side of this, our explainer on XLR vs TRS cables for live sound shows which connector does what.

Connecting each instrument

Electric guitar and bass

Run the instrument (or the amp’s line/DI out, or a pedalboard output) into a DI box, then an XLR cable from the DI to a mic input on the PA or mixer. If you want amp tone, mic the cabinet instead with a dynamic mic.

Keyboards, synths and drum machines

These usually output line level. Use a stereo pair of TRS or two mono cables into two line inputs, or a stereo DI if the run is long. Pan them hard left and right for a wide stereo image.

Acoustic-electric guitar

The onboard pickup is high-impedance, so route it through a DI box into a mic input, just like an electric.

Microphones and vocals

Plug the mic straight into an XLR input. Condenser mics need phantom power switched on; dynamic mics do not. For singers, our guide to micing a singer live covers placement.

Set the gain before you set the level

Once connected, bring up each channel’s gain (trim) with the fader down. Play or sing at performance volume and raise the gain until the channel meter peaks healthily without clipping. Only then bring the fader up into the mix. Setting gain channel by channel is the foundation of a clean live mix — see how to gain stage a live mixer.

Keep signal paths tidy

If your stage is more than a few metres from the mixer, a snake cable keeps your runs neat and your channels organised. Label your inputs and you will never lose track of what is plugged in where.

Frequently asked questions

Can I plug a guitar straight into a PA?

You can physically, using a quarter-inch to XLR adapter, but the impedance mismatch usually gives a thin, dull tone and noise. A DI box solves this and is the standard approach.

Do keyboards need a DI box?

Not strictly — most keyboards output line level and can go straight into a line input. A DI is only needed for very long cable runs or to convert to balanced XLR.

Why is my instrument so quiet through the PA?

Almost always a gain problem or wrong input type. Check the channel trim, make sure a line-level source is on a line input and a mic/instrument source has enough preamp gain, and confirm the channel is not muted.