How to Connect an Audio Device to Your Keyboard to Hear Both Together

To play keyboard alongside your favorite song, of course, that song has to be playing on something. Many electronic keyboards have inputs for plugging another device (such as another instrument, a microphone, or a music player or iPod or phone) into them. This setup simplifies your cabling and connections and lets you listen to both devices at the same time through headphones.

Get some good headphones. You want to be able to listen to the song very intently, and that’s best done with headphones on. If you’re going to be figuring out a song, you’ll be repeating sections of it over and over (and over), which can get pretty annoying to other members of your household who can’t help but hear what you’re doing.

Finding a line input and getting connected

Take a look at the back panel of your keyboard for jacks labeled Line In, Audio In, Aux In, and so on. If your instrument has this kind of jack arrangement, then connecting an audio player to it is no problem.

With the jack located, you need to determine the right type of cable to use. Most portable CD players and all MP3 players have a stereo 1/8-inch (actually mini 3.5-millimeter) jack for the output. If your keyboard has a single jack labeled for input, you need a cable with a stereo 1/8-inch (3.5 millimeter) male plug on each end.

This size plug is the most common one found on mobile phones, media players, and most earbud headphones. It’s available in mono and stereo versions, so be sure you have the stereo version, indicated by dual black rings near the tip of the plug.

The 3.5 millimeter plug makes a good connection, but can be a bit fragile. Always be careful not to tug on the cable or put pressure on this connection.

If your keyboard has dual inputs, they likely use 1/4-inch phone plugs.

Credit: Illustration by Lisa Reed

At most stereo, music, and electronics stores, you can find cheap adapters that let you convert 1/8-inch connectors into 1/4-inch connectors and vice versa. So if you have the wrong connectors for what you’re trying to do, go get an adapter.

1/4-inch size is the most common plug used in musical instruments, mixing boards, and instrument amplifiers. It’s the largest plug used and makes a great connection because of its long shaft. It’s available in mono and stereo versions, so be sure you have the mono versions, indicated by single black rings near the tip of the plug.

To connect this kind of jack to your device, you need a cable that has a male 1/8-inch stereo plug on one end and splits out into dual mono 1/4-inch male plugs on the other. You can find this Y cable in some electronic stores and online. Or use the adapter mentioned earlier.

Finally, if your keyboard has dual RCA inputs — round inputs with a raised ring with a deep hole in the middle — you’ll need a cable with a male 1/8-inch stereo plug on one end and dual RCA male plugs on the other. The RCA plug is commonly used in home stereo and home theatre audio/video products. It makes a great connection.

With the music player connected, you should check your owner’s manual for instructions on setting the levels for the inputs and test out your connection by listening to some music through your keyboard (ideally on headphones).

No input? No worries: Moving forward with a mixer

If your keyboard doesn’t have dedicated inputs to connect your music player to, you need to use a device called a line mixer or mixer. A mixer combines multiple sources of audio and allows you to hear them all from a single set of outputs, such as headphones.

Your music player likely has a stereo 1/8-inch (3.5-millimeter) output that needs to connect to the mixer; the keyboard probably has dual 1/4-inch or RCA outputs. Or you can use the single stereo headphone output (either 1/8-inch or 1/4-inch) to connect the keyboard to the mixer.

Mixers have inputs called channels, and these are usually mono. Because your device and keyboard have stereo outputs, your mixer needs two channels to connect your music player and another two channels for your keyboard. Therefore, you need a four-channel mixer.

Some mixers have stereo channels (two inputs for one channel) or have stereo tape or aux inputs, so you can get by with fewer channels in these cases. Some two-channel micro mixers have a stereo 1/8-inch input for one channel and dual RCA inputs for the other channel, which would also covers your needs.

Bottom line: You have some options when it comes to mixer setup. As of this writing, there are models costing less than $60 that work with most standard keyboards and music players. Just be sure that the mixer has a headphone output (1/8-inch or 1/4-inch stereo jack; it may not specifically be labeled “headphones”).

Credit: Photograph courtesy of Alto Professional

The cables you use to connect your keyboard and audio player to the mixer have male plugs on both ends, though what kinds of plugs those are depends on your specific equipment.