A question we’re often asked is, ‘how do you connect a keyboard or digital piano to a mixer or keyboard amplifier?’ Maybe you’re preparing for your first ever live gig, maybe you’re figuring out how to make home-studio recordings, or your sonic instrument of choice needs more volume if it’s going to compete with your drummer in the rehearsal room. If you’re not familiar with them, the sheer number of different ways of connecting up your gear can be a little overwhelming. But luckily, it’s all pretty straightforward once you know how.
Bear in mind that, since the sound engineer will probably (well, around nine times out of ten) connect up your instrument to the sound system for you, you might only need to take your current setup to any booked shows since there are often cables and other stage accessories at the venue. If you’re playing shows in less professional venues, then it’s definitely worth having your own gear on hand – especially some longer cables and definitely some power extension cords.
- In a Nutshell
- Keyboards & Digital Pianos
- Mixers & Keyboard Amplifiers
- MIDI Keyboards
- Do You Need a DI Box for Keyboards/Digital Pianos?
- See Also…
In a Nutshell
In most cases you can use a simple and familiar 6.3mm mono jack. Just stick one end into the Left (mono) output of your keyboard or piano, then stick the other end into a mono input of the mixer or keyboard amplifier you want to use. If there are a bunch of different sockets on the back of your instrument, or if you want stereo sound, then read on!
Keyboards & Digital Pianos
Most keyboards will have two ‘line’ outputs. These are 6.3mm jack outputs fitted next to each other and are usually found around the back. Most of the time, the jack socket on the left will be labelled ‘L/Mono’ or ‘L/L+R’, while the jack socket on the right will be marked with an ‘R’. As such, you’re free to use both outputs for stereo sound or just the left output for mono sound. Mono is usually all you’ll need, but if your keyboard has stereo sounds, like an effect that moves the sound from the left to the right, or a big 3D-sounding piano then you can use both outputs to get the full sound.
- Keyboard setup 1: If you’re just using the L/Mono output, then you can just use a 6.3mm mono jack cable (also known as a TS jack cable). You could also use a stereo jack cable (also known as a TRS jack cable) since the sent signal will still be mono.
- Keyboard setup 2: If you’re using both the left and right outputs, two 6.3mm mono jack cables are used to make the stereo connection. Here, you can also use two stereo cables, but this won’t necessarily add anything to the stereo image, since both cables will be carrying the single left or right channel.
- Keyboard setup 3: Some keyboards or digital pianos only have a headphone output. Headphone outputs are always stereo outputs. Using a cable with a stereo (TRS) 6.3mm jack plug at one end and two mono (TS) 6.3mm jack plugs at the other end, you can make a stereo connection. If you have a smaller, 3.5mm mini-jack headphone output, then you can just use a cable with a 3.5mm TRS mini-jack plug at one end and two 6.3mm TS jack plugs at the other end.
Note: If you’re setting up to play live, bear in mind that stereo sound is not as important on stage as it might be in your living room. To get the full stereo experience, you need to be sitting right in the middle of it, which isn’t always going to work when you have a crowd of people that might be standing more to the left or right of you, so they’ll only get one half of the stereo effect. As such, don’t be worried about setting up your keyboard in mono when playing gigs.
A keyboard with a big headphone output on the left (a 6.3mm stereo jack output) and a set of line outputs on the right:
Mixers & Keyboard Amplifiers
Good, now you know what cables you need to use and where you need to plug them in, it’s time to take a look at the mixer or amplifier side of things. When we talk about amplifiers in this blog, we’re not talking about the stereo amplifier you’ve got set up for your stereo speakers at home, since you’ll be in danger of blowing them up. Here we’re talking about keyboard amplifiers that are specially designed to amp-up the sound of digital pianos and synthesizers as well as keyboards.
- Mixer/Amplifier setup 1: Some keyboard amplifiers simply have a 6.3mm mono jack input, so you can plug a 6.3mm mono jack cable into the L/Mono output of your keyboard and the mono line input of your amplifier or mixer (see the example we’ve helpfully included below).
- Mixer/Amplifier setup 2: Mixers (and some keyboard amplifiers) usually have at least one stereo channel. You’ll recognise it since it’ll be a pair of 6.3mm jack inputs with one fitted above the other. Here, you can simply use two 6.3mm mono jack cables to connect the L/Mono and R line outputs of your keyboard to the two inputs of the stereo channel of your mixer or amplifier.
- Mixer/Amplifier setup 3: If your mixer or amplifier only has mono channels, but you want to set up stereo sound, you can connect the L/Mono output of your keyboard up to one mono channel of the mixer/amp, and then connect the R output of your keyboard up to the next mono channel of the mixer/amp. All you need to make sure of is that 1) the volume if both channels is always at the same level, so that the left channel is never louder than the right and the other way around, and 2) that the ‘pan’ control knob of the left channel is pushed all the way to the left and that the pan control knob of the right channel is pushed all the way to the right.
- Mixer/Amplifier setup 4: A bad situation: you’ve got a keyboard or digital piano with just one headphone output (therefore stereo), and now you want to hook it up to a keyboard amplifier that has just a single mono input. Unfortunately, no single cable can be used to convert a stereo signal into a mono signal. While you could try using a stereo or mono jack cable, you would get sound but it’s unlikely to sound ‘right’. There are two ways to solve this problem – one of which is clean while the other is a bit more messy.
- The clean solution is to hook up a little mixer in between. So, you connect your keyboard to the mixer in the same way as in Keyboard setup 3, then connect the two mono jacks up to two mono channels of the mixer, as explained in Mixer/Amplifier setup 3. Make sure not to connect the cable to the stereo input of the mixer, and in this case you can leave the pan knob of both mono channels set to the middle. Then, you can take either the L or R main output (it doesn’t matter which) of the mixer and connect this up to the input of your keyboard amplifier using a 6.3mm mono jack cable. This solution will only work if you have a little mixer with separate main outputs for the left and right – and most mixers will have this.
- The more messy solution is to use a jack cable with one stereo plug at one end and two mono jacks at the other end. You don’t need to add a mixer to your setup to do this, but by connecting the stereo plug to your keyboard and one of the mono plugs to the amplifier, you only get one side of the stereo audio image and one jack plug is left unplugged. Most of the time, you may not need the full stereo audio image of your keyboard, but if you use effects that pan the sound from left to right or use a really full, 3D-style piano sound, then this setup is likely to sound less full and balanced, since the left side will probably sound much louder or quieter when compared to the right. It’s worth trying out to see if the result will work for you or not.
Note: most keyboard amplifiers have one built-in speaker. In other words, most keyboard amplifiers only deliver mono sound. That’s not to say that some amps don’t come with a stereo channel though, it’s just that this channel is usually intended for hooking up a stereo source.
Below, you can see a really straightforward mixer. Channels 1 and 2 are both mono channels, and are for plugging in gear like a microphone (‘mic’) or audio equipment like a keyboard (‘line’). Channel 3/4 is a stereo channel with a separate input for the left and right channels.
Below, you can see a keyboard amplifier with many connection options. On the left, there’s a mono channel for a microphone or line input, and next to that, there’s a stereo channel with separate left and right channels. Channel 3 is another mono-channel which (as indicated by ‘Hi-Z’) can be used for string instruments with a jack output like an electric guitar, bass, or an electro-acoustic instrument.
- Here, you can connect your computer or laptop up directly to a mixer or amp via the headphone/line output using a cable with a 3.5mm stereo mini-jack plug at one end and two 6.3mm mono jack plugs at the other end.
- If you also use an external audio interface with your laptop (which we actually recommend since it can give the sound quality a nice boost), then it’s very likely to have a set of two 6.3mm mono jack outputs. In that case, you can connect it up to two inputs of your mixer or amp using a pair of mono jack cables (further instructions included earlier in this blog).
Do You Need a DI Box for Keyboards/Digital Pianos?
A DI box, or just ‘DI’, is a small device that converts an unbalanced signal into a balanced signal, which is explained in more detail in this blog. Most of the time, your keyboard will sound just fine when connected to the line input of a mixer or audio interface, but many sound technicians use a DI box to connect instruments like keyboards to a mixer, and they do this for a number of reasons. For a start, there are mixers that simply don’t have any line inputs and only have microphone inputs. Here, a DI box is useful since it prepares the (usually unbalanced) line signal of your keyboard for a microphone input. A DI box can also weaken the signal and prevent it from overloading the microphone preamp. It also protects your keyboard from phantom power which often comes built into mixers to provide specific microphones with power. With most mixers, the phantom power function can be switched off, but you can’t always do this per channel. So, by using a DI box, you can happily feed your condenser microphones with power without any danger of frying the output of your keyboard. Linking up a lot of audio equipment can cause signal ‘hum’ which is usually the result of a ground loop. To help counter this, many DI boxes will have a ground-lift switch which, when active, breaks the ground loop and removes any hum from the signal. As we’ve already mentioned, most keyboards have unbalanced outputs. As long as you don’t use really long cables, this won’t cause any issues, but if your cables need to travel all the way from the stage to the back of the hall, then your sound is likely to suffer signal loss and noise, all of which is solved by sticking a DI box in between.
Below is an example of a setup including a DI box. If stereo sound isn’t so important to you, then you can just use a mono DI box. The cable used to connect the DI box to the mixer is normally an XLR cable.
» Can You Connect a Microphone to a Computer?
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» How to Connect a Microphone to a Speaker
» How to Connect Your Speakers to Your Audio Gear
» How to Connect Up Studio Monitors
» Help! My MIDI Keyboard isn’t Making Sound!
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