I was just lent a keyboard (a Korg SP-200) and would like to buy low-cost external speakers for it. What should I look for in speakers for a keyboard?
A keyboard like this creates a full spectrum of sound, and you don't generally expect your amplifier and speaker to add colour to the sound. The keyboard outputs stereo (or, optionally, mono) line level, unlike the much quieter "instrument level" that comes from a guitar.
As a result, you're looking for most of the same properties as a you'd be looking for in a set of speakers for a CD player or an MP3 player.
Whatever the output connectors on the keyboard are, you will be able to find adapters to make it fit any of the solutions below.
- PC speakers -- a pair of speakers and maybe a subwoofer, with a built in low power amplifier and a 3.5mm plug designed to go into a PC's sound card. They range from cheap and tinny sounding to more expensive and as good as a hi-fi
- A hi-fi -- just connect it up as if it were a CD player, or any other sound source.
- A powered PA speaker / keyboard amp. -- now we're approaching "gigging" territory. These look like guitar amps, but they're designed to have a full frequency response and not to distort the sound. They have the disadvantage of usually being mono. They have the advantage of being all in one unit. They range from small units that'll fill your living room with sound, to 4 foot high monsters that will fill a large hall.
You need two things to be able to get external sound, an amplifier and a speaker. Often these will be combined.
In addition to budget, the other consideration is use. Are you planning on playing with a band? At home? How load does it need to be? How great does the quality need to be?
Assuming that you just want to practice at home, I would suggest one of two things:
- Plug it in to your home stereo. Your stereo almost certainly has some inputs that you can plug in to (probably RCA or 1/8th inch) and your keyboard probably has 1/4 inch output. All you need is an adapter to take you from one size to the other, and you are good to go. If you already have a stereo, you're done. You could also buy a cheap stereo, or even an ipod dock, just as long as it has some kind of input.
- Search for "Keyboard Amp" online. You can get one that is quite cheap (all things considered). This might be a bit more portable and will be designed for a keyboard. If you want to play with other people or travel with the keyboard, this may be easier.
Most small speakers that sit at ear level do a poor job of reproducing the frequencies of the low notes. You may hear the bass notes, but they don't sound as rich and full as the signal being sent out of the keyboard. Thus it is essential to purchase speakers with a powerful subwoofer. Commercial keyboard amps have a bass speaker or subwoofer built in. Other kinds of speakers have the subwoofer as a separate component in its own cabinet that sits on the floor.