Amplifiers, Sound-Systems, and How To Use Them

I've always believed that the sound of a musical instrument should inspire its performer, and that inspiration actually lifts the performer to new heights in the quality of a musical performance.

The KeyMusician Keyboard has no exemption from that rule, and indeed, is subject to it even more so than other instruments.

If you use only your laptop speakers for playing music, no matter how good those speakers are said to be, it won't inspire you as a musician, and it won't impress people listening.

So how do we go beyond using the laptop speakers, to a sound that will both inspire, and impress?

Your laptop computer, and your desktop computer have plugs for connecting to an external sound system:


The plugs on the side of a Mac laptop – notice the round hole with the earphones symbol

The earphones plug-in is what you use to connect to an external sound system. Sometimes this plug-in is on the front of your laptop. There is also a microphone input plug-in next to it.


The plugs on the front panel of a desktop computer – notice the round hole with the earphones symbol

The earphones plug-in is what you use to connect to an external sound system. There is also a microphone input plug-in next to it.

A lot of desktop computers also have a back-panel connection into the computer's sound-card, as shown in the picture below:


Plugging Into a computer's sound-card, on the back panel – use the green plug-in

The blue plug-in is for line-level (AUX) input, and the pink plug-in is for microphone input.

Be aware that when you insert a plug into the front-panel plug-in, it disables (turns-off) the back-panel plug-ins. This means that if you plug-in earphones to the front-panel, the amplifiuer & speakers (plugged into the back-panel) are silent, letting you listen in private.

On laptops, sometimes it is necessary to change the system's sound options to toggle between the laptop speakers, and a connected sound system (or headphones).

So now we know where we connect a sound system to your computer, what do we connect it to?

The quickest and easiest way to get good sound is to plug-in headphones, or ear-buds:


Stereo Headphones

Notice the 1/8” (3 mm) stereo plug, which could be plugged into your computer. Notice that next to it, is an adapter plug you could plug it into, for components that require a 1/4” stereo plug connection.

The headphones shown above are low/medium quality. Quality headphones tend to be more bulky.


Ear-Buds, With 1/8” (3 mm) Stereo Plug

Some people (not me) like ear-buds.

But there is one problem with headphones or ear-buds. When using them, you get good sound from quality headphones or ear-buds, but you can't share the sound of what you're playing with anyone nearby. Sometimes you want that privacy, but sometimes you want to show people what you can play.

There are small sound-systems available having better sound than most laptop speakers, such as this cube-speaker:


A Cube-Speaker and Amplifier

The USB cable (mini-USB to USB) cable shown supplies power. There is an audio cable plug-in, or you can use Bluetooth for sending the computer's audio to the speaker.

But speakers this small, having no 'woofer' (or sub-woofer) for the bass (low notes) is still barely tolerable for sound.

Here is a touch-screen computer, that boasts of “THX move-quality sound”, but with out a 'woofer' speaker for the low notes, it's inadequate:


Touch-Screen Computer With “THX” Quality Speakers – Yet Still Inadequate

There are sound systems for your computer that include a 'woofer' speaker for those low notes.

When I was starting out, I purchased the sound system below from RadioShack, which has left and right (stereo) speakers with a volume control, but also includes a sub-woofer:


Computer sound-system (inexpensive), with left & right speakers, and...


A sub-woofer under the desk

This system has a good sound – including the low notes. I still use it on one of my test systems. But it's power is only sufficient for a small room – even at full volume.

There are better versions of this type of sound system:


Left and right desktop speakers of a good computer sound system, with...


A sub-woofer under the desk

This system produces really good sound – including the low notes. But it would be a pain to transport to (and setup at) a concert site, and wouldn't have enough power for most performance venues.

Another way of getting quality sound in your home, is to connect to your home stereo system, such as shown below:


Home Stereo System (with computer monitor on top) – Very good quality sound, and good power

This sound system produces the best quality sound of all of my systems. But how do you connect to it?

If you shine a flashlight behind it, and use a mirror to look at the back of it, you'll see something like this:


Home stereo system, showing “RCA Plug” connections in the rear

There are audio cables (purchased at places like Guitar Center, or RadioShack), which will convert from the 1/8” (3 mm) stereo plug, to dual (left/right) RCA plugs needed by the stereo amplifier. There are also all kinds of audio cables and plugs available, such as the ones shown below:


Audio cables and plugs (left to right, A to H)

A. Microphone, with 1/8” (3 mm) mono plug (male)

B. 1/8” (3 mm) stereo (male) plug, to XLR connectors, for connecting to house/hall/church sound system

C. 1/8” (3 mm) stereo (male) plug, to 1/8” (3 mm) stereo (female) plug-in

D. 1/8” (3 mm) stereo (male) plug, to dual RCA plugs (male), for connecting to a home stereo system

E. 1/8” (3 mm) stereo (male) plug to 1/8” (3 mm) stereo (male) plug, most commonly used cable

F. Dual 1/8” (3 mm) stereo plugs to single 1/8” (3 mm) stereo (female) plug Y-cable

G. 1/8” (3 mm) stereo (female) plug-in, to 1/4” mono adapter plug, used for plugging into a guitar amplifier (silver color)

H. 1/8” (3 mm) stereo (female) plug-in, to 1/4” stereo adapter plug (gold color)

I reference these cables or adapters later in the article by the letters in the list above.

A home stereo system can get you a great sound, but needless to say, is not easily portable to a performance venue.

But one of the cables above (B) will let you (with the help of the sound person of the performance venue) connect to the house sound.

There is a version of the home-stereo system model that I have used in performances. Early on, I used a stereo amplifier (purchased at RadioShack), shown below, with cable “D” to connect to it:


Small stereo amplifier I used early-on in performances

This amplifier barely had enough power for a church, and its sound quality depended on the speakers used. The speakers shown below (still used in one of my test systems) were barely adequate. Better speakers would have helped:


Speakers used with the small stereo amplifier shown above

This brings up the subject of quality of speakers.

Speakers have small speakers (the cones within them) for making the high-pitch notes. But for the low (bass) notes, they need a larger speaker cone. Probably any speaker having less than an 7-inch diameter cone, will not give you the power in the low notes that you need.

In shopping for speakers, have the store person demonstrate them, both for the sound of the high notes, and the low notes. Just because a speaker has a fine wood finish, does not mean it is a good speaker!

As I began doing more public performances, I used other sound systems that worked better.

The first of these, was a modern boom-box – the sort of system used by disk-jockeys at parties:


Boom-box, used in performances

This amplifier is stereo, and has a very good sound. It has the power to fill church size halls (barely). It has a bass-boost, which helps with the low notes. I used cable “C” (shown un-plugged above) to connect to it.

One of the advantages of this system, is that it can be run on battery power, so I have been able to use it in outdoor venues (such as out camping).

The disadvantages of this amplifier, is every time you turn it on, you have to manually set the volume level, and also indicate to use the audio interface. You can't set a volume level, and leave it set for next time. Also, it barely had the power to fill the halls where I performed.

To solve these short-comings, we purchased a guitar amplifier (shown below):


Guitar amplifier used in performances – particularly in large halls

This amplifier has more power, but it is mono-phonic (a single speaker). In performing, that has been fine, as long as both the left and right channels from the computer's stereo sound, are merged together – you don't want to have only the left, or only the right channel sound.

This is because some instrument sounds (such as stereo harp, but also many piano sounds) have the low notes stronger on the left, and the high notes stronger on the right. If you only had the right channel, low notes would be too soft.

Here is the control panel of this amplifier:


Amplifier plug-in and control panel

Most of the time, I would use cable “E” (of the cables shown earlier), to connect to the “AUX IN” connection. But if I wanted to have a set volume level, or use any of the available effects, I would plug in the “G” adapter plug into the “INPUT” plug on the left, and connect the computer to it using cable “E”.

With the “AUX IN” plug-in, the computer totally controls the volume, and the volume knobs have no effect. Of course, it's easy to control the volume from the keyboard.

The problem with this amplifier, is that it is over-powering for a small venue, and it won't run from battery power.

We got another amplifier (shown below) for smaller venues:


Amplifier used in smaller venues, having a separate microphone control and plug-in

The “AUDIO” knob controls the computer volume, and there is a separate volume control for the microphone. Even though the two speaker-cones within it are less than 7 inches diameter, it does have a good bass (low notes) sound, and it is (to a limited degree) stereo, rather than mono.

Here is the left plug-ins panel of this amplifier:


Left side-panel of Roland Mobile AC amplifier, with audio plug-in from computer, and AUX input (RCA plugs) from another computer

This amplifier also runs on battery power, so it can be used in outdoor venues, such as around the campfire.

We've covered a lot of material in this article, and there is another article (yet to come) covering details of this subject relevant to performing in public.

I hope this article gives you the details to make changes, so that your instrument inspires you to new heights as a musician, and impresses your fans!

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