Lou Hinkley

Amplifying the Acoustics

articles from Acoustic Musician Magazine


Amplifying the Acoustic’s # 2


You are no longer just a straight acoustic musician. You have "plugged in". And there is a whole new language that goes with plugging in. So unless you’ve spent some time in a band with an electric guitar, you’re vocabulary probably needs to be expanded. If you thought that maybe "effects loops" is a breakfast cereal and "patch cable" is the sound-techs’ dog, read closely.

First I should briefly describe what’s called the signal path. This is the path where the sound created at the instrument (mechanical vibration) is translated to electrical energy (the signal) and then back to a mechanical vibration (sound) at the speaker. The path is essentially the same whether you are using a small one piece amp, a component system, or a sound system at a festival. In a later article I will describe this path in detail, but for now I just want to stress that every part of this path will help determine the quality of your sound. Including the cables that carry the signal from your instrument to the speaker.

Patch and instrument cables are shielded audio cables that rout the signal from one source to another, beginning with your instrument and ending with the power amp.

Shielding is when the ground wire is braided around the other wires in the cable to guard against hum. The copper wires within these cables are usually 20 gauge, which is much smaller than speaker wires. By using good patch cables and keeping them as short as possible you can prevent signal loss. Quality is especially important for the cable from your instrument, as this is conducting the weakest signal.

Speaker cables connect the amp to the speaker. They are not shielded and they use large diameter wire, typically 12 gauge. These cables must conduct a large amount of power to the speaker without losing information or altering the signal in any way. All wire is not created equal and all copper is not the same. A heavy, low resistance wire (oxygen free copper is best), can improve your sound.

Acoustic instruments have many subtle nuances that can be lost by using inferior cables. You don’t have to use the most expensive esoteric cables but good, solid quality is necessary to get the best from your amplifier and your acoustic instrument.

Now for a few rules of the road about patching;

Never substitute speaker cables for patch cables or visa versa. Never use a Y cable to sum two signals, this can damage your amp. Always be sure the amp is connected to a speaker and don’t connect the speaker output of an amp to anything other than a speaker. This may sound obvious but I’ve had people do this, with disastrous results.

By connecting the send and return jacks of the pre-amp to the return and send jacks of the effects unit with patch cables, we make a loop in the signal path, yep it’s called an effects loop. If you have problems here, the first place to check is that the input connects to the correct output and that all patch cables are fully inserted.

When you "plug in", your instrument is no longer the end of the chain, it is the beginning. What your audience actually hears is the amplifier and speaker at the other end of that chain. And your sound may only be as good as the weakest link in that chain. AM

Acoustic Musician / January1997