Plugging in Guitars
| Site: | QSC |
| Course: | House of Worship Audio Training |
| Book: | Plugging in Guitars |
| Printed by: | Guest user |
| Date: | Thursday, 21 November 2024, 7:53 AM |
Description
Lesson Description
Learn the different ways to get both electric and acoustic guitar signals into your PA systems mixing console.
Video Transcript
00:14
In this video we are going to be discussing how to properly plug in and connect an acoustic or electric guitar,
00:21
as well as a bass guitar to a PA system.
00:24
We’ll also look at a few techniques for miking guitar amplifiers and acoustic guitars directly.
00:30
Let’s dive right in and get into part 1: The D.I.
00:35
Instruments like electric guitars and basses
00:37
produce an output signal that has a so-called high impedance.
00:41
In addition to being high impedance, it is also an unbalanced signal.
00:47
Remember our discussion on balanced and unbalanced signals from the Audio equipment video.
00:52
For the purposes of this video, all you need to know
00:56
is that in most cases a signal from a guitar cannot be directly sent to a microphone or mixer preamp.
01:03
To make it compatible, we have to convert the signal from high impedance, unbalanced
01:09
to low impedance, balanced.
01:12
To do this we need something called a Direct Box or D.I..
01:17
We discussed this briefly in the “Go with the Flow” video in which we walked through the signal path of a PA system .
01:24
Without a D.I., connecting an instrument such as an electric guitar or bass directly to the PA
01:30
will cause signal degradation and unwanted noise.
01:34
Using a D.I. also allows to use much longer cable runs.
01:38
We start by connecting the instrument into the D.I. with a ¼” TS cable. Also known as an instrument cable.
01:47
The TS stands for Tip/Sleeve, in reference to the hot and common connection points being soldered to the Tip and the sleeve of the connector.
01:57
This is an unbalanced cable.
02:00
The output of the D.I. then needs to find its way to the mixer.
02:03
In some cases, if the location of the mixer permits, the connection can be made directly.
02:09
This is done simply by connecting XLR cables, which are balanced,
02:14
from the outputs of the D.I. to the inputs of the mixer.
02:18
Many times the D.I. will connect to either a digital or analog signal snake on the stage
02:24
that then carries the signal to the mixer. And that’s it. From there, you simply dial in your mixer preamp to the appropriate level.
02:34
It is also good to note that this practice is most commonly used with acoustic and bass guitars.
02:41
While it certainly can be used with electric guitars, it’s not quite so common.
02:46
With that said, if you are dealing with an electric guitar,
02:50
you are probably working with either an amplifier and a speaker cabinet on stage,
02:55
or what is called an FRFR guitar setup.
02:58
This is essentially a digital guitar modeling device that does not require an amplifier and loudspeaker on stage.
03:06
We’ll talk about these both..
03:08
We’ll start with an amplifier and speaker cabinet on stage.
03:12
To get this into our PA system, we’re going to use a microphone to capture the sound coming from the cabinet and deliver that into the PA.
03:21
We’re going to take a look at a couple of common ways that a guitar amplifier can be miked.
03:26
The first thing we’ll need is a dynamic microphone to capture the sound of the guitar cabinet.
03:32
Now, when placing the microphone in front of the cabinet, there are a few things to take into consideration.
03:38
One of them is the distance at which the microphone is placed from the grill cloth of the cabinet.
03:44
The other thing to consider is the position of the microphone in relation to the speaker within the cabinet.
03:50
Placing the microphone directly in front of the speaker driver will produce a different sound than placing it in the middle of the cone
03:57
or even on the outer edge of the cone.
04:00
For most dynamic microphones, you are going to want to place the microphone about an inch, or 2.5cm away from the grill cloth.
04:09
This will cut down on some of the low frequency build up that can occur if the microphone is too close.
04:15
If the microphone is placed directly in front of the center of the speaker,
04:18
you are going to get a lot of high frequency content in the microphone. It will be very bright sounding.
04:25
With the microphone placed in the center of the cone, you will get a good amount of mid-range which will result in a fuller tone than a center mic position.
04:35
On the outer edge, the sound loses high frequency content and is richer in mid and bass content
04:42
The choice you make is fairly subjective
04:44
and also depends on the type of guitar amplifier and speaker driver.
04:49
Ok, now, let’s talk about an FRFR setup.
04:53
Depending on the performer, you might approach this in two different ways.
04:58
In the simplest setup, the modeler would be run direct to the mixer using a Direct Box.
05:04
Sometimes, however the player will use a loudspeaker such as a K.2 or CP series,
05:10
connected to the modeler as an alternative to a standard guitar amplifier and cabinet.
05:15
In this instance, you would use the direct output from the loudspeaker to carry the signal to the mixer.
05:21
That covers the basics. There are more techniques that can be used,
05:25
such as placing the microphone further away from the cabinet to capture a more natural sound and blend the ambient sound of the room in a little.
05:34
Changing the angle of the microphone or even using two microphones and blending the two together in the mix is also possible.
05:43
For the purposes of this video, we aren’t going to get too far into these techniques.
05:48
Well, that covers it for now. I'll see you on the next video