This page explains how to connect microphones, mixers, CD players etc.
There are three considerations with these connections: signal level, balanced/unbalanced and stereo/monoral. These are determined by the specifications of the signal output and input equipment.
There are three considerations with these connections: signal level, balanced/unbalanced and stereo/monoral. These are determined by the specifications of the signal output and input equipment.
Signal Level
The audio inputs and outputs of devices have rated levels. Basically, terminals with the same level must be connected together.
Please note that this article does not cover how to connect an amplifier to speakers. Please see this page.
Specifically, check the rated levels on the specification sheets for both devices.
In the above example, the microphone is -54dB and the amplifier (A-1706) input is -60dB. Although there is a slight difference, they are roughly the same level, so they can be connected.
The level difference can be adjusted with the volume of the device, but if the difference is too great it can cause various problems. Please connect devices within the range of about 6dB.
In the above example, the microphone is -54dB and the amplifier (A-1706) input is -60dB. Although there is a slight difference, they are roughly the same level, so they can be connected.
The level difference can be adjusted with the volume of the device, but if the difference is too great it can cause various problems. Please connect devices within the range of about 6dB.
For TOA products, specification sheets are available on this site.
The units used to express signal level are mainly V (volts), dBu, and dBV. Each of these has a relationship as shown in the difference table. Depending on the value, it is called microphone level or line level. MIC level is mainly output from a microphone and is a very small signal. It is easily affected by noise. Line level is higher than MIC level and is the level used by CD players, mixers, etc. Many mixers have a function to boost the MIC level to the line level. It is important to boost the level to the line level as early as possible to reduce the influence of noise. |
Because dB uses fewer digits, dB is often used rather than V. For historical reasons, dBu and dBV are often used interchangeably, but there is no functional difference between the two units.
Mismatched Connections
What will happen to the output sound if the levels are mismatched?
Here are some examples of incorrectly connecting MIC level and line level.
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Balanced / Unbalanced
There are two types of connection: balanced and unbalanced.
Balanced: Connects with three wires and is less susceptible to noise.
Unbalanced: Connects with two wires and is more susceptible to noise.
Of course we would prefer a balanced connection, but what is available depends on the device.
Unbalanced: Connects with two wires and is more susceptible to noise.
Of course we would prefer a balanced connection, but what is available depends on the device.
Whether a device supports balanced or unbalanced is confirmed on the specification sheet. Both connected devices must have the same specifications.
Stereo/Monoral
Currently, entertainment sources such as CDs and BDs are stereo. Stereo has different audio signals for the L and R channels. On the other hand, most broadcasting in buildings (PA system) is mono. This page does not discuss the effects of stereo and mono themselves, but rather explains their combination with balanced/unbalanced.
The table above shows some common connectors and how the terminals are used for balanced/unbalanced and stereo/mono.
Although it is up to the installer to decide what to use the terminals for, there are certain standard ways of using them, and it is possible to distinguish between balanced and unbalanced by looking at the connector. Generally, if RCA, 3.5mm mini, or Phone is used, it is unbalanced.
Although it is up to the installer to decide what to use the terminals for, there are certain standard ways of using them, and it is possible to distinguish between balanced and unbalanced by looking at the connector. Generally, if RCA, 3.5mm mini, or Phone is used, it is unbalanced.