= Alsamixer-Plus User Guide
:alsmixer-plus-page:

anchor:table_of_contents[]

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[[toc]]
[compact]
* link:#under-toc[Conventions]
* link:#_what_is_alsamixer_plus[What is Alsamixer-Plus]
* link:#_typical_use_cases[Typical Use Cases]
* link:#_overview[Overview]
* link:#_boosting_a_low_volume_level[Boosting a Low Volume Level]
* link:#_setting_a_preferred_frequency_balance[Setting a Preferred Frequency Balance]
* link:#_changing_the_defaults[Changing the Defaults]
* link:#_summary_of_files[Summary of Files]

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[[under-toc]]
== Conventions
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[icon="./images/icons/info.png"]
[NOTE]
This is additional information

[icon="./images/icons/tip2.png"]
[NOTE]
This is a tip

[icon="./images/icons/settings.png"]
[NOTE]
This is an example configuration or setting

<<table_of_contents,Table of Contents>>

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== What is Alsamixer-Plus

It adds extra facilities to an alsamixer audio controller by providing a pre-amp and a frequency band equalizer.

<<table_of_contents,Table of Contents>>

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== Typical Use Cases

The local loudspeakers under or over emphasise some audio frequencies. +
The equalizer can correct the imbalance. +
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The local system outputs a low audio volume level. +
The pre-amp can boost the overall volume level.

<<table_of_contents,Table of Contents>>

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== Overview

The audio signal passes from the default ALSA device along a chain which includes two signal processing stages.

*Stage 1: Equalizer* +
Various frequency ranges in the signal can be boosted or cut. +
Alternatively the signal can be left unchanged i.e. it remains flat.

*Stage 2: Pre-Amp* +
The entire signal level may be boosted or cut. +
This adjusts the overall volume of both playback and recording.

The last link in the chain passes the audio signal to the local loudspeakers or to an external audio system.

[icon="./images/icons/info.png"]
[NOTE]
The effect of the stages is cumulative and works in conjunction with changes you make to other alsamixer controls.

[icon="./images/icons/tip2.png"]
[TIP]
Both the equalizer and pre-amp may be operated from within the usual alsamixer interface. +
You can switch between them by using the F6 key on your keyboard.

<<table_of_contents,Table of Contents>>
 
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== Boosting a Low Volume Level

Open alsamixer +
If neccesary use the -> key on your keyboard to scroll to the Pre-Amp control usually located at the extreme right of alsamixer. 

image:alsamixer-plus/pre-amp.jpg[]

The pre-amp level can be adjusted in the usual way by the up/down arrow keys on your keyboard.
[icon="./images/icons/info.png"]
[NOTE]
Using an excessively high level may overload your loudspeakers, which is usually heard as distorted sound, and may result in damage.
Set the lowest level of boost that gives you an acceptable volume level.
 
<<table_of_contents,Table of Contents>>

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== Setting a Preferred Frequency Balance

Open alsamixer +
Press the F6 key on your keyboard to _Select sound card_. 

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image:alsamixer-plus/equalizer_f6.jpg[] +
Use the up/down arrows on your keyboard to highlight _enter device name..._ and press the return key.

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image:alsamixer-plus/equalizer_device_name.jpg[] +
Enter _equalizer_ and press the return key.

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image:alsamixer-plus/equalizer.jpg[] +
The frequency band levels can be adjusted in the usual way by the up/down arrow keys on your keyboard.

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Press the _F6_ key to return to the previous alsamixer window or the _ESC_ key to close alsamixer.

<<table_of_contents,Table of Contents>>

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== Changing the Defaults

Usually the default settings do not have to be changed, they work with most kit.

If your hardware requires different settings they may be changed in the file _/etc/asound.conf_.

[icon="./images/icons/settings.png"]
[NOTE]
==== 
Use root privileges to edit the settings in your preferred text editor
----
# Audio card/chip and device to use and control
# In most cases these settings should remain commented (#)
# When commented, card and device 0 are usually automatically selected
# When uncommented, the item corresponding to the number is selected
#defaults.pcm.card 0
#defaults.pcm.device 0
#defaults.ctl.card 0
----
====

<<table_of_contents,Table of Contents>>

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== Summary of Files

/etc +
└── asound.conf

<<table_of_contents,Table of Contents>>

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