From the ALSA wiki
This is the result of some considerable time spent tinkering with a Soundblaster Live Value, reading the ALSA documentation and source code and comparing the Live to other cheap cards people might be familiar with. Some of this information might be helpful to people with any type of Creative Soundblaster Live card, but I don't have any other kind so I can't be sure. Don't bother reading this if you have an Audigy, the mixer controls in particular are quite different from a Live of any kind. If you find any possible mistakes please indicate which ALSA version you were using, some behaviour of the Live has changed between ALSA versions and likely will again.
- 4 Comments
Some of the mixer controls on the Soundblaster Live are just like those on older consumer sound cards like Creative's own SB16. They directly control an analogue circuit and need to be adjusted carefully to produce good results without distortion. On the other hand, the Live also has some controls which are implemented entirely by programmable digital hardware. The latter type of control may change its meaning if you use software that re-programs your SB Live. This guide covers playback controls first (ie those which influence what you hear on your speakers or headphones) and then explains the capture/ recording controls.
There are many programs for changing ALSA mixer controls, and so the description below may not precisely correspond to what you see on the screen in your program. For example a control might be called "Master Playback" instead of "Master" and there might be separate left & right controls for stereo channels or a single slider and a left-right pan.
The controls the first stereo mini-jack Line Out (also doubling as a headphone out). Settings above \~90% will introduce significant distortion. If you have an external amplifier you should be able to set this control once to an acceptable level and then control the volume from the amplifier. If you don't have an amplifier this control (rather than PCM, Wave etc. playback controls) could be used instead.
So far as I can tell, on a Value these controls are redundant. Presumably the Live Drive headphone out levels are controlled by these mixer settings if you have such a thing.
This does not seem to be implemented in the ALSA drivers
Tone, Bass and Treble
The Tone control is an on/ off switch. When it's switched off the Bass and Treble are bypassed (have no effect). Otherwise Bass controls the volume of low frequency sounds while Treble does the same for high frequencies. Their mid-setting is similar to but different from leaving Tone off. Turning on the Tone control can introduce some distortion, and it should be left off if possible.
On the SB Live PCM doesn't just refer to ALSA's PCM playback (see Wave for that) but to all PCM signals on the card, which also includes those created by the EMU10k1 MIDI synth and (if you have installed the necessary software) the onboard programmable DSP unit. You may want to set this to its maximum level, since doing so should not introduce distortion.
Rumour has it that a 12db+ boost is applied when this is above 75% (https://bugtrack.alsa-project.org/alsa-bug/view.php?id=612 ). If you are finding that you are getting distortion you could try lowering this setting to 75%.
This directly corresponds to ALSA's default PCM playback (ie your XMMS, Unreal Tournament etc.). You may want to set this to maximum to preserve maximum fidelity (there is no distortion in this stage of the mixer because it's entirely digital).
The Wave Surround control duplicates the sound from the front output channels to the rear. See the surround section below.
This controls levels for the onboard MIDI wavetable synthesiser. Once samples are uploaded to the card (see sfxload) you can play the built-in synthesiser using any ALSA sequencer application. When many notes are played at once the output is saturated quite easily so you may need to turn down this control to compensate.
The analog mini-stereo jack goes through the AC97 part of the Live. If listening to Line In via the Live you will need to adjust this control to get suitable results without too much distortion. See Capture Controls below for information about recording the Line In.
There are several CD connectors even on the budget SB Live. This mixer control affects only analogue CD connections, not TTL digital found on many modern drives. See IEC958 TTL for those. It also doesn't affect DAE (digital audio extraction), if your media player software does DAE then CD playback is treated the same as any WAV, MP3 or any other PCM audio. Mute this channel if it's not connected on your system or otherwise experiment to find a suitable level without distortion.
In addition to the Mic control itself which functions much as the Line In and CD level controls, there is also a Mic Boost switch (which enables a +20dB amplification, useful if the microphone seems otherwise much too quiet) and a Mic Select switch which should be left set to Mic 1, since there is no facility to connect an alternate microphone to the card.
Video, Phone, Aux
There may be several more analogue connections, most of which probably aren't connected to anything on your board. The associated mixer controls should work much like the Line or CD controls. If you don't have any hardware connected please mute the channel to reduce noise.
The AC97 playback and capture levels are correctly setup by default and should be left alone. That is, the AC97 playback level should be zero (other settings cause digital feedback), and the AC97 capture level should be at its maximum for proper analogue recording.
SB Live Analog/Digital Output Jack
Some variants (not the one I have) of the SB Live include a mini jack output which does double duty. With a suitable connector it can be used as a digital output. If you have such a thing switching this control on will enable it. In a lot of mixer apps on/off switches are always labelled as mute controls, so you'll need to unmute it. If you've got a regular analogue jack plugged in ensure the control is switched off (muted).
Capture Controls (Recording)
Many of the digital mixer controls for the SB Live are accompanied by Capture controls, with a separate level control in the mixer. The recording levels are independent of the playback levels, so you can adjust them separately to suit your application. Using the Wave Capture you can do â€œloopbackâ€? recording of sounds from software, and using Music Capture you can record performances with the MIDI synth. Use recording software with a digital level meter and adjust the capture levels for best results. Ensure that Capture is switched on only for the source or sources that you want to record.
The analogue mixer connections, such as Mic In, Line In and the old-style CD audio connectors are connected via an AC97 codec. Exactly one of these sources can be captured (but see Mix below), and the choice will probably be presented either as a list or as radio button controls next to the playback levels for each of the sources. The AC97 Capture switch (often just labelled "Capture") can be turned off altogether when not recording from an analog source.
The Mix and Mix Mono capture sources enable loopback capture in the AC97 circuits, recording from the output analogue signal as though it was an input. These should only be selected if you need to capture multiple analog inputs which are handled by AC97, such as Line In and Mic In at the same time. In that case, select the Mix capture source and adjust playback level controls for the inputs needed. You will also need to turn on the AC97 Capture control. Distortion is fairly inevitable when using this capture source. Do not use this source to capture output from OSS applications, see the information about Wave Capture above instead.
The SB Live Value has a pair of two channel mini-jack outputs suitable for analogue 4.0 surround. The front left and right should be connected to the first jack, and the rear left and right to the second jack. If you just want to drive two extra speakers (or an extra pair of headphones) with ordinary stereo playback, you can use the mixer setting Wave Surround playback to control the volume of the rear speakers. When using applications able to support better than stereo (such as many DVD players) the ALSA device should be surround40, or you should select the 4.0 surround option if available.
Very useful page .. learned a bit more about my card and all those settings in the alsamixer interface. Wonder what all the IEC958 entries are though (Coaxial/LiveDrive/TTL). I came to this page trying to get my Mic working, and it didn't help in the least bit however.
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