[mythtv-users] Analog multi-channel sound, optimal configuration 0.24?

Jean-Yves Avenard jyavenard at gmail.com
Fri Dec 3 11:02:26 UTC 2010


Hi

On 3 December 2010 21:13, Terjesen Jens Peder
<Jens.Peder.Terjesen at devoteam.com> wrote:
> I have it up and running with the MythTV box connected to the receiver with 3 minijack to RCA cables (front, center, surround and LFE).
> I first tried the onboard soundcard which worked but didn't give very great sound.
> Yesterday I installed an old unused Creative Soundblaster Audigy 2 which I had lying around and it was a significant improvement.
>
> What is the best configuration in MythTV for this setup?

scan for channels, then select the soundblaster one.

>
> I have selected ALSA:surround51 as sound device.
> At the moment I do not have a Subwoofer and have said so in the setup in the receiver which I think then will mix the LFE channel to the front speakers.
> Would it be better to use ALSA:surround50? Would alsa or MythTV do this mixing instead then?

won't make a difference

surround40, surround41 surround50 surround51 are all aliases to the same device.

so surround40 will report 6 channels, just like surround51

>
> When running speakertest with 6 channels it displayed LFE but the played sound said "center rear".

there is nothing internally really to differentiate say surround41 to surround50


> Is this normal or an indication that the channels are mixed up?
>
> Also when the cable for LFE was connected to the Subwoofer input on the receiver there was no sound, I had to pluf it into the Center input to hear the sound.

on my machine, LFE and center are on the same jack output, maybe you
just inversed those ?

if you do not have an LFE device, the best result you will get is by
setting a custom alsa pcm and mix the LFE though the front and left
speaker

> Is it probable that the frequency of the sound from speakertest is too high for the sound to be mixed to the front speakers by the receiver? Or is this an indication that the LFE is not mixed to the front speakers at all by the receiver? Is there an easy way to send a low frequency to the receiver to test this?

you can usually set the threshold for the frequency cut out on your amplifier

>
> I guess that I should select upmix of stereo to surround if I want sound from all speakers all the time?

the upmixer is really stereo to 5.0


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