From alsa-user-owner@alsa.jcu.cz  Sun Dec 20 11:46:09 1998
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	Sun, 20 Dec 1998 11:44:52 +0100
Date: Sun, 20 Dec 1998 11:44:52 +0100 (CET)
From: Jaroslav Kysela <perex@jcu.cz>
To: Shaw Terwilliger <sterwill@dogbert.io.nu>
cc: alsa-user@alsa.jcu.cz
Subject: Re: My TB Malibu is _still_ Noisy
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On Sat, 19 Dec 1998, Shaw Terwilliger wrote:

> [this is long -- I've tried to be as complete in my description of
>  the tests I've done to get rid of this noise]
> 
> This shouldn't be happening.  I have a Turtle Beach Malibu card, which
> I'm generally happy with.  The only problem is that the right channel
> gets noise when run through an amplifier (well, the noise is always
> there, it's just noticeable when at medium to high volumes).
> 
> I was running the analog output into headphones, or into a stereo
> amplifier and getting massive amounts of clicking and popping and
> humming (like when moving around windows in X).  
> 
> I did move my video cards to the very opposite end of the computer
> case, so that the ISA card is 8 inches from the video cards.  This
> _did_ help quite a bit, but a seperate layer of noise has appeared.
> 
> Last night, as sort of an early Christmas present, I bought a 
> Sony STR-DE925 (like Jaroslav has).  I'm quite happy with it...
> I'm running sound out of the Malibu through the coax output, through
> a high grade digital audio cable, into the Sony.  I'm still getting
> noise on the right channel... and it's very much in sync with
> the same system events (video) that caused my other problems.

For me looks your problem as:

1) broken soundcard
2) some DMA conflict or PCI<->ISA bridge problem on your motherboard

If you can - try your soundcard in another computer (with another
motherboard chipset). If problems are still remaining - you got probably
broken soundcard (with some bug in digital part).

I don't know only why is affected only right channel. If you have some
trouble with DMA then probably both outputs should be corrupted.

> But if the analog signal path is completely bypassed (all channels
> except PCM and master volume are muted, so no CD or Line In
> or Mic garbage is being mixed), why am I getting this?  Is there
> some problem with the CS4237B's DSP?  I can't imagine why this is
> happening.

This is correct for CS4237B chip (look to mixer diagram in CS4237B
datasheet). If you want get some sound from analog inputs, you must turn
on digital loopback interface and record source for appropriate channels.
I don't recommend this - signal must go through ADC at first and you can
lost some information from input signal. If you want work with analog
input - connect your soundcard via standard way (line-out <-> receiver).

							Jaroslav

-----
Jaroslav Kysela <perex@jcu.cz>
Academic Computer Centre, University of South Bohemia
Branisovska 31, C. Budejovice, CZ-370 05 Czech Republic


