From alsa-user-owner@alsa.jcu.cz  Wed Dec 16 18:06:37 1998
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From: Monty <xiphmont@mit.edu>
Message-Id: <199812161700.MAA28268@cutter-john.MIT.EDU>
To: alsa-user@alsa.jcu.cz
Subject: Re: CS4236B: Loud "popping" sound every time a sound is played 
In-reply-to: Your message of "Wed, 16 Dec 1998 19:07:53 +1300."
             <36774E39.6BECBEAD@albatross.co.nz> 
Date: Wed, 16 Dec 1998 12:00:07 EST
Reply-To: alsa-user@alsa.jcu.cz
Sender: alsa-user-owner@alsa.jcu.cz
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>The problem: Whenever a sound FINISHES playing (and the app releases the
>sound card) I get a very loud clicking/popping noise. I have tried
>virtually every possible combination of ports, IRQs, DMAs, and buffer
>sizes but I allways get this annoying sound. MUTING the master channel
>does prevent the problem (but then, obviously, I dont get any sound!!)

Playback is probably ending at some voltage value, and as soon as it
ends and the output stage is disabled, it's yanked to ground (POP!).
This is a bit of a guess, I've just recently dived into ALSA (having
gotten incredibly fed up with OSS).

Anyone got a Crystal based notebook?  I have a scope :-)

Having breifly perused the driver source, it looks like the
infrastructure is there to reasonably easily gently bring the voltage
level to an off state before playback ends.  Do any of the honest to
goodness driver contributers have a comment?  I don't have one of the
Crystal chips to play with, and the AudioDrive does not exhibit this
behavior.

>Windows and OSS work fine, but the Linux-kernel drivers and ALSA both
            ^^^^^                   ^^^^^^^^^^^^^^^^^^^^
>seem to exhibit this problem.

OSS works just fine?  You're one of the lucky few ;-) Of course the
Linux kernel drivers *are* OSS, just an old, buggy, unmaintained,
forgotten version.  It's conceivable that Hannu's commercial version
works better (and that is *such* a pity)...

Given the quality of the free version, though, I'm happier sticking
with ALSA as new as it is. But now I'm preaching to the choir...

Monty

