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From: Philip Peake <philip@vogon.net>
Message-Id: <199812051743.JAA14696@vogon.net>
Subject: Re: ES1370 and Microphone
To: alsa-user@alsa.jcu.cz
Date: Sat, 5 Dec 1998 09:43:09 -0800 (PST)
In-Reply-To: <Pine.LNX.3.96.981203202746.27045D-100000@entry.jcu.cz> from "Jaroslav Kysela" at Dec 3, 98 08:33:12 pm
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> > Does anyone successfully make ES1370's mic working?
> 
> My two ES1370 soundcards are working well with MIC input. I really don't
> know (as author of ES1370 driver) for which reason on some ES1370
> soundcards MIC input failures :-((( One soundcard is Sound Blaster PCI 64
> and second Ensoniq AudioPCI OEM - both soundcards are from Creative Labs..
> 
> Any help is appreciated...

My *guess* (I havn't had time to check it out yet) is that some machines are
using electret microphones, which require a low voltage feed to work, and
that some cards may have some (undocumented ?) feature to turn on that
voltage.

Doing the "stick a finger on the input" trick with my card, I get lots
of hum and random pick-up, but plug in the mic and thee is absolutely
NOTHING.

Of course it works fine on Win95.

I need to dig out my meter and get access to the mic to see if there is any
voltage present under winows which isn't there with the Alsa driver.

Of course, if this turn out to be the case, finding out how to turn that
supply voltage on is going to be interesting ...

Philip

