Specifications

Philipp Braunbeck reported that on his ESS−1868 sound card there was a jumper to turn off the built−in
amplifier which helped reduce noise when enabled.
On one 386 system I found that the kernel command line option no−hlt reduced the noise level. This tells
the kernel not to use the halt instruction when running the idle process loop. You can try this manually when
booting, or set it up using the command append="no−hlt" in your LILO configuration file.
Some sound cards are simply not designed with good shielding and grounding and are prone to noise pickup.
6.23. I can play sounds, but not record.
If you can play sound but not record, try these steps:
use a mixer program to select the appropriate device (e.g. microphone) •
use the mixer to set the input gains to maximum •
If you can, try to test sound card recording under MS−DOS to determine if there is a hardware
problem
•
Sometimes a different DMA channel is used for recording than for playback. In this case the most probable
reason is that the recording DMA is set up incorrectly.
6.24. My "compatible" sound card only works if I first
initialize under MS−DOS.
In most cases a "SoundBlaster compatible" card will work better under Linux if configured with a driver
other than the SoundBlaster one. Most sound cards claim to be compatible (e.g. "16 bit SB Pro compatible"
or "SB compatible 16 bit") but usually this SoundBlaster mode is just a hack provided for DOS games
compatibility. Most cards have a 16 bit native mode which is likely to be supported by recent Linux versions
(2.0.1 and later).
Only with some (usually rather old) cards is it necessary to try to get them to work in the SoundBlaster mode.
The only newer cards that are the exception to this rule are the Mwave−based cards.
6.25. My 16−bit SoundBlaster "compatible" sound card
only works in 8−bit mode under Linux.
16−bit sound cards described as SoundBlaster compatible are really only compatible with the 8−bit
SoundBlaster Pro. They typically have a 16−bit mode which is not compatible with the SoundBlaster 16 and
not compatible with the Linux sound driver.
You may be able to get the card to work in 16−bit mode by using the MAD16 or MSS/WSS driver.
The Linux Sound HOWTO
6.23. I can play sounds, but not record. 24