Having trouble with your M571 On Board Sound drivers? Here is Brad’s solution for getting your M571 Sound working correctly:
A PCI sound
card is a preferable solution but the on-board sound is ok for casual stuff.
The following link is for the 0n-board sound drivers you should use for
win-98SE:
Unzip the
files into c:\
Put your
PCI video card in PCI-1, and the modem in PCI-2 or 4.
Now disable
the on-board sound in the BIOS. Re-start Windows and run the uninstdrv.exe
utility in the driver package to uninstall the drivers. Now go into the device
manager and remove all traces of the on-board sound devices. Reboot to let
Windows clean up the registry and make sure Windows doesn't find it again.
Now enable
the on-board sound in the BIOS again, and let windows re-start. When it finds
the on-board sound and asks for the drivers, point windoze to C:\ and it should
find the cmi8330.INF file. Let it proceed and that should fix it.
This
information was contributed by Brad from the EYO
Tech Forum. It contains his solution to the low mic gain of the M571 on
board sound capability. In Brad's words:
Anyone who
has tried to use a standard computer microphone with a M571's on-board sound
knows there is a problem. The volume is far too low, virtually unusable. In
fact, the gain is about 10db low by measurement. Granted, many M571 users
upgrade to a PCI sound card but more casual users often can't justify the added
expense. This piece explains the problem and offers an inexpensive, proven
solution.
The
"soundpro" chip used in a M571 is a C-Media CMI8330. The chip and
Windows drivers contain support for a "mic boost" feature, but it
isn't available and never appears in the Windows volume control or C-Media
Audio Rack Mixer Panel. I believe the problem is the way the chip was
integrated into the motherboard, which prevents or "locks out" its
availability.
The
solution is to use a preamplifier to make up for the 10db gain shortfall. A
simple, inexpensive, and effective solution that I have implemented in several
M571 based systems with excellent results is to construct a simple two
transistor preamplifier using a commercially available kit (DIY Kit 98) which
can be ordered on-line from:
For those
who want to build their own from scratch, the schematic diagram and parts list
are contained in a PDF file at:
http://www.kitsrus.com/pdf/k98.pdf
NOTES:
Optional
resistor R9 must be installed to provide the power for the microphone that
would normally come from the motherboard or sound card. This 10K resistor is
included in the kit.
The preamp
provides 23 db of gain. This is perfect for driving the Line Input but is too
high for the Mic Input and will cause distortion. Changing the value of R6 from
100 ohms to a value between 300 and 500 ohms will bring the gain down to a more
appropriate level. 500 ohms has proven optimal for most desktop computer
microphones I have used and/or tested.
For those
building this preamp from scratch, the specified transistors may prove hard to
find so generic substitue transistors may be used instead. A NTE123 can be
substituted for the BC548, and a NTE159 can be substituted for the BC558. If
either or both are substituted, the resulting gain may be different and the
value of R6 may need to be changed accordingly.
Use
shielded cable between the preamp output and M571 Input. The center conductor
must be connected to the tip of a miniature stereo plug that is to be connected
to the M571's Mic Input. Motherboard Jumper JP9 must not be installed.
If your
microphone has unshielded cable, you may find it necessary to replace it with
shielded cable to eliminate hum and other unwanted electrical interference.
The preamp
may be constructed as an external battery powered unit, in which case a small
plastic box is adequate. The preamp draws 1 or 2 milliamps from a 9 volt
battery, thus providing long life, but a ON/OFF switch should still be
provided.
The preamp
may also be built into the computer. In this case it should be built in a small
metal box and electrically bonded to the case to shield it from digital
interference. It may be powered by a 9 volt battery or from a 12 volt line from
the power supply.
This
solution provides excellent audio quality. When recording to a .wav file, I
suggest using a 22050 Khz or higher sample rate. I've used it for internet
voice chat using Paltalk with very good results.
This page was last modified on 28 August 2002