A7N8X-X with Realtek ALC650 sound problem

[Larry Gagnon]

I have recently built a box for a friend based on the A7N8X-X (which has a
Realtek ALC650 sound chip) and an XP2500M CPU. Using WinXP Home and the
nVidia drivers (not the Realtek drivers). This mobo has only 3 audio out
connectors (Line In, Line Out and Mic). The driver software enables you to
choose Line Out and/or Mic for extra sound channels.

We are attempting to get 5.1 sound out of this board, but unsucccesful so
far. We are unable to get the rear channel speakers working from either
Line In or Mic connectors, despite having stated 5.1 sound in the WinXP
sound setup boxes. A question I have is do these speaker have to be
amplified speakers? We are using unamplified speakers If this is
definetely our problem then it is an easy fix. Otherwise any ideas where
we look to fix the lack of rear channel sound out would be appreciated.

Larry Gagnon

 

[Paul]

I have recently built a box for a friend based on the A7N8X-X (which has a
Realtek ALC650 sound chip) and an XP2500M CPU. Using WinXP Home and the
nVidia drivers (not the Realtek drivers). This mobo has only 3 audio out
connectors (Line In, Line Out and Mic). The driver software enables you to
choose Line Out and/or Mic for extra sound channels.

We are attempting to get 5.1 sound out of this board, but unsucccesful so
far. We are unable to get the rear channel speakers working from either
Line In or Mic connectors, despite having stated 5.1 sound in the WinXP
sound setup boxes. A question I have is do these speaker have to be
amplified speakers? We are using unamplified speakers If this is
definetely our problem then it is an easy fix. Otherwise any ideas where
we look to fix the lack of rear channel sound out would be appreciated.

Larry Gagnon

On the AC97 chips I've looked at, normal output drive is 600ohms.
If the chip has "headphone drive", it will likely be only on two
channels (like the Lineout connector). The drive there is 32 ohms,
suitable for 32 ohm headphones.

Info on ALC650 can be found here. It has a poorly written datasheet,
and says Lineout has a 20 ohm drive, stronger than some others I've
looked at. They don't say what the drive on the other channels
is like, but it should be weaker. (The block diagram doesn't show
any amp on the other outputs.)

http://www.realtek.com.tw/downloads/downloads1-3.aspx?refdesign=True&compamodel=ALC650

Plug amplified computer speakers into the three jacks and it should
work for you.

Some of the Intel boards using the new Azalia chips, have flexible
headphone drive. The headphone drive can be moved to any port where
a headphone is plugged in. What I cannot tell you in that case,
is whether the Azalia software will allow all channels to go to 32 ohm
mode at the same time - that would likely not be the design
intent of the flexible headphone drive.

Paul