Notebook with AC97 "single plug output"-- Can it support Dolby 5.1?

Posted on 2003-03-27
Medium Priority
Last Modified: 2013-11-09
I just bought a Targa Visionary with the AMD Athlon 2200+ with "AC97 3D Sound". My question is:

I don't really understand the technical aspects of it, but I am under the impression that AC97 means that surround sound is coded into a single stereo-style output. According to:

How can I get Dolby 5.1 out of the single headphone style jack? Do my speakers need to have a special decoder built in to support?

I have a set of Dolby 5.1 compatible speakers that have signal inputs for subwoofer, front, rear, and center channels... But that would need 4 plugs while my laptop only has one..

Is there an additional piece of hardware required to decode this to Dolby?

Question by:da_hog
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Expert Comment

ID: 8219182
i think with ac97, your line-in also works as sound-out when you wish to work with 2+ channel of sound....
LVL 49

Expert Comment

ID: 8220148
It's talking about an RCA connection to a home theatre system, which then does the decoding.  Your Dolby system needs to be plugged into a home theatre system which can assign the music to the correct speakers.

You WONT get Dolby 5.1 out of a single headphone jack.

If your computer supports it - that is has 5.1 output - then the LINE_IN, LINE_OUT, MICROPHONE jacks are the 5.1 channel audio output.


Author Comment

ID: 8223231
Yeah, maybe that is the problem... this laptop only has a headphone and a microphone jack... no line-in...

dbrunton-then it should be possible for the headphone jack to be used as this RCA output to line into my home theater system right?
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Expert Comment

ID: 8223633
Well, no.

If you read the specification again, it's coming out of the S/PDIF output which is a different connector altogether from the headphone socket.  These can be found on PC motherboards.

Author Comment

ID: 8228345
yeah, but an RCA connector has 2 connections in it while the headphone jack has 3, so technically speaking, the headphone jack can even output more information than the RCA connection. that was my thought.

Of course to get that signal output, there would have to be an encoder inside the built in sound of the laptop...

This is what I thought the AC97 was, but unfortunately I cannot find a good explanation of exactly what AC97 really means. I see "AC97 3D Sound" listed as a selling description for many, many computers, but what does this mean? I thought that 3D Sound would mean more than just a stereo output through a headphone jack. I guess that this is the answer I am really looking for.
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Accepted Solution

kiranghag earned 150 total points
ID: 8228903
this is what i found at http://www.fujitsu-siemens.co.uk/rl/servicesupport/techsupport/Boards/Soundcards/AC97/AC97.htm
What is AC97 Sound?
The AC97 Specification provides a way of providing a low cost, high quality sound solution to board manufactures.
This is done by embedding half of the required technology in the motherboard chipset (South Bridge) and the other half is a separate chip from an OEM supplier. As the solution is fitted/provided in two locations, it sometimes must be disabled in two locations should you wish to add another PCI sound card.
  The Embedded part of the solution (Southbridge) provides the Sound output and can normally be enabled/disabled in the BIOS.
  The Additional Chip (Such as the AD1881) provides the effects (such as reverb) to the sound signal and sometimes has to be enabled / disabled by a link on the motherboard. Some Chips such as the Analogue Devices AD1885 also offer advanced features such as surround sound.
Please be aware that the AC97 Specification also includes provision for Modem and LAN technology built within the chipset.
As a result changing your AC97 Sound configuration can also effect your AC97 Modem/LAN card.
Please try to follow the following rules:

1) If an AC97 Modem/LAN card is used in conjunction with an AC97 Sound solution, then use the links on the Modem / LAN card to set the card as the Slave device (Sound must be master by default).

2) If you disable the AC97 Sound solution (by BIOS & sometimes link on the MB), then you need to promote the modem/LAN to be Master (by links on the Modem/LAN card) . You cannot have a Slave device without a master.

Author Comment

ID: 8247960
OK Guys. I figured out that this AC97 stuff doesn't support surround sound (at least not Dolby 5.1 so what's the use for DVD playback?). However, I found that there are some cool add-on devices to support Dolby 5.1 and others. I am attaching the web addresses as follows:

Maya EX (USB)

Soundblaster Extigy (USB)

Echo Indigo (CardBus)

There are probably a couple more, but to anyone else that is searching here for high quality audio from a laptop, check these devices...

Just out of curiosity, does anyone know what laptops support Dolby 5.1 internally??

Thanks again!

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