On the card photo you provided, the jack only goes to a 74F244 octal buffer so it cannot provide analog audio at all. IMO JP2 and JP3 appear to be test points for the SPDIF output.

Hi, @NeoG,
And thanks for your input.

NeoG_ wrote on 2026-03-01, 08:22:

On the card photo you provided, the jack only goes to a 74F244 octal buffer so it cannot provide analog audio at all.

This makes sense. But I didn't trace the PCB for any analog connections to this S/PDIF jack. I read a lot of search results on the i-net about these SB Live! X-Gamer and SB Live! 5.1 sound card variants and seems like there is an early variant card from the third generation SB Live! 5.1, which is using the very same PCB as Live! CT4760. Or maybe this information is not 100% correct.

NeoG_ wrote on 2026-03-01, 08:22:

IMO JP2 and JP3 appear to be test points for the SPDIF output.

The missing JP2 looks like it may be "test point", but I'm not sure. If some slight modification is done (move the R71 resistor to R82 missing resistor pads) it may switch the "yellow line" output of the 74F244 (3-state output buffer):

For JP3 jumper header there are two variants to install jumpers.

This one seems more reasonable (deactivating the "yellow" output from 74F244 by connecting it to ground and connecting "red" outputs from 74F244 to S/PDIF jack):

And in the second variant (I see not much of a reason to connect "red" and "yellow" outputs from 74F244):

aVd wrote on 2026-03-02, 05:13:

This makes sense. But I didn't trace the PCB for any analog connections to this S/PDIF jack. I read a lot of search results on the i-net about these SB Live! X-Gamer and SB Live! 5.1 sound card variants and seems like there is an early variant card from the third generation SB Live! 5.1, which is using the very same PCB as Live! CT4760. Or maybe this information is not 100% correct.

I think the information is correct, however the 6 channel capability for the CT4760 is digital only as it does not have the additional DAC channels to power the analog outputs. I found an article which outlines the whole process of adding 5.1 support to a CT4670 and it requires the digital DIN extension bracket and is designed to interface with Creative/Cambridge branded speakers that can accept the digital DIN connector.

http://ixbtlabs.com/articles/livetolive51/index.html

As pointed out in the article, it is possible to provide your own center/sub analog output by decoding the SPDIF signal from the digital extension header using your own decoder, the article writer used a second sound card to perform the decoding. I supposed it would be possible to do it all onboard by isolating the digital jack and using a small SPDIF decoder circuit between the digital extension header and the now isolated digital jack. Isolating the jack would be done by removing all JP3 jumpers and removing R71. That would allow you to feed Left, Right and Ground into the JP3 header pins from the decoder circuit.

That would be in addition to modifying the EEPROM to allow the use of the 5.1 liveware drivers of course, if the card does not already have a 5.1 enabled eeprom code.

Also it makes clear why there are two independent SPDIF lines to the digital jack in the PCB design, it supports two stereo SPDIF streams using a stereo minijack plug for 4 channel digital

NeoG_ wrote on 2026-03-02, 09:39:

I think the information is correct, however the 6 channel capability for the CT4760 is digital only as it does not have the additional DAC channels to power the analog outputs.

Something doesn't add up here or CT4670 really does have 6-channel version (5.1).

I noticed that this CT4760 (in the photo from RetroWeb) has 2ch DAC Philips UDA1330A in addition to main 4ch AC'97 codec (Sigmatel STAC9721T).
This combination (or similar Philips/Sigmatel chips) can be found on other Live! 5.1 cards.

I also heard that UDA1330A had better sound quality than Sigmatel, and it was popular to use the rear outputs.

ott wrote on 2026-03-02, 11:45:

Something doesn't add up here or CT4670 really does have 6-channel version (5.1). […]
Show full quote

Something doesn't add up here or CT4670 really does have 6-channel version (5.1).

I noticed that this CT4760 (in the photo from RetroWeb) has 2ch DAC Philips UDA1330A in addition to main 4ch AC'97 codec (Sigmatel STAC9721T).
This combination (or similar Philips/Sigmatel chips) can be found on other Live! 5.1 cards.

I also heard that UDA1330A had better sound quality than Sigmatel, and it was popular to use the rear outputs.

I think it is used for some other purpose because all versions of the Live card have this additional philips stereo I2S DAC as well as the sigmatel codec, both G1/G2 4 channel and G2/G3 6 channel live cards

Edit: So it seems like the story is that the G1/G2 cards have a stereo AC97 codec (STAC9721/CT1297) plus the additional stereo I2S DAC for a total of 4 analog output channels, and the G3 cards have a 4 channel AC97 codec (STAC9708) plus the additional stereo I2S DAC for a total of 6 analog output channels.

NeoG_ wrote on 2026-03-02, 09:39:

I think the information is correct, however the 6 channel capability for the CT4760 is digital only as it does not have the addi […]
Show full quote

aVd wrote on 2026-03-02, 05:13:

This makes sense. But I didn't trace the PCB for any analog connections to this S/PDIF jack. I read a lot of search results on the i-net about these SB Live! X-Gamer and SB Live! 5.1 sound card variants and seems like there is an early variant card from the third generation SB Live! 5.1, which is using the very same PCB as Live! CT4760. Or maybe this information is not 100% correct.

I think the information is correct, however the 6 channel capability for the CT4760 is digital only as it does not have the additional DAC channels to power the analog outputs. I found an article which outlines the whole process of adding 5.1 support to a CT4670 and it requires the digital DIN extension bracket and is designed to interface with Creative/Cambridge branded speakers that can accept the digital DIN connector.

http://ixbtlabs.com/articles/livetolive51/index.html

As pointed out in the article, it is possible to provide your own center/sub analog output by decoding the SPDIF signal from the digital extension header using your own decoder, the article writer used a second sound card to perform the decoding. I supposed it would be possible to do it all onboard by isolating the digital jack and using a small SPDIF decoder circuit between the digital extension header and the now isolated digital jack. Isolating the jack would be done by removing all JP3 jumpers and removing R71. That would allow you to feed Left, Right and Ground into the JP3 header pins from the decoder circuit.

That would be in addition to modifying the EEPROM to allow the use of the 5.1 liveware drivers of course, if the card does not already have a 5.1 enabled eeprom code.

Also it makes clear why there are two independent SPDIF lines to the digital jack in the PCB design, it supports two stereo SPDIF streams using a stereo minijack plug for 4 channel digital

Yeah, I know about this article with EEPROM model ID modification and that's the reason I started to search for info on Live! X-Gamer 5.1 CT4760 or will it be possible to modify the standard Live! X-Gamer card in such way, so there will be no need of the additional connections to second sound card used solely as digital to analog convertor. There's also similar article in Russian language here. Seems like the undocumented jumpers JP3 or JP2 may be used for connection to Digital-In on the second sound card.

I'm wondering if SB Live! X-Gamer 5.1 sound card really do exist, and if so what will be it's model ID stored in the EEPROM.

ott wrote on 2026-03-02, 11:45:

Something doesn't add up here or CT4670 really does have 6-channel version (5.1). […]
Show full quote

NeoG_ wrote on 2026-03-02, 09:39:

I think the information is correct, however the 6 channel capability for the CT4760 is digital only as it does not have the additional DAC channels to power the analog outputs.

Something doesn't add up here or CT4670 really does have 6-channel version (5.1).

I noticed that this CT4760 (in the photo from RetroWeb) has 2ch DAC Philips UDA1330A in addition to main 4ch AC'97 codec (Sigmatel STAC9721T).
This combination (or similar Philips/Sigmatel chips) can be found on other Live! 5.1 cards.

I also heard that UDA1330A had better sound quality than Sigmatel, and it was popular to use the rear outputs.

Hi, @ott,
And thanks for this info. My SB Live! CT4760 sound card has both Sigmatel STAC9721T and Philips UDA1330A chips just like the one on TRW's picture. And that's why I used the same picture for my drawings on JP2 and JP3 connections. But the card from the link is still the standard Live! X-Gamer (non-5.1), right?

Actually I just reviewed the information on the DOSDays site and it says the CT4760 "X-Gamer 5.1" has 6 channel analog output, but it's not possible based on the PCB design so I think the information is not correct. I also emailed the site owner recently about an incorrect piece of information on the CT1770. I assumed the "5.1" version referred to was digital output only, but if it claims to have 6 channel analog I don't think it exists.

NeoG_ wrote on 2026-03-02, 11:59:

Edit: So it seems like the story is that the G1/G2 cards have a stereo AC97 codec (STAC9721/CT1297) plus the additional stereo I2S DAC for a total of 4 analog output channels, and the G3 cards have a 4 channel AC97 codec (STAC9708) plus the additional stereo I2S DAC for a total of 6 analog output channels.

Thank you, @NeoG! This explains everything except the purpose of the JP2 and JP3 jumpers 😀

I'll consider the SB Live! X-Gamer 5.1 and the SB Live! 5.1 with PCB from CT4760 models as non-existing or never released models. And now I see no point to modify my 4-channel CT4760 to 5+1 channel SB0060 as it will need connection to additional sound card for the sub/center channels output.

NeoG_ wrote on 2026-03-02, 13:17:

Actually I just reviewed the information on the DOSDays site and it says the CT4760 "X-Gamer 5.1" has 6 channel analog output, but it's not possible based on the PCB design so I think the information is not correct. I also emailed the site owner recently about an incorrect piece of information on the CT1770. I assumed the "5.1" version referred to was digital output only, but if it claims to have 6 channel analog I don't think it exists.

Yep, seems like the current info for SB CT4760 models on dosdays site is not 100% correct. This site contains a lot of useful info and resources about retro hardware, so I hope the author will correct the things according to your notes.

... JP2 and JP3 jumper headers on CT4760 will remain a mystery.

Why? Why I opened those Sigmatel STAC97xx datasheets?! 🤣

Now I'm totally confused.

This is the pinout of Sigmatel STAC9721 "Stereo AC'97 Codec With Multi-Codec Option", which is on my Live! X-Gamer CT4760 card:

And this is the pinout of Sigmatel STAC9708 "Multi-Channel AC'97 Codec With Multi-Codec Option", which is on Live! 5.1 cards like SB0100 and SB0220:

And all of the pins and analog outputs match except in the names of LNLVL_OUT_L/R on STAC9721 and DAC_OUT_L/R on STAC9708 (legs 39 and 41 are for analog output signals on both chips).

After all Live! X-Gamer CT4760 cards with Sigmatel STAC9721T and Philips UDA1330A chips seem capable for 6-channel analog audio. What do you think, guys?

aVd wrote on 2026-03-02, 14:47:

After all Live! X-Gamer CT4760 cards with Sigmatel STAC9721T and Philips UDA1330A chips seem capable for 6-channel analog audio. What do you think, guys?

You are conflating multi-codec and multi-channel

It clearly states in the documentation two sigmatel chips are required to exceed a single chips output channel capacity in a multi-codec configuration.

The STAC9721T only has two onboard DACs

NeoG_ wrote on 2026-03-02, 21:34:

You are conflating multi-codec and multi-channel

It clearly states in the documentation two sigmatel chips are required to exceed a single chips output channel capacity in a multi-codec configuration.

The STAC9721T only has two onboard DACs

My confusion is due to lack of detailed descriptions for LNLVL_OUT_L/R (STAC9721) and DAC_OUT_L/R (STAC9708) analog outputs. I didn't expect to see more analog outputs on STAC9721 legs 39 and 41.

aVd wrote on 2026-03-03, 03:48:

My confusion is due to lack of detailed descriptions for LNLVL_OUT_L/R (STAC9721) and DAC_OUT_L/R (STAC9708) analog outputs. I didn't expect to see more analog outputs on STAC9721 legs 39 and 41.

LNLVL_OUT is a copy of the stereo mixer output, Sigmatel says it's a "true line-level out for headphones or speaker amplifiers". I guess that means it has a different impedance or drive capability than the standard line out. You can see in the STAC9271 mixer functional diagram that the two sets of outputs are ganged together. On the STAC9708 line out is independent from dac out.

NeoG_ wrote on 2026-03-03, 04:02:

LNLVL_OUT is a copy of the stereo mixer output, Sigmatel says it's a "true line-level out for headphones or speaker amplifiers". I guess that means it has a different impedance or drive capability than the standard line out. You can see in the STAC9271 mixer functional diagram that the two sets of outputs are ganged together. On the STAC9708 line out is independent from dac out.

While using search function in both pdf-files I missed these mixer functional diagrams. Now everything is clear. Thanks!

NeoG_ wrote on 2026-03-02, 21:34:

The STAC9721T only has two onboard DACs

Thanks for correcting me!
Indeed, the SB Live (CT4760) only has 4 analog outputs: STAC9721 (2ch DAC) + UDA1330 (2ch DAC).

The SB Live! 5.1 (SB0100/SB0220) has different set: STAC9708 (4ch DAC) + UDA1334 (2ch DAC).