Sound BlasterX G6 - For science

Stejo · 11-29-2019, 03:57 AM

I'm quite confused by this card's behavior. It would be great if somebody could help me understand what's going on.

The card officially supports up to 8 channel output in 32/96 and 2 channel up to 32/384. This is also reflected in windows settings for shared mode, where changing the device configuration between 2 and 7.1 enables or disables the additional high sampling rates.

I noticed however in foobar2000 that when setting the device to WASAPI exclusive mode, it can play multichannel 32/384kHz streams no problem.

Intrigued by this, I fired up reaper to further investigate. Here's what happened.
In WASAPI shared, as expected it follows windows settings, outputting up to 8 channels in 32/96.
In WASAPI exclusive it does not output 8 channels under any circumstances(!)
In ASIO however, it outputs 8 channels in 32/384 just fine.

These results have me baffled really. Why is it that reaper can't do multichannel at all in WASAPI exclusive while foobar can?
And what possible reason could there be for the device limiting its multichannel directsound and WASAPI shared mode to 32/96 when it can clearly work in 32/384?

I'm not even using this card for audio production and if anything it works better than expected, so this is strictly for science.

cyrano · 11-29-2019, 05:02 AM

Many moons ago I tried to get a Soundblaster something to work with a Mac. It worked, as long as you kept to 44.1 kHz, 2 channels. Once you used more channels or higher sample rates, it ran out of sync, resulting in small dropouts. It was class compliant, but not entirely.

It seems it's behaviour hasn't really changed.

Have you tried if the outputs work? Discrepancies between what's reported and what's possible aren't unusual.

Stejo · 11-29-2019, 05:24 AM

Yea, they actually work just fine in ASIO 32/384.

I can route audio to any channel and it plays without issues. So it's not a case of seeming to work; it actually does work even though it shouldn't.

cyrano · 11-29-2019, 05:42 AM

It's sold as "32-bit/384kHz, -130dB"...

Lives up to it's promise.

Stejo · 11-30-2019, 07:50 AM

Discussing the matter further on a creative board, it seems that the card should be capable of outputting up to 8 channels 32/384 in any exclusive mode.
So the only remaining mystery is why reaper can't do more than 2 channels through wasapi exclusive, while foobar can. I suppose reaper's wasapi implementation isn't really up to snuff?

cyrano · 11-30-2019, 09:08 AM

Reaper supports older Windows versions. I seem to remember Wasapi being limited to 2-channel, unless it was AC encoded surround. Or was that another part of the Win sound system?