No constant signal over SPDIF from Vista/Windows 7 to receiver

I am having a problem in getting my Auzentech Xfi Prelude card to send a constant audio signal over SPDIF to my receiver in Wndows 7 (same in Vista). This works fine in XP but it seems that in Vista/7 if there is no audio playing then the OS seems to turn off the audio signal/carrier to the receiver for some stupid reason. This causes a problem for me because my receiver (Marantz SR5300) auto detects the incoming signal and sets it to stereo say. If there is not a contant signal then any audio doesn't get played immediately as the receiver takes a second or so to detect the signal. A soon as the sound stops (stereo desktop sound) the signal disappears and the receiver no longer is showing a stereo audio being detected. This is bloody annoying. Is there a way to force a constant signal to the receiver from the sound card?

Many thanks,
Richard.

it seems to be a common problem with 7, more so than vista. try enabling a mic input but turn the gain right down, it'll force the soundcard to stay on if it works

Thanks for the suggestion, but unfortunately it didn't work. It seems to be the same behaviour for the onboard AC97 chip on my motherboard too, so it looks like a Vista/Win7 behaviour issue. Surely there must be lots of other people having this issue with their cards too using SPDIF and a receiver.

Yes, but on the Xonars it's an easy fix, using the above technique.

So are there any fixes or workarounds for other cards? Seems like a fairly significant fault/flaw in Windows 7 / Vista.

XP had the same issue too.

Actually, it's not a PC issue. It's a receiver issue. Some receivers switch off DD or DTS if the DD / DTS stream is silent. My Victor SU-DH1 detects a silent DD / DTS stream and will play the sound instantly over either DD or DTS. On my Logitech z680s I get the same delay you're describing. Same soundcards and same settings.

it isnt, it's an issue with the pc. ive had different driver and os configurations causing this. In windows 7 built 7100 my pc didnt do this, now with build 7126 (i think) it does, and not just over DD/DTS but LPCM as well. No other hardware causes my onkyo to keep switching every time a sound is played. I probably could solve it temporarly by enabling the mic input but i havent got around to trying yet.

Hmmm interesting. Thanks for the comments guys. Glad its not just me seeing this.

If I force on DD or DTS on my Prelude card I get a constant signal sent to the receiver and all channels are detected. It is only when I turn OFF DD or DTS that the standard "stereo" mode over SPDIF doesn't send a constant signal. On XP I do not see this issue and I get a constant stereo signal all the time. I'm assuming this is what you guys are describing here?

Using on board sound or using a spare Creative xfi gamer card I also see the same issue in Vista/Win 7. In XP it is 100% fine so it almost looks like the way Vista/7 handles sound devices. I've logged a ticket with Auzentech so I'm waiting to see what they come back with. I'll post here if they have any suggestions that work.

Cheers.

Hmmm this is the reply from Auzentech :

"Thank you for contacting Auzentech. Windows XP have one Audio device supported in O/S. In this struction, the signal can be transferred to the receiver continuously. In Windows Vista and 7, MicroSoft separates the Audio device to Speakers, SPDIF and HDMI for some reason. It is not easy to explain how the audio signal is transferred through each device. The O/S select the 'Speakers' as basic audio device signal keep going on the Speakers though you set the default device to "S/PDIF Out". When the signal is sent to the "S/PDIF Out" or "HDMI", signal start being output, and receiver detects the audio source. We recommend you to set the default device to "Speakers". It will not take a second or so. This is just the Windows7 and Vista's audio structure. The issue that you explained may occur not only with our sound card but also other sound card line. "


So this sounds like the SPDIF functionality is screwed in Vista/7 as a primary output. Surely they can't expect me to hook up analog connections from the card as the SPDIF was the primary reason I bought this card.

Surely there must be a way of sending a constant signal from the driver somehow.

Pretty sure it's by design... on Vista/7 there's no data sent to my DAC when nothing is playing, but it doesn't matter for me personally because the receiver activates immediately when there is (so no cut-off sounds and the like). When I used XP the signal was indeed constant regardless of whether anything was playing or not, but that seemed to be due to white noise in the background which I couldn't get rid of for whatever reason.