Soundcard for digital XO using brutefir

So here's the idea, and it's not a new one: Arrive at your magic brutefir filter which is just perfect for your speakers and your room, split two-channel stereo into 4 or 6 (depending on how many drivers you have) uncompressed PCM channels and store it on disk.

Now I just need a way to dump all of this data, in uncompressed multi-channel PCM form, to my receiver. The receiver's DACs are used, and I connect the amplified outputs to the appropriate drivers.

There are two issues here.
1. Do most receivers (mine is a Harman/Kardon AVR-135) accept multi-channel PCM in their digital input?
2. Do they like 44.1KHz multi-channel PCM? Or only 48/96KHz?
2. Most soundcards don't output multichannel PCM. They do 2-channel PCM and DD5.1/DTS. So are there any (hopefully cheap) soundcards which do this?

I realize I could use the DACs on the soundcard and run the analog outputs to my receiver and still get the job done. However, I would really like to go digital upto the receiver. I'd be happy with just 4 channels, 16-bits, 44.1 or 48KHz.

I'm also toying with the idea of burning a video dvd with 4 channel LPCM at 48KHz and running it on my DVD player.

Any suggestions?
 

dwk123

Member
2002-02-06 4:51 pm
1) Some, yes, most no. Firewire and HDMI are the only ways to get uncompressed multichannel PCM into a receiver, and these only work with DVD-A as far as I know (SACD can go over firewire, but of course it's not PCM). The cheapest I know of is the Panny XR70 via HDMI, but it may only work when paired with it's matching DVD player (S97?) since DVD-A over HDMI is either new or non-standard. Most of the firewire units are pricey, but I *believe* there has been some level of interoperability between brands there.

2) I *believe* that any format supported by DVD-A should work in theory, but since I've never done it, I don't know.

3) Yes, but not ones that work with the above mentioned receivers. You can output 8 channels of 24/48 via ADAT, or there are cards like the Lynx AES-16 which have up to 8 pairs of spdif, but none of these work with conventional receivers.
Your only real hope is firewire, and as far as I know it's best described as 'not there yet', although it's probably not that far off. Might actually work on OS X, and Linux drivers are making progress. I have no personal experience with this, though

Right now, if you don't want to do the normal multichannel analog out, I think the only viable way is to use say Discwelder to burn a DVD-A which you then play back via conventional DVD-A digital paths (assuming you have one). This is probably limited to a 2-way system, though.
 
Thanks a lot.

dwk123 said:
1) Some, yes, most no. Firewire and HDMI are the only ways to get uncompressed multichannel PCM into a receiver, and these only work with DVD-A as far as I know (SACD can go over firewire, but of course it's not PCM).


Hmm. That's bad news. I don't have a DVD-A stack, nor can I acquire one in the near future. However, I believe the DVD Video paper spec mandates support for multi-channel linear PCM, upto 8 channels, 16/20/24 bits per sample and sampling rate of 48 or 96KHz. You need to pick values such that the total bitrate doesn't exceed 6144 Kbps.
DVD-Video audio spec

I tried burning a DVD with 4 channels/48KHz/16bits LPCM and it kind of worked. As in, the DVD player (Philips DVP642K), connected to the H/K AVR-135 with coax digital, didn't barf on it. I got a 48KHz PCM line displayed in the receiver's OSD.

So the question is, will any *soundcard* do what my DVD player seems capable of? i.e. 4 channels on a single connection? From the rest of your post, it appears not. 2 SPDIFs are no good unless I use external DACs.

I will probably be better off trusting the soundcard and getting 4 channels of analog output. The new Audigy is supposed to have decent DACs and a very good SNR. That or one of the M-Audio series.