CurtPalme.com Home Theater Forum

sgkcem · Joined: 24 Jun 2008 Posts: 3

For my home audio I have an Integra DTR 6.4 surround receiver. The receiver is 6 channel with the option to run 7 channel via pre-outs. I've already set up the 7 channel pre-out by using an external amp. The receiver does not come equip with an HDMI input. My question is by running a digital optical cable from a Blu ray player can the receiver produce similar sound or an unnoticeable sound difference then from Dolby HD?

Thanks!

**kal** · Posted: Wed Jun 25, 2008 1:50 pm Post subject:

The lossless audio formats like Dolby TrueHD or DTS-HD Master Audio can only be sent over HDMI. Digital Toslink/SPDIF cables do not have enough bandwidth.

There are no hacks, workarounds, or mods to get lossless over regular digital Toslink cables.

Kal

ecrabb · Posted: Wed Jun 25, 2008 2:48 pm Post subject:

I'll just add to what Kal said, since I think the real meat of your question wasn't so much whether you could get advanced audio over SPDIF, but more whether the sound you get over SPDIF is similar or unnoticeably different from the sound you get from Dolby TrueHD or DTS-HD Master Audio. The answer is, it depends on the quality of your amp, your speakers, and whether your room is treated properly. If you have a budget speakers, a low-end amplifier, and no room treatments, the difference between Dolby Digital or DTS via SPDIF and advanced audio will probably not be that great. If you do have a good system with no significant deficiencies in your amplifier, speaker system, or room treatment, then there is no comparison.

While good Dolby Digital and DTS usually sound pretty good, they're extremely compressed... usually well under 450 kbit/s on DVD. That's almost a 6:1 compression ratio. Now, not all channels are compressed equally, but suffice it to say, much is lost in the compression. Blu-ray and HD-DVD upped the data rate a little for DD, but it's still not much less compressed.

Contrast that with TruHD, which is 1.7 Mb/s - more than 3x the date rate, and most important, the compression is lossless - which means you're hearing the original track as it was mixed by the pros, not the track after psychoacoustic compression was applied.

DTS-HD MA can do data rates up to 24.5 Mbit/s on Blu-ray to support 24-bit/96khz streams.

There's a significant difference if your system is good enough to reveal it.

SC

Axatax · Posted: Wed Jun 25, 2008 3:24 pm Post subject:

ecrabb · Posted: Wed Jun 25, 2008 3:54 pm Post subject:

I think Kal meant there were no mods that you can do to typical equipment like the AVR the OP has. It wouldn't make much sense to BUY an MC12, and THEN mod it to support multi-channel PCM when you could just buy a processor that would support multi-channel PCM, lossless and even the new codecs themselves. Different story of course, if you already spent big bucks to buy an MC12 and wanted to add that capability.

Even then, the mods wouldn't give you high-res, either... so, no 24/96 for you.

SC

Axatax · Posted: Wed Jun 25, 2008 4:18 pm Post subject:

ecrabb · Posted: Wed Jun 25, 2008 4:32 pm Post subject:

Wow, I didn't know SPDIF would support that kind of bandwidth. 24/192 is insane bandwidth. So, what sources are people modding to be able to use that medium?

SC

Axatax · Posted: Wed Jun 25, 2008 4:37 pm Post subject:

SPDIF will do 24/192, but only for two channel (which is why the card uses 3x SPDIF).

ecrabb · Posted: Wed Jun 25, 2008 4:43 pm Post subject:

I didn't even know SPDIF could handle 2 channels of 24/192, though... If it can handle 2 channels of 24/192, then it should also be easily be able to do 7 or 8 channels of 16/48khz. I had no idea.

Is that optical and coaxial, or just coaxial?

SC

Axatax · Posted: Wed Jun 25, 2008 4:55 pm Post subject:

You can get the DVD Upgrades card in either coax to optical. They don't mention if both interfaces support all bit rates.

sgkcem · Joined: 24 Jun 2008 Posts: 3

Thanks everyone for your input!