[lemm]

Quote:

Interconnect cables and speaker wires have nothing to do with it. Your Philips receiver has a manufacturer rated signal to noise ratio of 60 db (it could be worse since manufacturers exaggerate). That's not any better than a good cassette 1990s era tape deck. CD audio generally has a over 90 db (I think 96db maybe?).

Thanks Cel. I figured that was the case but since I don't have a HMDI receiver yet I wanted to make sure if it was something that switching from analog to digital would automatically solve (as RFI/EMI in cables is usually the obvious source of similar noise). So just to confirm, even speakers hooked up through a digital solution like HDMI (or optical) receiver does exhibit noise in the speakers, and that noise is a result of a poor SNR in the components, not whether the cable used is analog or digital.

 

[PurpleAngel]

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Sending computer audio to process in a separate DSP for virtual headphone surround is why I needed DDL. Like yourself headphone use was what I wanted from the computer and DDL input is needed to process that in my DSP. hdmi vs analog was just an extension of that thought since I had all the equipment to achieve that too for when I'm not using headphones.
 
Thanks for the links. I thought I read somewhere that CMSS-3D is very different from Dolby Headphone, but if CMSS-3D and Dolby Headphone both work with native 5.1 then I guess I'd be ok with either implementations.

You really want to process headphone audio with a sound card, not some other separate DSP (like a receiver)
Creative Labs (CMSS-3D) and Asus (Dolby Headphone) sound cards can take a 6 or 8-channel digital audio feed and convert it into (modern) Headphone Surround Sound, Headphone Surround Sound is a 2-channel audio signal (can be digital or analog), Creative Labs & Asus can send this Headphone Surround Sound out thru the front speaker/line-out (green) jack, as an analog audio signal or thru S/PDIF (optical or coaxial) as a digital audio signal.
The Philips and other receivers can take in this digital or analog signal and send it to their headphone jack.
 
You need DDL (or DTS-Connect) only if your are trying to send more then 2-channels of audio thru S/PDIF (optical or coaxial).
 
In the past if you wanted good headphone surround sound for PC games, game makers would include built in support in the PC game, for Creative's EAX 5.0, that would work with the Creative sound card EAX 5.0 hardware/software. The Creative Recon3D and Z series audio processors do not come with the EAX hardware, that the older (Titanium) cards had. Today a lot more gaming audio is processed using software and the computer's CPU, then with the sound card's audio processor itself.

 

[lemm]

Quote:

You really want to process headphone audio with a sound card, not some other separate DSP (like a receiver)
Creative Labs (CMSS-3D) and Asus (Dolby Headphone) sound cards can take a 6 or 8-channel digital audio feed and convert it into (modern) Headphone Surround Sound, Headphone Surround Sound is a 2-channel audio signal (can be digital or analog), Creative Labs & Asus can send this Headphone Surround Sound out thru the front speaker/line-out (green) jack, as an analog audio signal or thru S/PDIF (optical or coaxial) as a digital audio signal.
The Philips and other receivers can take in this digital or analog signal and send it to their headphone jack.
 
You need DDL (or DTS-Connect) only if your are trying to send more then 2-channels of audio thru S/PDIF (optical or coaxial).
 
In the past if you wanted good headphone surround sound for PC games, game makers would include built in support in the PC game, for Creative's EAX 5.0, that would work with the Creative sound card EAX 5.0 hardware/software. The Creative Recon3D and Z series audio processors do not come with the EAX hardware, that the older (Titanium) cards had. Today a lot more gaming audio is processed using software and the computer's CPU, then with the sound card's audio processor itself.

 
The DSP is not on the receiver but a specific headphone processor that has both analog and digital inputs which I think we have establised as identical in terms of audio transmission. One of its functions is that if it receives a Dolby Digital signal it would do the surround processing. This is great for movies as they can be set to output in a Dolby Digital format. However for games the DSP won't do this as my soundcard does not support DDL.
 
For games I could of course switch of the internal Dolby Digital processing of the DSP and rely on the soundcard or CPU to handle a similar encoding through either CMSS-3D or Dolby Headphone. That's exactly what I was thinking I could do even though the DSP has the relevant processing for a Dolby Digital signal.
 
However my soundcard does not support any of these options for games so I'm essentially starting new. I would have thought offloading the work from the soundcard / CPU would provide a better virtual surround. Why do you suggest leaving the processing on the soundcard rather than the DSP?

 

[PurpleAngel]

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The DSP is not on the receiver but a specific headphone processor that has both analog and digital inputs which I think we have establised as identical in terms of audio transmission. One of its functions is that if it receives a Dolby Digital signal it would do the surround processing. This is great for movies as they can be set to output in a Dolby Digital format. However for games the DSP won't do this as my sound card does not support DDL.
For games I could of course switch of the internal Dolby Digital processing of the DSP and rely on the sound card or CPU to handle a similar encoding through either CMSS-3D or Dolby Headphone. That's exactly what I was thinking I could do even though the DSP has the relevant processing for a Dolby Digital signal. However as my sound card does not support any of these options for games.
Why do you suggest leaving the processing on the sound card rather than the DSP?

I just do not know of any good external DSP that I would use myself for headphone surround sound processing.
Best I know of is the Astro Mix-amp, I would put it's processing power about equal to an Xonar DG, which costs $20 (after rebate).

 

[lemm]

Quote:

I just do not know of any good external DSP that I would use myself for headphone surround sound processing.
Best I know of is the Astro Mix-amp, I would put it's processing power about equal to an Xonar DG, which costs $20 (after rebate).

An Asus or Creative card would have both DDL and it's own version of headphone surround processing so I could use either method. I'm not familiar with the differences in virtual surround processing between the different versions as I've only tested Dolby processing but it's very convincing to me. I think I'll follow your advice and try one of the gaming links to see what people think between CMSS-3D and Dolby Headphone. Thanks.

 

[cel4145]

So just to confirm, even speakers hooked up through a digital solution like HDMI (or optical) receiver does exhibit noise in the speakers, and that noise is a result of a poor SNR in the components, not whether the cable used is analog or digital.

You have to think about the SNR of the source material, the receiver/amplifier, and the DAC. Everything has noise. Just depends on how much and what is audible. But since audio CDs are at best 90+ db SNR, optimum is to have a receiver/amp and DAC that has SNR over that so that the noise floor does not get lower. This is why many modern receivers have 100+ db SNR and good DACs are 100+ SNR.

 

[lemm]

Thanks. My source material were bluray so I was surprised to encounter any noise over digital. I expected some noise over analog I suspected due to RFI/EMI but as the consensus seems to be that HDMI and Analog are largely the same, the higher noise level over Analog must be due to the poorer SNR/DAC on the current soundcard
 
I guess the original question should have compared SNR & DAC of various components rather than the connection being HDMI vs Analog.
 
Thanks to Purple, Cel and Protege for taking the time to reply.
 
Best Regards,
Islam

 

[lemm]

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Didn't you say you have another system in the house? Is it a name brand receiver of some type? Might be worth switching it out for some testing, even if it is 2 channel.
 

 
I finally ran an analog comparison test on the multichannel analog input receiver and a higher quality stereo receiver. It turns out that the receiver is just fine when used for a multichannel analog source. If it's set to the 2 channel aux source the noise increased significantly and was representative of the lower spec quoted. However, when using the multichannel inputs the noise drops significantly. Although not quite on par with the <1% THD stereo receiver when at max volume which exhibits negligible noise, at any reasonable volume it shows that the SNR/THD etc results in a clean signal and is still of good quality when using the multichannel analog inputs, so ideal for complementing a soundcard that has analog out. I probably should have done this test first. Could it be that the same receiver has different circuits for multichannel analogs vs 2 channel analogs that result is such a vast difference in audio quality? Seems that way.