DSD/PCM and bass Management - AVS Forum
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post #1 of 16 Old 05-07-2009, 09:43 AM - Thread Starter
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I hate to ask a relatively elementary question, but I wanna get this straight. When digital bass management is applied to SACD (meaning DSD), does that mean it gets converted to PCM?

Here's my scenario. I'm looking at a new preamp/processor that does not accept DSD over HDMI. I'm also looking at a new Blu-ray player (the forthcoming Oppo BDP-83), that will (I think) output SACD three ways:

1. Straight to analog
2. As DSD over HDMI (which wouldn't work for me)
3. As PCM over HDMI (converted from DSD first)

But here's the real question: If you apply bass management at any point, doesn't it convert the bitstream to PCM anyway? I mean, if my preamp did accept a DSD bitstream input over HDMI, wouldn't it convert that signal to PCM for bass management? For that matter, if I configured bass management in the player and used analog outs, wouldn't the player have to do a DSD-to-PCM conversion before converting to analog?

Ergo, assuming I'm applying bass management (and I will be), does it really matter that my preamp wouldn't accept a DSD input?

(Hope all this made sense.)
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post #2 of 16 Old 05-07-2009, 10:19 AM
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Applying any processing to DSD is beyond the capabilities of any receiver I know of.

Receivers with DSD handling DACs must bypass the DACs.

Maybe there's a DSP in a receiver which can handle DSD but I doubt it.

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post #3 of 16 Old 05-07-2009, 04:48 PM
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Quote:
Originally Posted by MichaelJHuman View Post

Applying any processing to DSD is beyond the capabilities of any receiver I know of.

Not sure what you mean here by "any processing." Digital volume control? Bass management? DPLIIx?

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Receivers with DSD handling DACs must bypass the DACs.

Again. What are you saying? If it has DSD handling DACs, how/why does it bypass the DACs?

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Maybe there's a DSP in a receiver which can handle DSD but I doubt it.

Ergo, it will convert it to PCM.

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post #4 of 16 Old 05-07-2009, 04:55 PM
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I mean that no DSP I know of can process DSD directly - it must convert it to DSD. Volume attenuation is applied after conversion to analog in any receiver I have looked at.

Which is what I thought the OP wanted to know. I apologize if I am confused or gave a confusing answer.

I think I also type the wrong sentence somewhere ( I meant type type DSP at typed DAC,) so am glad for any correction to what I originally typed.

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post #5 of 16 Old 05-07-2009, 04:58 PM
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Quote:
Originally Posted by MichaelJHuman View Post

I mean that no DSP I know of can process DSD directly - it must convert it to DSD.

Typo, I guess you mean PCM.

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Volume attenuation is applied after conversion to analog in any receiver I have looked at.

Which is what I thought the OP wanted to know. I apologize if I am confused or gave a confusing answer.

Understood.

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post #6 of 16 Old 05-07-2009, 05:03 PM
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Sorry, my brain must be having issues today Yes, I meant PCM. Maybe tomorrow will be a better day for posting

And I don't even have beer to blame.

"But this one goes up to 11"
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post #7 of 16 Old 05-07-2009, 06:57 PM
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Quote:
Originally Posted by MichaelJHuman View Post

And I don't even have beer to blame.

But it might be the solution.

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post #8 of 16 Old 05-07-2009, 09:50 PM
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But it might be the solution.

Beer, it's not just for breakfast anymore -

"But this one goes up to 11"
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post #9 of 16 Old 05-07-2009, 10:10 PM
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Quote:


But here's the real question: If you apply bass management at any point, doesn't it convert the bitstream to PCM anyway? I mean, if my preamp did accept a DSD bitstream input over HDMI, wouldn't it convert that signal to PCM for bass management? For that matter, if I configured bass management in the player and used analog outs, wouldn't the player have to do a DSD-to-PCM conversion before converting to analog?

The Oppo, and any other player, cannot do any processing of DSD, period. If you choose to send DSD to the analog outs on the Oppo, it is 100% unprocessed. Only when first converted to PCM can it be processed for things like bass management.

AVRs likewise cannot process DSD, and either convert it to PCM for DSP or send it directly to analog.

So to answer your question: while it is possible with some setups to have DSD all through the chain, there will be no processing of any kind save for volume control in the final stage. Most people will find that converting to PCM for DSP is the preferred approach since it allows things like bass management and all the other DSP goodies that make surround systems work best. With that assumption, it makes a good deal of sense to let the player convert to PCM whether you intend to use analog or HDMI connect. Although, if the AVR converts DSD to PCM, you can choose to let it do the work instead of the player. I seriously doubt you would hear any difference, except possibly different levels.
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post #10 of 16 Old 05-08-2009, 01:19 AM
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Here's my scenario too
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post #11 of 16 Old 05-08-2009, 08:47 AM - Thread Starter
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Quote:
Originally Posted by rdgrimes View Post

So to answer your question: while it is possible with some setups to have DSD all through the chain, there will be no processing of any kind save for volume control in the final stage. Most people will find that converting to PCM for DSP is the preferred approach since it allows things like bass management and all the other DSP goodies that make surround systems work best. With that assumption, it makes a good deal of sense to let the player convert to PCM whether you intend to use analog or HDMI connect. Although, if the AVR converts DSD to PCM, you can choose to let it do the work instead of the player. I seriously doubt you would hear any difference, except possibly different levels.

Thanks, that answers my question and essentially confirms my original impression: If I want to apply bass management (and I do), it doesn't matter that my preamp/processor won't accept a DSD signal, because the signal would be converted to PCM at some point anyway.

Neat connections are in vogue, and I'm thinking that I'd set the Oppo to output everything as PCM over HDMI (which I presume it can do, even for SACD), use that one cable as my do-everything connection, and be done with it.

As long as I'm using digital bass management, is there any good reason to include the multichannel analog connection?
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post #12 of 16 Old 05-08-2009, 09:15 AM
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Quote:
Originally Posted by Mr. Brownstone View Post

As long as I'm using digital bass management, is there any good reason to include the multichannel analog connection?

Not unless you like to compare. Multichannel analog will also very likely bypass the DSP in your AVR.

Quote:


Neat connections are in vogue, and I'm thinking that I'd set the Oppo to output everything as PCM over HDMI (which I presume it can do, even for SACD), use that one cable as my do-everything connection, and be done with it.

You have 2 options. SACD settings are separate from the HDMI audio settings. So you can have the player send PCM for SACD and bitstream for all other audio over HDMI. Or, PCM for everything.
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post #13 of 16 Old 05-08-2009, 02:28 PM - Thread Starter
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Quote:
Originally Posted by rdgrimes View Post

Not unless you like to compare. Multichannel analog will also very likely bypass the DSP in your AVR.

I assumed as much. Otherwise the processor would have to re-digitize the signal, and what'd be the point of that?

Quote:
Originally Posted by rdgrimes View Post

You have 2 options. SACD settings are separate from the HDMI audio settings. So you can have the player send PCM for SACD and bitstream for all other audio over HDMI. Or, PCM for everything.

Very good to know. Thanks.
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post #14 of 16 Old 05-08-2009, 03:32 PM
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Of course, one option that no one has mentioned....

Outlaw Audio ICBM Bass Management System

Just look for a nice used one.

Avatar - My guard dog, Bogi

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post #15 of 16 Old 05-08-2009, 03:33 PM
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Quote:
Originally Posted by Mr. Brownstone View Post

I assumed as much. Otherwise the processor would have to re-digitize the signal, and what'd be the point of that?

To use the DSP, of course. Anthem D2 does it quite well.

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post #16 of 16 Old 05-26-2009, 07:22 AM
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Quote:
Originally Posted by MichaelJHuman View Post

Applying any processing to DSD is beyond the capabilities of any receiver I know of.

Receivers with DSD handling DACs must bypass the DACs.

Maybe there's a DSP in a receiver which can handle DSD but I doubt it.

If I remember correctly, the Sony receivers that included Sony's S-Master Pro Digital Amplifiers converted everything into DSD and processed it as such.

Matty
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