Bitstream vs PCM (Direct & Pure Direct MCh)

[AcuDefTechGuy]

Okay, I'm sure many people have asked or been asked this question: Is it better to let the receiver do all the processing or let the player do all the processing?

I did a little experiment using the Denon AVR-5308CI, Denon DVD-3800BDCI, & Toshiba HD-XA1.

First, I let the players (BD & HD DVD) do all the internal decoding and send PCM via HDMI to the receiver. I set the 5308CI to Multi-Channel Direct Mode, which bypasses all tones, EQs, DSPs, bass management. The LCD on the receiver reads "Multi-Ch Direct".

Second, I would then switch to PURE DIRECT MODE Multi-Channel. Yes, that is actually possible, although the manual says nothing of this. Surprise, surprise. So now in addition to Direct Mode, the Pure Direct mode shuts down all the video circuitry, except for the HDMI video. The LCD on the receiver goes to BLACK. But if you change volume or other changes, the LCD lights up and it reads "Mutli-Ch Pure Direct".

Yes, it actually says "Multi-Channel Pure Direct"!

Third, I let both the BD & HD DVD players Bitstream to the Receiver and set the audio mode to Standard Audo Decode. So I put in "Red Cliff" BD. I change the audio output on the BD player from TrueHD to DTS-MA to LPCM, and the receiver reads "Dolby TrueHD", DTS-HD MASTR", and "LPCM" respectively.

So which sounded the best?

Hands down, the Bitstream sounded the best.

The MCh Direct and MCh Pure Direct seriously lacked the BASS.

I did not have this issue when I used 3 PMA-2000IVRs and analog cables!

So is the HDMI PCM the culprit here?

Do you think I messed up somehow on my setting?

 

[ParadigmDawg]

Try Multi-Channel Standard and let the BD player decode and send PCM and see what you come up with. You should retain the bass and not hear any difference between this and Bitstreaming to the Receiver.

 

[the grunt]

Yes, that is actually possible, although the manual says nothing of this. Surprise, surprise.

I also found out buy accident that my Denon 2807 does the same thing. Ya gotta love Denon manuals.

The MCh Direct and MCh Pure Direct seriously lacked the BASS.

I don’t have weak bass when I use MCh Direct on my Denon 2807. I use it exclusively when I play 5.1 audio because otherwise with MCh Standard the AVR always kicks in Dolby PLIIx for 7.1 and I don’t like what that does for discrete 5.1 audio.

 

[darien87]

Dude, you have WAY too much time and money on your hands.

 

[Blue Dude]

I think that the original setup doesn't make for an apples-to-apples comparison. Direct or pure direct probably keeps the receiver from doing any processing, including basic setup like speaker distances or crossovers, or Audyssey room correction. Put the receiver in a basic multichannel mode when playing back PCM. This will allow the receiver to operate the speakers with its setup info just as it does with bitstream, but refrains from further altering the input. Now you can make the comparison with bitstream. Also make sure that your receiver handles LFE the same way between PCM and bitstream. Some will automatically put -10dB on bitstream but may leave PCM alone. If you're used to your PCM setup, then the bass from bitstream will be anemic. Conversely, if you're used to bitstream (DD, DTS, etc.) then PCM could make your system sound very muddy and bottom heavy, but it's the setup, not the delivery method.

In theory there should be no difference between decoding a lossless signal in the player or in the receiver, but demonstrating it on your equipment could be tough to bring off.

 

[zumbo]

Thanks for the test, and posting the results. Very important post.

As someone who has been playing with these ideas, these facts need to be out there.

If other members don't get this, it is another slap in the face for ACDTG and myself. Decoding players seem to be a waste, and ACDTG and myself bit the bullet.

Our players do have other great features that make them not a total waste.

 

[itschris]

I'm just letting my 94 do everything. I've read elsewhere, buried in AVS somewhere, that some people tend to think that they're losing bass and some surround dynamics when they have the Sony 550 or Panny 55 do the decoding as opposed to just letting they're resceivers doing it. I haven't verfied this on my own, but there was some good chatter about it. I don't know why it would be that way unless somehow the setup is preventing accurate bass management or something like that.

Either way, I think if you have a decoding player, and a receiver that decodes everything, it might behoove you to experiment.

 

[AcuDefTechGuy]

Try Multi-Channel Standard and let the BD player decode and send PCM and see what you come up with. You should retain the bass and not hear any difference between this and Bitstreaming to the Receiver.

Well, but I wanted the Pure Direct Multi-Channel!

 

[AcuDefTechGuy]

I also found out buy accident that my Denon 2807 does the same thing. Ya gotta love Denon manuals.



I don’t have weak bass when I use MCh Direct on my Denon 2807. I use it exclusively when I play 5.1 audio because otherwise with MCh Standard the AVR always kicks in Dolby PLIIx for 7.1 and I don’t like what that does for discrete 5.1 audio.

Did you hook up the 5.1 audio via HDMI cable or the 5.1 Analog cables?

 

[AcuDefTechGuy]

Thanks for the test, and posting the results. Very important post.

As someone who has been playing with these ideas, these facts need to be out there.

If other members don't get this, it is another slap in the face for ACDTG and myself. Decoding players seem to be a waste, and ACDTG and myself bit the bullet.

Our players do have other great features that make them not a total waste.

I'm just letting my 94 do everything. I've read elsewhere, buried in AVS somewhere, that some people tend to think that they're losing bass and some surround dynamics when they have the Sony 550 or Panny 55 do the decoding as opposed to just letting they're resceivers doing it. I haven't verfied this on my own, but there was some good chatter about it. I don't know why it would be that way unless somehow the setup is preventing accurate bass management or something like that.

Either way, I think if you have a decoding player, and a receiver that decodes everything, it might behoove you to experiment.

Yeah, the Sound Quality with the Receiver doing all the processing/decoding (Standard Mode) is outstanding.

I tried that Pure Direct Multi-Channel again and got the same results: Lack of Bass.

I did a channel level manual test tone with the DVD-3800BDCI in Pure Direct MCh and the SUBWOOFER channel was 100% SILENT!

But here is the kicker. Even when I set the receiver to NO SUBWOOFER and let my 2 front speakers do all the bass and set the receiver to Standard TrueHD/DTS-MA (instead of Pure Direct or Direct), I get TONS of bass!!!!!

So for some reasons, and I will ask Denon on this, in Pure Direct MCh, the bass is cut OFF.

But in Pure Direct 2-Channel, I also get TONS of BASS.

And it's not the Source Direct Mode in the 3800BDCI either. I tried turning that off and it didn't work.

Like darien87 says, I might have too much time, but I just gotta know.

So for now, letting the receiver do all the work is absolutely best thing.

 

[trnqk7]

I also found out buy accident that my Denon 2807 does the same thing. Ya gotta love Denon manuals.


^^^
I found this out this weekend as well, direct and pure direct modes on multi channel pcm from my ps3. Thought it was strange. Bass was still there, but I leave my sub turned on in the settings when in those modes as my towers are not true full range. Lol, that is also something I didn't think I should be able to do either...agreed, Denon manuals stink.

 

[AcuDefTechGuy]

Standard vs Direct modes

Okay, what is the difference between these 2:

1) Standard mode w/ Tone Off, Room EQ Off, & Dynamic EQ Off

vs.

2) Direct mode ???

I guess in Direct/Pure Direct modes, the Bass Management (crossover, etc.) is also OFF?

But in Standard mode, the Bass Management is always on?

 

[AcuDefTechGuy]

I found this out this weekend as well, direct and pure direct modes on multi channel pcm from my ps3. Thought it was strange. Bass was still there, but I leave my sub turned on in the settings when in those modes as my towers are not true full range.

But the bass was still there in Pure Direct MCh PCM via HDMI from PS3.

I must be doing something wrong then.

 

[trnqk7]

Maybe not-I have my towers crossed at 60hz I think...might be 40hz, but regardless...I have the "double" bass setting on as well, so maybe that is what is doing it? I do this b/c I know my towers don't play very low and my "sub", if you can call it that, is more of an upper bass (50Hz to 100Hz) "reinforcer" if you will. I know it's not optimal, but I'm just trying to explain my settings and perhaps why I'm not noticing the same issue you are?

 

[AcuDefTechGuy]

Maybe not-I have my towers crossed at 60hz I think...might be 40hz, but regardless...I have the "double" bass setting on as well, so maybe that is what is doing it? I do this b/c I know my towers don't play very low and my "sub", if you can call it that, is more of an upper bass (50Hz to 100Hz) "reinforcer" if you will. I know it's not optimal, but I'm just trying to explain my settings and perhaps why I'm not noticing the same issue you are?

When I listen to Pure Direct 2.0 (no external subwoofer/LFE), I get awesome bass.

When I use MCh Direct, I don't even get the same bass from the fronts. And the subwoofer is completely absent. When I do a test tone in the BD player, I get the 5.0 Ch, but the LFE is absent.

I emailed Denon to see what they have to say.

I'm sure people are thinking, "If you get great sound from the Standard Mode, why even bother with Direct and Pure Direct?"

I just can't stand it knowing I didn't do something right.

Another thing I noticed in the manual is that even in Pure Direct, they say you can turn on the external subwoofer? How is that? Man, this manual sucks.