Receivers capable of phantom center without engaging Dolby DRC? - AVS Forum
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post #1 of 21 Old 12-22-2006, 05:21 PM - Thread Starter
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EDIT: I thought I'd add some information on this issue here so it could serve as a point of reference. Corrections and clarifications are encouraged; I'll try to maintain this first post as a summary.

Summary:

There is a very good chance that your AVR or processor enables Dolby Dynamic Range Compression (DRC) if you play a DD 5.1 source with less than a full 5.1 speaker configuration; for example it may happen in a phantom center configuration. This is done without your knowledge and with no way to disable it. The result is that peak levels are noticeably compressed and you do not experience the full dynamic range of the original source.

A quote from Roger Dressler describing the situation in practice:

Quote:


Downmixing can take many forms. In a DVD player, a 2-ch downmix is always (I have not seen an exception, but who knows) done with DRC activated. This ensures the average level is maintained while preventing clipping.

In an AVR, 2-ch downmixes will probably be done the same way. However, if it is desired to downmix without DRC, every Dolby Digital decoder IC knows how to do it. The output level is scaled down 11 dB, then there's no way to cause clipping.

In the case of "speaker management" as descibed here, the AVR may allow the decoder to run in full 5.1 mode, no DRC, then downmix the C into L/R with the usual -3 dB mix level. With a little bit of scaling in the DSP, clipping can be prevented, and the gain is made up in the analog stage.

The AVR maker can use this method, or they can use the "downmix in the DD chip with DRC on" method. It's their choice.

In practice, it so far appears that most AVRs which have been tested will use the DD chip to downmix and leave the DRC enabled. Here are a couple of links to some testing to support the claim that this happens in the real world:

http://www.avsforum.com/avs-vb/showt...8&page=1&pp=30
http://www.hometheatershack.com/foru...formation.html

I will add more information and/or a summarize the list of receivers capable of downmixing without DRC here, if folks have interest in this issue.

---------------------------------------------------------------------

My original post is below here for continuity:

As has been tested, discussed, and documented in other threads, many (most) receivers will engage Dolby DRC when downmixing a 5.1 track to other speaker configurations. Unfortunately this is not limited to a 2.0 downmix; perhaps the most obnoxious is that DRC will be engaged in a phantom center configuration. This affects me and I'd like to reclaim my missing dynamic range.

Which receivers are capable of downmixing Dolby to phantom center configurations without DRC being engaged? So far the only receivers I'm aware of which can do this are certain Denon receivers, e.g. 3805 and above. I was browsing the manual from the Sony ES series and I saw two ways to configure phantom center: set the center to OFF or MIX mode. Perhaps MIX mode does not engage DRC?

Anyway, I'm in the market for a new receiver for a few reasons. I'd appreciate any input on this issue. Thanks.
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post #2 of 21 Old 01-24-2007, 05:12 PM
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I did a quick test on my Yamaha RX-V1500.
It doesn't appear to apply DRC when dropping the hard center.
The system has a hard center.

Master and Commander: chapter 4, "Under Attack" 0:09:00-0:09:11.
MV @ -25
86db with or without center.
78db with "Night Mode" engaged.

War of the Worlds: chapter 6, "Heat Ray", first ray at 0:26:22.
MV @ -25
83db with or without center.
73db with "Night Mode" engaged.

Two would seem to be two too many to me too.
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post #3 of 21 Old 01-24-2007, 05:51 PM
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My Onkyo 602 does not enable DRC in the phantom center mode.
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post #4 of 21 Old 01-24-2007, 06:13 PM
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Quote:
Originally Posted by Oliver Deplace View Post

I did a quick test on my Yamaha RX-V1500.
It doesn't appear to apply DRC when dropping the hard center.
The system has a hard center.

Master and Commander: chapter 4, "Under Attack" 0:09:00-0:09:11.
MV @ -25
86db with or without center.
78db with "Night Mode" engaged.

War of the Worlds: chapter 6, "Heat Ray", first ray at 0:26:22.
MV @ -25
83db with or without center.
73db with "Night Mode" engaged.

What was the setting for dynamic range in the receiver? MIN/STD/MAX
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post #5 of 21 Old 01-24-2007, 10:27 PM
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Max.

Two would seem to be two too many to me too.
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post #6 of 21 Old 01-24-2007, 11:09 PM
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Some of the older yamahas like rx-v1400/1500 have weird implementation of this functionality. You may want to set dynamic range to std (or min) and repeat your tests.
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post #7 of 21 Old 01-24-2007, 11:33 PM
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Anything other than Max and you've engaged full-time DRC.
I checked them when I did the initial setup.
It seems like a redundant setting. If I want DRC, I'll engage "Night" mode, it's a lot easier to access.

edit:
I'm not sure whether you meant the DRC setting for "Night" mode or the one in the "Sound" setup menu. Anyway, the "Night" mode is set to MIN and the setup menu is set to MAX.
Other than today, I've used "Night" mode once and that was just to see what it did.

Two would seem to be two too many to me too.
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post #8 of 21 Old 01-25-2007, 02:24 AM
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Has anyone tested on an HK AVR?

DD stereo downmix seems to sound fine and dandy on my AVR635, but I'd like to see some official words.
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post #9 of 21 Old 01-25-2007, 10:45 AM - Thread Starter
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Quote:
Originally Posted by Megalith View Post

Has anyone tested on an HK AVR?

DD stereo downmix seems to sound fine and dandy on my AVR635, but I'd like to see some official words.

You can almost always count on the stereo downmix being compressed; I don't have an HK to test with unfortunately.
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post #10 of 21 Old 01-25-2007, 12:05 PM
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Oliver and brendy, please describe the methods you used to determine DRC isn't being applied.
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post #11 of 21 Old 01-25-2007, 02:09 PM
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Loaded the movie, selected DD 5.1, selected the chapter, played the selected section while measuring the SPL with center enabled and without "Night" mode engaged.
Replayed selection while measuring SPL with "Night" mode engaged.

Disabled the center (set to "None"), replayed the selection while measuring the SPL without "Night" mode engaged.
Replayed the selection while measuring the SPL with "Night" mode engaged.

I tested with "Night" mode to be sure the DRC would, in fact, show a measurable difference. It does.

Master volume control and channel trims were the same for all tests.

Is there a trick to it?

Two would seem to be two too many to me too.
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post #12 of 21 Old 01-25-2007, 09:47 PM
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Here is a discussion about some Denons. Seems to be a menu item available for DRC ON and OFF when downmixing.


QUOTE:

"In my manual for the 2805, it describes the dolby digital setup option (drc or no drc) as

"sets the down-mixing method when not using a center speaker or surround speakers"



http://www.avsforum.com/avs-vb/showthread.php?t=794094
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post #13 of 21 Old 01-25-2007, 10:05 PM
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Quote:
Originally Posted by Oliver Deplace View Post

I did a quick test on my Yamaha RX-V1500.
It doesn't appear to apply DRC when dropping the hard center.
The system has a hard center.


That is a THX select unit.

I wonder if that is a THX requirement, of is it a Yamaha implementation. Do you have a DRC ON / OFF when downmixing in your setup menu?
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post #14 of 21 Old 01-26-2007, 07:55 AM
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Oliver, and so you are saying that with center disabled, you achieved the same max output levels as with center enabled, or just that it wasn't as reduced as with Night Mode activated? The level of DRC when all 5 speakers aren't in play doesn't necessarily have to be as potent as Night Mode.

Quote:


That is a THX select unit.

I wonder if that is a THX requirement, of is it a Yamaha implementation. Do you have a DRC ON / OFF when downmixing in your setup menu?

My Yamaha is also THX Select2, and the menu system should be the same as the 1500, seeing as they have the same internals - they are essentially the same unit with different casings. That's why I think something is strange.
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post #15 of 21 Old 01-26-2007, 01:09 PM
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Quote:
Originally Posted by J_Palmer_Cass View Post


...Do you have a DRC ON / OFF when downmixing in your setup menu?

The "Dynamic Range" setting is "MAX", as indicated in post #5.
It is the setting for maximum dynamic range (no compression), as indicated in post #7.


Quote:
Originally Posted by SteveCallas View Post

Oliver, and so you are saying that with center disabled, you achieved the same max output levels as with center enabled...


Not necessarily. I didn't test for maximum SPL. I thought this was signal limiting and would be apparent at any output level. If its effect is only realized when the system is reaching its maximum output, then I guess it's not such a big deal.



Quote:
Originally Posted by SteveCallas View Post

...or just that it wasn't as reduced as with Night Mode activated?

No. It wasn't reduced at all. The readings were identical. I only included the "Night" mode test to show that DRC did function and was disengaged.


It's all in my previous posts.

I thought you said this would be an easy test. :chuckle:

Two would seem to be two too many to me too.
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post #16 of 21 Old 01-26-2007, 01:45 PM
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Hmm, perhaps it's just that scene? Do you by any chance have War of the Worlds? If so, try the scene when the pod emerges from the ground. In addition to a drop in max levels, it should be pretty easy to hear less bass and less top end clarity, like when it blasts its horn or when glass shatters.
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post #17 of 21 Old 01-26-2007, 03:34 PM
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Quote:
Originally Posted by SteveCallas View Post

Hmm, perhaps it's just that scene? Do you by any chance have War of the Worlds? If so, try the scene when the pod emerges from the ground. In addition to a drop in max levels, it should be pretty easy to hear less bass and less top end clarity, like when it blasts its horn or when glass shatters.

Oh-boy.

Please read, or re-read, my posts in this thread.

Again, it's all there.

Instead of "max level", maybe you could call it "peak level".

I ran another test with "WOTW", chapter 5, 0:23:35 - first steps (just after the flying Jeep).
MV @ -10
102db with or without center (Meaning: They are the same).
Crashes and glass shatters are there in full. Huge crunching thuds as well.

I don't know about you, but I can't see it being another 10-15db louder at this MV setting. Plus, I'm sure power compression is rearing it's head and it may not get much louder. I want my stuff to continue functioning and have decided this is the limit. This system wasn't assembled for maximum SPL, it's a bedroom system.


You make the call.

OD has left the building.

Two would seem to be two too many to me too.
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post #18 of 21 Old 01-26-2007, 09:12 PM
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One last question This is with DD and NOT DTS, correct? DTS does not succumb to this issue - both of the movies you used have a DTS track, just wanna make sure.
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post #19 of 21 Old 01-26-2007, 10:45 PM
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Yes, Dolby Digital 5.1 (see post #11).

Two would seem to be two too many to me too.
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post #20 of 21 Old 01-23-2011, 03:30 PM
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Quote:
Originally Posted by SpectralD View Post

EDIT: I thought I'd add some information on this issue here so it could serve as a point of reference. Corrections and clarifications are encouraged; I'll try to maintain this first post as a summary.

Summary:

There is a very good chance that your AVR or processor enables Dolby Dynamic Range Compression (DRC) if you play a DD 5.1 source with less than a full 5.1 speaker configuration; for example it may happen in a phantom center configuration. This is done without your knowledge and with no way to disable it. The result is that peak levels are noticeably compressed and you do not experience the full dynamic range of the original source.

A quote from Roger Dressler describing the situation in practice:



In practice, it so far appears that most AVRs which have been tested will use the DD chip to downmix and leave the DRC enabled. Here are a couple of links to some testing to support the claim that this happens in the real world:

http://www.avsforum.com/avs-vb/showt...8&page=1&pp=30
http://www.hometheatershack.com/foru...formation.html

I will add more information and/or a summarize the list of receivers capable of downmixing without DRC here, if folks have interest in this issue.

---------------------------------------------------------------------

My original post is below here for continuity:

As has been tested, discussed, and documented in other threads, many (most) receivers will engage Dolby DRC when downmixing a 5.1 track to other speaker configurations. Unfortunately this is not limited to a 2.0 downmix; perhaps the most obnoxious is that DRC will be engaged in a phantom center configuration. This affects me and I'd like to reclaim my missing dynamic range.

Which receivers are capable of downmixing Dolby to phantom center configurations without DRC being engaged? So far the only receivers I'm aware of which can do this are certain Denon receivers, e.g. 3805 and above. I was browsing the manual from the Sony ES series and I saw two ways to configure phantom center: set the center to OFF or MIX mode. Perhaps MIX mode does not engage DRC?

Anyway, I'm in the market for a new receiver for a few reasons. I'd appreciate any input on this issue. Thanks.

Hi There!

How do the Receivers today manage this - is the dynamic reduction still a problem for AVR today or not??

Greetz!
Barnie
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post #21 of 21 Old 07-28-2013, 11:19 AM
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I don't know about today's receivers, but I see it not happening on some Dolby on BluRays, but for my 2005 Pioneer 1014 receiver, it did on a Netflix rental Total Recall 2012 TrueHD.

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