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Sup y'all. maxmercy was curious about how the OPPO BDP-105 would handle a worst case scenario with 7 channels of re-directed bass added to LFE so he was nice enough to send me a bare bones version of his upcoming test disc project. So I got to play with sine wave tones from 1Hz to 60Hz held to just under 0dB on all channels. From there I had fun experimenting with re-directing each set of channels and viewing the effect on the waveform on an analog scope. Max's upcoming test disc will be a more comprehensive version with many more test tones and sweeps and will hopefully be available sometime this summer. It's going to be a powerful tool and I recommend it to anyone who wants to find out how their system handles re-directed bass so you can avoid sending a clipped signal out to your amplifiers when playing strong bass content.

 

I hooked the subwoofer out of the OPPO to a dummy load in parallel with the scope. The dummy load and the scope's input impedance measured 9.86K. I figured this was kind of a worst case input impedance load too as most amps that I've used were equal to or higher than that. I double checked voltages with my Fluke meter but I'm not going to bother posting the numbers because the scope was in agreement with it for the following pictures. I post the volts per division for the scope's graticule (grid) in some of the following pictures. From there you can find the peak of the waveform and have a good idea what the peak voltage is. Also, for all of the following measurements, sub trim was kept at 0dB.

 

What I found for the OPPO is that it's analog out is even more robust than I was told it was and does not clip in WCS 7.1 channels of full bass even when volume was pushed to a maximum level of 100. It peaked out at a level of ~3.1V with 7ch of re-directed bass at 100MVL.

 

Now for the bad news... when the OPPO adds even 1 WCS channel (center) with the WCS LFE channel, it starts to clip the waveform. The more channels from there that you re-direct to the sub out, the more prominent the clipping becomes and therefore, the more distortion is added to the signal. The OPPO does output a full level LFE by itself very clean however and it is unclear at this point how much additional level it takes from other channels to begin clipping.

 

This clipping has nothing to do however with the analog output IMO. The clipping is present and unchanging no matter what the MVL is set to. It must be reaching some kind of headroom limit on the digital side of things when the signals get summed together. I plan on contacting OPPO's tech department this week and I will keep you guys posted on what the explanation/fix might be. I am disappointed to say the least because I believe that this will affect the hottest peaks of strong bass content and there is no way to compensate with a trim/MVL adjustment.

 

I have more to post about this and other tests and will do so as time permits.

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Nooooooooooo!  One of the flattest FR output pieces of equipment and it does this?

 

Man.....that stinks.  I was hoping to hear otherwise.  What about turning down the dub trim to -10 or -11?  Clean waveform then?  If so, then the box is still functional.

 

 

JSS

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Great work!

 

I'll be interested to hear what the tech dept have to say (if anything...) as they seem to have taken great care in the original design.

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Thanks Chrap.  Me too MemX.  Good point on the trim levels max, I didn't think of doing that at the time because I figured it was an attenuation/boost feature that took place after the summation of the re-directed bass.  I went back today and verified that it didn't affect the amount of distortion (see attached pic). 

 

Came across this in the 105's manual. 

b722cc84f57e778bf8817bd8f1f37a5c.png

 

I think OPPO just admitted that their test noise for leveling channels isn't accurate and apparently reducing the trim level is not effective in removing distortion. 

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I went back and tested the good ol' cheapo Sony STR-DE597 with the WCS disc.  For anyone out there who missed my original post about this receiver using HTTYD as source test material, they can find it here:

http://data-bass.ipbhost.com/index.php?/topic/284-bossobass-raptor-system-3/?p=6188

 

This receiver is only 5.1 compatible so my guess is that it either down mixed or omitted the 2 extra channels from the disc but that isn't a big deal.  This AVR's volume goes from 1-74(max).  56 was the highest value with sub trim set to 0dB that it would go without distorting the sine waveform.  I included a THD test below for that level and for the previous level (66) that I tested HTTYD on. 

 

Look at the 2 waveforms below.  They are both with the Sony at 66MVL.  One is a sine wave and the other is a square wave.  It surprised me that the waveforms are almost identical. 

 

At least this cheap POS AVR can actually re-direct 5 channels without clipping as long as you keep in mind it's analog output limit and adjust your system to that level.  Evidently, the OPPO doesn't even give you that kind of control as it clips when it sums the channels together before you even have a chance to control the levels.  I am just so disappointed in this whole deal with the OPPO that it's hard to even post stuff about it.  :(

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I also went back to the HTTYD source test I did: http://data-bass.ipbhost.com/index.php?/topic/284-bossobass-raptor-system-3/?p=6168 and I noticed the similarities in the peaks of the waveform for the Dragon Crash scene to the way the OPPO clips the peaks of the sine waves.

 

To close to call it just coincidence IMO.  So much for the whole -"worst case scenarios with re-directed bass levels don't apply to source material" argument. 

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The 105's SW trim is minimum at -10dB. It made no difference. MVL was then reduced from our reference point of 91 (on a scale from 0-100) to 40. It made no difference.

 

The 7 sats channel speakers were all set to 'small'. Not that it mattered but the 7 channels trims were set to '0'. The crossover was set to 100 Hz and then to 80 Hz.

 

The decoding was set to LPCM 7.1. Dynamic Range Control was OFF.

 

Point One channel only = AOK in all volume level scenarios. Add any channel and the waveform is clipped. Clipping of the waveform increases as more channels are set to small.

 

The only thing left to check is the authoring software used to encode the signals onto the disc. But, it sure looks like the Oppo flagship is improperly summing redirected bass before the SW jack. So, one cannot "...reduce the trim level until the distortion is removed."

 

If the HDMI out is fine then you can find a pre/pro or AVR that doesn't clip the summed bass to the SW jack but then why buy the 105? If it's whole analog section is whack, it's just a drive that sends digits to the AVR and the Sabre DACs are useless.

 

B-U-M-M-E-R!!!    Hey OPPO, WTF??!!

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If all else about the 105 is good, it would seem the way to ensure non-clipped SW Out jack is to run all speakers at Large and then apply some individual high-pass filters on each channel before the signals reach the speakers, to effectively make them 'Small'?  But that would be a bit of a faff... lol

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How capable is the oppos hdmi input? 

Can the oppo act as a full fledged avr if you input 7.1 pcm from other hdmi source? 

 

I'm thinking now of using whatever bd player,  set to pcm decoding,  nanoavr or similar for bass management on the digital side and then just the oppo for dac, volume  and analogue out...

 

Edit: cause it seems to me the only way to be sure regarding how bass management is handled is to set it up yourself,  with appropriate attennuations to avoid clipping digitally... 

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0dBTP?

 

JSS

True peak, ie intersample peaks that exceed 0dBFS. Jriver calculates this per channel (as described in http://yabb.jriver.com/interact/index.php?topic=82025.msg559613#msg559613) and then reduces the level by that peak is required to prevent clipping. It still does bass mgmt on the basis of 5dB attenuation to account for summation though so it can still clip unless you apply the appropriate extra attenuation yourself. It would be easy, if tedious and slightly time consuming, to calculate this yourself and apply custom DSP per track to guarantee you avoid the problem.

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I bet that it reduces some films a lot more than others, as the recent crop of clipped messes must have plenty of over-reach.

 

JSS

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Thanks for the information Shred. Man...Things are NOT looking good. Seems like a lot of units are clipping digitally which cannot be corrected by lowering the gains.

 

So far what units have been able to pass the WCS test? The Denon DN-500AV and a cheap Sony avr and both at greatly diminished overall gain? I'm really trying to avoid going to a HTPC for simplicity, but it keeps getting more difficult. I do wonder how many PC soundcards with surround decoding might also fail this test.

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 I do wonder how many PC soundcards with surround decoding might also fail this test.

 

My bet would be just about everyone.

And pc soundcards are rarely geared towards home theatre so using the driver software's bass management would probably not take into account that lfe channel is meant to be 10dB above every other channel etc... 

The decoding of truehd dtshd and the like would take place in player software,  not at the soundcard. 

 

No,  going the pc route like I have would mean the equivalent of using the nanoavr together with bd player, that is doing things manually. 

I use the peq section of jriver  mediacenter for all processing,  and a vst plug in for bass management.

Sound is routed to jriver via wasabi loopback, so all sound gets processed,  games,  movies and music alike. 

I'm using mediaportal as mediacenter btw, just use Jriver for sound processing. 

 

But if simplicity is needed I'd probably go with regular bd player and nanoavr for processing.

That way you can control all processing,  making sure you are within the limits digitally. 

And use your avr of choice for dac and volume adjustment,  sending the audio straight to dac without any channel mixing or bass management... 

But,  by doing things manually, and applying appropriate atennuations might raise the noise floor unnecessarily much most of the time as often this huge headroom is not needed,  but you are sure to never clip digitally...

Also,  this much atennuation would mean a lot lower signal on sub out at receiver,  so one has to have enough headroom on the amps gain to compensate for it,  or a signal booster before amp... 

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Regarding 'TP' (True Peak), keep in mind that Max's disc consists of pure sine waves. If they are properly encoded <0dBFS, the summing block in the chipset should easily handle the task. The True Peak is below 0dBFS.

 

Whether or not HTTYD presents a clipped waveform, if the effect is encoded <0dBFS in all channels, they should sum with no additional (digital) clipping, therefore being faithfully reproduced digitally, before the DAC.

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I checked the 120 BDs I have in jriver, 60 have >0dBTP (though many are only a bit over 0). Here's a list (desc sort by dBTP), C is the most prevalent offender then LR, hardly any show up as >0 in the SW. Whether consumer equipment accounts for this sort of clipping is another Q (seems unlikely given the dynamic nature of it).

 

Film                                 Total   L       R       C       SW      RL      RR      SL      SR

The Wolf of Wall Street              3.1     0.0     0.1     3.1    -9.7                    -5.8    -6.6
WALL-E                               2.6     0.0     0.0     2.6    -1.7                    -5.3    -4.8
Inglourious Basterds                 2.4     1.0     0.8     2.4    -0.2                     1.3     1.2
Prisoners                            2.4     0.0     0.4     2.4    -6.8                    -8.1    -7.2
Bolt                                 2.2     0.1     0.2     2.2     0.0                     0.1    -0.1
Captain America_ The Winter Sold     2.1     0.4     0.4     2.1     0.0     0.1     0.0     0.2     0.1
The Polar Express                    2.1     1.3     0.5     2.1     1.3                    -0.4    -1.2
Adele_ Live at the Royal Albert      2.0     2.0     0.7     0.8   -13.2                    -3.7    -3.7
Lone Survivor                        1.8    -0.1    -0.1     0.0    -0.4                     1.8     0.5
Monsters Inc                         1.6     0.2     0.1     1.6                             0.0     0.1
The Chronicles of Narnia_ Prince     1.6     0.2     0.2     1.6     0.0    -1.5    -1.7    -3.2    -2.2
Toy Story 2                          1.6     0.1     1.4     1.6     0.0                     0.4     0.3
Oblivion                             1.5     0.6     0.5     1.5     0.0     0.1     0.1     0.4     0.4
Pacific Rim                          1.4     0.4     0.6     1.4    -0.9     0.2     0.1    -0.5     0.0
Captain Phillips                     1.4     0.2     1.1     1.4    -3.8                    -1.2    -0.1
Monsters University                  1.2     0.0     0.2     1.2    -0.1     0.0    -2.6    -0.8     0.1
The Muppets                          1.2     0.0     0.1     1.2     0.0    -5.4    -3.0    -3.0    -3.0
The Hobbit_ An Unexpected Journe     1.2     0.8     0.7     1.2    -1.4    -1.0    -1.9    -0.9    -0.9
TRON_ Legacy                         1.1    -0.9     0.0     1.1    -0.2    -1.7    -1.7    -1.8    -1.8
Watchmen                             1.1     0.4     1.1     1.1    -0.1                    -2.6    -2.8
21 Jump Street                       1.1     0.1     0.3     1.1    -1.3                    -0.2    -0.4
Amy Winehouse_ I Told You I Was      1.1     1.1     0.8     0.6    -5.4                     0.0     0.2
Pixar Short Films Collection - V     1.0     0.2    -0.1     1.0     0.4                    -2.6     0.0
How to Train Your Dragon             0.9     0.0     0.1     0.9    -0.1                    -0.1    -0.1
Rush                                 0.9     0.9     0.3     0.4    -1.0                     0.0     0.2
Nowhere Boy                          0.9     0.0    -0.9     0.9    -3.3                    -4.2    -2.6
Toy Story 3                          0.7     0.1     0.2     0.7     0.0    -4.6    -6.6    -3.0    -3.0
The Hunger Games                     0.7     0.2     0.2     0.7    -0.1    -0.4    -0.5    -0.9    -0.2
Kill Bill_ Volume 1                  0.7    -1.0    -0.8     0.7    -1.4                    -1.1     0.0
Despicable Me                        0.7     0.0    -0.9     0.7    -1.0                    -5.2    -4.3
In Bruges                            0.7    -0.2     0.0     0.7    -0.9                    -0.7    -0.6
Kick-Ass                             0.7     0.1     0.1     0.7     0.0                     0.0     0.1
Kung Fu Panda                        0.7     0.0     0.0     0.7    -0.1                     0.1     0.0
The Smurfs 2                         0.7    -1.4    -0.2     0.7    -0.2                    -2.7    -4.6
The Hunger Games_ Catching Fire      0.6     0.0     0.0     0.6    -0.2    -0.7    -0.2    -0.1     0.2
Changeling                           0.6    -0.7    -1.1     0.6    -1.9                    -3.8    -7.0
Birdsong                             0.6     0.6     0.1     0.6    -1.9                    -3.8    -4.0
Spy Kids 2                           0.6     0.0     0.0     0.6    -7.5                    -4.3    -5.8
Toy Story                            0.5     0.2     0.0     0.1     0.5                    -0.4     0.2
Rio                                  0.5    -2.3    -2.2     0.5    -6.1                    -2.1    -2.0
Elysium                              0.4     0.0    -1.0     0.4    -6.0    -5.1    -5.8    -0.8    -2.8
Up                                   0.4     0.0     0.1     0.4     0.3                     0.0     0.1
Bee Movie                            0.4    -0.2    -0.2     0.4    -0.3                    -4.6    -7.3
Argo                                 0.4     0.1    -0.2     0.4    -0.6                    -0.1    -0.5
Spy Kids 3                           0.4     0.1    -0.4     0.4    -1.0                    -0.7    -0.7
The Raid                             0.4     0.1     0.3     0.4    -1.2                    -0.6     0.1
22 Jump Street                       0.4    -0.2    -1.0     0.4    -8.9                    -1.8    -0.8
Beauty and the Beast                 0.3     0.1    -0.7     0.3    -8.4    -0.5    -0.4    -2.6    -3.9
                             300     0.3     0.0     0.1     0.3    -0.3                    -3.1    -3.0
The Lego Movie                       0.3    -0.2    -0.2     0.3    -0.2                    -4.6    -4.3
Yellowstone                          0.2    -2.3    -3.0     0.2    -3.9                   -11.0   -10.8
The Lion King                        0.1    -1.3    -2.4     0.1    -5.0    -1.0    -0.5    -4.5    -5.2
Misery                               0.1     0.1     0.1     0.1    -3.3                    -5.2    -3.4
Predator                             0.1     0.0     0.1    -0.8   -11.1                     0.1     0.0
AVS Reference                        0.1     0.1     0.1     0.1    -6.0                    -0.2    -2.7
The Dark Knight                      0.1    -0.6    -1.4     0.1    -1.7                    -2.1    -2.2
Under the Skin                       0.1     0.0     0.1     0.1   -11.3                     0.0     0.0
The Double                           0.1    -0.5    -0.6     0.1    -1.2                    -2.5    -1.6
Enchanted                            0.1     0.0     0.1     0.1     0.0                    -1.8     0.1
True Romance                         0.0    -0.6    -0.9     0.0    -6.6                    -7.9    -7.3
The Town                             0.0    -1.1    -1.0     0.0    -4.7                    -1.7    -1.9
Pleasantville                        0.0     0.0     0.0    -1.8   -14.6                    -4.8    -6.8
Do The  Thing                        0.0    -0.5    -0.5     0.0   -14.3                    -3.1    -4.1
Sea of Love                          0.0    -8.0    -2.0     0.0   -16.3                    -6.3    -6.4
The Smurfs                           0.0    -1.1    -0.9     0.0    -1.8                    -0.2    -0.2
Alan Partridge_ Alpha Papa           0.0    -1.1    -0.7     0.0    -1.4                    -5.3    -0.8
Rachel Getting Married              -0.1    -3.1    -1.3    -0.1   -10.9                    -2.4    -1.0
Drive                               -0.1    -3.6    -2.3    -0.1    -4.7                    -3.1    -3.2
Locke                               -0.1    -2.9    -3.0    -0.1   -14.4                    -3.1    -3.0
X-Men_ First Class                  -0.1    -0.4    -1.8    -0.1    -4.6                    -4.9    -4.9
Cloudy with a Chance of Meatball    -0.1    -0.6    -0.4    -0.1    -1.2                    -0.6    -3.0
Reservoir Dogs                      -0.2    -3.5    -3.0    -0.2    -6.8                   -10.4   -11.9
The Conversation                    -0.3    -4.0    -4.5    -0.3    -5.3                   -10.7   -10.5
Home Alone                          -0.3    -2.5    -1.6    -0.3    -7.1                    -1.6    -1.7
Arthur Christmas                    -0.3    -1.6    -4.1    -0.3    -2.4                    -2.8    -3.0
Philomena                           -0.5    -9.8   -13.1    -0.5   -23.0                   -13.5   -16.7
Frozen                              -0.6    -0.7    -0.9    -0.6    -1.0    -1.0    -1.4    -1.0    -1.0
The Breakfast Club                  -0.6    -8.2   -15.4    -0.6    -4.7                   -14.8   -15.0
Gaslight                            -0.6    -0.6    -0.6
The Remains of the Day              -0.8    -4.0    -6.2    -0.8   -23.7                   -11.3   -13.3
Despicable Me 2                     -0.8    -1.0    -1.8    -0.8    -4.4                    -9.1    -8.7
Metallica_ Through the Never        -0.8    -0.8    -0.9    -1.0    -0.9                    -0.9    -1.2
Springsteen & I                     -0.9    -1.0    -0.9    -3.0   -12.3                    -3.4    -3.7
Elf                                 -0.9    -1.2    -0.9    -1.0    -2.3                    -4.9    -4.3
True Detective S1 D1                -0.9    -6.3    -6.4    -0.9    -8.8                   -14.7   -14.6
Gnomeo & Juliet                     -1.0    -4.9    -4.9    -1.0    -5.3                    -6.9    -5.7
The Pirate Fairy                    -1.0    -2.9    -1.0    -1.0    -4.3                    -5.4    -7.2
Secret Of The Wings                 -1.1    -5.1    -6.0    -1.1   -10.4                    -7.1    -6.7
TRON                                -1.1    -2.3    -1.9    -1.1    -1.9                    -6.2    -6.2
Pulp Fiction                        -1.3    -1.7    -1.3    -1.5    -5.1                    -6.0    -6.8
Barney's Version                    -1.3    -1.9    -1.3    -1.4    -6.9                    -1.9    -1.9
Behind the Candelabra               -1.5    -1.8    -2.0    -1.5   -14.7                    -4.0    -4.5
Planes  Trains and Automobiles      -1.5    -3.3    -3.0    -1.5   -16.8                   -10.5   -10.0
Se7en                               -1.7    -3.3    -3.3    -1.7    -3.4    -1.7    -1.7    -8.0    -8.4
Alice in Wonderland                 -2.0   -11.6   -12.0    -2.0    -9.6                   -10.8   -11.0
Mr. Peabody & Sherman               -2.1    -3.8    -4.2    -3.1    -4.3    -2.1    -2.1    -5.2    -5.4
The Fox and the Hound               -2.1   -10.4    -8.6    -2.1    -5.3                    -9.8    -9.4
Snow White and the Seven Dwarfs     -2.6    -9.3    -8.4    -2.6    -5.8   -11.1   -11.2    -4.7    -2.9
Moonrise Kingdom                    -2.9    -3.8    -3.5    -2.9    -6.3                    -4.2    -4.2
True Detective S1 D2                -3.0    -4.3    -4.3    -3.0    -3.6                    -5.0    -4.5
Kill Bill_ Volume 2                 -3.4    -4.7    -4.1    -3.4    -7.0                    -5.6    -4.9
Pinocchio                           -3.6   -10.8   -11.3    -3.6   -10.5   -15.4   -15.4   -15.6   -15.2
Peter Pan                           -3.8   -10.8   -12.5    -3.8   -13.4                    -7.6    -7.4
A Separation                        -3.8   -10.1    -6.6    -3.8  -144.0                  -144.0  -144.0
Ice Age_ Dawn of the Dinosaurs      -3.9    -5.5    -5.9    -3.9    -6.2    -9.6   -11.2   -11.0   -13.2
True Detective S1 D3                -3.9    -5.1    -7.6    -3.9   -16.7                   -13.2   -12.7
Sunshine On Leith                   -4.2    -6.1    -7.2    -4.2   -11.0                   -10.4    -9.6
Nebraska                            -4.7   -16.7   -17.4    -4.7  -144.0                  -144.0  -144.0
Wonders of the Universe             -4.9    -5.7    -4.9
Jackie Brown                        -5.9    -6.5    -6.6    -5.9   -13.3                    -7.0    -7.0
Frances Ha                          -6.0    -6.3    -6.0    -9.0    -9.5                   -14.4   -14.1
American Graffiti                   -6.6    -6.8    -6.6
Once                                -6.8    -6.8    -7.0
Death Proof                         -6.9    -7.2    -7.2    -6.9    -8.3    -8.3   -10.6   -11.8   -10.8
Some Like It Hot                    -8.2   -11.3   -10.4    -9.3    -8.2                   -18.8   -14.6
Pixar Short Films Collection - V   -12.0   -15.4   -14.7   -12.0  -144.0                   -24.9   -22.6

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It is not possible to encode information to a disc that is above 0dBFS.  That is the maximum headroom for digital media and the peaks would get lopped off and look similar to a square wave.  The only reasons that any decent to high end AVR's, pre/pro's, multichannel soundcards or players would send a clipped signal on the analog outs when playing a disc with content under 0dBFS are insufficient testing and poor design.  This is unacceptable.  It shouldn't fall into the consumer's lap the task of testing and evaluating the product to see where it fails. 

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0dBTP?

 

JSS

He meant 0 dBFS. In 64-bit float processing there is no digital clipping and one can see the overages of 0 dBFS before the the final output. 

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Good work on the Oppo! Most are also clipping the signal through an iNuke DSP amp or miniDSP based on the settings I've seen. 

 

It is not possible to encode information to a disc that is above 0dBFS.  That is the maximum headroom for digital media and the peaks would get lopped off and look similar to a square wave.  The only reasons that any decent to high end AVR's, pre/pro's, multichannel soundcards or players would send a clipped signal on the analog outs when playing a disc with content under 0dBFS are insufficient testing and poor design.  This is unacceptable.  It shouldn't fall into the consumer's lap the task of testing and evaluating the product to see where it fails. 

Intersample peaks can be higher than 0 dBFS and most certainly are on the disc. These are called 0 dBTP (0 dB True Peak). This is why the the Benchmark DAC2 HGC provides the following capability:

 

"HIGH HEADROOM DSP - WITH 3.5 DB "EXCESS" DIGITAL HEADROOM

All of the digital processing in the DAC2 HGC is designed to handle signals as high as +3.5 dBFS. Most digital systems clip signals that exceed 0 dBFS. The 0 dBFS limitation seems reasonable, as 0 dBFS is the highest sinusoidal signal level that can be represented in a digital system. However, a detailed investigation of the mathematics of PCM digital systems will reveal that inter-sample peaks may reach levels slightly higher than +3 dBFS while individual samples never exceed 0 dBFS. These inter-sample overs are common in commercial releases, and are of no consequence in a PCM system until they reach an interpolation process. But, for a variety of reasons, virtually all audio D/A converters use an interpolation process. The interpolation process is absolutely necessary to achieve 24-bit state-of-the art conversion performance. Unfortunately, inter-sample overs cause clipping in most interpolators. This clipping produces distortion products that are non-harmonic and non-musical . We believe these broadband distortion products often add a harshness or false high-frequency sparkle to digital reproduction. The DAC2 HGC avoids these problems by maintaining at least 3.5 dB of headroom in the entire conversion system. We believe this added headroom is a groundbreaking improvement."

You can read more here:  https://auphonic.com/blog/2012/08/02/loudness-measurement-and-normalization-ebu-r128-calm-act/.

To be in compliance with EBU R128, JRiver Media Center allows one analysis of dBTP and will adjust the digital levels as necessary to not exceed -1 dBTP.

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How often in a track does 0dBFS+ really happen?  In the bass freqs, you are talking fs/240 frequencies.  Interpolation techniques would be hard pressed to reconstruct much above 0dBFS unless clipping/hard limiting is present, and it depends on the interpolation algortihm.  Only way to be sure is to look at digital in vs analog out to amplifier.

 

The WCS disc shred has only goes to 60Hz, all channels encoded at -0.1dBFS.  Such a low freq and smooth waveform to begin with would have difficulty having dBTP/0dBFS+ problems.  But I can easily see where Pacific Rim, and Transformers 4 would have 0dBFS+ in spades, especially the most-often clipped center channel.  The interpolation would try to take those squared-off peaks and make something smoother out of them, overshooting the voltage coincident with 0dBFS.

 

All the more reason to like a clean mix.  Unfortunately, if you take one look at the AVS Bass thread, clipped mixes are almost nearly always praised/lauded.  Let the loudness wars continue.

 

JSS 

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I contacted OPPO and roughly explained the situation.  I referred them to this thread for the details of the test.  They sent me an email:

 

"Paul,

We have forward your E-Mail to our engineers whom will try to replicate them in-house. We will then provide you with additional feedback once they are able to work on replicating the problem.

Best Regards,

Customer Service
OPPO Digital, Inc."

 

I am remaining hopeful that there will be a way to fix this problem with a firmware update. 

 

As far as the 0dBTP stuff, I don't understand if this has to do with peaks that are not being detected during production (using standard level meters) and are therefore being badly distorted due to the lack of headroom on the disc or if it is a thing that happens with the signal reconstruction algorithms after the fact. 

 

Either way, for me it's a simple scenario of reproducing the waveform that is on the disc out of the analog out with as little distortion as possible.  I showed that even a cheap Sony AVR can accurately preserve the sine wave on max's disc with 5 channels of re-directed bass as long as the analog levels are kept in check.  This is all that I'm asking for.  If it is too hot of a mix and it is going to clip on reproduction, I at least want an accurate reproduction of what's on the disc without adding clipping to the clipping.  Especially when sending that signal to high powered amplifiers and long throw drivers. 

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The true peak issue seems to be a mixing error, whether through ignorance, incompetence or just misaligned incentives is difficult to say and, to the end user, largely irrelevant.

 

It seems the same problem on the hardware side anyway, namely that hardware is designed and built that has either inadequate headroom, or software that is inadequate, for the job at hand and thus contributes its own distortion under load.

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