Dolby Surround and Dolby Enabled speakers force processing in main left and right speakers?

[Mike Up]

I mainly have just watched Atmos shows and movies with my Elac Debut 2.0 A4.2 Atmos upfiring speakers. I usually watch news on my tv speakers. I don't watch much else.

Well I decided to watch the news which comes in DD+ 5.1 with Dolby Surround, upmixing to use my Dolby Enabled Upfiring speakers. What I found was that my news anchors voice was not anchored to the TV with the center channel speaker image. IT was raised higher and followed where I sat. I was sitting of to the left so the center image was pulled to the left of the screen.

This surprised me as I was using my center channel which always anchors to the center of the screen no matter seating position. So I did some comparisons and sure enough this weirdness wasn't happening when I just used DD+ 5.1 processing and not Dolby Surround Upmixer. So the center image drifting was directly from the Dolby Surround Upmixer.

Then I compared a bit more, and went into setting, if I chose Front Height, Front Top or Middle Top speakers, using the Dolby Surround Upmixer with DD+ 5.1 left the center image alone or the same as DD+ 5.1 processing.

So I found that only using the Dolby Enabled upfiring speakers changes the processing in the main left and right speakers, which is garbage. It just destroys the front image, by allowing center voices to drift to the either side of the tv plus raise the center image above the television. I guess Dolby Surround Upmixer is forcing some type of virtualization when only the Dolby Enabled Up Upfiring speakers are used.

Maybe it has been doing this on Atmos movies as well, but I usually only watch action movies where sound is everywhere and doesn't draw attention to itself like watching the news.

Does anyone else hear this or know of this effect?? Like I said, if you choose any other type of atmos speaker, the center image stays the same as DD+ 5.1 and doesn't change like it does with Dolby Enabled speakers?

I do have the Dolby Enabled speaker setup by the book and they do provide overhead sounds that were missing with just 5.1 but not sure the trade off is equal as a stable center image is more important to me.

 

[m. zillch]

So I found that only using the Dolby Enabled upfiring speakers changes the processing in the main left and right speakers, which is garbage.

"Dolby Enabled upfiring speakers" Which ones specifically are you talking about, out of curiosity?

 

[Mike Up]

"Dolby Enabled upfiring speakers" Which ones specifically are you talking about, out of curiosity?

I use the Elac Debut 2.0 A4.2 Atmos speakers, but this is a processing issue. There's hardly any audible sound coming out of the Dolby Enabled Elac speakers but the sound is changed significantly in the front main speakers going from DD+ 5.1 to Dolby Surround (Upmixer). Using the Upmixer, center image is destroyed with center image going above and to the left of the tv when I sit off center. Using DD+ 5.1 decoding, the center image stays horizontally and vertically centered on the television if I'm sitting off center or not.

When I change the setup to be Front Height speakers instead of Dolby Enabled speakers, there is no change now to the main speakers. Switching back and forth from DD+ 5.1 to Dolby Surround Decoding makes no difference at all. Both sound the same. So there is some processing happening in the main front right and left speakers ONLY when Dolby Enabled speakers are chosen in the speaker setup.

Now here's the odd thing, obviously due to the way the original 5.1 is mixed, Chicago Fox station and Chicago ABC have the weirdness. When I watch Chicago NBC or Chicago CBS, there is barely any difference at all between the Dolby Surround Upmixer and straight DD+ 5.1. So its definitely Dolby Surround Processing in the main channels that affected by the 5.1 mix itself.

Just as I said, watching a movie in Atmos and switching back and forth to DD+ decoding(as you can do with Denon Receivers when Atmos is using DD+), there's no difference in the center image. This could be because of the mix again, or it having discrete information.

I'm ready to pull the Atmos Dolby Enabled upfiring speakers out of my system after hearing this. I want my system to sound good with all content.

 

[Mike Up]

Found the problem through extensive troubleshooting. Its the Denon receiver. It flipped the polarity of the center channel while in Dolby Surround. Compared this AVR-X2800H to my AVR-S960H, and the 960 is fine so its the 2800. I did a factory reset which didnt help so doing a firmware reset to see if that works. If not, to the repair center.

Heres to hoping!

 

[Mike Up]

Wow, i finally found the problem and Google AI was actually helpful where a normal search didn't provide any results.

On Denon receivers, when you select you have Dolby Enabled speakers and select a crossover frequency over 100Hz, the receiver automatically reverses the polarity of the center channel speaker as not to interfere with the reflection phasing of the upfiring speakers.

Now here's the good part, you have to use Room Correction to get the polarity correct if your room reflection make this not work well.

I don't use room correction as I don't like it's results. So I was stuck with this weird sounding center image.

So to fix this, I just change my Dolby Enabled crossover to 100Hz, instead of the previous 180Hz, and now the center channel speaker stays in the correct polarity.

I did verify this on both my Denon AVR-X2800H and Denon AVR-S960H. Pretty stupid that Denon automatically reverses the center channel polarity with any Dolby Enabled Speaker Crossover from 110Hz to 200Hz.

 

[m. zillch]

Wow, i finally found the problem and Google AI was actually helpful where a normal search didn't provide any results.

On Denon receivers, when you select you have Dolby Enabled speakers and select a crossover frequency over 100Hz, the receiver automatically reverses the polarity of the center channel speaker as not to interfere with the reflection phasing of the upfiring speakers..

Obviously AI doesn't own a Denon AVR to test this all by itself, so it must have read it somewhere. Did it give you a link to where it determined this info?

 

[Mike Up]

On both my receivers, x2800h and s960h, when having speakers configured as front dolby enabled and any crossover frequency above 100 Hz, the receiver is flipping the polarity of the center channel. You can switch between DD+ +Dolby surround to straight DD+ to hear how the center image changes.

I physically flipped the polarity of the center channel to troubleshoot and the smeared center image went from DD+ +Dolby Surround to Straight DD+ now so it is the center channel polarity being reversed.

Choosing a crossover at 100Hz fixed the issue. Crossovers from 110Hz to 200Hz caused the polarity reversal and smeared center image.

Google AI provided no link but here is the statement from AI:

When using Dolby Enabled (up-firing) speakers in a Denon AVR-X2800H without Audyssey (manual configuration), the receiver’s DSP (Digital Signal Processor) may invert the polarity of the center channel speaker to manage phase cancellations at the listening position.
Here is why this behavior occurs when up-firing speakers are configured with a crossover of 100 Hz or higher:

• Phase Interference Management: Up-firing speakers work by reflecting sound off the ceiling, which introduces a delay and phase shift compared to direct-firing speakers. To blend these "height" sounds with the front soundstage (Left, Center, Right), the receiver tries to align the phases.
• Up-firing Crossover Threshold: Setting the Atmos enabled speakers to a 100Hz+ crossover means the receiver forces the main speakers (specifically the center, in this case) to handle less bass. When the DSP calculates the interaction between the ceiling reflections and the direct sound of the center speaker, it often determines that a 180-degree polarity reversal on the center channel improves the summation (reduces cancellation) at the MLP (Main Listening Position).
• Manual Setup vs. Audyssey: Because you are not using Audyssey, the receiver is likely defaulting to an internal, generic algorithmic compensation pattern designed for Dolby Atmos modules rather than adjusting specifically for your room's unique reflections.
• No Adverse Effects: While it looks "wrong" in the manual setup menu, this behavior is intentional. A reversed polarity on the center speaker alone often helps blend with the front left/right speakers in these configurations. If the audio sounds clear and integrated, you can safely leave this setting as is.

Recommendation:
If the center channel sounds thin or empty, try setting your Up-firing speaker crossover lower (e.g., 80 Hz or 90 Hz) or setting them to "Small" without explicitly setting a high crossover, and see if the receiver stops reversing the polarity.

 

[Mike Up]

So now I dont know if the ceiling affects were primarily the psychoacoustics or the speakers output. Then will these effects even be heard at all.listening spots or just the main listening spot.

Im ready to pull these speakers out of my system now. They offered only minimal effects to begin with but now seeing they ultimately destroy the center image.

I tried a crossover of 100Hz where the center image problem is gone but there must be cancellations as now the ceiling height effects arent there like they were with a 180Hz crossover.

The previous AI information stated that the crossover trigger of over 100Hz was because most upfiring speakers require a crossover 110Hz to 180Hz.

 

[TLS Guy]

I mainly have just watched Atmos shows and movies with my Elac Debut 2.0 A4.2 Atmos upfiring speakers. I usually watch news on my tv speakers. I don't watch much else.

Well I decided to watch the news which comes in DD+ 5.1 with Dolby Surround, upmixing to use my Dolby Enabled Upfiring speakers. What I found was that my news anchors voice was not anchored to the TV with the center channel speaker image. IT was raised higher and followed where I sat. I was sitting of to the left so the center image was pulled to the left of the screen.

This surprised me as I was using my center channel which always anchors to the center of the screen no matter seating position. So I did some comparisons and sure enough this weirdness wasn't happening when I just used DD+ 5.1 processing and not Dolby Surround Upmixer. So the center image drifting was directly from the Dolby Surround Upmixer.

Then I compared a bit more, and went into setting, if I chose Front Height, Front Top or Middle Top speakers, using the Dolby Surround Upmixer with DD+ 5.1 left the center image alone or the same as DD+ 5.1 processing.

So I found that only using the Dolby Enabled upfiring speakers changes the processing in the main left and right speakers, which is garbage. It just destroys the front image, by allowing center voices to drift to the either side of the tv plus raise the center image above the television. I guess Dolby Surround Upmixer is forcing some type of virtualization when only the Dolby Enabled Up Upfiring speakers are used.

Maybe it has been doing this on Atmos movies as well, but I usually only watch action movies where sound is everywhere and doesn't draw attention to itself like watching the news.

Does anyone else hear this or know of this effect?? Like I said, if you choose any other type of atmos speaker, the center image stays the same as DD+ 5.1 and doesn't change like it does with Dolby Enabled speakers?

I do have the Dolby Enabled speaker setup by the book and they do provide overhead sounds that were missing with just 5.1 but not sure the trade off is equal as a stable center image is more important to me.

Get rid of the upfiring speakers. They are a bogus concept and worse then useless. They are a big downgrade.