Help with Atmos setup on Oppo 205

[tlake6659]

I am using 5.1 analogue cables from an Oppo 205 to an older Denon receiver. When playing Atmos mixes from Blu-rays my rears lower in volume when setting the Oppo player to downmix to 5.1. When choosing not to downmix and leaving playing as 7.1, the rear channels are correct volume but I lose any info from the height channels. When downmixing to 5.1, I get the height channel info mixed to my rear channels, but the rears are lower in volume. Really confused. If anyone could help I would really appreciate it.

 

[SeeMoreDigital]

As you may or may not know...

You can only obtain Atmos (spatial) audio by connecting you OPPO via HDMI to an AVR that has an Atmos decoder.

 

[tlake6659]

The 7.1 mix from the Bluray should downmix properly to 5.1.

 

[SeeMoreDigital]

Have you visited and changed your OPPO's 'Down-mix Mode' options: -

 

[tlake6659]

Yes. My issue is the player lowers the volume of the rear channels when downmixing 7.1 to 5.1.

 

[tlake6659]

Must be a setting on the player but I can't figure what I am doing wrong.

 

[SeeMoreDigital]

After selecting the correct 'Down-mix Mode' option have you visited and altered all your 'Speaker Settings' options: -

 

[DuncanS]

My feeling is that as it is downmixing (i.e. merging) two channels into one it will lower the level of each identically by a fixed amount (I would think each lowered by 6dB) so that if each channel had exactly the same signal level the overall signal level going to the amplifier would be the same as the unmixed signal - so an amplifier input is not clipped.

 

[tlake6659]

Thanks. That makes sense. So raising each rear channel by 6dbs should get it back to normal. Where dud you get 6dbs. Just wondering

 

[DuncanS]

If you add two equal numbers the answer is double in size, which is a 6dB increase in level.

 

[LuvMyQuad]

My feeling is that as it is downmixing (i.e. merging) two channels into one it will lower the level of each identically by a fixed amount (I would think each lowered by 6dB) so that if each channel had exactly the same signal level the overall signal level going to the amplifier would be the same as the unmixed signal - so an amplifier input is not clipped.

It's a doubling of power so its a -3dB adjustment (per channel) I believe. And that only holds true for a mono signal as would be the case for mixdown of a center channel that is split between the front L/R channels. I'm not sure of the rule for combining rear and side surrounds. Its not the same thing as a center channel mixdown. My guess would be no adjustment at all, but I'd like to know for sure.