AVR routs monomixed parts of DD2.0 content from TV apps to center even when not upmixing?

[XaVierDK]

The setup:
AVR: NAD T758 v3
TV: LG C3 OLED

After a longer period of running 2.1 and 4.1 for several reasons, I finally had the chance to reintroduce a center channel speaker to our system.

Set up things as usual, ensuring no upmixing was selected as default and so on.
Watching 5.1 content from the TV's built-in apps are played back perfectly with no issues. However, all 2.0 tracks from the TV when outputting bitstream result in any monomixed parts being muted, but only above the crossover point.

If I turn on Dolby Surround, the missing audio is output correctly through the center channel.
Stereo tracks from streaming on the receiver are fine, as are 2.0 PCM.
I have reset the HDMI ARC handshake and reset the TV.
Do you guys have any suggestions or possible causes? My next moves are a reset of the AVR and a new HDMI cable.

This TV and receiver have previously worked with a 5.1.4 setup with no issues pertaining to stereo playback.


Thanks in advance

 

[TLS Guy]

The setup:
AVR: NAD T758 v3
TV: LG C3 OLED

After a longer period of running 2.1 and 4.1 for several reasons, I finally had the chance to reintroduce a center channel speaker to our system.

Set up things as usual, ensuring no upmixing was selected as default and so on.
Watching 5.1 content from the TV's built-in apps are played back perfectly with no issues. However, all 2.0 tracks from the TV when outputting bitstream result in any monomixed parts being muted, but only above the crossover point.

If I turn on Dolby Surround, the missing audio is output correctly through the center channel.
Stereo tracks from streaming on the receiver are fine, as are 2.0 PCM.
I have reset the HDMI ARC handshake and reset the TV.
Do you guys have any suggestions or possible causes? My next moves are a reset of the AVR and a new HDMI cable.

This TV and receiver have previously worked with a 5.1.4 setup with no issues pertaining to stereo playback.


Thanks in advance

I think you have had no replies, as we also need to know your exact settings. Your question can not be answered as you posed it. That receiver is quite old and not well thought of. One strange thing I did find in the manual, is that if you select stereo, the default is Dolby surround, which is nuts. So if you select stereo, you then have to select none. If you don't you will get Dolby surround and therefor get output from the center channel.

After looking into it, I am certain this is not a device I would want to own.

 

[XaVierDK]

I think you have had no replies, as we also need to know your exact settings. Your question can not be answered as you posed it. That receiver is quite old and not well thought of. One strange thing I did find in the manual, is that if you select stereo, the default is Dolby surround, which is nuts. So if you select stereo, you then have to select none. If you don't you will get Dolby surround and therefor get output from the center channel.

After looking into it, I am certain this is not a device I would want to own.

I appreciate your opinion on the receiver's performance, though it's served us well enough these past 8 years.
The default setting for Dolby Digital 2.0 is as you say Dolby Surround, by my guess because the more universal Dolby Surround upmixing was new at the time and they wanted to promote its use. It's simple to disable and does not come on as default on power-on afterwards. It is also not the case for 2.0 PCM (eg. music)

To specify, we went from a 4.1 setup to a 3.1, replacing our old fronts with our current surrounds, as these match our new center, and then finding a second pair of identical speakers to slot into the surrounds' position.

So currently we have:
Fronts: small, 80 Hz crossover
Center: small, 80 Hz crossover
Subwoofer enabled.
All upmixing disabled for all listening modes
DIRAC not calibrated.

Since posting I've gone through a factory reset of the receiver and replaced the HDMI cable to ensure no hardware defects. These did not resolve the issue.

As it turns out, when setting up the receiver for a 3.1 system is where the fault occurs. If I enable the surround channels, the 2.0 Dolby Digital stream is decoded without issue and plays properly through the front L/R speakers.
I can't figure out why though it seems a firmware error, and seeing as the 3.1 setup was only an intermediate step, the solution seems to be to just get hold of a pair of surrounds ASAP and live with the Dolby upmixing for 2.0 DD content in the meantime.
I do recall us at some point running a 3.1 system without issue during a remodeling, so it might be something introduced in a firmware update sometimes in the time since then.

Best regards

 

[TLS Guy]

I appreciate your opinion on the receiver's performance, though it's served us well enough these past 8 years.
The default setting for Dolby Digital 2.0 is as you say Dolby Surround, by my guess because the more universal Dolby Surround upmixing was new at the time and they wanted to promote its use. It's simple to disable and does not come on as default on power-on afterwards. It is also not the case for 2.0 PCM (eg. music)

To specify, we went from a 4.1 setup to a 3.1, replacing our old fronts with our current surrounds, as these match our new center, and then finding a second pair of identical speakers to slot into the surrounds' position.

So currently we have:
Fronts: small, 80 Hz crossover
Center: small, 80 Hz crossover
Subwoofer enabled.
All upmixing disabled for all listening modes
DIRAC not calibrated.

Since posting I've gone through a factory reset of the receiver and replaced the HDMI cable to ensure no hardware defects. These did not resolve the issue.



As it turns out, when setting up the receiver for a 3.1 system is where the fault occurs. If I enable the surround channels, the 2.0 Dolby Digital stream is decoded without issue and plays properly through the front L/R speakers.
I can't figure out why though it seems a firmware error, and seeing as the 3.1 setup was only an intermediate step, the solution seems to be to just get hold of a pair of surrounds ASAP and live with the Dolby upmixing for 2.0 DD content in the meantime.
I do recall us at some point running a 3.1 system without issue during a remodeling, so it might be something introduced in a firmware update sometimes in the time since then.

Best regards

I suspect that this is a firmware problem, from what you say and not fixable unless handled with some future software update. Usually they don't not occur this late in units age profile, but it might. Would not hurt to ask NAD about it.

These are the measurements obtained by Amir of Audio Science Review.

 

[XaVierDK]

I suspect that this is a firmware problem, from what you say and not fixable unless handled with some future software update. Usually they don't not occur this late in units age profile, but it might. Would not hurt to ask NAD about it.

These are the measurements obtained by Amir of Audio Science Review.

Yeah, I'm not exactly holding my breath for a FW fix. I did notify NAD of the issue and my observations though, as the T758 V3i (same unit but with a BluOS update with Airplay support) is still a current retail model.

I am aware of Amir's measurements, though I'm not overly concerned by them, as I never turn it up past -10 dB, where its performance IS better, even if the noisefloor is still high for the amplifier section.
At the time I bought it, no as thorough objective testing had been conducted, DIRAC was a large selling point for me personally, as was the full preamp-out capability for future 7.1.4 Atmos. Had I had the same budget today I'd have looked at some of Denon's or Onkyo's offerings I'm sure.

Best regards