Another thought

Both receivers I have owned have had a “center width” adjustment. Increasing the “center width” sends the center channel more to the left and right fronts. The booklet with my current receiver says a center width of 7 or above may send no sound to the center channel. So I think turning up the centre channel will be most effective with the “center width” set to its lowest value

At last a benefit from getting older!
Our appetite for blockbuster films with battle scenes, car chases and whizz bangs has disappeared. This means we can happily watch stuff on our 5 yr old telly through its inbuilt speakers and everything sounds lovely.
Some of the action scenes on Dad’s Army can get a bit scary though.

To be honest we have only really dealt with the issue by accepting high volume levels in action sequences.

Some amps have a ‘night mode’ which will curb loud sequences and boost quiet ones.

OK, I have tried all sorts.
The source is not the problem. BR is the same as streamed via the WD-TW.

I have lowered all the other channels to help out the higher level of the dialogue. Also switched on the ‘Enhancer’ mode and turned the dynamic range to low. It is better, in some films.

I think the issue is that the center channel on some films includes some of the action, explosions and music. Rather than being just for voice. So if I increase the voice level, I also increase the noisy bits. Not good for a family house with the lounge below the kids.
Other films direct the action to the front left/right and the voice to the center. This was the way I thought it was designed back in the days but it appears that some newer films are pushing ‘all to all’ for increased wow factor maybe?.

That sounds like you need to set the channels up yourself.
EG, set FL, FR, RL & RR to 80htz, set sub to 80htz but set centre to 120htz & increase volume it by +4db 8)

I had this for a while. I thought it was the puny Tannoy 5.1 speaker set up I had. Not the case. Nor was it the Yamaha RX-V379.

I did something similar to what 2unfit2ride did.

To fix it so that dialog was at an audible volume I used the auto-setup microphone to get initial settings. Then I bumped up the mid-range frequencies and relative loudness of the centre channel by a few dB on the amp’s setup. Problem solved. Centre channel speech loud and clear. Other sounds OK. Though I’ll add that the centre channel speech could sometimes be a bit harsh because of the frequency boost.

I’ve since changed a few things and now use a pair of MA GR60s for the front rather than the Tannoys and I’ve removed the centre speaker altogether. A 4.1 setup. Sound is great IMO, speech clear, other sounds balanced.