SR//Mono: Does It Exist?

[Tony Bandiera Jr]

That was gonna be my follow up question. Our AP20 is not currently configured with a 2.0 preset, but it sounds like it would be worth having one?

Should a similar effort be made for 1.0 films, rather than playing them exclusively using the center channel?

Absolutely not. You will end up with odd "hole in the middle" and phasing artifacts in the between speaker seat positions. And if the levels of LCR are even .5dB off from each other, the effect gets worse.

Real life example: I started in the industry at the AFB theatre in Tuscon, Az. We had constant complaints about not being able to understand dialog during the films. It didn't help that there were NO acoustic treatments (it was built in the early 1950's) so think school auditorium or gym.

I finally got the chance to go downstairs while running a test reel of trailers..and found that our stage side speakers were ON as well as the Altec A7 behind the screen. I went to the rack and found the jumper some previous operator had installed (and against the AAFES rules, they even mention it in the manual!) and removed it. Problem solved (although we had to run the film sound on fader setting 7 instead of 4, old school individual faders on each machine, with a toggle to select film/Music (non sync)).

The very next show the manager came up and said everyone was raving about how great the sound was.

A few years after I left, AAFES upgraded all of its theatres to Dolby Stereo with CP-50's.

[Ryan Gallagher]

So only recommended adding a preset for 2.0 DCP that might have some encoding to deliver SR... and leave 1.0 alone (played using 5.1 preset)?

[Tony Bandiera Jr]

So only recommended adding a preset for 2.0 DCP that might have some encoding to deliver SR... and leave 1.0 alone (played using 5.1 preset)?

Correct. And make sure your 5.1 preset doesn't try to decode into mono off of a DCP with both tracks in mono, as any errors in phase or level in those two tracks WILL decode out and cause noise or echos. (Some processors call it "True Mono" or "Direct mono")

I haven't been around DCPs since my Bel Aire days some years ago, so not sure if mono DCPs with 2.0 encoded tracks even exist.

[Ryan Gallagher]

I haven't been around DCPs since my Bel Aire days some years ago, so not sure if mono DCPs with 2.0 encoded tracks even exist.

All our classics I have had the pleasure of screening in 1.0 format indeed were true mono with only the center channel active on the AP20 in 5.1.

I guess the crux of your hypothetical is, the DCP will be labeled 2.0 most likely, even if the source audio was 1.0 and split into stereo. Watching for exact meters or doing a bit of googling would seem to be the only way to catch these and change the processor settings to something plays mono referencing only one of the two channels.

[Tony Bandiera Jr]

All our classics I have had the pleasure of screening in 1.0 format indeed were true mono with only the center channel active on the AP20 in 5.1.

I guess the crux of your hypothetical is, the DCP will be labeled 2.0 most likely, even if the source audio was 1.0 and summed into stereo. Watching for exact meters or doing a bit of googling would seem to be the only way to catch these and change the processor settings to something plays mono referencing only one of the two channels.

Yep, that sums it up better than I did. A simple meter check and you're good to go.

[Steve Guttag]

No, 1.0 film should play just from center (and with a pro-logic decoder, they should still just play from center, anyway).

[Sascha Roll]

And exactly this need for 2.0 Matrixdecoding makes the CP 950 pretty useless for my needs - or does it Feature Matrixdecoding on AES EBU Inputs by now?

[Steve Guttag]

Why, no. No, it doesn't. It does for HDMI sources or the 1xAES inputs or even analog stereo...but for the 8xAES inputs (DCP)...sorry, no...that is not an option, at this time. Please complain. That is the best way to address the problem.

A "typical" control layout on one of my QSYS cinema systems:



Ironically, the CP750 could handle 2.0 formats from DCP.

[Tony Bandiera Jr]

No, 1.0 film should play just from center (and with a pro-logic decoder, they should still just play from center, anyway).

I may have misunderstood what you meant there Steve, so apologies if I did.

Should? Absolutely. But for the reasons I mentioned in my post above there is still a possibility of decoding issues with a 2.0 "mono" track. (To be fair, a much bigger problem with film optical sound, but I have encountered certain Laser Disc and DVD movies where one channel is phase inverted or has random issues and you know what happens when that is ran through a matrix decoder. ) That's why I don't always trust decoders. Now a single channel (1.0) digital data stream should play correctly to center, unless the stream is assigend to the wrong channel.

BTW for some reason your control layout capture isn't showing on your post above. Clicking on it gets and "Invalid File Specified" error.

[Steve Guttag]

Yeah...every once in a while, something goes wonky the attachments. it looks fine when I post it but later on, it appears broken. Here is the image:

Screen Shot 2024-01-27 at 3.00.16 PM.png

[Don Furr]

[QUOTE=Jim Cassedy;n35308]Was there / is there such a thing as DolbySR™️ Mono?

- - but getting back to my original question, i[B]s there / was there, anything ever done in
Mono+SR?

Short answer,,,yes. About 15 years ago when there was still a Cinevator in LA, Ca. I had 1600 feet of a 1960 title printed to upgrade a print. The positive print was done in SR mono. Compared to the rest of the print it's go a booming center channel. Sounds great, just loud. (and it was expensive !!)