SR separation

[Frank Raia]

Steve, I wish I had atmos! SR for now, haven't been able to hook up Dolby digital or DTS readers yet. So I guess even in the digital space it all comes down to the sound design of the movie.

[Steve Guttag]

...To test you can use the cat69T. That has a 1KHz (was it 998Hz?) tone ...

Neither. Dolby Tone is 850Hz and frequency-modulated. It is raised to ~935Hz with a duty cycle of about 4%...hence its distinctive sound.

[Edited to correct improper quote formatting]

[Marco Giustini]

thanks - can you remind me why they added the 935Hz modulation?

[Tony Bandiera Jr]

thanks - can you remind me why they added the 935Hz modulation?

As a WAG, I'd say to make it audibly distinctive from a standard 1k test loop so you wouldn't accidentally try to set levels with the wrong loop...but Dolby most likely had a good technical reason too, but I am not sure what it would be..... (NR triggering, maybe?)

[Steve Guttag]

It is strictly to create a unique tone. That tone is "Dolby Tone" and I'm sure its sound has intellectual legal implications behind it.

[Marco Giustini]

very interesting thanks Steve!