Film-Tech Forum ARCHIVE: dolby 360 nr

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Posted by Fabio Bozzoli (Member # 3694) on 03-19-2006, 03:01 AM:

I have a small cinema.
We are using stereo track without noise reduction.
i have bought on ebay
http://cgi.ebay.ca/Dolby-Model-360-w-SR-Module-Cat-No-280_W0QQitemZ7373167208QQcategoryZ23793QQcmdZViewItem

two dolby 360 with 280 nr for mono track
but i am not able to find the manual.

I have to calibrate them but I know that i should use dolby noise.
We have only (because film processors use only it) dolby tone ( tone al 50% of range at 1000Hz)

I want to generate dolby noise (pink noise)

do you know how it is? I have read that it is 15 dB lover dolby tone. is it true?
The you know frequency range.

thanks
Fabio

Posted by Christos Mitsakis (Member # 143) on 03-19-2006, 03:18 AM:

Fabio,
Use Dolby Tone (cat 69T) and adjust input until the needle is in mid position (dolby level). I'm shure you're using also some sort of preamp. The processor comes after that so be careful not to overload its input.
Christos

Posted by Fabio Bozzoli (Member # 3694) on 03-19-2006, 07:36 AM:

I have used this procedure but i am not sure about it.
The sound seams innatural.
Have you tried it?

I have read on 363 manual http://www.dolby.com/assets/pdf/tech_library/151_363_8.Manual.pdf

that pink noise (used for sr) is 15 dB lower than dolby tone (ad display make an automatic shift of 15 dB)

thanks

if i use

Posted by Christos Mitsakis (Member # 143) on 03-19-2006, 10:26 AM:

Fabio,
can you describe unatural sound?
Also your sound set up? ie. what precedes and what follows the NR processor.

C.

Posted by Fabio Bozzoli (Member # 3694) on 03-19-2006, 11:35 AM:

ok
i have a leser head
an preamplifier ( stereo mic amplifier)
two dolby 360 with 280 nr
an equalizer
and finally apmlifier

i heard some distotion (with dolby sr) with loud voice (but not with hight music )

and i feel some problem with high frequency .. a lack of them
(but not in all scenes)

for this a am thinking about problem of level

thanks

Fabio

Posted by Gordon McLeod (Member # 33) on 03-19-2006, 01:02 PM:

Have the 280 been set for playback mode?

Posted by Christos Mitsakis (Member # 143) on 03-20-2006, 03:24 AM:

I was going to ask the same thing Gordon did. As far as I can understand you adjust the house levels from the amp, or you use the preamp you have?
By turning NR off does the sound issues disapear?

Posted by Fabio Bozzoli (Member # 3694) on 03-20-2006, 04:20 AM:

the card is set on play (non rec) by 360 unit bottons.
On the back of 280 there are tree bridge: 360, M, 361 Do you know how do they work?
How can i force 280 to work only in play mode?

I adjust level by preamp (for the dolby sr) and after i adjust cinnema's level by amplificator control.

if i switch of dolby sr , the sound is great.

if i switch off

Posted by Christos Mitsakis (Member # 143) on 03-23-2006, 07:52 AM:

Cat 280 can fit in diferend dolby mainframes as the 360 and 361. In your case the 360.

Although I would not recomend to modify the cards for playback only since you are actually using a NR that has the switching on its main panel here are some links here that adress this issue:
http://www.film-tech.com/ubb/ultimatebb.php?ubb=get_topic;f=1;t=007344#000000
http://www.film-tech.com/ubb/ultimatebb.php?ubb=get_topic;f=1;t=002615

On the distortion issue.
By lowering the level on your preamp below dolby level does the distortion on loud voice passages go away? HF loss will be more apparent though.