Film-Tech Forum ARCHIVE: 35mm 4-track mag through CP-500 (Bass separating)

This is topic 35mm 4-track mag through CP-500 (Bass separating) in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Zdenek Stepanek (Member # 8695) on 09-30-2016, 05:47 PM:

Hi guys,

I have CP-500 with Cat 669 with 3x 222SR/A and 685 (analog input card). We work mainly with 70mm.

Now we want to play 4-track magnetic 35mm movie. Main and one question is about separating of subs into Sw output.

When i select format 43 (stereo-surround for 70mm) it works fine. 1Khz test tone inserted into Le or Re input play from L or R surround and 120Hz test tone play from subs.

But I need this for L/C/R channels. As for normal 35mm movie.

There is absolutely same situation when I want to play regular 70mm Todd-AO title. Tracks are full-band and processor should remove subs from channels any play them in one subwoofer output.

Many thanks.

Posted by Gordon McLeod (Member # 33) on 09-30-2016, 06:16 PM:

Like the cp65 mag support was minimal in both the 500 and 65
you probably would want to get a small summing mixer to sum LCR togather and bandpass it and use the external 5.1 input

Posted by Marin Zorica (Member # 1716) on 10-01-2016, 03:46 PM:

This why i do not like to use any of cinema processors on festival solution, but something like yamaha DME or my older tascam dm mixer is great solution, you can eq all channels and do matrix (mix) all things you like.....and just feedeng external SR or A noise reduction.

My idea is to get you're self digital crossover with three inputs, send all three to it and output L C R to amps, do setups internal as sum of L C R and filter it with 120Hz and send to SW amplifier....something ok and cheap as behringer DCX2496 can do job ok!

Posted by Zdenek Stepanek (Member # 8695) on 10-02-2016, 01:12 PM:

Yes, we have external SRA-5 racks (6 channels), we have external bass-separator (6 input - 1 output), but CP-500 is all-in-one and this is reason why I experimenting with it.

In another thread I read that OBE (Optacil Bass Extension) is what i search for.

Posted by Mark Gulbrandsen (Member # 72) on 10-02-2016, 08:55 PM:

There isn't going to be much sub bass on 4 track mag, you're lucky to get 50 or 60 hertz as the bottom end. You might want to use a downward expander on the input to the amplifier to actually help create some very low frequencies.

Mark

Posted by Zdenek Stepanek (Member # 8695) on 10-05-2016, 09:46 AM:

Okay, and what is behavior of standard 35mm optic. With or without matrix. For example also for mono optic - format 01.

There is only one full-range input signal, but on output must be two signal. Mid and High on C channel and Low on SW output.

This is what I want to setup in Custom format for L/C/R -> Sw.