I have a BACP RSTR2000 analog reader. I have a Dolby CP500 that I have the analog going to now. I also have a Sony DFP-D3000 that I would like to hook the analog into also. Can I split the outputs of the BACP RSTR2000 to go to the analog inputs of the Dolby CP500 and to The analog inputs of the Sony DFP-D3000? Is this a no no? Is there a different preferred method?
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Probably. It depends on the output impedance of the reader and the input impedance of the inputs. You may have a level drop on both and need to readjust Dolby level, or it might not change. -
I would avoid it. As to input impedance, optical inputs are pretty low impedance (typically less than 300Ω and often more like 150Ω). The loading affects frequency response as original solar cells are designed as current sources. The basement readers were designed to emulate that though they do have in-line resistors to be able to deal with unbalanced inputs used on the lower-end cinema processors.
Why would you want BOTH connected? So you can have SDDS digital with an analog fall back?Comment
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No and hell no.
I once (and only once) tried switching between optical inputs to separate processors. There were hum issues, and the switching was very flaky. It lasted less than two weeks before the client demanded I take it out. I finally convinced them to shitcan the SDDS and just run Dolby and DTS.
Even the relay circuit I had to use to make a changeover for magnetic sound for a certain amusement park I used to work at proved to be very problematic and it took me a lot of changes and modifications to make it switch cleanly. (and those were line level signals, not the tiny optical solar/reader signals.)
IIRC both the Dolby and System Dumps During Show both use DB9 connectors for the optical inputs. Just swap the cables when needed, BUT:
NEVER, EVER HOT SWAP OPTICAL (or digital reader) INPUTS!! I don't care if it's a solar cell or reader, you can easily damage the preamp in the processor and/or the reader. (Remember that modern processors use a direct input to an IC front end, wheres the older Cat 108's (Dolby) and the optical preamp in the CP 100 used transformer inputs, which helps provide a bit of protection to the high gain optical preamps.)
You also run the risk of creating a high level thump or buzz which can damage speakers.
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Thanks Tony,
I will leave it be. I dont run SDDS often anyway.Comment
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How are you switching things on the output end when you switch between processors? And are you set up with 8 channel on the Sony or just 6?Comment
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Now I see the problem, the catch is if the SDDS drops there isn't an obvious automated way to trigger the CP500 between aux and optical. I didn't work with the 3000's that often so don't know if there is any sort of a status or some other signal you could use to do a trigger.Comment
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From the DB37 'ACC RACK' connector on the CP500, you can get Lt/Rt out at (probably) line level.
What I can't remember, is what combination of option cards internally make this work.
*some* of the ACC RACk pins are live regardless of cards, IIRC the AccNRR/AccNRL were always there (I used to use them for hooking up 16mm Mag Followers or video inputs).
Clipboard_09-23-2026_01.jpgComment
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I have done so, connecting retro scan from Kinotones to a DFP 3k and the Cp 650, but used 220 ohm resistors in the signal path ion both. And it worked neatly. As both units have voltage amplifiers in the input path, and the Dolby board has an actively driven balanced output.
With a standard solar cell it will not be recommended.Comment
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