This is topic Input Volt-Level of Analog Processor ??? in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
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Posted by Nic Dreier (Member # 333) on 08-11-2000, 03:09 AM:
Hi there,
well your my last hope, but I'm sure someone can help me. I live in Switzerland, Europe, so please excuse my English. Ok, this is my problem: I need to know, at what Level (Volts) the analog Soundhead output-signal, that is sent to the Pro1&2-inputs of the Dolby-Processor do work? A think that it's far lower than for example a CD-Player, but which is it ??? Unfortunately after hours of reading manuals and tech specs, my question still didn't get an answer.
Thanks for your help in advance, an greetings from SwitzerlandNic
By the way. This is really the best place to learn all about cinema stuff !!!
Posted by Russ Kress (Member # 461) on 08-11-2000, 03:17 AM:
Dolby processors don't need much. They can use a solar cell output to drive them. The LED readers have a pre-amp that supplies sufficient signal.So long as you can achieve "Dolby-Level" without cranking gains wide open you should be okay.
I'd ask lj@dolby.com if you need the exact voltage.
Russ
Posted by Russ Kress (Member # 461) on 08-11-2000, 03:19 AM:
Okay, now I know what you are asking.The input signal is not "line level". It's probably closer to a turn table level. For exact voltages, ask Lonny or Ken.
Russ
Posted by Oscar Neundorfer (Member # 458) on 08-11-2000, 05:44 AM:
I believe it is around 5 to 10 milliVolts when playing Dolby tone and this assumes a processor is connected to provide the proper load. Someone please correct me if I am wrong.
------------------
Oscar Neundorfer
Chief Engineer
SMART Devices, Inc.
oscar@smartdev.com
Posted by Bill Purdy (Member # 202) on 08-11-2000, 10:03 AM:
Many years ago I used to align exciter lamps by reading the DC output from the cell. Mind you that this was done without a load other than the meter which was usually one of the early Flukes. So, into almost no load at all, I typically would see around 350 mV. This whole subject is a bit slippery because as has been covered before, those cells are current producing devices and the voltage will depend upon the load, which should be quite low. ------------------
Bill Purdy
Component Engineering
Posted by Rory Burke (Member # 512) on 08-11-2000, 11:29 AM:
If your A-chain is properly aligned then with pink noise in the projector soundhead running , you should be reading .100 ACV per channel.
I believe this information is accurate; just looked at my R2 and Achain readings with pink noise are at 100 mv. hope this helpsRORY
Posted by Gordon McLeod (Member # 33) on 08-11-2000, 12:58 PM:
It will vary on the model of processor used since even with in the Dolby line of equipment the internal refference level varries.
The output of the cell itself can be as low as -45db when measured into 600 ohms
I am alittle confussed are you actually useing a dolby processor or a consumer prologic one?
The consumer equipment is usually based around a .7voltrms =0db
Posted by Nic Dreier (Member # 333) on 08-11-2000, 05:51 PM:
Thanks everyone for your support.All right, maybe my question was not written quite clear. We are talking about a CP-50 (yes, the good old holy CP-50). Now our intension is, to be able to show DVD and TV in our smaller theater. For that reason I am trying to hook up a CP-50 and a DVD-Player or VCR so that the sound is decoded by the CP's Matrix. My problem is, that I don't know the operating level of the Proj1&2 inputs. So I thought I could transform the DVD line out level to a lower level which can be used of the CP-50. But maybe I am wrong, cause lately I got another idea. As far as I studied the internal card array of the CP-50 I saw that the Cat108 is a "simple" preamplifier which amplifies the signal of the solar cells to 300mV operating level for the further cards. So why should I transform a signal, just to amplify it later ? Shouldn't there be a possibility to connect the DVD lineout-Signals to the CP-50 AFTER the Preamplifier-Card and the Noise Reduction Cards ??? I don't think I need a Noise Reduction in combination with a DVD Player ;-). Does anybody know, which pins on the Cat-Cards are used to transfer the Signal from card to card ??? If I knew that, I think I could connect the DVD-Lineout just with the right pin after the Noise Reduction cards. And that would be my solution. The DVD signal should be sent trough the matrix and EQ-Cards :-) !!! What do you think, could that work or will I toast my sound equipment ???
Thanks for your opinions in advance
Nic
Posted by Gordon McLeod (Member # 33) on 08-11-2000, 06:03 PM:
If you have the 150 style matrix it is very simple
Feed the signal in at the to SA2 teriminal block and unplug the link card (or 160)
If you want the base extension and you still have the older mechanical pushbutton format card input it at the preamp out terminals (unplug the preamp card)
and select stereo, surround NRoff
The level should be 300mv
Posted by Marc Jones (Member # 29) on 08-11-2000, 07:12 PM:
I have a question like the one that started this thread.
You set the levels from the proj1 or 2 with Cat 69, what is the desired Voltage Peak to Peak?
Thanks
Posted by Nic Dreier (Member # 333) on 08-11-2000, 07:29 PM:
Dear Gordon,I think you got the solution for my problem :-) ! Unfortunately I don't know exactly what the "SA2 teriminal block" is ? The link card is the Cat110, right ? I hope you can describe, where exactly I have to feed in the Right and Left Lineout signals of my DVD-Player (all 4 wires), because it's not so easy for me to understand all the tech stuff written in english.
Thanks for your patience and good night.
Nic
Posted by Gordon McLeod (Member # 33) on 08-11-2000, 08:20 PM:
It wouldbe a good idea to check what cards are actually installed
If you actually have a cat110 in the 110 slot I would not attempt to run a DVD through the system as the cat 110 and the cat116 cards probably will not like the dynamics of a digital source(they definitly don't like SR)
If in the 110 slot there is a 110L (a blank card ie no components on it) then feel free to inject the signal into the terminal block on the centre top I believe labled to surround adapter
If there is a 160 card installed in the 110 slot (sub bass card) then inject the signal at the preamp out terminal block (it is labled that) remove the optical preamp card
You must be able to select the format Stero/Surrround/no Noise Reduction though
Posted by Nic Dreier (Member # 333) on 08-12-2000, 03:27 AM:
Hi Gordon,OK I think we're getting close to the solution! Just one more question and you shall be released ;-). Actually there's a Cat110L card installed. So that should work fine. But I still quite don't understand exactly the term "terminal block." Do you mean the connectors on the back of the CP-50 ? As far as I understand your explanations and the internal diagramms (see fig 9.7.1 in the manual), I have to feed the DVD left and right signal to the connectors labeled "output to surround adaptor (only left/right)" and then, the stereo signal should be decoded by "the matrix" (always sounds a bit strange since the film ;-). And to make sure, that the Preamp- and Noise Reduction cards are not damaged, the 110L has to be taken out, and sound should be then on by selecting format 05 (future format) ?!?
Ok I hope I got it now !!! Thank you for your support. It's always great to solve a problem with the help of this forum. I have to propose my manager, that we install a PC in each booth to check film-tech all day ;-) !!!
Hava a nice day !
Nic
Posted by Gordon McLeod (Member # 33) on 08-12-2000, 09:52 AM:
Terminal block terminal strip the screw on points on the back upper centre area
select 04