Netmux audio breakout: Difference between revisions

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Revision as of 11:00, 6 October 2011

Harry will do pretty much what Roger did, but will have newer chips, and some nice added features. Basically, Hrry's job will be to convert any "finished" audio source, i.e. vidserv, sound desk to whatever they are needed as somewhere else, like vidserv, stream, and Desk. So, a format convertor.

Input Sources

Source Stereo? Balenced? Level Adjustable?
Vidserv Yes No -10dBV Yes
Analogue Tuner Yes No 1V No
Digital Tuner Yes No 1V or -10dBV No or Yes
Sound Desk Yes Yes +4dBu No*
No No ? No

By adjustable Rihard meant whether there is a control that can be used to vary the signal level. The sound desk is not adjustable because the meters on the output show a fixed reading for a given signal level, and we always mix to the same point on the meters. It doesn't actually matter because the sound desk will be the reference level to align all the other sources to anyway.

Processing

These are the connections to other pieces of equipment hidden behind the breakout box, which are used to control and process the audio. Mux connections

Practically the whole point of this box being here.

Net Mux inputs are balenced, on 25pin D connectors and do not have individual level controls

Net Mux outputs are balenced assuming the inputs are, buffered (to give two outputs) and have "Master" level control potentiometers.

Question: Do unused inputs get shorted to ground? Answer Richard thought not; otherwise vidserv loopthrough wouldn't work, but he was not sure. We'd have to check this.

Compressor Connections

We currently use one channel of a dual channel compressor to compress everything. Logically using one channel to compress 'stream' and the other to compress 'net' makes sense, since they would potentially have different sources in the future.

Compressor inputs can be balenced or unbalenced, the outputs are balenced and will drive unbalenced, and the whole device can be switched between -10dBV and +4dBu levels (affects inputs and outputs). There is also an output level control on the front panel.

Outputs Loop-through outputs

Unaltered (buffered) outputs

Signal Destination Stereo? Balenced? Adjustable?
Vidserv Sound Desk Yes Yes Yes
Analogue Tuner Sound Desk No Yes Yes
Digital Tuner Sound Desk No Yes Yes
Spare / OB Sound Desk No Yes Yes
Sound Desk Control Room Amp Yes No No

Outputs are marked as Balenced if they are capable of accepting balenced signals (they obviously can take unbalenced as well), and Adjustable if they have a trim control to compensate for the level of the input signal. Tuners are shown as Mono because they are only on the sound desk as a conveience, and have historically been mono.

Main Outputs

These carry the output signals from the Mux, and are controlled by the mux settings

Signal Destination Stereo? Balenced? Adjustable?
Net Sound Network No Yes Yes
Net Sound Local TVs No No Yes
Net Sound Control Room Amp Yes No No
Net Sound Campus Stream No No No
Net Sound Net audio VU No No Yes
Stream Sound Stream No No No
Stream Sound Control Room Amp Yes No No
Stream Sound Stream audio VU No No Yes

Outputs marked Stereo are not truly stereo, but have stereo inputs so both channels need to be driven, preferably without special splitter cables. Campus Stream and Stream Sound to Control Room Amp are included for future flexibility, and the two VU outputs are so we can put VU bargraphs alongside the monitors on the rack. They are classed as "adjustable" because they don't need their own level control pots on the breakout, we can fit trimmers on the VU meters to set up the 0dB level to match our desired ouput level to network.

Block Diagram

apparently, one used to exist, but has been lost over time.

Circuit Details

Text description of individual blocks of the machine.

Parts List

This is the old parts list.

Item Supplier Part Number Quantity Price Total
TL081 Dual Op-amp Rapid 82-0064 20 0.17 3.40
8-Pin IC Socket Rapid 22-0150 20 0.014 0.28
100nF Ceramic Capacitor Rapid 08-0235 20 0.014 0.28
Dual Gang 10k Log Pot Rapid 65-1460 3 0.93 2.79
Single Gang 10k Log Pot Rapid 65-1424 5 0.43 2.15
15mm Black Knobs Rapid 32-0270 8 0.125 1.00
Veroboard 95x432mm Rapid 34-0535 1 2.40 2.40
XLR Female (panel) CPC AV10285 4 0.97 3.88
XLR Male (panel) CPC AV10284 9 0.97 8.73
Mono Jack Socket CPC CN00002 16 0.37 5.92
4-pin DIN socket Rapid 20-0360 1 0.175 0.175
4-pin DIN plug Rapid 20-0260 2 0.13 0.26

Power Supply

Apparently, a box exists to do this, except no-ones seen it for over a year...

Wiring Details

Tables straight from the old website, probably needs comparing during the holdiay with Net Mux inputs/Outputs just in case it's been changed.