Talkback Controller Definition Part 4: Feedback Session!
Some great feedback was solicited from the first three posts.
- Control Room monitor output should be attenuated 20dB when the talkback microphone is enabled.
- Cue output should not simply switch back and forth
- Balanced system only required on i/o, entire system needn't be balanced.
Lets address each of these
1 - Control Room Monitor should attenuate 20dB
A simple H pad and a relay thats controlled when the user pushes the push to talk button. It does mean additional connections on the back panel.That feeds the concept that this is a rack mount unit. A remote makes sense, but switching still needs to happen in the rack.
2 - Cue output should not simply switch back and forth
The original switch used a relay to switch between mic and line.
Two people contacted me on facebook suggesting that the cue should be a mix between mic and line.
That suggests that the line in select relay and mute relay are still valid, but a mixer should be set up between the mic and line ins. I figure this could be done using a TL072. Cue mixes don't require 0.000x% THD.
I figure a simple mixer like that shown on http://sound.westhost.com/articles/audio-mixing.htm will do the trick.
The mix level for microphone input can be set by setting the gain in the mic pre. Alternatively, trim pots could be provided.
3- Balanced IO
Easy Peasy Lemming Squeezy. Get an I/O board with XLR's on it, with INA134's to receive and a DRV134 to transmit.
More sooon. Cheers
Rochey