- Joined
- Dec 10, 2016
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- 119
Forgive me if this sort of thing has already been asked and answer but searching the forums didn't turn up anything.
I need some help understanding what might be involved in building a remote mic pre.
Here's my thought:
I would like to build (16) remotely controlled API-style mic press. Why API? Mainly because the shunt-to-ground approach to gain. I would think that using relays to control which resistor is in the path to ground would be doable and not an audio nightmare (but I could be wrong).
A brief description:
Or more simply put:
Gain Switch -> MCU -> SBC ~(Ethernet or WiFi) ~> SBC -> MCU -> Relays
I was thinking of using something like a ATtiny or PIC12/16 with four or more ADCs to read the resistor value of the switch (using a voltage divider) and the controller ID (0-7).
The gain switch would have a resistor value for each position into a voltage divider that could be read by a 10bit ADC to give the value. The ID would require (3) ADCs to allow using (3) jumpers to set the ID, simple Binary value. Eight channels per SBC was a thought, I could bump it up to four jumpers and four ADCs for a total of (16) ID's.
The SBCs would talk to the SBC in the rack housing the mic pre's. Then it would sort of go in reverse with the SBC talking to the individual MCUs in each pre. The MCU would probably talk to a DeMux to trigger the appropriate relay. Or I could use another device to handle the relays. Again, not sure what the best approach would be.
Here are my questions:
The big problem is that I don't know what I don't know (and barely know what I do know!).
Thoughts?
Thanks,
James
I need some help understanding what might be involved in building a remote mic pre.
Here's my thought:
I would like to build (16) remotely controlled API-style mic press. Why API? Mainly because the shunt-to-ground approach to gain. I would think that using relays to control which resistor is in the path to ground would be doable and not an audio nightmare (but I could be wrong).
A brief description:
- Each of the (16) gain rotary switches (6-12 positions possibly, not sure on the number gain steps) is connector to a micro controller (MCU).
- Each of the (16) MCU's connects to a single Small Board Computer (SBC), a Raspberry Pi or maybe something simpler like an Arduino.
- Over Ethernet or WiFi, the 'Control' SBC speaks to the SBC in the Preamp Rack.
- The SBC in the Preamp Rack talks to the individual MCU in each mic pre.
- The MCU in the mic pre controls the gain step relays.
Or more simply put:
Gain Switch -> MCU -> SBC ~(Ethernet or WiFi) ~> SBC -> MCU -> Relays
I was thinking of using something like a ATtiny or PIC12/16 with four or more ADCs to read the resistor value of the switch (using a voltage divider) and the controller ID (0-7).
The gain switch would have a resistor value for each position into a voltage divider that could be read by a 10bit ADC to give the value. The ID would require (3) ADCs to allow using (3) jumpers to set the ID, simple Binary value. Eight channels per SBC was a thought, I could bump it up to four jumpers and four ADCs for a total of (16) ID's.
The SBCs would talk to the SBC in the rack housing the mic pre's. Then it would sort of go in reverse with the SBC talking to the individual MCUs in each pre. The MCU would probably talk to a DeMux to trigger the appropriate relay. Or I could use another device to handle the relays. Again, not sure what the best approach would be.
Here are my questions:
- What would be the best (or at least good) approach to getting the gain setting from each switch? I know I could use a voltage divider and read the voltage using a ADC pin or I could connect each switch position to a pin on the micro controller or De-Mux the connections. Would it be better to use transistors for the gain steps on the control side? Looks like there are lots of options and I don't know the pro's and con's of each.
- Do I need an MCU for each gain switch? Would it be possible to use just a single SBC instead of having a MCU for each gain switch? If so, which one?
- What method could I use to have the MCUs talk to the SBC and SBC to MCUs? I2C? PWM? USART? Morse Code? Smoke Signals?
- What would be the most reliable protocol for sending messages between the SBC's? HTTP/TCP/IP? I2C? Yelling Loudly?
The big problem is that I don't know what I don't know (and barely know what I do know!).
Thoughts?
Thanks,
James
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