Monsoon amp turn on signal comes from 6v detected on the left negative input. Explained very well here:
Ground loop could be a factor.
Signal inout level to the amp
Here is my build design with questions and unknowns identified throughout.
Mac Mini audio output will come from the 3.5mm mini plug using a TOSLINK cable. Digital out that needs to be converted to analog. I have been researching several solutions and my initial design uses minidsp.com components.
The DAC will consist of a miniDigi which takes the digital inout from the mac mini and converts it to an analog output to the minidsp. The minidsp provides 4 RCA outputs. Two outputs for the monsoon amp and two outputs for the powered sub.
- Concern: this arrangement will not plug and play to phase 2 (new 2x two channel amps and speakers). To gain fader control I plan on using 2x 2 channel amps when I upgrade. So, I might consider using a 2 x 8 minidsp which gives me the addition outputs for both future amps.
- Question: how is the fader controlled on the monsoon amp?
- Question: how is fader controlled on an aftermarket 4 channel amp?
- I need this insight to determine how best to control the front to rear fade and to decide if the DAC needs to be 2 x 4 or 2 x 8.
Power for the DAC will come from the P2140 DC-DC power supply.
- Concern: the PSU will power both the Mac mini and the audio DAC.
The next step is to "wire" the DAC RCA outs to the monsoon amp connector. I have a connector and wire on the way.
I also have to inject 6v on the left negative amp input to turn on the amp. I would also like to delay the amp power-up to avoid the thump.
I plan on building a box with RCA inputs on one side and speaker connectors on the other to tie the DAC to the amp.
I will also provide 12v to this box and regulate it to 6v to inject power to the left negative to turn on the amp.
Question: could I use the 5v power from the PSU as the amp turn on signal?
Power to this circuit will be controlled by the miniDC isolator which creates a time delay for the amp to be powered.
- Question: the P2140 PSU has a delay circuit to start and stop the carpc. Can I use the delayed signal from the P2140 PSU as input to the miniDC isolator. This would ensure the the audio amp powers on after the computer.
I will install a ground loop isolator between the minidsp and the point I inject 5v into the negative left line. This will prevent the 5v from flowing back to the minidsp and will help with any ground loops that might develop.