Symmetric power supply and phantom power from battery

[Baiste]

Hello,

I made an INA217-based portable mic preamp powered by a 9V battery using a rail-splitter (TLE2426). It works and sounds well. The only thing missing now is phantom power.

The 9V battery solution is great and I’d like to keep it that way. So I made a boost converter (using a LT8330) that seems promising and delivers low noise 36V from the 9V battery (which will be enough for my purposes).

Now, my problem is that I can’t figure out how to integrate that boost converter regarding the different ground potentials. Please see the attached schematic, there’s

- mic in ground & line out ground
- boost-converter ground (which equals to INA’s V- pin)
- virtual ground for the INA

And obviously I can’t simply connect virtual ground with boost-converter ground.

So in short, is there a way to make this work?

Thanks!

 

[PRR]

.

 

[Baiste]

Thanks PRR, I was thinking about that too ... But is that really all it takes? Doesn’t the mic‘s ground need to be connected to the INA?

 

[PRR]

> Doesn’t the mic‘s ground need to be connected to the INA?

No; but it is, through the rail-splitter.

 

[Baiste]

Ah sure of course. I just tested it in LTSpice and so far everything works fine.

Thanks!