Ok, A lot of stuff I didn't know here, but good to be cleared up

I am trying to think about current comsumption here, but one thing to note is that this circuit isn't running constantly. It's for a drumset so each amp is only active when it's corrisponding drum pad is hit, and each hit only lasts a fraction of a second.

At this point I'm mostly just messing with the circuit, then I can figure out it's power requirements.

There are designs such as mine which exist commercially and run off of USB power. I'm putting more than one design into the main device though.

 

Each opamp draws current ALL THE TIME but they are low power opamps so their current is low. The LEDs draw most of the current.

 

the leds won't be on all the time. only when there is an input pulse do the LEDs come on.

One problem I am having here is that when the op-amp is set to no gain, the LED will stop working when the input trim goes below 85%, and at full gain the LED stops working when the input trim goes below 55%.

Not sure how to fix that in a simple fashion as the LED only needs to indicate any minimum signal or rather that there actually IS a signal, doesn't matter how big or small it is.

 

The minimum gain of your opamp is 1.0 and the maximum gain is 1.55 which is not much more. You probably need more gain, reduce the value of the 180k resistor.

If the 180k resistor is changed to 10k then the minimum gain is still 1 but the maximum gain is 11. If the 180k resistor is changed to 1k then the maximum gain is 101.

 

I don't have more gain because I don't think it's needed by the drum set, and in simulation the output stops at 7.65V anyway no matter what the gain is.

It also produces a clipped signal. I don't know if that carries over to real life functionality but I basically adjusted the gain so when the pots are maxed out it;s producing it's highest signal, unclipped.

 

The output stops at 7.65V because with a 9V supply the output of an LM324 saturates at 1.35V less than the power supply voltage and that is why it is clipped.

Your negative power supply does nothing and can be removed if the negative wire is connected to 0V.

 

Yes exactly, so there would be no need to have a gain of 101 when the maximum I can do is only about 1.5.

When I remove the negative voltage it does funny things because the input signal swings below 0V.

 

This e-drum preamp uses a low voltage Schottky diode to prevent the input from going too much negative:

 

I've simulated that one before, when P1 goes above about 50% it reaches it max output of 6.85V with a 10V input, so it wasn't even amplifying the signal. Then above 50% it makes the wave square.

In any case I only get half wave positive output.