[sevs]

Can I use only one 9V battery instead of using 2 9V batteries on the BANZAI V2 CMOY Headphone Amplifier?

Why/why not?

If so, then what should I do?

 

[ShinyFalcon]

Minimum voltage for the JRC 4560D opamp is ±4V, which means you'll quickly run into battery life issues. You can't use one battery without modifying the circuit because of the way the Banzai CMOY splits the voltage rails.

 

[sevs]

Quote:

Minimum voltage for the JRC 4560D opamp is ±4V, which means you'll quickly run into battery life issues. You can't use one battery without modifying the circuit because of the way the Banzai CMOY splits the voltage rails.

If I do like shown in this bad diagram I made in Paint, will it work then, you think? Will I damage something?
FIG 1: Original schematic made by Electric Sumo
 
 

FIG. 2: Bad schematic made by me. The green and blue wires are for eventually adding an external 230V to 9V adaptor, so I could connect it to the wall outlet, or add an external battery.

 

[ShinyFalcon]

You will short the batteries if you wire it like that. You need a rail splitter after the switch to create a ground if you want to switch between battery and wall-power.
 
Information on virtual ground: http://tangentsoft.net/elec/vgrounds.html
In your case, it can be as simple as adding a resistor across the capacitors' pins.

 

[sevs]

Quote:

You will short the batteries if you wire it like that. You need a rail splitter after the switch to create a ground if you want to switch between battery and wall-power.
 
Information on virtual ground: http://tangentsoft.net/elec/vgrounds.html
In your case, it can be as simple as adding a resistor across the capacitors' pins.

Thanks!

 

[bootdsc]

I run my banzai v2 off a single 9v battery or two 3.7 li-ion in series. it is vary easy to mod the circuit with the only extra part you need being a rail splitter. 
If you need some help still i can draw up the changes i made and give you part numbers for digi-key. 
 
For some reason my kit came with 220uf caps, switched them for 470uf. Tried all the Op-Amps i had on hand, the opa1642 sounds best with
the headphones i own but that's my opinion  and doesn't mean its best for everyone. The v2 is still far from perfect but i like it all the same.