For this application, electric bass pre-amp, battery opperated, I'd go with a lower power opamp such as the TL061 (single) or TL062 (dual).
Each opamp unit drains only 0,2mA. (0,2mA TL061 and 0,4mA TL062)
In addition, I'd use a single 9V battery and decouple both input and output with bipolar capacitors with cutoff frequency of about 1Hz or less.
In audio path you don't want to have any type of DC level, specially on potentiometers.
Single reverse diode on battery input and you'll be safe.
Polarization at half of battery voltage is so simple, just 2 resistors at the opamp input.
Each opamp unit drains only 0,2mA. (0,2mA TL061 and 0,4mA TL062)
In addition, I'd use a single 9V battery and decouple both input and output with bipolar capacitors with cutoff frequency of about 1Hz or less.
In audio path you don't want to have any type of DC level, specially on potentiometers.
Single reverse diode on battery input and you'll be safe.
Polarization at half of battery voltage is so simple, just 2 resistors at the opamp input.
They connect EV batteries in parallel but they all start from zero volts and then charged up to stop massive current flow between the batteries.
In my experience if you get two identical fresh batteries from the same batch, they are at a very similar voltage and can be connected in parallel without significant discharge. (Parallel: negative leads connected and positive leads connected to form a single negative-positive lead pair)
Yes, indeed. That is, usually the current an op-amp draws increases very slightly with voltage, it certainly won't decrease.
Thanks for your input. Together with @MarcelvdG's information about power consumption, it seems a single supply approach is a no brainer really.
Single supply circuits can have a (often very large) start-up thump though, as the input and output coupling capacitors charge up... You can make a symmetric circuit though, with a bit of careful design. Just be aware that there's no such thing as matched pairs of electrolytic capacitors...
@Mark Tillotson by symmetric circuit I presume you mean something like what I initially had in mind? With two batteries and a true ground reference? If you can expand on the important points of careful design for the symmetric circuit you mention, I'd be truly grateful.
A symmetric virtual ground for instance, using symmetric film caps in the midrail divider followed by opamp follower. Then at power up the virtual ground is actually at mid-rail throughout the transient. Main bulk decoupling needs to be between the two rails, not to (virtual) ground...
@Mark Tillotson hello again. Is this somewhat close to the circuit you describe? I'd love to hear your feedback/corrections.
The left hand side is what I expect to generate the virtual ground, but you've shorted it to the Vin... Call the negative side of the battery V-, and the positive side V+, then GND will be the output of U2.
Hello all, happy new year!
@Mark Tillotson I did check the circuit and it seems to work as intended. By connecting the first op amp's output to the non-inverting input of the audio op amp I am just biasing the input signal to the bias voltage. I did have trouble running simulations to verify it works. I discovered that the reason was my sine signal generator needed to be referenced to 4.5V instead of 0V otherwise the simulation would fail. When I set dc to 4.5V, DC operating point simulation ran, and I also did a transient analysis and AC sweep. Here's the final circuit, and related pictures. This is with just buffering, without any gain.
So I think it functions well. The only thing I didn't manage to do is somehow show Vin swing around 0V instead of the bias voltage (without affecting the simulations), but that's no biggie.
@Mark Tillotson I did check the circuit and it seems to work as intended. By connecting the first op amp's output to the non-inverting input of the audio op amp I am just biasing the input signal to the bias voltage. I did have trouble running simulations to verify it works. I discovered that the reason was my sine signal generator needed to be referenced to 4.5V instead of 0V otherwise the simulation would fail. When I set dc to 4.5V, DC operating point simulation ran, and I also did a transient analysis and AC sweep. Here's the final circuit, and related pictures. This is with just buffering, without any gain.
So I think it functions well. The only thing I didn't manage to do is somehow show Vin swing around 0V instead of the bias voltage (without affecting the simulations), but that's no biggie.