Many modern Op-Amps (eg, TL072) will work well for instrument-level (<2V) signal with a "single" 9V supply -- one just needs to bias an AC-coupled input signal up to the mid-point (~4.5V) which can be obtained many ways.
The TL072 isn't specified at voltages below 10V, the graphs on the datasheet and other specifications such as common mode input range and output voltage swing, suggest it will stop working at voltages below 7.5V but it could be higher, depending on how it's used.
For maximum battery life and stability, use an op-amp specified down to 6V or less. The TLC072 is a good replacement for the TL072
That is a good tip. I guess I'm used to work with that voltage because of the university labs, but there is really no need for such a high voltage in the signal, as most pedals are not power amplifiers. Nevertheless, I'm currently working on a Mu-Tron III clone pedal and the schematics show that it was used with two 9v batteries (for the +/- rails). I'm planning on using this circuit to generate the +/- rails from a laptop charger, but I'm not sure if it will be able to feed enough current to the opamps.
What do you think?
That will work but beware the TLE2426 is unstable under certain combinations of load current and capacitance, see the datasheet. Connecting two 4.7uF capacitors, each with 100nF in parallel, from the output to either supply rail, giving a total effective output capacitance of 9.6uF should avoid any problems, as well as reduce the output impedance at high frequencies.
EDIT:
Is the laptop PSU output connected to earth? If so, this could be a problem if you connect your circuit's 0V terminal to another device's 0V with is connected to earth. If this is the case the laptop's negative rail with be 0V relative to earth, leaving your 0V rail at half the PSU voltage relative to earth, which will be short circuited if you connect it to another device who's 0V rail is also connected to earth.