To power just opamps (light load), I have done this:
Note that a 12V transformer gives ±17V, which is enough if you plan to use an LM7812/LM7912 to regulate the opamp supplies. A 9Vac out Wall-Wart would make ~ ±12V without regulation.
Unless you are using the +12V or -12V as reference Voltages in your circuit, opamp supplies do not have to be regulated. Most modern opamps have Power Supply (ripple) Rejection Ratios of > 90db, so regulating their +- supplies is not needed. Look up the specs for the 741.
btw-the 741 is an extremely crummy old opamp. There are hundreds of modern, cheaper ones with better specs.