Hi Mr. DEB,
1) In the Tilt Filter, U1 and U2 pins 8, 9 and 10 can be replaced by a piece of wire.
2) The power supply has transistors, diodes and resistors that do nothing. The power supply can be just two 220uF capacitors, one for +9V and the other for -9V.
3) The pots on the LM3915 ICs have a value that is too high (then the LED current and brightness are very low). Added limiting resistors are also needed.
Replace the pots with a fixed 1k resistor for a full-scale sensitivity of 1.25V and 12mA through each LED.
4) The outputs cannot drive many models of headphones because they have low current opamps, not high current driver amps. Maybe U1 and U2 pins 12, 13 and 14 must be headphone driver ICs, not opamps.Try it and see (hear?) if it is loud enough with the headphones you will use.
The TL074 and many other good opamps oscillate when they directly drive the capacitance of a cable. Adding a 100 ohm resistor in series with each output decouples the cable's effect but then the output to low impedance headphones will be very low.