Compared with the original circuit, this circuit has some improvements. A buffer circuit (NE5532) is added to the input mono part, so that the intensity of the left and right channels will not be affected when adjusting the MONO balance. The potentiometer spacing is 24-24-24-35mm。

In addition, the power supply part can use your own high-quality positive and negative 15v power supply for power, and the reserved positive and negative 15v interfaces are available.

The final improvement is the use of a small relay to switch between IN and BYPASS functions, allowing rapid response at the millisecond level.

PCB size：181*130mm 

Mounting hole spacing 172.5*121mm

Power supply: 15VAC/±15VDC

Potentiometers: 100K 5 pieces（If you don't need to install the potentiometer, please email me.）