BGW 750C

The BGW 750C was introduced in 1978. She was widely used in discos and movie theaters. Her rated power is 225W into 8Ω and 360W into 4Ω. Mono Bridged power is 720W into 8Ω.

Her front-end is a LM318 op-amp (Fig 1). The input signal enters Pin2, the Inverting input. The Non-inverting input (Pin 3) is used for Negative Feedback (NFB).

Fig 1 – BGW 750C Amplifier Schematic

The LM318 output is amplified by 680Ω resistors which in turn feeds the VAS. After this stage are the Pre and Main Drivers. They ensure that the TO-3 power transistors do not run out of base current when the amplifier is driver hard.

Fig 2 – BGW 750C Module

Fig 2 is a power module for 1-channel. A hefty heatsink is used to cool ten TO-3 power transistors. On the under-side is a large pcb containing the electronics.

Summary

They simply don’t make power amplifiers like this 750C anymore. She is built like a tank. Many are still in use in discos around the world today. Her longevity is a testament to her outstanding design and reliability.