73P Class-A Mic Preamp 500-series extender cable (recommended for testing):None Sidechain high pass filter (HPF)

Sidechain high pass filter (HPF) to prevent pumping on sources with big low end

Vocals / Acoustic Guitars: HPF = 120 Hz

The full clockwise throw of these knobs is dedicated to either boosting or cutting its relative frequency

the higher-priced transformers will exhibit less noise

This has the benefit that no regulation or DC-DC conversion is required

73P Class-A Mic Preamp 500-series extender cable (recommended for testing):None Sidechain high pass filter (HPF)The 73P is an authentic, complete adaptation of the vintage 1073* mic preamp circuitry to the 500 series format. The 73P is authentic in that it uses only components that are hand selected to match the original, and there are no changes to any of the preamp circuitry. The 73P is complete in that it adheres to the original, three stage amplifier design. The 73P is an intermediate DIY kit. To successfully build it, you should have some experience