High performance active volume control with balanced differential input and ground-sensing output (goodbye cross-channel ground loops!).

It can serve as:

• Part of an integrated amplifier (great with LM3886 or similar chipamp based power stages);
• With an input selector, a high performance balanced line stage or a minimalist analog preamp;
• An output stage for a DAC to form a "digital preamp".

This board uses the PGA2310, a high quality digital volume control chip from TI, for adjusting volume. Also available digitally controlled variants based on WM8816/MAS6116 or MUSES72320, as well as analog variant with a dual linear potentiometer.

• Bare board only.
• Parts are not included and need to be obtained separately.
• Assembly is required.

Features and benefits:

• Balanced differential input with excellent common mode rejection - works very well with single ended sources, too!
• Output stage that can be configured as balanced - best for downstream stages with differential input - or ground sensing (a.k.a. ground cancelling) - best if followed by a single-ended input referenced to its local ground, such as the vast majority of audio power amps;
• Compact (2.9x2.6in or 74x66mm) two layer PCB, all easy to solder though hole parts.

The PGA2310 is controlled via its SPI interface and requires a microcontroller. You can use anything suitable, such as a 5-volt Arduino. To help you get started, we provide a simple Arduino sketch.

Documents:

• Schematic
• Board size and component placement
• Part list (BOM)
• Shared project at Mouser
• Example Arduino sketch
• Discussion at diyAudio.com
• PGA2310 datasheet (@ti.com)