Balanced input Gainclone amps


2007-05-15 10:14 pm
Did a version of the Gainclone/ChipAmp with balanced inputs for a line array speaker project. Needed a total of 16 amps for the first stage of the project.

These are DC coupled both input and output to drive the BG planar drivers. No Zobel or Thiel network as the load is nearly resistive. Just using the speaker cable as the distributed inductance and resistance of the cable for stability. The cable capacitance is 210pF for each run and all 16 are identical.

The PC board is the Audio Sector board on Ebay for the LM3875TF. Modified the component and wiring install for balanced operation, with resistors values modified for lower gain but higher input impedance. The power supply boards are from ChipAmp.

Here is what they look like on heatsinks. The mic is a Dayton Audio UMM-6 USB calibrated mic for measurements using MathAudio Room EQ on a PC music server.


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