Igor S. Popovich

How to Use, Calibrate, Repair and Upgrade Vacuum Tube Testers - Igor S. Popovich

Audiophile Vacuum Tube Amplifiers - Design, Construction, Testing, Repairing & Upgrading, Volume 1 - Igor S. Popovich

Sound Improvement Secrets For Audiophiles: Get Better Sound Without Spending Big - Igor S. Popovich

Audiophile Vacuum Tube Amplifiers - Design, Construction, Testing, Repairing & Upgrading, Volume 2 - Igor S. Popovich

Audio Tests & Measurements: How to Test Electronic Components, Audiophile & Guitar Amplifiers and Loudspeakers Using Modern and Vintage Test Instr - Igor S. Popovich

Tube Guitar Amplifiers Volume 2: How to Repair, Modify & Build Guitar Amps - Igor S. Popovich

Audiophile Vacuum Tube Amplifiers Volume 3 - Igor S. Popovich