Electro Harmonix 12BH7 Preamp Vacuum Tube

Each tube is individually tested, measured, and precisely matched to the same milliamp to ensure consistent electrical performance across every set. This careful matching process promotes balanced operation, reliable response, and long-term stability in your amplifier. Precision milliamp matching is a standard part of our quality control and is included at no additional cost.

Every tube is subjected to a comprehensive testing process using custom-designed, calibrated equipment to evaluate key electrical and performance characteristics. Each tube is measured for proper operation, stability, and consistency before it is approved for sale. This thorough testing ensures that only tubes meeting our strict performance standards are shipped, providing dependable operation and long service life.

Every tube is subjected to a controlled burn-in process at no additional cost prior to shipment. During burn-in, tubes are operated under load for an extended period to identify early failures and ensure stable, reliable performance. This process helps eliminate weak or unstable tubes before they ever reach your amplifier.