KT550

About the KT550

The Lafayette KT-550 is a stereo power amplifier designed and manufactured in the United States around 1961. It uses a push-pull configuration with four 6550 or KT88 tubes (two per channel) to deliver 50 watts RMS per channel, totaling 100 watts output. The amplifier is known for its warm, round, and harmonic-rich sound, favored by hi-fi enthusiasts for deep bass and smooth treble reproduction. It features preamp and phase inverter tubes typically of 12AX7 or 12AU7 type, ensuring sonic transparency and low distortion. The frequency response ranges from 20 Hz to 20 kHz with less than 1% total harmonic distortion at full power, aided by negative feedback. The output impedance is adaptable to 4, 8, or 16 ohm speakers, and input sensitivity is about 1.5V for maximum output. The amplifier weighs approximately 62.4 lbs and measures 17 x 9 x 14 inches. Originally50, it was available as a wired and tested unit or as a kit. The KT-550 is appreciated for its excellent performance, ease of construction, and attractive two-tone brown and gold appearance.