LAFAYETTE KT-550

The Lafayette KT-550 is a stereo power amplifier, designed in the 1960s in the United States. This amp uses tubes to provide an output power of 50 watts per channel, which was considerable at the time.

It uses a push-pull configuration with 6550 tubes (or KT88 in some variants), known for their ability to produce a powerful sound with low distortion. Push-pull also helps reduce noise and improve signal clarity.

Tube amplifiers like the KT-550 are appreciated for their warm, round and harmonic-rich sound, which is different from that of transistor amplifiers. Hi-fi enthusiasts particularly appreciate this amplifier for its ability to reproduce deep bass and smooth treble.

Power:

2 x 50W RMS per channel in stereo, or 100 watts in total, which is remarkable for a tube amplifier of this era.

Tube Configuration:

- Power Tubes: 4 x 6550 or KT88 tubes (two per channel, mounted in a push-pull configuration).

- Preamp and Phase Inverter Tubes: Typically 12AX7 or 12AU7, popular for their sonic transparency and low distortion.

Frequency Response:

20Hz to 20Khz, with very low harmonic distortion, ensuring a balanced and detailed sound throughout the audible range.

Harmonic Distortion:

Total Harmonic Distortion (THB) of less than 1% at full power, which is excellent for a tube amp, thanks to the addition of negative feedback.

Output Impedance:

Adaptable to different speaker impedances: 4, 8 and 16 ohms. This versatility allows the KT-550 to be connected to a wide variety of speaker systems.

Input Sensitivity:

Around 1.5V for maximum output power, making it compatible with most audio sources of the time (and even modern ones with suitable preamps).

Weight and Dimensions:

Weight: around 22 kg (48lbs), due to the massive output transformers and the robust construction.

Dimension: 43 cm (width) x 15 cm (height) x 30 cm (depth), making it an imposing amp for its category.