Stereo Class AB power and a high-current power supply
Rotel RB-1552 MKII is a Class AB stereo power amplifier rated at 130 W per channel into 8 ohms and 185 W per channel into 4 ohms, with a toroidal transformer using independent rectifiers for the two channels and RCA and balanced XLR connections.
The design is built around an oversized power supply and discrete output stages intended to drive demanding loudspeakers. Low-ESR slit-foil capacitors support the supply. The internal layout limits interference between the two channels and keeps current paths short, while the available inputs allow use in traditional or balanced stereo chains.
Key features
- Continuous power of 130 W per channel into 8 ohms.
- Continuous power of 185 W per channel into 4 ohms.
- Class AB amplification with THD below 0.03%.
- Toroidal transformer with independent rectifiers for the two channels.
- Low-ESR slit-foil capacitors.
- RCA and balanced XLR inputs.
- Damping factor of 450.
- Frequency response from 10 Hz to 100 kHz within ±0.5 dB.
Power and drive capability
RB-1552 MKII delivers 130 W per channel into 8 ohms and 185 W per channel into 4 ohms, retaining suitable reserve as loudspeaker impedance falls. Declared total harmonic distortion remains below 0.03%, accompanying an output section designed to combine current, control and linearity.
Power supply
A toroidal transformer with independent rectifiers for the two channels forms the core of the supply. It is sized to support transients without compressing dynamics, because loudspeaker drive depends on available current as much as on nominal power.
Energy reserve
Low-ESR slit-foil capacitors are selected to release stored energy quickly and support bass during more demanding passages, while limiting internal losses and supply-voltage variation under load.
Class AB and bandwidth
The output stage operates in Class AB and declares a frequency response from 10 Hz to 100 kHz within ±0.5 dB. A damping factor of 450 contributes to woofer control and transient precision, while the topology maintains bandwidth wide enough not to constrain the audio signal.
Inputs and preamplifier
RCA and balanced XLR inputs allow connection to preamplifiers with different topologies and output levels. Balanced connections are particularly useful with long cable runs or systems where reducing sensitivity to picked-up noise is important.
Loudspeakers and system control
The loudspeaker terminals accommodate substantial cable sizes and a 12 V trigger synchronises power with a compatible preamplifier. The internal arrangement is close to dual mono after the transformer and includes 12 V triggering for coordinated power. The amplifier can therefore work in a traditional chain or a centrally controlled system.
Chassis and cooling
The chassis measures 431 x 144 x 339 mm and weighs 12.4 kg. Much of the mass comes from the transformer, heatsinks and output stages, while the mechanical layout keeps heat-generating components away from the more sensitive input sections.
