Compact stereo power amplifier with ULTIMA topology
Chord BerTTi is a fully balanced stereo power amplifier, built in Britain in the format of the Table Top (TT) series. Chord Electronics presents it as the most affordable stereo power amplifier with ULTIMA technology in its portfolio. In the description the manufacturer speaks of a 75 W amplifier without stating the load; in the specifications it declares 55 W into 8 Ω.
The ULTIMA dual feed-forward topology relies on error correction that monitors the signal and corrects it immediately, before the output stage. According to the manufacturer this gives very high accuracy for a compact-chassis device. The power devices are proprietary, custom-made MOSFETs.
Power supply and connections
The power supply is a high-frequency switch-mode design. Chord mentions two modified power supplies for increased performance and an auxiliary rail dedicated to the front end, which provides the extra voltage needed to drive the MOSFETs. Stated consumption is 240 W at full power and 1 W in standby.
There are two inputs: a balanced XLR stereo pair and a gold-plated unbalanced RCA pair, both with an impedance of 100 kΩ. The loudspeakers connect to a pair of gold-plated terminals and the mains inlet is a 10 A IEC, with the cable included. Input sensitivity is 0.78 V, for a gain of 30 dB; the stated frequency response runs from 5 Hz to 100 kHz within ± 0.5 dB.
In the Table Top system
BerTTi brings the ULTIMA topology to the Table Top range and shares its format: 235 mm wide by 59 mm high, in a solid aluminium chassis weighing 3.75 kg. The pairing indicated by the manufacturer is with the Hugo TT 2 DAC and preamplifier, for a complete system of small size.
The Hugo M Scaler upscaler can be added to this pair, taking audio up to 705.6 kHz, 16 times the native resolution of CD: the result is a three-box system that Chord places at the top of its class. Hugo TT 2 and Hugo M Scaler are separate units from the BerTTi.
Technical data
- Output power: 55 W into 8 Ω.
- Inputs: 1 balanced XLR stereo pair, 1 gold-plated unbalanced RCA stereo pair.
- Outputs: 1 pair of gold-plated loudspeaker terminals.
- Frequency response: 5 Hz-100 kHz ± 0.5 dB.
- Total harmonic distortion: 0.008 %.
- Signal-to-noise ratio: 87 dB (A-weighted).
- Input impedance: 100 kΩ (unbalanced and balanced).
- Input sensitivity: 0.78 V.
- Gain: 30 dB.
- Power consumption: 240 W at full power, 1 W in standby.
- Dimensions: 235 × 256 × 59 mm (W × D × H).
- Weight: 3.75 kg.
- Finishes: black and silver.
- Included: 10 A IEC mains cable.
