Integrated Amplifiers

All Gato's amplifiers are distinguished by their use of just two power FETs per channel [see Opinion, HFN Jun '17], typically in a quasi-complementary Class AB design. Only in the DIA-400S [HFN Oct '16] and this latest DIA-250S are these FETs employed in the high-speed PWM switching stage of a Class D amplifier design – versions of International Rectifier's MOSFET-based IRAUDAMP and switchmode power supply solution. IR was acquired in 2015 by Infineon Technologies AG, and Gato Audio has availed itself of this well-supported technology to offer huge power outputs from a very compact and well-screened enclosure.

Running at 85-90% efficiency ensures the case barely gets warm even when your speakers are 'cooking'. However, like other Class D amps of this type, the DIA-250S's response is still influenced by speaker load impedance, the treble falling away as impedance drops [see inset Graph: no speaker load, grey trace; 8ohm, black; 4ohm red; 2ohm, blue; 1ohm, green]. Also, in order to optimise PSU performance, the DIA-250S's left channel is inverted, and its red speaker terminal connected to the right channel's grounded black speaker output. As a result, you must avoid any earthed speaker types. PM