Product Description - Model 1721 240 Watt Power Amplifier

Whether playing jazz, rock, pop or classical music, the Model 1721 delivers superb imaging,  micro-dynamics and outstanding mid and high frequency sonic finesse, underpinned with massive reserves of fast, deep, extended bass. The result is an utterly fatigue free, natural sound no matter what the power output level or the type of music.

The Model 1721 employs the latest amplifier design insights and technology to dramatically reduce distortion and power supply artefacts without the use of large amounts of feedback . Like its smaller stablemate, the Model 1701, considerable engineering effort along with CAD/Simulation optimization of the circuit, PCB layout and mechanical design has resulted in what we think is an extraordinary high-end power amplifier.

The Ovation High Fidelity Model 1721 Power Amplifier. Engineered for Art

Product reviews

“Deep notes [of the Kodo drums] were presented with well-controlled power and a real perception of the decaying vibrations of the drum skin. At the other extreme, rim shots were fast, dynamic and tonally textured. ”

“The 1721 managed to create a great image of this instrument [First Congregational Church organ in Los Angeles] with good breadth and depth and all the gravitas, power and acoustics you would expect from such a magnificent location. ”

“Voices were clear and uncluttered even on complex passages while cymbals were fast and shimmered cleanly. The atmospheric feel of “Roses On A Breeze” and “Love Can’t Stand Alone” were beautifully portrayed as intended by the artists. ”

“When an amplifier is this good everything seems to just work and it disappears from the conscious mind and allows you to immerse yourself in the music, which is what it should do. ”

You can read Alex Colburn’s full review in HiFiWigwam here

Delivering 240 Watts RMS per channel into 8 Ohms and 440 Watts RMS into 4 Ohms (both channels driven) and over 700 Watts RMS into 2 Ohms (single channel driven), this high performance, fully symmetrical, current mode topology (CMT) class AB power amplifier features wide bandwidth, sub one microsecond rise/fall times and a very large, high energy 1200 Watt power supply, allowing it to drive any speaker load to concert hall sound levels.

Twelve 250 Watt matched power transistors per channel featuring exceptional SOA (Safe Operating Area) capability allow dynamic loudspeaker current demands in excess of 60 A to easily be supported.

On the outgoing factory test, the Model 1721 typically achieves <7ppm (0.0007%) distortion at 200 Watts into 8 Ohms (1 kHz), which is at the limit of the test equipment, while at 220 Watts, the figure is <30 ppm. Further, distortion remains in the low double digit ppm level down to load impedances of 3 Ohms thanks to the Locanthi ‘T’ triple output stage. These figures attest to the extraordinary linearity of the Model 1721 power amplifier, no matter what the load.

The oversized 1200 Watt power transformer is custom wound in England and incorporates an inter-winding screen and a flux band to keep mains noise ingress and radiated EMI within the amplifier chassis to -110 dB ref the full output voltage swing.  A very large, low impedance capacitor bank provides the instantaneous energy reserves required for driving any conceivable dynamic speaker load with any source material.

Comprehensive non-intrusive microprocessor based protection circuits monitor the amplifier for DC offsets and overcurrent conditions, which if arising, will result in the speakers being instantly disconnected from the amplifier output. Connection between the amplifier output and the speaker terminals is by means of an innovative solid state relay using ultra-low Rds(on) ‘Trench’ technology MOFET’s with a 500 J energy handling capability. These devices operate 5~10x faster and with 10x lower ON resistances than the conventional electro-magnetic relays (EMR) used by our competitors. Importantly, our solution suffers no wear out mechanism whatsoever compared to EMR’s. Further protection features include mains switch-on inrush current limiting and loudspeaker muting during power up and power down cycles. In the unlikely event that the amplifier overheats, a thermal protection system will disconnect the speakers until the temperature drops to a safe level after which the outputs will be reconnected again.

The Model 1721 can accept balanced or single ended inputs which are selected via a push-button switch located on the rear of the unit.

A +12V (40mA max) trigger input (0V = OFF and +12V = ON) enables the amplifier to be remotely powered up and down by a system controller or preamplifier equipped with a trigger facility.

Connection to the loudspeaker is by means of very large gold plated CMT loudspeaker terminals rated at 100A which accommodate both 6 mm spade connectors and standard 4mm banana plugs. A unique mechanism clamps banana plugs securely, ensuring they cannot be inadvertently removed.

To minimize 3rd harmonic magnetic induction distortion, the chassis is constructed out of aluminium which is of course non-magnetic, including the substantial 10mm thick internal transformer mounting brace, while for selected parts like air vents, stainless steel is used. Attention to this type of detail is a prerequisite in an amplifier with a distortion profile measured in parts per million.

See below for detailed product specifications.

Designed, engineered and hand built in England. 5-year warranty on parts and labour.

Gallery

Specification

Inputs Balanced or single Ended - selected via push button on rear panel
Input Sensitivity for Rated Output 2 V into 10k Ohms on balanced inputs; 1V into 10 k Ohms for single ended inputs
Output Power - 20 Hz to 20 KHz at 0.1% distortion both channels driven 240 W RMS into 8 Ω 20 Hz to 20 kHz; 400 W RMS into 4 Ω 20 Hz to 20 kHz; 700 W RMS into 2 Ω (single channel driven)
Peak Power Output Capability (Single Channel Driven) > 1200 Watts (t < 50ms)
Peak Current Output Capability (single channel driven) > 60 Amps for 20 ms
Distortion ≤ 30 parts per million (0.003%) at all frequencies and power levels up to 220 Watts into 8 Ω; ≤ 5 parts per million (0.0005%) 20 Hz to 20 kHz 1 Watt into 8 Ω; <7 parts per million 200 Watts into 8 Ω at 1kHz
Signal to Noise Ratio Better than -100 dB ref 1 V output; ~120 dB ref max output voltage swing into 8 Ohms
Frequency Response - 1W into 8 Ohms 20 Hz to 20 kHz +0 dB -0.1 dB; 2 Hz to 250 kHz +0 dB -3 dB
Slew Rate 10% to 90% in both +ve and -ve directions >250 V/us
Rise/Fall Time 10-90% Small signal: <100 ns; large signal (120V pk~pk) <500 ns
Trigger Input +12 V at 40mA max via 3.5mm Phono Jack located on rear panel
Power Consumption 1200 Watts maximum; <100 Watts Idle
Weight 22 kgs unit only; 27 kgs including packaging
Dimensions 450mm wide x 450mm deep x 130mm high
Warranty 5 years parts and labour from date of purchase; Terms and conditions apply - see user manual for details, or click on 'Commercial' at the foot of this page for further information

Ovation High Fidelity. Audio Equipment Engineered for Art.