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Spectral DMA-360

Beschrijving / Description

The DMA-360 Monaural Reference Amplifier is the first limited production monaural amplifier from Spectral Audio. The DMA-360 is also the most powerful high-speed amplifier ever developed for high-end music applications. An impressive array of engineering "firsts" in the DMA-360 culminate seventeen years of high-speed fet design to produce the "ultimate" Spectral amplifier.

The very high-speed launch and enormous current reserves of the DMA-360 are made possible with the use of Spectral's proprietary "Focused Array" construction. This breakthrough topology aligns high-current vertical fet output devices for rapid, pistonic signal launch. The output section is comprised of eight individual V-FET amplifier modules paralleled to achieve a minimum 300 watt RMS output with 90 amp capability, and full rated power is delivered with absolute load stability at an unprecedented 1 MHz. Output current is approximately double that of any previous high-speed amplifier design. The "Focused Array" output section design of the DMA-360 makes possible the practical use of ultra-fast vertical fet devices for the first time in a high powered audio application. Each device, having vacuum tube like operating character, is energized from its own dedicated high energy storage capacitor, rectifier, and individually powered from an isolated ultra-low coupled transformer winding. Individual teflon bias trimmers calibrate each V-FET output device separately for maximum linearity and precise alignment. Groups of these individually powered output sections utilize field folded RF type construction and electronic shielding to banish noise and eliminate low level propagation of stray interference. The resulting "Focused Array" of eight individually powered output sections performs as one with virtually no cross-coupling or energy storage artifacts reflecting between output devices. During extreme program dynamics, this arrangement can launch an instantaneous high-current drive of over 90 amps to the most sophisticated loudspeakers with unprecedented waveform tracing precision. Gone are performance damaging magnetic and electrical field propagation problems of conventional high-powered amplifier construction. Without stray radiation, critical small signal paths within the DMA-360 can perform with lowest possible distortion and settle to signal extinction in millionths of a second. Hence, the DMA-360 works with high power and great speed yet behaves inert to other system components. Reproduction is extremely articulate and naturally resolving yet has all the powerful unlimited sonic character of the most brutal high power amplifier designs.

The DMA-360 utilizes custom FETs and high speed bipolar transistors in a dense, fully balanced topology to achieve high-current launch and ultra-fast settling capability. RF (radio frequency) design techniques are employed to achieve a DC coupled power band with intrinsic bandwidth to almost 5 MHz!
Input Stage.
The shielded input stage utilizes a balanced, double cascode design using matched differential pairs of J-FETs. The cascode design derives its own ground reference and produces extremely high levels of isolation from the preamplifier and between the stages of the DMA-360 itself.

Gain Stage.
The gain stage utilizes super high frequency (RF) bipolar transistors matched in a cascode configuration to bring the circuit gain into the power device realm.

Output Stage.
The output stage consists of eight individually powered VMOS-FET output amplifiers. This precision amplifier array features individual push-pull drivers, high-speed power supplies and individual biasing to function as a single ultra-fast, high current output section. The result of these techniques is unprecedented fast settling and remarkable intertransient silence.




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Specificaties / Specifications

DMA-360 Monaural Power Amplifier
Power Output (continuous): @ 8 ohms - 300 Watts RMS
@ 4 ohms - 533 Watts RMS
@ 2 ohms - 680 Watts RMS
Output Compliment: 90 Amps peak
Frequency Response: +-0.1 dB, DC - 150 KHz
+-1 dB, DC - 1 MHz
+-3 dB, DC - 1.8 MHz
Distortion
Static: less than 0.015% from DC
to 100 KHz, typically
0.009% @ 300 WRMS at 8 ohms
Dynamic: 8 Tone Cluster Test 20
KHz @ 500 Hz separation
0.01% @ 8 ohms
0.015% @ 4 ohms
Speed:
Risetime: less than 300 nanoseconds
Settling: 1.5 microseconds to -40 dB
Slew Rate: 600 volts/microsecond
Noise:
Signal to Noise: 97 dB nweighted,
107 dB ASA A
Crosstalk: 98 dB @ full power 8 ohms
Input:
Impedance: 10k ohms
Sensitivity: 1.5 volts / nominal output
Power Supply:
Line Voltage: 100 volts, 120 volts,
240 volts (internal wiring)
AC Voltage Range: +-10%
Maximum Consumption: 2000 Watts
Quiescent Consumption: 250 Watts
AC Main Fuses: 120v 5A or 220v 2.5A slo blo
Size and Weight:
Dimensions: 20" (50.8 cm) W,
7.23" (18.4 cm) H,
19.6" (49.9 cm) D,
Weight: 67 lbs, 30.4 KG Net

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