A real new-generation class-D amplifier
with latest highly accurate PWM switching devices
By employing the latest developed class-D amplifier devices, power MOS-FET achieves ideal highly accurate current switching in the power stage, and high-voltage gate driver IC with excellent time-axis control maximizes the ultimate PWM switching. The exceptional performance of the class-D devices ensures ultimate real-sound with quality damping in the mid to low ranges even when driving low-efficiency speakers. Furthermore, the sweet and rich tonal character in the mid to high ranges of the amplifier is almost like the tone of the best triode tube amplifiers.
In order to maximize the potential of the unprecedented high performance of this amplifier (power utilization in the power stage at maximum output; 96%), we daringly employed a classical and very simple plus/minus power source composed of minimal numbers of high quality components, such as only transformers, bridge-diodes and capacitors.
The sound of this class-D amplifier owes a lot to the individual parts of low-pass filter in the final stage of the amplifier. The capacitor and the coil employed for the low-pass filter were custom-ordered after careful listening tests and guarantee the excellent musical sound of RSA-F33EX / RSA-M3EX / RSA-V1EX. Above all, many custom hermetic seal paper-oil filled capacitors are employed in the low-pass filter and snubber circuit of RSA-F33EX because of the natural and vivid character of the sound only those old type capacitors have. These paper-oil filed capacitors have been supplied to the aerospace industry for the past half century and made to meet the strict MIL standards for getting the highest reliability.
In an unusual endeavor for an audio amplifier, natural wood was used for the base chassis and insulators.
Base-chassis of RSA-F33EX: A solid laminated panel of European spruce from Austria was used for the under-base. Spruce has long been used for the top plate of stringed instruments and the soundboard of pianos, and is known as a material with excellent sound quality that provides quick vibration trans-mission and moderate damping.
The combination of this material with the rigid steel chassis produces a rich pleasant sound.
Insulators of RSA-F33:Three insulators combine pure painted maple from Hokkaido, Japan and hickory from North America. Maple has excellent strength and is used in combination with spruce for the sides and backs of stringed instruments. Hickory is a hard material that absorbs impact well and is used for drumsticks for example. The maple and hickory insulators moderate the vibrancy of the spruce material and help provide rich musicality.
|Maximum output||120 W × 2 (4Ω), 90 W × 2 (6Ω), 60 W × 2 (8Ω)||100 W × 2 (4 Ω), 75 W × 2 (6Ω), 50 W × 2 (8Ω)|
|Frequency response||10 Hz - 30 kHz ±1dB (6Ω, 1W)|
|Harmonic distortion ratio||0.02% (at 1 kHz, 80% output)|
|Input sensitivity, gain||300 mVrms, 37.3 dB (at MAX volume, 6Ω, 1kHz, unbalanced input)|
|Line input terminals||XLR input: 1 RCA inputs: 3|
|Power supply, other|
|Power voltage||220 V AC, 50 Hz|
|Electrical consumption||With no signal: 15 W, during maximum output: 215 W (8 Ω, 100 Hz)||With no signal: 15 W, during maximum output: 180 W (8Ω, 100 Hz)|
|External dimensions||450 mm (width) × 130 mm (height) × 422 mm (depth)||440 mm (width) × 125 mm (height) × 414 mm (depth)||440 mm (width) × 120 mm (height) × 414 mm (depth)|
|Weight||20 kg||15.5 kg||14.5 kg|
A newly developed withstand high voltage “ Ultrafast Soft-recovery” diodes for professional use in RSA-F33EX ensures clear and transparent but also rich and powerful sound with spacious atmosphere across the entire range.
The main custom electrolytic capacitor and the high voltage custom oil filled capacitor for best signal-use in parallel achieve smooth and beautiful sound over upper and middle range to the ultra-low range.
The custom made genuine paper oil filled capacitor by Arizona capacitors, Inc. with excellent sound quality and the rare and valued mica capacitor employed achieves the artistic “ Real-Sound ”of RSA-F33EX.
Special made inductor selected only by hearing allows the low-distortion and like an open air sound through the entire range.
The three insulators combine pure real maple from Hokkaido, Japan and hickory moderates the vibrancy of the spruce base-chassis and cut off the vibration from out side help provide nice musicality.
A solid laminated panel of European spruce from Austria is used for the base-chassis produces a rich & warm pleasant sound.
|Tip Echipament||Solid State|