An amplifier for the music. It's a Reference Model of SPEC

Real-Sound Power Amplifier


An amplifier is a musical instrument

The top of a violin is made of spruce.

The back and ribs are made of maple.

Because an amplifier which has high gain is sensitive to rigidity and vibration, wooden structure provides suitable vibrational damping property.Like a musical instrument maker , we select materials and consider grounding method.As a result,the bottom plate is made of spruce, and the insulator is made of maple with hickory embedded in the center. They are the same as the material used for a violin.They vibrate with music and bring out the beautiful sound.This is why we say "the amplifier is a musical instrument".

The parts made of natural materials play a natural sound

The parts made of natural materials play the sound which is gentle to listen and fine textured.

These PAPER-OIL-CAPACITORS have been tuned exclusively by SPEC. It's a CAPACITOR for the MUSICALITY. Inner KRAFT PAPER brings completely beautiful tone.


Mica capacitoers used in SPEC amplifiers are made of highest quality ruby mica.It is produced only at the foothills of the Himalayas. It is made by orogeny of the Himalayas.Mica of high purity is a great benefit from Himalayan orogeny movement and we can hear a profound silence.


Capacitor blending

We blend several capacitors to obtein the sound with MUSICALITY.
And,EMC coating absorbs internal noise reflections to offer especially transparent sound playback. As a result,the sound is warm,smooth and exceptionally creamy while keeping details.

SPEC sticks to the R-core transformer.

R-core transformer plays a dynamic and powerful sound.

Class-D doesn't generate heat at all

Because Class D system is using switching technology, the power stage doesn't generate heat at all. Therefore, HEAT SINK is not required.
In addition,you can't find any cooling hole on the amplifiers. This SEALING STRUCTURE prevents entering of the dust to the inside of an amplifier.
No heat and no dust mean long life with clean environment.From circuit point of view, small size circuit will playback highspeed and detailed signal as it is.It is most important for the Musical expressions.

It’s an “ANALOG” amplifier

The myth that a "CLASS D" is a DIGITAL AMPLIFIER is incorrect. SPEC CORP. has adopted "Pulse Width Modulation" in our "CLASS D". This "PWM" converts "signal amplitude" to "duration switching" through “ANALOG PROCESSING”. This system doesn't digitize the audio signal. This is in fact type of analog amplifier because magnitude resolution is infinite. “CLASS D” with PWM contributes to bring you beautiful acoustical sound. In the past, some audio makers adopted delta sigma modulation for “CLASS D” . This is quite simply “1bit digital” modulation. Combination of switching technology and analog technology makes the sound realistic and beautiful.

RSA-F33EX appearance


Maximum output 120 W × 2 (4Ω), 90 W × 2 (6Ω), 60 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
Speaker terminal 1
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)
External dimensions 450 mm (width) × 130 mm (height) × 422 mm (depth)
Weight 20 kg
Included items
Power cord 1
Operation manual 1

* Due to improvements the above specifications and external appearance may be changed without notice.

Related products

The following separately sold accessories are available.


Operation Manual