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Review methodology. The amplifier was placed on the Base IV Custom Version rack and a wooden shelf. For some time it also sat on additional decouplers from Audio Replas (their OPT-30HG-PL/OPT-30HG-SC quartz insulators). The CD player was connected via XLR SAEC XR-4000 cables.

The sound was better than over RCA. That result will largely depend on the CD player and the player/amp power cords. I used a Harmonix X-DC350M2R Improved Version cord. The test was an A/B comparison where both A and B were known. In addition to my reference amplifier, the RSA-V1 was compared to the Struss R150 and Hegel H200. Music samples were two minutes long.

Design. The first amplifier from this manufacturer was the RSA-F1. The reviewed RSA-V1 is a newer less expensive version with somewhat simplified housing and electronics but it was ‘dumbed down’ only to the point of making sense. It is an integrated amplifier based on analog amplification working in class D with newly designed power Mosfets. The amplifier comes without remote but may be ordered with a beautifully designed external receiver module and wand. That set is called the RSR-3 and you have to pay for it separately.

Front and back panels. From the outside the amplifier is very simple but interesting. Its mechanical design is based on combining a steel casing with an integrated anti-vibration wooden plinth. According to the maker that plinth is what gives it its deeply saturated sound. The platform combines several components: solid oak wood with two feet in the front (the bar bears the Oak Village logo) and European Spruce ply cut in Austria with one footer in the back. These footers are Japanese maple from Hokkaido Island called hickory and were also recently used by Acoustic Revive in their RAF-48H and RST-38H anti-vibration platforms (the 'H' in their names derive from hickory). The front panel features only three parts - an input selector, volume knob and power switch. The volume knob illuminates blue but the backlighting may be turned off with a switch on the back panel. Both knobs are very solid aluminium and very attractive. The power switch is even cooler. Its design borrows from airplane cockpits. To switch the amp on or off you must pull the switch pin to release its latch.

Next to this switch are red and green LEDs. The red one lights up when you turn the amp on and slowly dims when you switch it off. After turning off the amp the volume control backlighting also fades slowly – really cool. The quality lettering is beautifully silk-screened and the Designer Audio logo is engraved in the center. The back panel is quite simple. In the center we have two pairs of gold-plated rather plain binding posts. To the right we get three pairs of RCA and one XLR inputs. The RCAs are high-quality rhodium-plated issue. To the left we find the IEC mains socket, a switch controlling the volume knob back light and a small socket for the external remote control receiver

The interior. The interior divides into several sections carefully shielded with steel sheets. From the inputs the signal proceeds via Belden cables to the mechanical switch on the front panel and from there to the main circuit board with the power stage. The RSA-V1 is a power amplifier with adjustable gain. The latter isn't completely passive because it features an integrated 3310 IR01 circuit, a digitally controlled analog resistor ladder by Japanese Tachyonix which was apparently custom programmed.

A quick check shows it to be the International Rectifier Japan version 01 of the CS3310/PGA2310 chip. The Japanese potentiometer on the front panel is only a driver that's not in the signal path. After the gain adjustment the signal goes straight to the small main board. That is a complete class D IRAUDAMP4 DB Rev.03 module from International Rectifier and as such the PWM modulator. This circuit is fully balanced so it is worth driving the amplifier from its XLR connectors. SPEC designed the output stage with newly developed Fets bolted to a tiny heat sink.

One of the most important components of a class D amplifier is its output filter which recovers the musical signal from the modulator signal. Its quality to a large extent determines the final sound. Here SPEC went all out and used special oil capacitors designed in collaboration with Arizona Capacitors Inc. The power supply is equally important. The Japanese usually don’t like switching power supplies and prefer linear designs. This amplifier is no exception. Under the shielding metal we find a very large powerful R-core transformer.

The rectifier features a bank of ultra-fast modern Schottky diodes and a number of filtering capacitors of various types. These include ‘Super Through’ and ‘Gold Tune’ Nichicons bypassed by oil capacitors from Arizona Capacitors bearing the SPEC Corp logo. It is a very clean well thought-out design. Although the amplifier is built around the stock heart from International Rectifier, it is supplemented by high-end custom designed components.

Technical data according to the manufacturer:
Output Power: 2 x 50W/8Ω | 2 x 75W/8Ω peak | 2 x 100W/4Ω peak
Frequency response: 10Hz – 30kHz ±1dB (6Ω, 1W)
Total harmonic distortion: 0.02% at 1kHz, 80% of nominal power
Input Sensitivity: 300mVrms, 37.3dB (Volume max, 6Ω, 1kHz)
Power consumption (max): 180W (8Ω, 100Hz)
Dimensions: 440 x 120 x 414mm

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