Fidelix CERENATE Power Amplifier with Volume

CERENATE is compact and lightweight because it uses a U.S. patented ultra-low noise serinity switching power supply operating at 220 kHz sine wave and a forced air cooling system with a fan that does not rotate during normal use. The secondary side of the transformer is completely left and right independent.

A remote sensing terminal (BNC) is also provided for reliable speaker drive by applying feedback from the speaker side, and a high-frequency NFB is applied before the output inductor at 50kHz and a low-frequency NFB is applied afterwards to achieve both stability and high sound quality through a split-feedback system. The system achieves stability and operates effectively even without using remote sensing.

The headphone output is output simultaneously with the speaker terminals, and if no speakers are connected, the amplifier can be used almost exclusively as a headphone amplifier with Class A operation.

CERENATE uses high quality sound parts. Schottky barrier diodes, which Fidelix was the first in the world to use, are used in key locations, DALE resistors, Takman resistors, audio chemi-con, copper foil polypropylene capacitors, gold plated terminals and switches, thick power cables, highly rigid foot structure, all litz wire transformers, as well as power lines with ground 2-wire system with no terminals, yet non-polarized; no AC inlets, hi-use holders, power main switches, output relays, or connector contacts.

In the event of abnormal heating, the unit has built-in dual fan rotation and muting protection, short circuit protection, and speaker protection.

By connecting the left and right balanced inputs in parallel, with one of them connected to the opposite polarity, fully balanced BTL operation is achieved, enabling even higher sound quality and output power as a monaural power amplifier.

The upper waveform in the photo below shows the voltage waveform on the secondary side applied to the switching power supply transformer, and the lower waveform is the voltage waveform on the primary side center tap. The switching frequency is 220kHz, which is marginally higher than the 192kHz sampling used in DVD audio, and is a very clean waveform for a switching power supply. This means that the switching noise is extremely low, and the high frequency range is not colored too brightly, which is often the case with switching power supplies, thus achieving the origin of the name SERENITY (clear, bright, peaceful, calm, serene).

The switching noise is an astonishing value with a noise margin of nearly 40dB against the strict CISPR 13, the international standard established for audio equipment, so it is 30dB or more less compared to ordinary switching power supplies. This is the result of thoroughly eliminating the habit of high frequency glare and contamination that is common in switching power supplies. 1MHz or higher switching noise cannot be observed, making it the world's best ultra-low noise power supply. Noise suppression is mainly focused on the fundamental, 2nd overtone, and 4th overtone waves, and is achieved through the selection and placement of filters (2 common mode chokes, 2 Y capacitors, and 1 X capacitor).

This is the response waveform at 100 kHz. The response is very straightforward, indicating that phase compensation has been perfectly performed.

Since this is a perfect DC amplifier, it is naturally a brilliant square wave even at 10Hz. The phase response is also extremely accurate over a wide frequency range.

[Lightweight, compact power amplifier with low-noise switching power supply]
Wide range, non-habitual, instantaneous and high braking power.

Fidelix has developed an audio switching regulator "serinity power supply" with unparalleled low noise, and has released a 40W+40W/8Ω class-AB DC power amplifier with volume that is both compact and lightweight and has high sound quality using this power supply.

The input terminals are RCA unbalanced and composite balanced connectors compatible with XLR and TRS, and the output terminals have banana plug-compatible speaker terminals and headphone terminals; when headphones alone are used without speakers connected, the amplifier operates in class-A operation.

The amb section uses National Semiconductor's LM3886 power amplifier IC, which has a high reputation for sound quality and is used in Jeff Ruland's MODEL10 and other products.
It is operated as a complete DC amp capable of amplifying even direct current to build a wideband amplifier.
This IC incorporates multiple protection and muting circuits to prevent hop noise during power on/off, and output relays, which tend to degrade sound quality, have been banished.
A BNC remote sensing terminal is provided on the rear panel, and feedback can be applied from the speaker terminals to the amplifier to compensate for degradation caused by speaker cables.

The serinity power supply features high instantaneous current supply capability and ultra-low noise, and since the AC input is electrically and sonically non-polarized, the direction of the power plug is not a concern.
The S/N and transparency of this unit are so excellent that it is hard to believe that a switching power supply is used, and the sound is so crisp and clear.
It also has a wide range, is habit-free, and has instantaneous and high braking power, producing a sound so energetic and powerful that it is hard to believe that it is a small, lightweight amplifier.
With a rated output of 40W, I was concerned about the lack of power, but it seems to be able to produce a considerable amount of power instantaneously, as I did not feel a lack of power even when listening with the Artemis EOS, which has an 88dB efficiency rating at higher volumes.
When used as a headphone amp with the speakers disconnected, the sound was very large in scale and extended, and I was impressed by this as well. *Audio Accessories