About the Filarmonía

Filarmonía is a stereo integrated amplifier with a maximum output power of 30 watts RMS per channel at 8 ohms. Its output stage makes use of a pair of hand-matched E34L pentodes in Push-Pull configuration per channel. The E34L is a special version of the EL34/6CA7 tube. The drive and phase inversion stage uses a JAN5814-A (E82CC/6189/12AU7/ECC82) double triode, whilst the input section is driven by an E88CC (6922/ECC88/6DJ8) double triode.

One of Filarmonía's most remarkable characteristics is the topology of its output stage, which does not use the typical ultra-lineal configuration, but a special screen-grid regulated pentode circuit with auto-regulated polarization, designed by Ars-Sonum which allows an extremely accurate and steady working point at the final path. This technology makes possible to use a very low global negative feedback of only 6dB helping to keep distortion levels low and bringing no few advantages, such as a greater phase coherence, better frequency response stability at all levels and across the audio band and lower TIM Distortion levels. This global negative feedback is complemented by the slightest use of local negative feedback at the previous stages.

The output stage’s polarization circuit uses high precision components, matched for tolerances below 1%. The output transformers and the cathode resistors deserve special mention as they are matched within a 0.5% tolerance.

The E34L JJ tubes are object of a meticulous selection process to attain matched quartets within a 2% of their specs, ensuring that stability and performance is kept uniform and unaltered along the aging process of the tubes. It also allows them to be easily replaced by the user without any further adjustments. Furthermore –and fundamentally– it allows a very precise class A working point for most of the power delivery of the amplifier. Only during the shortest transients the output section works into Class B, quickly returning to its optimal working point for a better musical performance.

The output transformers –designed by and exclusively manufactured for Ars-Sonum– are conceived to reach ultra wide frequency responses, even without using global negative feedback. Their main attributes are a high primary inductance (>50Hy), extraordinarily low fugue inductance (<2mHy) and the highest precision balance (<1%) between primary windings. All these distinctive specs are  achieved with proprietary winding techniques and the most careful craftsmen work.

The power supply

Special care has been taken on the power supply.

It includes five sections, four of them independently stabilized for each channel and stage, to achieve the lowest crosstalk and inter-modulation.

An input transformer with electrostatic screen brings an outstanding common mode noise rejection and also provides an extra degree of protection to the user. The passive components within this section have been selected in an unusual way; the Filarmonía sports professional quality filtering and decoupling caps of special series (Aerovox/BHC, Elna and Panasonic electrolytics and Wima MKP polypropylene film ones). The power resistors are selected at 1% tolerance and they are also over specified to ensure the most reliable performance for many years.

The driver and phase inversion stage uses tubes from professional series (JAN 5814A Philips) and low-noise, high-precision components, such as metal film resistors selected and pair-matched at 0.5% as well as special series film & foil top audiophile grade capacitors (Hovland Musicap).

The input stage is based in an exceptionally low noise tube (JJ E88CC) and the associated components have been carefully selected to achieve the highest signal to noise ratio. They include precision metal film resistors from Vishay and Philips and an ALPS Blue Velvet volume potentiometer.

The amplifier is built using both point-to-point wiring and a printed circuit board. We have found that this technique helps the different stages to reach their maximum performance. A great deal of the time devoted to research, design and development of the amplifier was put into the layout of the internal wiring and the circuit board. Our quest was to achieve the best signal-to-noise ratio keeping the interferences and parasitic capacitances among components and stages the lowest possible.

The chassis is made of die cast steel, folded and soldered with the highest precision and then polished and chrome plated. The lathe-turned, hand-polished, solid aluminum control buttons are exclusively hand-crafted for Ars-Sonum. Finally, the new SE version utilizes high quality, pure copper Cardas speaker terminals.

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