Feliks Audio Echo MKII Vibe

Echo MKII Vibe Feliks Audio: OTL tube headphone amplifier

Fresh from the Polish workshop in Lubliniec, this Vibe version takes the Echo MKII’s OTL design and reworks three specific points: a new transformer cover with improved shielding against interference, revised capacitors for greater precision in the upper part of the spectrum, and CNC-engraved solid oak side panels. A targeted update to a tube amplifier already appreciated for its warm rendering with high-impedance headphones.

Differences from the Echo MKII

The relationship with the previous model is openly claimed: same OTL topology (Output Transformerless, without an output transformer), same tube set in a 2 × 6N6P configuration for power and 2 × 6N1P for input, same 380 mW output power. The developments focus on three areas. The rectangular cover over the toroidal transformer provides better electromagnetic shielding, which lowers background noise. The output capacitors have been replaced with higher-quality components, a choice aimed at better treble definition and more dynamics. The solid oak side panels feature CNC engraving and incorporate matching feet, whereas the Echo MKII made do with more understated cheeks.

OTL topology and tube stage

The Output Transformerless principle consists of removing the usual output transformer from tube amplifiers, driving the headphones directly from the power tubes. This approach shortens the signal path but imposes a constraint: it works best with high-impedance headphones, with the target optimum ranging from 80 to 600 ohms. The pair of 6N6P tubes provides the voltage gain, relayed by the 6N1P tubes that deliver the final 20 dB of amplification. The tubes supplied as standard are NOS (New Old Stock), mounted on ceramic sockets with gold-plated pins. The manufacturer lists several equivalents for tube rolling: E88CC, 6N23P, 6DJ8 or 6922 on the input stage, 6N6Pi on the power stage. Bias is automatic, and no manual adjustment is required after changing tubes.

Steel chassis and solid oak side panels

The structure remains a sheet steel chassis, mounted on four rubber feet that isolate the device from unwanted vibrations. The transformer cover, now rectangular and more enveloping, changes the unit’s silhouette and improves control of electromagnetic radiation. The solid oak side panels, CNC-engraved, extend the vintage aesthetic of the Echo range while incorporating angled supports that slightly raise the front panel. The ALPS RK27 volume potentiometer replaces the Blue Velvet used on the Echo Classic, with revised travel for finer level control. Manufacturing remains entirely manual, carried out in Lubliniec, Poland, and the manufacturer’s warranty is extended to three years on the device (six months on the original tubes).

Front panel, connectivity, and automation

The front panel groups together a 6.35 mm jack socket for headphones, a three-position rotary source selector with Mute function, and a large central volume potentiometer. At the rear, three stereo RCA inputs simultaneously accommodate a DAC, a turntable (via an external phono preamp), and a third line-level source. An RCA pre-out completes the connectivity. Protection circuits on the input and output eliminate unwanted noise during power-up and shutdown. A “preamp safe” mode secures use as a preamplifier. The manufacturer recommends a warm-up time of fifteen minutes before listening, and 30 cm of clearance above the unit for tube ventilation.

Supported headphones

The target optimum covers the 80 to 600 ohm range, which includes most high-impedance dynamic headphones on the market: Sennheiser HD600, HD650, HD660S and HD800S, the Beyerdynamic range in 250 or 600 ohms, ZMF Auteur, Auteur Classic or Atrium models. Low-impedance orthodynamic headphones such as Audeze LCDs or certain Hifiman planars can be connected but fall outside the operating range of an OTL topology, and less sensitive models may lack dynamic headroom. For anyone hesitating between several headphones, the Echo MKII Vibe paired with 300-ohm headphones (Sennheiser HD600 or HD650, for example) remains the combination most faithful to the spirit of the product.

Built-in preamplifier function

Aside from headphone amplification, the RCA line output allows the Echo MKII Vibe to be used as a tube preamplifier in a two-channel system. The pre-out signal is taken just after the tube input stage, which gives the line output the sonic character of the 6N1P tubes. The unit can therefore drive a transistor or tube power amplifier, or a pair of active speakers, while retaining the three inputs switchable from the front panel. This flexibility covers hi-fi use in addition to headphones, without requiring a complex hardware setup.

Technical Specifications

Amplification

• Type: OTL (Output Transformerless) tube headphone amplifier with preamplifier output
• Power tubes: 2 × 6N6P (original NOS)
• Driver tubes: 2 × 6N1P (original NOS)
• Compatible alternative tubes (driver): E88CC, 6N23P, 6DJ8, 6922
• Compatible alternative tubes (power): 6N6Pi
• Tube sockets: ceramic, gold-plated pins
• Biasing: automatic (auto-bias)
• Power supply: stabilized toroidal transformer, electronic hum suppression, delay of anode voltages

Performance

• Frequency response: 15 Hz to 45 kHz (±3 dB)
• Output power: 380 mW
• Gain: 20 dB
• Total harmonic distortion (THD): 0.4% (300 Ω, 20 mW)
• Input impedance: 100 kΩ
• Recommended headphone impedance: 80 to 600 Ω

Connectivity

• Headphone output: 1 × 6.35 mm jack (front panel)
• Line inputs: 3 × stereo RCA (switchable from the front panel)
• Line output: 1 × stereo RCA (preamplifier mode)
• Functions: rotary source selector, Mute function, preamp safe mode, input and output protections

Settings and automation

• Volume potentiometer: ALPS RK27
• Start-up: no manual bias adjustment required after tube replacement
• Daily warm-up time: approximately 15 minutes
• Burn-in period: 30 to 50 hours to achieve the intended sound signature

Mains power supply

• Voltage: 230 V (50/60 Hz)
• Fuse: 1.25 A
• Power cable: included

Construction and finish

• Chassis: steel sheet, anti-vibration rubber feet
• Side panels: solid oak, CNC engraving, matching wooden feet
• Transformer cover: rectangular, reinforced electromagnetic shielding
• Origin: handcrafted in Lubliniec, Poland

Dimensions and weight

• Dimensions (without tubes): 265 × 220 × 115 mm (W × D × H)
• Weight: 3.5 kg

Conditions of use

• Operating ambient temperature: 15 to 30 °C
• Maximum continuous use time: 8 hours, followed by 1 hour of rest
• Waiting time after switching off before tube replacement: minimum 15 minutes

Box contents

• Echo MKII Vibe amplifier
• 1 pair of 6N1P NOS driver tubes
• 1 pair of 6N6P NOS power tubes
• Power cable
• User manual
• Warranty card

Warranty

• Device: 3 years (Feliks Audio extended warranty)
• Original tubes: 6 months