Encore Seven is a company with headquarters in Poland, active in the audio industry since 2010. The field of expertise is the production of tube amplifiers based on the V-TUBE concept. The company created the EGG-SHELL brand. Since 2021, he has been developing amplifiers under the name ENCORE SEVEN.
Past & Present
For more than 10 years, EGG-SHELL amplifiers have won the appreciation of users and the favour of trade journalists and have made a lasting mark in the history of the audio industry. Our greatest successes include the title of BEST PRODUCT 2016 awarded by High Fidelity magazine for the EGG-SHELL Prestige 9 amplifier and the award for one of the best-sounding systems at the Audio Video Show ‘2016 in Warsaw (Europe’s second largest industry show). EGG-SHELL amplifiers have found customers throughout Europe and Asia.
ENCORE SEVEN vacuum tube amplifiers take all the best ideas and features from the achievements of EGG-SHELL amps, in particular from the main and most developed EGG-SHELL Prestige series. At the same time, the now revised approach to amplifier design and construction elevates the new models to an even higher level in every respect – advanced design, better sound, appearance and quality of workmanship. The visual facelift has been entrusted to Krakow’s Szostak Atelier (Witold Szostak), whereas Rolof Audio (Robert Rolof) is responsible for the electronics design.
SYNCHRONICITY
The Encore Seven SYNCHRONICITY is the very essence of the EGG-SHELL Prestige series we produced between 2011 and 2021. Instead of several SET (Single Ended Triode) Class A models, differing primarily in output power from 9 W to 18 W, we have constructed a universal push-pull amplifier, which represents Class A for power up to 13 W and reaches a maximum of 40 W per channel. In fact, it is a completely new construction, a design created from scratch, to which we have devoted 2 years of work.
SYNCHRONICITY is integrated push-pull vacuum tube amplifier. It operates in a pentode circuit in ultralinear mode, producing a maximum of 40 W per channel in Class A/B. For power up to 13 W it represents pure Class A. The amplifier is designed to work with majority of loudspeakers and is recommended for medium to large rooms. Designed and built in a timeless style, it is austere and simple, but at the same time unique and eye-catching. It is designed and handcrafted in Poland.
Construction
The amplifier is constructed in a modular way so that it is easy to service. All components can be easily accessed, whereas the use of space inside is optimal. To build it, we used durable materials such as steel, aluminium and glass. All components are machined on CNC digital machines and finely finished.
The supporting structure (chassis) is constructed from thick powder-coated sheet. It consists of two separate parts – front and rear. We made sure of the high quality of the smallest details, such as the screws connecting the elements. The transformers are suspended on flexible pads to minimize the transmission of vibrations to the PCBs and tubes. The chassis is a ‘self-supporting’ structure, with the outer casing being merely an overlay. This makes the amplifier easy to assemble.
The radiator is called the outer casing. Indeed, this is the role it fulfils. It consists of approximately 100 aluminium sheets 6 and 8 mm thick. Each is precisely manufactured and individually painted. The whole is bolted together with twenty strings, creating a uniform block of a unique shape, embodying the idea of the V-TUBE design, the inclination of the power tubes. The front is fitted with a 6 mm thick glass panel, easily assembled on strong neodymium magnets.
Description and features
Input stage is built on the basis of a constant current draw amplifier (CCDA),which means that regardless of voltage changes (amplification of the input signal) the amount of current drawn from the power supply remains constant. This configuration prevents power supply voltage surges, which could adversely affect the quality of the input signal amplification. As ECC88 tube (6DJ8) is used in the circuit, it essentially lowers the output impedance of the power stage and has a major impact on optimal operation with phase inverter.
The KT88 power tube phase inverter and control stage circuit are based on a differential amplifier whose topology allows direct coupling to the input stage. This solution offers signal feeding without the need for a coupling capacitor. The idea of the amplifier is to keep the signal path as short as possible, hence the use of a differential amplifier (on 12BH7 tubes), which, in addition to the function of matching the phase of the signal to the output tubes, also gives an appropriate level of amplification of this signal. This eliminates the need for an additional control stage.
The anode power supply incorporates a semiconductor rectifier that supplies voltage to the capacitor bank, which consists of Miflex polypropylene and Nichicon electrolytes of a total capacity of over 1,200 uF. All decoupling and filter capacitors found in the signal circuits are exclusively Miflex polypropylene capacitors. Apart from the anode power supply bank, electrolytes were only used in the control and logic circuits and in the tube glow circuit.
Gyroscopic remote control
An innovative remote control with an unprecedented appearance and mode of operation is another bold idea that is changing previous standards in the audio world. The volume control has no moving parts. It is enough to twist it left or right to change the volume. When turned upside down, the LED indicators for battery status and charging indication become active. The charging socket and switch are located at the bottom. This gives us a visually homogeneous object without any buttons or other controls.