Accuphase c 27 brochure

Page 1

1 2 3 LEFT CHANNEL INPUTS -�1 -�1 BALANCED UNBALANCE D Same as LEFT CHANNEL RIGHT CHANNEL LEFT CHANNEL INPUT SELECTOR FILTE R GAIN MM-MC RIAA EQUALIZER NETWORK DC SERVO GAIN IMPEDANCE SELECTOR FEEDBACK NETWORK FEEDBACK NETWORK GND GND GND + -� +-� SUBSONIC FILTE R + -� MM AMP MC AMP IMPEDANCE SELECTOR LOAD IMPEDANCE BALANCE CONNECTION RIAA EQUALIZER NETWORK DC SERVO GAIN LEFT CHANNEL OUTPUTS The Ultimate Phono Equalizer Amp - Separate circuitry for MM and MC ensures ultra low noise performance and outstanding RIAA precision. Versatile load impedance selector with three settings for MM and six settings for MC brings out the best in every cartridge. Subsonic lter, and high gain capability of up to 70 dB with gain switching. Three analog player inputs with separate settings memory for each input. The analog phono record is experiencing a quiet boom among discerning music lovers. It goes without saying that a phono equalizer of high quality is essential to extract the enormous richness of sonic information engraved on vinyl records. Furthermore, the selection of tonearm, cartridge and other parts of the playback system requires a thorough understanding of audio fundamentals. This is a fi eld where some investment of time and effort can yield immensely satisfying results. Accuphase has gained considerable expertise in designing and building phono equalizers, either integrated in preamplifi ers or available as option (AD-2810 and AD-20). In response to the wishes of audiophiles worldwide, we have now developed the C-27 as a high-end standalone phono equalizer amplifier, capable of exploring the possibilities of the analog disc to the fullest. Because the output signal level of a record player is extremely low, high-gain amplifi cation is required before supplying the signal to subsequent stages. Distortion and noise should be kept to an absolute minimum, and excellent linearity from low to high frequencies is also a must. In the C-27, these goals are achieved by employing completely separate amplifi er sections for MM and MC, each with optimized circuit topology and strictly selected parts for no-compromise performance. S/N ratio, THD, high-frequency characteristics, linearity and all other parameters approach the ideal in performance. Whats more, the C-27 is perfectly equipped to accommodate a wide range of cartridge output voltage ratings and load impedance requirements. To ensure optimum matching, three different settings for MM and six different settings for MC can be selected. Designed to raise the bar for phono equalizer amplifi ers, the C-27 will bring out the characteristics and musical qualities of any phono cartridge to optimum effect, providing pure music enjoyment from those legendary analog discs. C-27 Functions and Features -�� Separate MM/MC amplifi er confi guration ensures ultra low noise -�� Highly precise equalization: RIAA deviation only ±0.3 dB -�� Monaural construction with separate toroidal power transformers and separate equalizer boards for left and right channel -�� Versatile impedance switching options MM/MC indicationMM/MC selector Load impedance indicators Load impedance selector Subsonic fi lter and gain indicatorsPower transformer Filter button Gain selector button Filtering capacitors Input selector MM Amplifi er Section MC Amplifi er Section-�� Two separate board assemblies for left and right channel, using Tefl on substrate and carrying dedicated MM and MC amplifi ers, phono equalizer amplifi ers, and logic relays for signal switching to ensure shortest possible paths between inputs and outputs. C-27 Circuit Diagram 1kΩ 47kΩ 100kΩ 3Ω 10Ω 30Ω 100Ω 300Ω 1kΩ 1kΩ, 47kΩ, 100kΩ 3Ω, 10Ω, 30Ω, 100Ω, 300Ω, 1kΩ MM MC -�� Subsonic fi lter (10 Hz, -12 dB/octave) -�� Gain switching enables high gain of up to 70 dB -�� Equalizer PCBs made from Tefl on* (glass fl uorocarbon resin) with low dielectric constant and low loss * Tefl on is a registered trademark of DuPont USA. -�� Gold-plating of all major parts in signal path -�� Three inputs for analog players or tonearms, each with a separate memory for MM/MC, load impedance, gain, subsonic fi lter and other settings (LEDs show selection status)

Page 2

Q18 Q17 Q20 Q19 Q24 Q23 Q22 Q21 Q8 Q1 Q2 Q3 Q4 Q5 Q6 Q12 Q7 Q10 Q9 Q11 Q14 Q13 Q16 Q15 B+ B- Q34 Q33 Q36 Q35 Q40 Q39 Q38 Q37 Q2 Q1 Q4 Q3 B+ B- MM Amplifi er Section Circuit Diagram Completely separate MM and MC sections MC amplifi er section MM amplifi er section One of the biggest challenges for a phono equalizer amp is the problem of noise. How to achieve high S/N ratio is a crucial point. In order to precisely match the circuit confi guration to the different requirements of MM and MC cartridges, the C-27 features separate sections employing purpose-selected components and optimized operating points. This uncompromising approach results in outstanding S/N ratio, minimum distortion, and excellent frequency response characteristics. Amplifi er performance fi nally approaches ideal levels. The MM section must provide a high impedance input while also reducing residual noise. To achieve this, FET devices were selected for the initial stage. The circuit confi guration is defi ned as 3-parallel low noise FET buffer amplifi er + 6-parallel ultra low noise transistor differential push-pull circuit. The MC section must provide low internal impedance over a wide range to properly handle the output voltage of MC cartridges, which is a level of magnitude lower than that of MM cartridges. Residual noise of the amplifi er therefore needs to be kept to an absolute minimum. This is achieved by using an 8-parallel ultra low noise transistor differential push-pull circuit to guarantee high S/N ratio. InputInput Ultra low noise transistor differential push-pull circuit in 6-parallel con- fi guration OutputOutput Low noise FET buffer amplifi er in 3-parallel confi guration Equalizer Components DC Servo Amplifi er Gain Control MC Amplifi er Section Circuit Diagram Ultra low noise transistor differential push-pull circuit in 8-parallel con- fi guration Equalizer Components DC Servo Amplifi er Gain Control