Stereo preamplifier C3PR


The most incredible listening experience. C3PR enhances your stereo listening experience with exquisite sound quality.

The tube type preamplifier with high performance transformer arranged for input and output

The tube type preamplifier with high performance transformer arranged for input and output

Realization of low distortion rate by two-stage configuration

It is impossible to eliminate distortion completely as long as using amplifying elements.
The countermeasure is whether to use a device with good linearity or reduce the number of devices.
C3PR is mounted highly reliable and linearity tube C3g developed by Deutsche Telekom.
C3PR consists only of two C3g tubes and minimizes intermodulation distortion and harmonic distortion in spite of non feed-back.

True balanced transmission is transformer

Complete balanced transmission which is possible due to transformer

The balanced transmission can only be done with a transformer.
Transformer is equipped with the input and output of C3PR, and perfectly balanced transmission is capable.

High performance transformer placed both input and output

Transformers of C3PR that are designed by ourselves and based on many rich experiences for years.
Transformers are the most important electronic components in among key parts that affect the performance of the amplifier, such as distortion, SN ratio, input and output impedance.
Every transformer is developed on the detailed parts design such as core material, wire material, winding thickness, winding ratio used.

Exquisite sound quality

Key technology is non feed-back

A negative feedback circuit was invented in 1927, and the performance of the amplifier improved markedly. However, as you examine it strictly, the negative feedback circuit (servo control) returns the signals that have gone too far to +, unnecessary vibration that restores the signals that have gone too far back to - and causes intermodulation with the audio signal, It becomes a heterogeneous sound compared with the original one. In order not to suppress this vibration, it is necessary to take servo control, or use high linearity components such as amplifying elements and capacitors with non feedback contorol.

Intermodulation distortion worse than harmonic

What is harmonic distortion means that when a signal passes through the component element, a signal of an integral multiple is output, and in a sense, it can be heard comfortably for humans. Among the distortion, it is intermodulation distortion that is worse, generating uncorrelated signals that are not in the original signal, resulting in an unpleasant sound. For example, when a signal of 1 kHz and a signal of 1.1 kHz pass through a rectifier or an amplification element, a sum signal and a difference signal of the respective signals are generated. 100 Hz and 2.1 kHz were not found in the original signal. The audio signal is a collection of many frequency components, and the frequency component of noise also causes intermodulation and invades the audio signal. This phenomenon occurring at MHz outside the audio band also causes noise to enter the audio band.

Outstanding noise suppression technology

It is source from which noise is generated from contact points of rectifiers and circuits in power supply. Since these noises are sharp rising noise they occur over the band of 50 Hz to several hundred MHz. Furthermore they cause intermodulation and enter the audio band. After all the sound becomes unnatural. Generally noise is greatly generated by switching power supply as well and the same thing happens. However CS port noise processing technology based on years of switching power supply design greatly suppresses / cuts unnecessary noise and achieves exquisite sound quality.


Each channel on the right power supply and left

One is independent as Hi-Fi unit. power supply The control circuit also works out independently as well.
The AMP circuit does not make up the SN, but the aggregate of the original characteristics creates SN. It is AMP which creates very quietness on hearing.

Switching power supply + analog power supply

It is not too much to say that the sound depends on the power supply that is good or bad C3PR stabilizes all the power supplies appropriate for the reference unit , such as insulation with AC line in multiple stages, and does not cause turbidity of sound. The voltage stabilized by the switching power supply is further rectified by the high-speed response non-feedback analog power supply. From there you can hear a sound like pure flow stream.

Various I / O plug

Various input / output plug

The input can be switchable to unbalanced 4 channels or balanced 2 channels. Each of unbalanced and balanced terminal is equipped with two outputs.

The real value of the preamp depends on attenuator

Resistor switching ladder type, constant impedance attenuator

For variable resistors with contacts sliding on the resistive element, point contact diodes are formed at the contacts, and noise is generated when sound signals pass through, which is the basis of distortion.
In C3PR, resistance ladder is switched by a high reliability relay with crossbar twin structure gold · platinum contact, and attenuation from 0 dB to -60 dB is performed. It can be adjusted in 0.5 dB from 0 dB to -38 dB, and from 1 dB in 5 dB units from -38 dB to -60 dB. By further pushing the knob it is possible to squeeze it down to -70 dB, and you can adjust the volume in 107 stages as a total.

Large viewable display

Large display easily to see

The 25mm attenuator level characters can be clearly confirmed from the remote position. The display brightness can be varied in 5 steps, and it can be adjusted to the brightness of the room.

Balance adjustment

Adjustable the left and right balance to ± 3.5 dB in 0.5 dB step.

Bass boost

Three levels of bass boost can be done in 2 dB steps.

Remote controller

All operations except the POWER switch are available from the remote listening position. Because rechargeable battery is built in, it is unnecessary to replace for over 5 years. You can charge from the USB terminal of the personal computer.

Remote controller

Product Summary

Stereo preamplifier C3PR


Model C3PR
Method Input, output transformer mounted vacuum tube type non-feedback preamplifier
Constitution Input transformer - C 3 g 3 connected - FET driver - 3 g 3 connected - FET driver output transformer
Frequency response 20Hz〜20kHz +0 −1dB
Gain 16dB
Maximum input voltage 4V/1kHz
Maximum output voltage 4V/1kHz
Input impedance 7kΩ or more ※1
Output impedance 50Ω or less
Minimum load impedance 600Ω
S / N ratio 80dB/ATT0dB 100dB/ATT−20dB
Total harmonic distortion ratio 0.05% 1kHz 250mV
Balance adjustment ±3.5dB
Compensator +2dB 3steps 100 Hz
Remote control operation Infrared remote control
Power supply AC100/120/200/240V 50,60Hz
Power consumption 30W 60VA
Size 470W×90H×400D Including protruding part
Weight 14kg
Finish Silver finish and precious rosewood veneer
Accessories AC power cable · remote control · USB cable for charging
Warranty period 5 years (excluding consumables) registration is required

※1:Please use the item whose output impedance of the preceding equipment is 1.5 KΩ or less.



External dimensions

External dimensions