Stereo preamplifier C3PR


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

Vacuum tube 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 amplifying elements are being used. The countermeasure is whether to use a device with good linearity or reduce the number of devices. C3PR uses a highly reliable, 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-feedback.

True balanced transmission is transformer

Complete balanced transmission which is possible due to transformer

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

High performance transformer allows both input and output

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

Exquisite sound quality

Key technology is non-feedback

A negative feedback circuit was invented in 1927, and the performance of the amplifier improved markedly. However, if you examine it closely, 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 to not suppress this vibration, it is necessary to take servo-control, or use high linearity components such as amplifying elements and capacitors with non-feedback control.

Intermodulation distortion is worse than harmonic distortion

Harmonic distortion is when a signal passes through the element, an integer multiple signal appears. In a sense it’s what sounds can be heard comfortably by 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

Rectifiers used in the power supply and contacts in the circuit are sources of noise. Since these are sharp and rising noises they occur at over a50 Hz to several hundred MHz. Furthermore, they cause intermodulation and enter the audio band. When this occurs sounds become unnatural. Generally, loud noises are created by switching power supply. However, CS port noise processing technology greatly suppresses and cuts unnecessary noise and achieves exquisite sound quality.


Independent right and left power supply channels

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 gentle quality on the auditory system.

Switching power supply + analog power supply

It is no stretch to say that the sound of the amplifier is determined by the power supply. C3PR stabilizes all the power supplies properly for the reference machine, such as insulation with the AC line in multiple stages and does not cause muddiness of the sound. The voltage is stabilized by the switching power supply and is further rectified by a quick response non-feedback analog power supply. Thanks to this you can hear a sounds a gentle as a clear stream from the Alps.

Various I / O plug

Various input / output plug

Input can switch between unbalanced 4 channels and balanced 2 channels. Each of the unbalanced and balanced terminal is equipped with two outputs.

The real value of the preamp is determined by attenuator

Resistor switching ladder type, constant impedance attenuator

A variable resistor having a structure in which a contact slides on a resistor, at this point of contact diodes are formed, and noise is generated when sound signals pass through, which is the basis of distortion. In C3PR, the resistance ladder is switched on 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 decrease it to -70 dB, and you can adjust the volume in a total of 107 stages.

Large viewable display

Easy to see, large display

The attenuator level has a character display of 25mm and can be seen clearly confirmed from any listening position. There are 5 brightness display options and they can be adjusted to the brightness of the room.

Balance adjustment

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

Bass boost

3 options for boosting the bass, this can be done in 2 dB steps

Remote controller

All operations except the POWER switch are available from the remote listening position. There is a built-in rechargeable battery with a 5 year or more usage period. You can charge it using the USB terminal on any 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