Yamamoto Acoustic Craft CA-03 Vacuum tube preamplifier with built-in phono

The ripple filter of the power supply is split from the rectifier circuit separately for each stage, and each stage is supplied from its own independent power supply. The rectification circuit is double-wave rectification for improved regulation. For the heater ignition of the Telefunken 6AK5W tube, each of the six tubes has its own rectifier circuit to eliminate interference between the tubes. The amplifier circuitry has been designed to achieve both high gain and low noise by setting the operating point at the optimum point.


The gain of the equalizer amplifier is a high gain type, 58dB at 1kHz. This is 24dB higher than the gain of a normal equalizer amplifier, which is about 34dB. By reducing the noise to 2.3mV, a signal-to-noise ratio of 110dB is achieved. The equalizer amplifier of this company is very simple with only two vacuum tubes for gain, so there is no lack of information. The maximum output is approximately 28V, so it can handle not only MC cartridges, but also large output MM cartridges and high output MC cartridges. It is at a level where the company's MC cartridges YC-03S and YC-03M (output of 0.25mV) can be directly connected and used without the use of a step-up transformer. The sound of MC cartridges without a step-up transformer is fresher and the amount of information is greatly improved. 100Ω is the optimum input impedance for the equalizer section of amplifiers such as the CA-03.

Line amplifier section

Tubes used	Telefunken 6AK5W x6
Maximum output	8V
Frequency Response	10-150kHz/-0.5dB
Output impedance	1.6kΩ
Line amplifier gain	14dB (approx. 5 times)
Residual noise	0.13mV
S/N Ratio	92dB

Equalizer amplifier

Maximum output	28V
Frequency Response	30-15kHz/+-0.5dB
Input impedance	47kΩ,1kΩ,100Ω
Output impedance	4.8kΩ
Amplification ratio	58dB/1kHz
Residual noise	2.3mV
S/N Ratio	110dB
Size	420(W)290(D)94(H)mm
Weight	6.3kg