Yamamoto Sound Craft
EQB-01 tube phono equalizer

The circuitry of the EQB-01 amplifier has been completely revised to significantly improve the signal-to-noise ratio of the amplifier.



The EQB-01 is a unique circuit system that uses pentodes in the amplification section.

The ripple filter of the power supply is split from a separate rectifier circuit for each stage, and each stage is supplied from an independent power supply. The rectification circuit uses double-wave rectification to improve regulation. For the ignition of the heater of the Telefunken 6AK5W tube, each of the six tubes has its own rectifier circuit to eliminate interference between the tubes. In the amplifier circuit, the same basic circuit is maintained, but the operating points are re-set to the optimum points to achieve both a large gain and a reduction in noise.



The gain of the equalizer amplifier is a high gain type, 58dB. The gain of a normal equalizer amplifier is about 34dB, so this setting is 24dB greater than the standard. The residual noise in this state is 2.3mV, resulting in a signal-to-noise ratio of 110dB. Since the gain is obtained with only two tubes, it is very simple and there is no lack of information. Although the CR-type circuit configuration is generally considered to be disadvantageous in terms of SN ratio, it has proven to obtain a fairly good SN ratio depending on how it is used. The maximum output is approximately 28V, so it can be used not only for MC cartridges, but also for large output MM cartridges and high output MC cartridges. The YC-03S and YC-03M can be directly connected and used without a step-up transformer. 0.25mV output of the YC-03S means that most MC cartridges can be used directly with the YC-03M. The sound of MC cartridges without a step-up transformer is very fresh and the amount of information is greatly improved. The input impedance of the equalizer section of amplifiers such as the company's CA-03 should be 100 ohms.
The EQB-01 omits the line amplifier section from the CA-03 and CA-03L, and also omits the input volume and selector switch. The board is made of copper foil 70µ thick and gold plated to improve the sound quality.
Equalizer amplifier section

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

Due to the almost made-to-order production, it may take 1~3 months for delivery.