Yamamoto Acoustic Crafts EQB-01 Vacuum Tube Phono Equalizer Amplifier

The circuit of the EQB-01 amplifier has been completely overhauled and the signal-to-noise ratio of the amplifier has been greatly improved.



The EQB-01 is a unique circuit system that uses a pentode for the amplifier.

The ripple filter of the power supply is divided separately from the rectifier circuit for each stage, and each stage is supplied from an independent power supply. The rectifier circuit has improved regulation with double-wave rectification. The ignition of the Telefunken 6AK5W heater has an independent rectifier circuit for each of the six vacuum tubes, eliminating interference between the tubes with each other. In addition, the amplifier circuit maintains the same basic scheme, but by resetting the operating point to the optimal point, we have achieved both large gain and noise reduction.



The gain of the equalizer amplifier is 58dB for the high-gain type. A normal equalizer amplifier has a gain of about 34 dB, so it is set 24 dB higher than the standard. With a residual noise of 2.3 mV, the signal-to-noise ratio is 110 dB. The gain is obtained with only two vacuum tubes, so there is no lack of information because it is very simple. In general, the CR type circuit configuration is considered to be disadvantageous in terms of signal-to-noise ratio, but it has been proven that it can obtain a fairly good signal-to-noise ratio depending on how it is used. Since the maximum output is about 28V, it can be used not only for MC cartridges, but also for MM cartridges with large output and MC cartridges with high output. In fact, the MC cartridges YC-03S and YC-03M can be directly connected to the level so that they can be used without using a step-up transformer. The output of the YC-03S is 0.25mV, so most MC cartridges can be used directly. The sound of the MC cartridge, which does not pass through a step-up transformer, is fresh and the amount of information is greatly improved. The optimum input impedance of the equalizer section of amplifiers such as the CA-03 is 100 Ω.
The EQB-01 is configured from the CA-03 and CA-03L by omitting the line amplifier section and omitting the input volume and selector switch. In addition, the sound quality of the substrate is improved by applying gold plating to a thickness of 70 μm of copper foil.
《Equalizer Amplifier》

Maximum Output	28V
Frequency response	30-15kHz/+-0.5dB
Input impedance	47kΩ,1kΩ,100Ω
Output impedance	4.8kΩ
Amplification factor	58dB/1kHz
Residual noise	2.3mV
SNR	110dB
size	420(W)290(D)94(H)mm
weight	6.3kg

Since it is almost made-to-order, it may take 1~3 months to deliver.