SONY TA-ER1

Commentary

This is an R series stereo preamplifier designed to recognize the role of the preamplifier and to focus on the basics of amplification.

In the TA-ER1, the balance input terminal is directly connected to a high-equilibrium balance amplifier, and the input signal is immediately differentially synthesized. As a result, the CMRR (common-mode rejection ratio) of 50 dB of the high-equilibrium balance amplifier can be fully utilized for noise reduction, and the SN ratio of the transmission path, which is usually around 120 dB, has been successfully raised to around 170 dB.

In order to reduce the voltage drop that causes signal loss, a high input impedance design that allows transmission with almost no signal current is adopted. By using a high-performance FET for the input element, the input impedance is increased from the normal 20k Ω ~ 100k Ω to a balanced input of 4M Ω. This reduces the signal current to 1/40 ~ 1/200 compared to the normal one, and at the same time, the distortion is sufficiently suppressed.
In addition, the high input impedance design reduces the load on the drive for the input device and allows the source signal to be transmitted faithfully. In addition, the distortion at the 0 crossing of the low-frequency signal from the + side to the - side and from the - side to the + side is greatly improved and low-level bass reproduction is improved.

It is designed to take advantage of the balance amplifier for unbalanced inputs. The hot and cold inputs of the balance amplifier are connected to the hot and cold inputs of the balance amplifier, and the hot and shield of the pin jack are connected respectively. Thus, only the signal transmitted between the hot shield of the pin jack is amplified, and the fluctuation of the ground potential inside the chassis is not amplified, so that the SN ratio can be increased.

A parallel switched function is used to manage the ground line thoroughly.
The input selector switches between hot and shielded simultaneously. Only the shield side of the selected input terminal is connected to the ground line, which is the reference for amplification, and the shield of other devices is disconnected. This eliminates the fluctuation of ground potential caused by multiple devices concentrating on the preamplifier, and improves the sound quality of unbalanced input.

We have developed and installed a high sound quality attenuator using conductive plastic resistor for the volume.
This resistor is made by mirror-coating a hard substrate with a low-strain carbon-based conductive resin. The precision of the resistor is extremely high, and it can narrow the input signal by more than 130 dB. It also boasts a gang error (difference in attenuation between channels) of less than 1 dB at -100dB.
The attenuator is housed in a brass case with a maximum wall thickness of 9.5 mm, and the case and electrode brush are gold-plated to improve electrical and mechanical performance.

In order to realize a strong signal drive to the power amplifier, a MOS Direct SEPP method complimentary service circuit using power MOS FET as an output pair is mounted.
Since the MOS FET has a transfer function of the second order characteristic, the distortion is mainly of even order, so that the adverse effect on the music signal is reduced. Furthermore, the combination of the MOS FET with the complimentary service SEPP circuit has the advantage that the second order characteristics cancel each other and lower distortion can be obtained.
To take full advantage of this, the MOS Direct SEPP scheme carefully designs the pre-stage bias circuit to eliminate the source resistance that is usually added for bias stabilization.
The direct output by the power MOS FET keeps the linearity of the signal good without losing the beautiful square characteristic of the element itself, and the bare output impedance is also sufficiently low. Therefore, even when a long cable is drawn from the preamplifier to the power amplifier, the drive performance is always stable.

In order to improve the performance of each circuit section, we have adopted a unit amplifier configuration with separate boards for each amplifier block of phono equalizer amplifier, input balance amplifier, and output balance amplifier. Each unit amplifier board is fixed to the main board of each amplifier block by pin point support. The two layer construction enables smooth signal flow and easy printed wiring.
In addition, a 12 mm thick stabilizer made of a high-rigidity resin composite material is mounted on the unit amplifier in order to improve vibration control, preventing the generation of modulation noise caused by vibration.
Furthermore, in order to avoid the deterioration of the S / N ratio and the irregularity of vibration mode caused by the formation of a ground loop due to excessive L/Rch separation, the distance between channels is reduced as much as possible, and the L/Rch unit amplifiers are arranged in equilibrium on the main circuit board. In electrical terms, the power supply line and ground line are strictly separated by L/Rch. By twin monaural wiring, 110 dB separation and characteristics are achieved.

A phono equalizer amplifier a phono equalizer amplifier for MC/MM cartridges. This amplifier has dedicated input terminals for MC and MM in order to reduce contact points caused by switching the switch.
For the MC input, a step-up transformer is installed to increase the gain of the signal, and an input impedance of 3 Ω / 30 Ω can be selected. In addition, a floating connection can be selected by separating the shield side of the signal from the ground, so that higher sound quality can be obtained when noise sources such as power transformers can be kept away.
For the MM input, a MM load terminal is separately provided. The input impedance / capacity of 100k Ω / 100 pf can be changed to 50k Ω / 100 pf by using the load pin.
The phono equalizer circuit uses an NF type and is assembled in a discrete configuration.

The balance input is equipped with a phase invert switch so that it can be used with either No. 3 hot or No. 2 hot input devices. In addition, the pre-out is equipped with one balanced output and one unbalanced output. Both are equipped with positive-phase / negative-phase pair output terminals so that it can be used with No. 2 hot balanced input power amplifier and balanced BTL connection which are often used overseas.

The volume control mechanism is equipped with a locking gear mechanism driven by an ultrasonic ceramic motor and can be operated by a remote control.
A thick gear plate is attached to the volume shaft, and the gear is engaged with the motor side gear each time the volume is operated, and it is separated after the operation. This structure prevents rattling because the drive mechanism is completely separated except during operation. Also, the motor itself is powered by piezoelectric ceramic displacement, so there is no harmful flux or spark noise, and it is used as a weight when stopped. It is also advantageous from the aspect of vibration.
In addition, the series of operations from start to stop of the motor is precisely controlled by a microcomputer, and stepping operation of about 1/128 rotation (1/5 scale) and continuous rotation operation can be freely performed.

Equipped with a dual-mode attenuator, which is useful for low volume situations. Switching to the low-extend position changes the resistance / rotation curve to expand the range of adjustment for low volume situations from approximately three scales to approximately eight scales from the left at normal volume levels. In this system, no extra circuit is used at normal volume levels, so that sound quality is not degraded.
Also, the L/Rch balance control employs a method that adjusts the gain of each L/Rch amplifier itself by switching the relay within a range of 1 dB step by 1 dB and 3 dB on one side.

Equipped with a muting switch, signal off operation is possible.

The power supply part is separated from the amplifier body in consideration of the effect of the flux of the power transformer, etc., and is designed in a separate case.
This power supply unit is equipped with a large toroidal transformer with low leakage flux and a high-quality power supply capacitor. It is designed to generate high-quality direct current before supplying it to the amplifier body. This protects the audio signal from noise and allows for a design with room for both the power supply unit and the amplifier body.

The TA-ER1 has a built-in microcomputer for remote control volume operation and input switching using a relay exclusively designed for audio.
To prevent this microcomputer signal from adversely affecting the audio signal, we have adopted a self-off system that stops all microcomputer operations within one second after the operation is completed.

Since the L/Rch ground and the ground of L/Rch is short-circuited, the crosstalk characteristic deteriorates. Therefore, it is advantageous for sound quality if the position of the headphone terminal is close to the ground reference of the amplifier.
Therefore, the headphone port is installed on the rear panel so that you can enjoy headphone listening with higher sound quality.

Specially designed OFC (oxygen-free copper) substrates manufactured by rolling OFC ingots are used for circuit boards, and 6N OFC wires with less than 1 ppm of impurities are used for all signal lines from input to output, power supply, and ground wiring.

Uses a brass machined gold plated pin jack terminal with sufficiently high flange strength.
Gold plating is more than 10 times thicker than that used in ordinary Hi-Fi equipment, ensuring long-term connection stability.

Wireless remote control is included.

Model Rating

Type	Stereo preamplifier
Input Sensitivity / Impedance	Balanced CD/Line : 250mV/4M Ω (2M Ω / 2M Ω, 100k Ω at Rec out on) Phono MM : 4mV/100k Ω · 100 pF Phono MC (3 Ω) : 0.2mV/125 Ω Phono MC (30 Ω) : 0.4mV/500 Ω CD/Tuner/Line1-4 : 250mV/2M Ω (Rec out on : 50k Ω) Tape1, 2 : 250mV/2M Ω (Tape Monitor : 20k Ω)
Output Level / Impedance	Balanced Pre out : 2. V/4 Ω (2 Ω / 2 Ω) Unbalanced Pre out : 1.25V/2 ohm Phones (Front/Rear) : 39mW/2 Ω Rec out : 375mV/1k Ω
Maximum output level	Balanced Pre out:20V Unbalanced Pre out:10V Phones(Front/Rear):1000mW Rec out:10V
Frequency characteristic	MC Transformer : 20 Hz ~ 20 kHz + 0 ~ 1.0 dB Phono equalizer deviation : 20 Hz to 20 kHz ± 1 dB CD → Pre out : 20 Hz ~ 20 kHz + 0 -0.1 dB
Distortion factor (THD + N, ATT-0dB 5 dB output)	Phono MM : not more than 0.003% Phono MC (3 Ω, 30 Ω) : 0.005% or less Line : ≤ 0.003%
Channel separation	110 dB or More (All Inputs)
Pwer	100 VAC, 50Hz/60Hz
Power consumption	45W
External dimensions	Body : Width 470x Height 135x Depth 420 mm Power Supply : W 260x H 135x D 395 mm
Weight	Body : Approx. 19.5 kg Power Supply Part : Approx. 12.5 kg
Included : Wireless Remote Control RM-ER1
Remote control system	Infrared pulse system
Pwer	DC3V, uses 2 AA dry batteries
External dimensions	Width 38x Height 160x Depth 22 mm
Weight	Approximately 220g (including dry batteries)