TAD-M700S Power Amplifier

The TAD-M700S power amplifier is a Reference Series two-channel model designed to serve as the dedicated power stage in a stereo system. It operates with a preamplifier or another variable-level analogue signal source. Its rated output is 350 W per channel at 1 kHz into 4 ohms. With an 8-ohm load at the same frequency, the specified output is 175 W per channel.

Role in Stereo and Home Cinema Systems

This two-channel power amplifier amplifies the signals for the left and right channels. The preamplifier selects the source and controls the listening volume. This arrangement is suitable for systems built with separate control and power-amplification stages.

In a home cinema system, the amplifier can power the front left and right channels. The processor must provide variable-level analogue outputs for this purpose. The home cinema processor then controls the volume, while the TAD-M700S operates as a separate power stage.

Symmetrical BTL Circuit

The amplifier is based on a BTL bridged transformerless configuration. Its circuitry is fully symmetrical from input to output. The same layout principle is applied to the circuit topology and printed circuit boards. It also extends to both transformers and the electrolytic capacitors arranged in parallel.

The internal layout has been designed with temperature changes, magnetic fields and vibration in mind. Both sides of the circuit follow the same arrangement. This is an important construction feature in a two-channel power amplifier, where the corresponding sections are organised according to a consistent design principle.

Power Supply

The power supply uses two power transformers with a combined rated capacity of 2.8 kVA. Their cores are wrapped by hand in insulating sheets without the use of coil bobbins. Four specially manufactured 33,000 µF electrolytic capacitors are installed beside them.

The capacitors are arranged in parallel inside the enclosure and incorporated into the overall symmetrical construction. This substantial power-supply section occupies considerable space. Before purchasing, it is therefore important to consider the amplifier’s depth and weight, as well as the load capacity of the intended equipment rack.

Enclosure and Vibration Management

The monocoque cast-aluminium enclosure has a high internal vibration-damping factor and low electrical impedance. The internal components are positioned to improve their resistance to vibration caused by sound pressure from the loudspeakers.

Each of the four height-adjustable pointed feet touches the supporting surface at a single point. Their wide stance and optimised angle lower the structure’s centre of gravity. Height adjustment allows this heavy amplifier to be levelled precisely on a suitable equipment rack.

The enclosure features curved sides and a redesigned front-panel emblem. Cooling vents are located at the rear of the top panel. These openings must not be covered by a shelf, another component or any other object.

Choosing a Suitable Location

The amplifier measures 516 mm wide, 296 mm high and 622 mm deep. It requires a deep, stable rack capable of supporting its 75.5 kg weight. Check the usable shelf depth before installation rather than relying only on the furniture’s external dimensions.

Leave sufficient space behind the enclosure for connected cables and their required bend radius. Open space must also remain above the rear section of the top panel so that heat can escape. Plan how the unit will be moved into place before connecting the rest of the system.

System Connection and Initial Setup

In the signal chain, the amplifier is connected between the preamplifier and the loudspeakers. Its input sensitivity is 1.5 V, while its input impedance is 100 kilohms. These figures help when assessing the electrical compatibility of a preamplifier and the output level it needs to provide.

The 29.5 dB gain describes the amount of signal amplification applied by the power stage. When switching on the system for the first time, turn down the preamplifier volume. Select the required source before raising the level gradually.

Understanding the Technical Figures

Both output-power ratings were measured at 1 kHz. They should not be interpreted as continuous power measurements covering the full frequency range. When comparing amplifiers, always check the stated load, number of channels and measurement conditions.

The distortion figure of less than 0.005% applies specifically at 1 kHz, 175 W and 4 ohms. The frequency range extends from 1 Hz to 100 kHz within +0/-3 dB limits. This describes the amplifier’s electrical range, not the acoustic response of the connected loudspeakers.

The signal-to-noise ratio of more than 125 dB describes the relationship between the useful signal and the electronic noise. It is meaningful to compare this figure only with values from other amplifiers that have been defined on the same basis.

Technical Specifications

Model	TAD-M700S
Type	Reference Series two-channel power amplifier
Circuit configuration	BTL bridged transformerless configuration
Circuit construction	Fully symmetrical from input to output
Internal layout	Symmetrical arrangement of circuits, printed circuit boards, transformers and capacitors
Rated output power, 4 ohms	350 W per channel at 1 kHz
Rated output power, 8 ohms	175 W per channel at 1 kHz
Distortion	Less than 0.005% at 1 kHz, 175 W and 4 ohms
Signal-to-noise ratio	More than 125 dB
Frequency range	1 Hz-100 kHz, +0/-3 dB
Gain	29.5 dB
Input sensitivity	1.5 V
Input impedance	100 kilohms
Power transformers	Two power transformers
Combined rated transformer capacity	2.8 kVA
Transformer cores	Hand-wrapped in insulating sheets without coil bobbins
Capacitors	Four specially manufactured 33,000 µF electrolytic capacitors
Environmental-effect management	Layout designed with temperature changes, magnetic fields and internal vibration in mind
Enclosure	Monocoque cast-aluminium enclosure
Enclosure properties	High internal vibration-damping factor and low electrical impedance
Internal component mounting	Arranged for resistance to vibration caused by loudspeaker sound pressure
Supports	Four height-adjustable pointed feet, each contacting the surface at a single point
Structural geometry	Wide foot placement, low centre of gravity and optimised foot angle
Exterior construction details	Curved sides, redesigned front emblem and cooling vents at the rear of the top panel
Dimensions	516 × 296 × 622 mm
Weight	75.5 kg

FAQ

What components are required for a stereo system?

You need a preamplifier or another variable-level analogue signal source. The power amplifier then drives the left and right loudspeakers. Source selection and volume control are handled by the preceding stage in the system.

Can this amplifier be used in a home cinema system?

Yes. It can serve as the power stage for the front left and right channels. The home cinema processor must provide variable-level analogue signals for those channels.

How should I prepare a location for the amplifier?

Choose a rack capable of supporting at least 75.5 kg and accommodating a depth of 622 mm. Allow additional room for the cables, and do not obstruct the cooling vents at the rear of the top panel.

How should I set the volume level for the first time?

Begin with the preamplifier volume turned down. Switch on the selected source and raise the level gradually. This lets you assess the system’s overall gain before choosing a normal listening volume.

Does the 350 W figure describe output across the full frequency range?

No. This rating applies per channel into a 4-ohm load at 1 kHz. Compare it only with figures measured under the same conditions.

What does the 1.5 V input sensitivity mean in practice?

This value helps you select a preamplifier capable of supplying the required variable-level signal. System volume must still be controlled through the preamplifier.