Description
TAD’s goal is to design a world-class preamplifier capable of remarkably accurate signal transfer from input to output. To this end, we have taken extra steps to achieve ultimate uniformity in circuit topology and right and left channel layout. Firstly, the C700’s fully balanced circuitry amplifies the positive and negative signal waveforms individually to ensure identical dynamic circuit characteristics for both signals. Second, the wire length and dressing are identical between the positive and negative signal paths and between the two channels, providing an ideal signal path from input to output. Thirdly, the dual-mono circuit design achieves maximum symmetry to provide identical amplification, both electrically and mechanically, to the positive and negative signals and to both channels, resulting in near-perfect stereophonic sound reproduction.
Highly simplified circuit topology eliminates any possibility of signal degradation from input to output
True to TAD’s fervent belief that “a signal path with minimal functionality is the surest way to achieve the highest level of accuracy and sound quality”, the C700’s input signals are amplified by a single stage voltage amplifier before output, after being levelled by the electronic volume control. In addition, a dedicated output amplifier circuit for each of the two line outputs prevents signal splitting and interference from connected equipment from degrading the sound quality. In order to transmit music signals in a straightforward and accurate manner, the C700 does not have a monitor switch for the recording output, as this could have a detrimental effect on sound quality. In addition, the audio pass-through mode outputs input signals from a pre-out jack without changing the signal level, eliminating the need for a switching circuit.
The dual enclosure design, which separates the power supply from the amplifier unit, is just one of many techniques used to minimise noise for ultimate signal clarity.
The C700’s power supply is physically separated from the main amplifier unit. This ingenious design prevents vibration and magnetic flux leakage from the transformer from adversely affecting the audio circuits inside the main unit. The outboard power supply unit houses a large, powerful 400 VA toroidal transformer – not uncommon in power amplifiers, but unheard of in preamplifiers. To increase the purity of the power supply, the transformer’s internal coil is connected directly to the power supply circuit, minimising contact with lead wires. In addition, the lead terminals, motherboard mounting terminals and clamping screws are all made from oxygen-free copper, coated with non-magnetic materials to eliminate even the slightest magnetic distortion. All these refinements incorporated into the power supply design enable faithful and accurate transmission of signals, regardless of sudden changes in their level. The combination of the ingenious power supply and the fully balanced circuit design, which eliminates unwanted noise currents, results in noise-free performance.
