More than eight years after introducing the TL-7.5 Reference preamplifier to universal acclaim, VTL presents the latest version, the TL7.5 Series III. The new model incorporates numerous technological advances while retaining the best elements of the TL-7.5 platform. The proven strengths of the original system architecture include: a fully balanced differential design; a hybrid circuit that combines tubes in the gain stage for voltage linearity (less than 2dB NFB) with a MOSFET buffer for greater current capacity; a high resolution volume control; and a clean box/dirty box architecture with multiple precision-regulated power supplies. The highly-regarded user interface of the TL7.5 platform sets the standard for intuitiveness, and ease of use.
The Series III builds on improvements made to the Series II for an even higher level of performance. The new design features an extensively revised power supply based on current-sourced shunt regulator technology that minimizes impact on the audio signal by eliminating high voltage gain. Far more precise power regulation yields dramatically improved rejection of noise and AC fluctuation.
The completely redesigned high current gain stage utilizes newly available FET technology developed for green technologies such as solar panels and electric cars that require a normally-on state. Unlike MOSFETs that need to be biased on, normally-on devices operate more like vacuum tubes in the audio output stage, with simpler circuits that continuously conduct current, resulting in a more tube-like sound. The high-current gain stage has been further optimized for linearity with zero global negative feedback in the circuit.
Also included in the upgrade are new specially selected audiophile grade capacitors and a fully bi-directional RS-232 control interface for increased compatibility with modern home theater systems.
Enhancements to the Series III result in an even higher level of coherence, integration and transparency of sound, with dramatically improved mid-bass and midrange, and a more tube-like sonic character.
Product features
Isolated Control Unit chassis with 12 separate fully regulated power supplies
Separate Audio Unit chassis with zero internal digital activity and isolated from AC and power supply noise
Audio unit features
Fully balanced differential circuit with balanced in and out, and mirror-image layout
Simple 2-stage circuit topology with differential gain stage and output buffers for musical purity and integrity
Ultra low impedance output stage to drive any length of cable and any power amplifier/paralleled amplifier/subwoofer load
30 microfarad output capacitors for vastly improved bass control
Tube complement: 2 – 12AU7 tubes
Gain switching between normal gain and low gain with 6dB gain reduction
Single fully balanced differential 95-step 70dB discrete resistor relay attenuator for all attenuation functions, using low signal instrumentation ruthenium relays for greatest resolution
Microphonically damped tube gain stage for greater vibration noise elimination
Control power supply unit features
Ramped B+ filament soft-start power up for extended tube life
Huge energy storage power supply for elimination of AC fluctuation and noise rejection
Low noise processor control design for all functions
User interface features
Processor loop – any of 8 inputs can be assigned as fixed unity gain pass through
Tape monitor function for both tape loops
4 separately programmable trigger outputs
Bi-directional RS-232 interface
Programmable input offsets
Selectable padded inputs
Rigid Combination steel and non-magnetic chassis and machined aluminum remote wand
Factory upgradeable from Series I and Series II
Audio unit features
New FET device output stage for more tube-like sound and simpler circuit
New device in the gain stage current source for improved musicality and better single-ended operation
Zero Global NFB for vastly improved faster dynamic and tonal resolution, and unconditionally stable circuit, without any phase shift.
All audiophile grade Mundorf capacitors in signal path with bypass system for improved HF resolution
Control power supply unit features
Vastly improved lower impact and greater precision-regulated current-sourced shunt power supply
Teflon power supply bypass caps for improved top end