VTL IT-85 Integrated Valve Amplifier

The VTL IT-85 Integrated Amplifier is designed for those who seek the simplicity of a single chassis system, but with the performance of separates. Designed with a fully active preamplifier stage, the IT-85 delivers a hearty 80 watts per channel with the sonic characteristic that is similar to their well regarded ST-85 Stereo amplifier and the TL2.5 preamplifier combination but at ¾ of the cost- fast, musical 3-D sound, and solid bass support that VTL is known for. The VTL IT-85 is designed to accommodate future upgrades -- when you are ready to add a subwoofer, separate pre- or power amplifier, surround processor or headphones to your system, the IT-85's many different output stage configurations can be easily and painlessly re-configured, often with just the flip of a switch.

Hand built in their factory in California with the proven VTL quality, the IT-85 will give you lasting value and listening pleasure for years to come.

Multi-function integrated amplifiers are similar to stereo receivers, in that they are usually specified in systems that have a prerequisite for simplicity and limited space availability. Integrated amplifiers offer the shortest link between music source and output device, with a minimum of interconnect cables and rack space required, and usually offering a headphone output for personal use in smaller living spaces.

The signal path is simple and direct, with a minimum number of gain stages. The signal path is usually source component to power amplifier (which has the volume control), and power amplifier to loudspeakers. This simplicity means not having to be concerned with impedance matching between components, and the sound is therefore purer with less inter-stage buffering involved.

With this minimalist approach the integrated amplifier acts as the primary electrical conduit between your music source, (e.g. CD, tuner, tape, etc.) and your loudspeakers. In such a system just one power switch activates the whole system, with minimal setup requirements.

The VTL IT-85 integrated amplifier has both a fully active high end preamplifier and power amplifier on one compact chassis. It offers the performance and features of high end separate components, with the space-saving approach of a receiver.

If simplicity of operation with high performance sound is key in your system selection criteria, then the VTL IT-85 Integrated Amplifier is the ideal product for you.

WHY TUBES?

VTL feels tubes are the best technology for audio, for the following primary reasons:

1. Tubes use simple circuits
2. Tubes overload gracefully
3. Tubes are more linear
4. Tubes require less overall negative feedback
5. Tubes are a more viable technology now than in yesteryear, as better components are now available for modern tube amplifiers

Simple Circuitry

In general, passing the signal through a lesser number of components yields a purer, more immediate sound. This is because there are fewer components to change, or distort the sound. Simple circuits also have inherently higher reliability, since there are less of the parts to fail. Tubes are more tolerant of circuit drift and parts deviations, and thus can be used in the simplest circuits.

Dynamic Handling Capability

Music has great dynamic swings, and in tube amplifiers the onset of clip/overload as maximum power is reached is gradual, with a low even-order harmonic.

Even-order harmonic distortion is somewhat benign, and less offensive to the ear than the harsh, odd-order harmonic distortion characteristic displayed by solid-state circuits, even though the distortion figures for tubes are somewhat higher.

Transistor amplifiers generally reach their power limit and clip in a mostly odd-order harmonic, which is more fatiguing to listen to. In such a transistor amplifier the distortion raises very quickly as the maximum power level is reached, with an almost square wave characteristic, and a high DC component, (which can destroy loudspeaker drivers).

As an example of the difference in the distortion characteristics between the two technologies, tube guitar amplifier manufacturers have traditionally designed their equipment to drive the output stages into overload distortion, using the resultant distortion to get the sound they like, also known as "tone". In a tube amplifier this tone contributes to the amplifier's sound, but in a solid-state amplifier this distortion would be intolerable and would destroy speakers.

Linearity and Feedback

Tubes are voltage amplifiers (as opposed to solid-state current amplifiers), with the result that tubes are a more linear amplification technology, requiring less overall negative feedback to make the circuit linear. (Overall negative feedback is a sample of the output of the amplifier re-injected into the input 180 degrees out of phase, and is used to correct non-linearity and distortions.)

Too much negative feedback in general tends to slow the amplifier down and suck the emotion and life out of the music. High feedback designs usually give a sterile and boring, lifeless sound, while low feedback designs give a more immediate sound to the music.

Zero to 20dB of negative feedback is generally considered acceptable, and is usually the maximum amount of feedback needed to make a tube amplifier circuit linear and to keep the output impedance down to an acceptable level. Transistors generally need over 50dB of negative feedback overall.

Power Supply

The higher working voltages present in tube amplifiers generally allows better voltage swing capability and better headroom. This higher working voltage yields higher audible energy storage with a lower value capacitor (audible energy storage is voltage squared divided by 2 multiplied by capacitance) Typically 600 working volts of tube amplifiers vs. 80 working volts of transistor amplifiers. This is most likely why many listeners feel that tubes sound more powerful.

Specifications
Vacuum Tube Complement: 4 x EL34, 2 x 12AT7, 2 x 12AU7
Output Power: 20 Hz – 25 kHz ± 0.1dB < 3% THD (Stable to 2W) 60w, 80 w into 8Ohms, 4Ohms
Small signal frequency response: (< 0.2% THD @ 1W) 1 - 75 kHz -3dB
Class of output operation: AB1
Input Sensitivity / Impedance Line in: 180 mV, Amp in 575 mV / Line in 20KW, Amp in 135KW
Output Impedance Amp Out: 1.55W, Headphone out: 16W, Preamp out: 400W
Power Consumption: Idle = 200W Full Power = 600W