VTL MB-450 Signature Series II

NOT FOR SALE

Beautiful designed and outstanding performance - VTL MB-450 Signature Series II Monoblocks!

As of Dec 2009, these are my new Reference amplifiers . Why? For a number of reasons that I will explain. For an introduction I will let VTL explain in their own words the design philosophy behind their latest MB-450 design. No point doing the same work twice, then I will give you my thoughts in more detail.

How Much Power Do I Need?

"The Series II now incorporates VTL's advanced Auto Bias and Fault Sensing technology-features formerly available only with our flagship Reference products. A revised power supply and improved electronics give the MB-450's an ultra-fast transient response and a dynamic range.

The MB-450 Signature Monoblock Amplifier (including its predecessors) has been a core model in the VTL line for almost 20 years. With the release of the Deluxe 300 monoblocks in the late 80's, VTL successfully introduced a high power amplifier that could drive a wide range of speakers and yield outstanding performance for a reasonable price. The model evolved incrementally over the years, including a name change to the MB-450 Signature Monoblocks in 1996.

The MB-450 Series II Signature Monoblocks debuted in 2007 and incorporate many of the recent technological advances first introduced in the flagship 800W Siegfried Reference monoblocks in 2004. The essential elements of Siegfried's "smart-tube" technology are now standard with the MB-450 Series II. This system encompasses logic-controlled automatic biasing--which continually checks each tube for optimal performance--and an array of fault-sensing diagnostics that alert users to the operating status of each tube.

The "smart tube" technology puts an end to the guesswork formerly inherent in large tube amplifiers, making the new MB-450s easier to use and maintain. Other technology that has trickled down from the Siegfried amplifier includes a precision-regulated power supply and upgraded circuitry components. As a result, the MB-450 has attained new thresholds of sonic performance, with greatly improved bass tightness and dynamics. Compared to former versions of the MB-450, the Series II offers an unrestrained sense of openness, tighter and more controlled bass, and an ease and musical neutrality that give you the most satisfying listening experience.

An all-tube amplifier, the MB-450 Series II is the culmination of VTL's most advanced thinking in performance engineering. A proprietary regulated power supply, high-grade parts, and an automatic tube bias system ensure ultra high fidelity audio reproduction, while tube fault diagnostics and user feedback offer the ultimate in usability and convenience.

The audio amplifier is comprised of a fully balanced input stage and a long-tailed differential phase splitter, coupled with a push-pull output stage. Within the latter section is a logic-controlled auto-bias system that continually checks and adjusts the output tubes to ensure they are operating at optimal condition for proper balance across the output transformer.

The power supply section is similarly advanced: All critical voltages are precision regulated for consistent and predictable performance under a wide variety of conditions. Large energy storage reservoirs mean that the amplifier is capable of delivering huge peak current swings into demanding loads for powerful musical performance.

Optimized operating voltages and timed current inrush limiting dramatically extend tube life, with low idle current draw on all stages. An ever-warm position further lowers idle current while keeping all voltages present so the circuit remains warm when not in use.

The amplifier can run in one of two operating modes: Tetrode or Triode. The user can change mode either in standby or in power-on mode. Users often prefer one mode to another, depending on the type of music. For example, Tetrode may offer a wider sound stage and greater dynamics for complex and demanding symphonic music, while triode may work better for small ensembles or solo instruments."

'Protection' - The reason whey these sell as fast as VTL can make them.

I had to wait 6 weeks for mine to be made.

You will fall in love with these masterpieces and what makes them unique.

Auto Bias / Fault Protection on all Output Tubes via easy to see LED Indicators.

"Comprehensive fault sensing monitors the status of the output tubes, and alerts the user to any adverse conditions. In the case of a problem in any of the output tubes, the amplifier will immediately shut down. The tube fault is indicated on the front panel, as well as by a blinking LED on the top deck next to the tube that caused the fault shutdown, making diagnosis and tube replacement easy.

The logic-controlled automatic bias system is designed to keep the tubes at peak performance and operates completely outside of the signal path. The tube biasing circuit checks and adjusts the tube bias values automatically during the power-on sequence, as well as when the amplifier is at idle (i.e. when no music signal is being amplified.), and drops out of the circuit path when music signal is detected."

New innovative removable side panels for easy vacuum tube access rather than having to remove the entire top cover of the amplifier. Nice touch, thanks Luke.

20 Amp Power Inlet Socket

Full Fuse Protection On All Circuits

Fuses for Main, Logic, Input, Plate & Screen Circuits

VTL's Super Balanced & Single Ended Inputs

12V Trigger for Mute, Mode and Power Functions

Suer Heavy Speaker Binding Posts

Massive Power Supply Capacitors and VTL's Signature Transformers.

MODE - Tetrode / Triode Switching

POWER - On / Off

MUTE - Mute / Idle Mode

"When the amplifier is in Mute Mode, the output tubes are drawn down to a very low trickle current with noticeably lower heat output to conserve tube life."

Feature List:

VTL proprietary Signature output transformer

Software microprocessor controlled

Tetrode/Triode Switchable

Auto Bias, Fault Sensing

Current in-rush limiting

Standby Mute function

450 watts per channel in tetrode;
200 watts per channel in triode

8 x 6550C or KT-88 tubes per monoblock

Regulated screen supply and separate fusing

Discrete regulated input and driver supply

Redesigned fully balanced input and driver stages

High quality audiophile grade coupling caps

12V Trigger and mute input

Extruded aluminum front panel with luxurious,
modern look – black and silver options available

Front panel window of thick smoked glass reveals
the glow of multiple output tubes

Rack mountable

Rigid construction and improved heat ventilation

MB-450 Series II Signature Monoblock Data Specification

Vacuum Tube Complement 8 x 6550C, 1 x 12AT7, 1x 12BH7

Output Power
20 Hz – 20 kHz into 5 ohm load Tetrode = 425W
Triode = 225W

THD 20Hz - 20kHz @ 450W Tetrode
THD 20Hz - 20kHz @ 200W Triode <2.5%

Input Sensitivity @ 450W Tetrode 2.0V

Input Impedance 42K Ohms

Optimum Load Range 4 - 8 Ohms

S/N Ratio @ 450W Tetrode
S/N Ratio @ 200W Triode -110dB, 120Hz

Power Consumption Idle = 300W
Full Power =1000W

Primary Main Fuse Rating 110/120V = 15A Ceramic Slo Blo
220/240V = 8A Ceramic Slo Blo

Input Fuse 110/120V = 1A Ceramic Slo Blo
220/240V = 1A Ceramic Slo Blo

Logic Fuse 110/120V = 1A Ceramic Slo Blo
220/240V = 1A Ceramic Slo Blo

B+ Fuse Rating Plate Fuse - 2.5A Fast Acting 600V
Screen Fuse - 0.75A Fast Acting 600V

Dimensions W = 18.5 Inches (47 cm)
H = 9 Inches (23 cm)
D = 18 Inches (46 cm)

Weight 93 lbs (42 Kg) unpacked
110 lbs (50 Kg) packed