Siegfried Series II Reference

Since its debut in 2003, VTL’s Siegfried Reference monoblock amplifier has been recognized as a standout in the realm of high-power, high-performance amplification, celebrated for its ease of use and musicality. As the first tube amplifier to feature true automatic bias and fault-sensing capabilities alongside precision-regulated power supplies, Siegfried has earned the admiration of discerning music enthusiasts worldwide.
The acclaimed Siegfried platform has now been fully reimagined in the new Series II version, featuring a completely redesigned signal path. Upgrades include a fully balanced differential input stage driving a differential phase splitter, a lower-impedance push-pull output stage, and a significantly improved, fully balanced, enhanced interleaved-coupled output transformer. VTL’s masterful engineering has elevated the renowned sound quality of the innovative Siegfried Reference platform to even greater heights.

All-new Siegfried Reference mono amplifier employs a shorter, faster, and fully balanced negative feedback loop to achieve zero global negative feedback, thereby further enhancing sound quality. This feedback loop completely eliminates ringing, preserving critical phase integrity and information content without the need for capacitive compensation. Consequently, the amplifier remains stable even under the most demanding load

Adjustable, precision-regulated plate and bias power supplies maintain constant operating points for the output tubes—even amidst AC line and mains fluctuations—and stabilize critical power rails, thereby ensuring tonal stability and sonic integrity under complex, dynamic signal conditions.

Another new feature is user-adjustable damping factor feedback control, which allows the user to regulate the amplifier’s output impedance by varying the amount of negative feedback. Impedance can now be precisely set to suit listener preferences and provide better control over the speaker load, thereby achieving optimal performance.

The four possible settings are:

Low – Lowest damping factor; offers excellent speaker control and the most natural sound.
Mid – Good speaker control, though there is some impact on sound quality.
Hi – Optimal speaker control; while the impact on sound quality is slightly greater, the sonic improvement is clearly evident for speakers that require tight control.
Max – Maximum damping factor, though noise interference becomes noticeable.
Finally, the amplifier has undergone extensive retuning and incorporates high-quality Mundorf silver-in-oil capacitors, resulting in sweeter, more extended high and mid-range tones; the sound is more relaxed, natural, fluid, and cohesive. The input stage capacitors have also been bypassed.

Even a brief listen to the new Siegfried Series II monoblock amplifiers reveals the successful implementation of new technologies. The mid-bass is more powerful and tightly controlled, while the crucial midrange displays an unprecedented sense of ease, faithfully reproducing the timbre and tonal colors of instruments. This superior command over the mid-bass and midrange allows the high frequencies to sound completely natural, fluid, and unconstrained.

Renowned for its immense power-handling capabilities, the Siegfried has always been celebrated for its effortless speed, dynamic agility, and precise low-frequency control, delivering a remarkably natural bass texture. This latest version allows you to fully appreciate musical nuances and micro-dynamics, even at low listening volumes. The Siegfried II handles everything from intimate performances to grand orchestral ensembles with ease, striking a perfect balance between authoritative, powerful bass and delicate, refined tonality.
Fully balanced differential circuit—generating a balanced signal from a single-ended input.
The redesigned fully balanced differential input and driver stages enhance signal swing, bandwidth, and stability.
Zero Global Negative Feedback
A shorter, faster feedback loop enables superior tonal control without phase shift.
Improved speaker load handling and enhanced signal stability.
This amplifier is absolutely stable and requires no capacitive compensation.
A novel current source that reduces the impact of noise in single-ended mode.
An output stage with lower impedance, improving speaker control.
VTL’s proprietary balanced reference output transformers significantly enhance interleaving and coupling, thereby achieving wider bandwidth and zero ringing.
User-adjustable DF feedback control allows for adjustments to output impedance and damping factor to achieve optimal matching with speaker load.
Software microprocessor control
Switchable tetrode/triode mode
Automatic offset, fault detection
Inrush current limiting
Standby mute function; reduces tube current to extend tube life
Full bidirectional RS-232 control
650 watts per channel in tetrode mode; 330 watts per channel in triode mode
Each monoblock module utilizes twelve 6550 or KT-88 vacuum tubes.
Adjustable, precision-regulated anode and screen grid power supplies ensure stable operating points; independent regulated power supplies for the input and driver stages deliver superior signal resolution and tonal quality.
This adjustable, precision-regulated bias power supply enhances signal resolution and noise rejection while improving isolation from mains voltage fluctuations; the output operating point remains stable regardless of AC power variations.
An improved automatic bias and fault detection system operates in fully balanced differential mode; the amplifier features comprehensive protection against output tube failure, and precise matching of output tubes is not required.
All capacitors in the signal path are premium Mundorf silver-in-oil types.
Film bypass capacitors are used across the power supply capacitors to achieve superior high-frequency resolution.
Featuring an extruded aluminum alloy front panel, it boasts a luxurious and modern look—available in black and silver.
Precisely regulated B+ and screen supplies
Sturdy structure, improved ventilation, and lower operating temperatures.
Upgradable from Series I factory units.
Vacuum Tube Complement 12 x 6550 or KT-88, 1 x 12AT7, 2 x 12BH7
Output power
20Hz – 20kHz <2.5% THD
Tetrode: 650W, Triode: 330W
Into 5Ω
Input sensitivity Variable between 1-2V, depending upon DF setting
Input impedance 45kΩ
Load setting 5Ω
Optimum load range 4Ω – 8Ω
S/N Ratio -110dB, 120 Hz
Power consumption Idle = 600W, Full power = 1500W
Primary mains fuse ratings 100/120V = 20A Ceramic Slo Blo, 220/240V = 10A Ceramic Slo Blo
Logic fuse 100/120V = 1A Ceramic Slo Blo, 220/240V = 1A Ceramic Slo Blo
Input fuse 100/120V = 2A Ceramic Slo Blo, 220/240V = 1A Ceramic Slo Blo
Filament fuse 100/120V = 2A Ceramic Slo Blo, 220/240V = 1A Ceramic Slo Blo
Secondary fuse rating Plate Fuse = 5A fast acting 600V, Screen Fuse = 0.75A fast acting 600V
Dimensions W x D x H 11.5 x 24 x 24 inches (29.2 x 61 x 61 cm)
Weight 200lbs (90Kg) per monoblock unpacked, 325lbs (147Kg) packed