SILK Invincible Preamplifier has been carefully combined the greatest quality of yesterday technology of vacuum tube with the best available technology of today industrial standard while having almost unlimited upgrade possibility for the future to come. The backbone of SILK Invincible Preamplifier consists of the highest performance professional broadcasting quality of Burr-Brown digitally controlled Analog Volume Control working together with special arrangement Vacuum Tube Buffer stage. Unlike any other digital volume control format, Invincible Preamplifier is taking full advantage of superior analog characteristics of passive (analog) volume element that is fabricated in a mixed-signal BiCMOS process into an Integrated Circuit (IC). This translates into an array of precision matched resistive network to form an attenuator (volume control). The mean of selecting the volume level is performed by digitally controlled switches via 16 bit serial interface resulting in one of the most shortest signal path of any passive volume control. This yields exceptional signal integrity (THD of less than 0.0002%), low crosstalk between channel (-130dBFS), and excellent dynamic range (120dB). The best part is that all these great performance are attained at all volume level. (other passive volume control's performance vary considerably with changes in volume control).

While the excellent quality of the volume control may make up a complete preamplifier by itself, SILK Invincible Preamplifier is taking new approach to integrate Pure Class-A Vacuum Tube Buffer Stage with premium grade NOS Russian 6N1P vacuum tube into its signal path to provide better impedance transition, filter out all nasty high harmonic distortion and improve dynamic headroom. Unlike most vacuum tube preamplifier, Invincible's special Vacuum Tube circuit employs ZERO global negative feedback topology yet keeping the total harmonic distortion to within 0.01% at maximum output level from 20Hz to 20,000Hz to produce very truthful music reproduction with lowest coloration from all sources. Extraordinary frequency bandwidth is one of the greatest property of SILK Invincible Preamplifier. Its frequency response is extremely linear at all volume level with deviation of less than 0.05dB from 20Hz to 20,000Hz, while maximum frequency bandwidth is extend beyond 1MHz (1,000,000Hz at -3.0dB)

SILK Invincible Preamplifier utilizes Burr-Brown digitally-controlled Analog Volume Control (PGA2311PA). For Premium Balanced version SILK Invincible Preamplifier also utilizes Burr-Brown Balanced convertor to convert all RCA inputs into true balanced signal.

There are 2 version of SILK Invincible Preamplifier available.
1) Basic Unbalance circuit with 4 RCA input and 1 RCA output connector.
2) Premium Balanced circuit with 1 XLR input 3 RCA input, 1 XLR output and 1 RCA output.

Premium version offers true versatility in today and tomorrow requirement as more and more high quality source and power amplifier are equipped with XLR connector. Professional audio has XLR as standard for signal transmission since it offers better protection for noise and interference. This version has unique feature that it converts all unbalance signal from all RCA input into true balanced signal (XLR) before entering the main preamplifier circuit thus making this Invincible Preamplifier the true balance in all input. Conversion from RCA to XLR is done via highest quality Burr Brown device usually found only in highest professional audio equipment. Since the conversion circuit processes very low distortion (THD of 0.0005%) and high slew rate (+15V/uS), your regular sources with RCA output are transferred into high performance true balanced signal within SILK Invincible Preamplifier.

SILK Invincible layouts in modular section design which enable easy upgradable paths for future options. Each separate section has been heavily shielded from each other to minimize digital/analog mixed up. The power supply section is carefully design and implement to the perfection. There are up to 3 separated power transformers (1 for digital circuit, 1 for vacuum tube buffer stage, and 1 for optional transformer or DC choke for future upgrade) that give absolute intermodulation free between digital and analog domain. This transformer separation alone brings up the quality of the Invincible Preamplifier to the unparalleled performance. All transformers are carefully handwound, shielded and potted in additional shield casing to prevent any stray magnetic leakage into any part of the circuit. Only highest quality power supply parts are used throughout the circuit to increase reliability and sonic performance.

The brain of the SILK Invincible Preamplifier is Digital & Logic control and LCD display board which located in front section of the chassis, shielded away from the rest of the circuit. Volume and selector change are done through high quality rotary encoders which offer smooth feeling and no machanical ware like other conventional selector or volume control, hence there is no sonic degradation for extended period of operation. Upon power up of the system, the volume control knob also serves as special hour meter function to let the user know the actual operating time of the system including the number of on/off sequence. Whenever the balance level control between channel is needed, the volume control knob also serves to this special function when the preamplifier is in operation mode. L/R Balance control function is capable of -0.5dB per step up to -8.0dB at each channel.

To make the shortest signal path, SILK Invincivle Preamplifier utilizes highest quality silver contact logic relay located closely with special nickel plating RCA connector. We select Nikel plating RCA since it offers numerous advantage over gold plating (especially gold plating connector of today's poor standard) since nickel has high surface durability and resistant to oxidization in long term, thus maximize signal connectivity and minimize signal impurity. These form an input board as depiced above and this board is located right at the rear of the chassis, making the shortest signal path goal become reality. Moreover the input board is also shielded away from the rest of the circuit to prevent any interference.

Frequency Response

20Hz – 20,000Hz  +0dB,- 0.05dB
20Hz – 100,000Hz +0dB, -0.5dB
1Hz – 1,000,000Hz +0dB, -3.0dB*

Total Harmonic Distortion + Noise (THD+N) at Maximum Output Voltage

0.01% from 20Hz – 20,000Hz
0.08% from 20Hz – 100,000Hz

Input Impedance

100K Unbalanced, 200K Balanced

Output Impedance

Less than 1 ohm for Balanced and Unbalanced

Input Sensitivity for Maximum Output voltage

0.073Vrms Unbalanced, 0.147Vrms Balanced

Maximum Output Voltage

2.8Vrms Unbalanced, 5.6Vrms Balanced

Maximum Gain

+31.5dB Balanced and Unbalanced

Gain Setting Level

Mute at -95.5dB with total 43 steps from -60dB to +31.5dB

Maximum Gain Error Between Channels

Less than 0.05dB

Signal to Noise + Distortion Ratio (SINAD)

90dB**

Input Channel

Basic Version with 4 Unbalanced Inputs, 1 Unbalanced Output
Premium Version with 1 Balanced Input + 3 Unbalanced Inputs, 1 Balanced Output, 1 Unbalanced Output

Dimensions

44cm x 40cm x 16cm (W x D x H) weight 13kg

All tests are performed with Hewlett Packard HP8903A without Filter on
* Test with Oscilloscope and Function Generator
** Test with Hewlett Packard HP8903A with 400Hz and 30KHz Filter on