SACThailand Presents
K&S Audio Design
Single-Ended Stereo Vacuum Tube Power Amplifier 300B
Code Name: BlackAmp II


All of the best techniques most DIY guru and audiophiles praise can be found in this 300B amplifier. It features:
" point-to-point wiring with high quality hook-up wire/ silver solder
" non magnetic chassis (cast aluminum with up to 10mm. thickness for stability and absolute beauty)
" Precision air-gapped perfect hand layered wound output and power transformer (SILK Transformer)
" Zero Feedback design
" Directly heated Triode output tube (300B) running in pure class-A1
" Soft start vacuum tube rectifier
" Choke filter for ultra smooth DC Supply
" Pure class A driving circuit
" High quality carbon film resistors throughout the circuit (Kiwame)
" High quality film and foil coupling capacitor (Hovland Musicap)
" AC Filament with very low hum level (below 5.0mV)
" Semi-conductor less design
" Matched section of driving tubes

Besides the use of good quality parts and special techniques, we take another step to ensure best sounding result and maximize the sonic integrity of this power amplifier by fine tuning the circuit via parts selection and value. This requires extensive time consuming process to adjust each tube parameter to work together at the right condition.

The final result could be viewed and confirmed via FFT Spectrum Analyzer.

  At 4.97% Total Harmonic Distortion (THD) this 300B amplifier produces very uniform overtone. Fig.1 shows 1KHz fundamental frequency with predominant 2nd harmonic which scientifically proved to be preferred by human ear than higher order harmonic.  
  When we zoom in and use Log Scale (Fig. 2) to put fundamental frequency and all harmonic spectrums visible in one window at 5.0KHz bandwidth (since actual harmonic spectrums are much smaller than the fundamental and may be invisible) we observe the linear roll off which indicates that our amplifier produce most of 2nd harmonic and small amount of 3rd harmonic overtone.

This measurement clearly indicates the excellent sounding characteristic of our 300B amplifier. When critically listening to this amplifier, we ourselves are amazed by the power of knowledge that could help us improve all aspects of this amplifier from scratch design to final configuration.

Product Type:
Stereo Vacuum Tube 300B Power Amplifier
Pre-Amp/Input Tubes:
6072 x 2
Driver Tubes:
5687 x 2
Output Tubes:
TJ Full Music 300B x 2
Rectifying Tubes:
5U4G x 1
Coupling Capacitors:
Hovland MusicCap
Output Transformer:
3K EI core 30 watts power handling
Output Power:
8 watts/CH pure class A1 design, 12 watts peak power
Frequency Response:
15-40,000Hz (-3dB)
5% at rated power
S/N ratio:
below 80dB
(W) 48 x (D) 33 x (H) 20 cm.
Approx 25 kg.
Direct From Factory Price :
Please Contact.