Audio Note Kit1 2014 Edition

8W Class A single-ended 300B valve integrated amplifier. More details on ANK Audio Kits website.

Audio Note Kit1 2014 Edition
Audio Note Kit1 2014 Edition
Audio Note Kit1 2014 Edition
Audio Note Kit1 2014 Edition
Audio Note Kit1 2014 Edition
Chassis
Chassis
Chassis
300B section wiring
300B Filament PCB
Power Supply PCB
Power Supply PCB
Driver PCB
Driver PCB
Chassis
Chassis
Chassis
Chassis
Chassis
300B section wiring updated
Power Supply board

INITIAL TUBES

  • Electro-Harmonix 5U4GB

  • Sovtek 6SN7GT

  • 2 x General Electric JAN 5687 WB

  • 2 x Shuguang 300B-98

LAYOUT

MEASURES

  • Idle current (measured at pin 8 of 5U4GB): 200mA

  • Gain (at 1 kHz): 37.2dB (left), 36.7dB (right)

  • THD+N (at 1 Watt into 8 Ohms at 1 kHz, source impedance 600 Ohm): 0.55% (left), 0.51% (right)

  • THD (at 1 Watt into 8 Ohms at 1 kHz, source impedance 600 Ohm): 0.54% (left), 0.50% (right)

TUBE ROLLING 1 - Sovtek 6SN7GT replaced by RCA JAN V-231 "Grey Glass" NOS:

  • Slightly lower gain (at 1 kHz): 36.6dB (left), 36.1dB (right)

  • THD+N (at 1 Watt into 8 Ohms at 1 kHz, source impedance 600 Ohm): 0.55% (left), 0.52% (right)

  • THD (at 1 Watt into 8 Ohms at 1 kHz, source impedance 600 Ohm): 0.52% (left), 0.51% (right)

  • Significant improvement comparing to Sovtek tubes - deeper, more 3 dimensional sound stage, a bit more delicate high frequencies, overall sounds lighter, but also much more realistic, musical.

TUBE ROLLING 2 - Electro-Harmonix 5U4GB replaced by Sylvania 5U4GB/5931 NOS:

  • Slightly stronger, better defined bass comparing to EH tube.

TUBE ROLLING 3 - General Electric JAN 5687 WB replaced by Tung-Sol JTL-5687 early 1950s matched pair:

  • Left tube: 9.8mA/4800, 10.2mA/4800

  • Right tube: 10.8mA/4800, 10.8mA/5000

  • Gain (at 1 kHz): 36.1dB (left), 36.2dB (right)

  • THD+N (at 1 Watt into 8 Ohms at 1 kHz, source impedance 600 Ohm): 0.56% (left), 0.77% (right)

  • Excellent sounding tubes, huge improvement comparing to the stock GE tubes.

TUBE ROLLING 4 - Shuguang 300B-98 replaced by Genalex Gold Lion PX300B matched pair:

  • Both tubes: 64mA / 5.8mA/V

  • Gain (at 1 kHz): 35.9dB (left), 36.1dB (right)

  • THD+N (at 1 Watt into 8 Ohms at 1 kHz, source impedance 600 Ohm): 0.39% (left), 0.49% (right)

TUBE ROLLING 5 - RCA JAN V-231 "Grey Glass" NOS replaced by Sylvania 6SN7GTA "chrome dome" (made in USA, 1953):

  • Unfortunately RCA tube started buzzing after about 8 months of use and I decided to try Sylvania.

  • iP / Gm: 8.9mA / 2600 and 8.7mA / 2600

  • Gain (at 1 kHz): 36.3dB (left), 36.4dB (right)

  • THD+N (at 1 Watt into 8 Ohms at 1 kHz, source impedance 600 Ohm): 0.46% (left), 0.33% (right)

  • First impressions: good, strong bass, great dynamics, a bit dry in the midrange, a little agressive upper frequencies, slightly sibilant

TUBE ROLLING 6 - Sylvania 6SN7GTA "chrome dome" replaced by RCA 6SN7GTB "black plate" (1960's):

  • I didn't like the upper range with Sylvania, which sometimes could be quite harsh and sibilant, so I replaced it with this RCA tube.

  • Balanced triode sections, low noise and microphonics

  • Gain (at 1 kHz): TBC (left), TBC (right)

  • THD+N (at 1 Watt into 8 Ohms at 1 kHz, source impedance 600 Ohm): TBC (left), TBC (right)

  • Comparing to Sylvania it sounds somewhat slower, bass is less controlled, but with smooth, rich midrange, harshness is gone completely

LINKS

Last update: 22.06.2018.

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