OVERVIEW
The circuit design is referenced to Grounded Ground preamplifier which can be found in earlier wireless radio applications which requirie to meet high signal-to-noise ratio (SNR) and wide bandwidth requirements. For audio application, it is capable of creating high dynamic responses and quiet background which perserves the originality of the beauty of audio signals with neglectable distortion due to the simplicity of the circuits. Also, thanks to the differential pairs of the input stages, it rejects most of common-mode noise and has high PSRR. This grounded grid (GG) preamplifier will not make any artifacts to the sound and play 100% originally and naturally.
Adoption of Dale resistors, WIMA and Solen capacitors for AC signal coupling. BHC and WIMA capacitors for bypassing. Three Shuguang 12AX7 vacuum tubes.
SPECIFICATIONS
1. Vacuum Tubes: Three 12AU7
2. Gain: 15dB
3. Bandwidth 600KHz
4. Input impedance: 100K Ohms
5. Output impedance: 200 Ohms
6. S/N ratio: >93dB
7. THD: <0.02%
8. Input: 4 single-ended RCA
9. Output 1 single-ended RCA
10. Dale 23-step Ladder-type Attenuator (0-60dB attenuation)
11. Four to one stereo channel selection.
12 Power requriement: 100-120V/220-240V, 50/60Hz
13. Dimension: 410mm(W)x100mm(H)x330mm(D)
14. Weight: 8 KG.
Pre-Amplifiers
