What's this? An audio project using a valve, actually described
in SILICON CHIP? After all those scathing things our esteemed
Editor and Publisher has said in the past about olde-worlde "bottles"? Yes, Leo finally gave in and approved the development of a valve preamp for guitars and other instruments, using the trusty 12AX7 dual hi-gain triode. We had to brush up on valve design to do it but the performance has turned out to be quite
impressive, better in fact, than was commonly achieved when valves ruled the electronics world.
Now you can build one up, so you can hear for yourself just how
good "valve sound" compares with that from modern solid state
gear.
|
Performance
| Voltage Gain: |
61 |
| Frequency response: |
-1dB at 20Hz and 160kHz (see Fig.5) |
| Harmonic distortion: |
< 0.2% for output levels up to 3V RMS (see Figs.6 & 7) |
| Signal-to-noise ratio: |
-81dB unweighted (22Hz to 22kHz) with respect to 2V |
| Input impedance: |
1MΩ |
| Output impedance: |
1.5kΩ at 1kHz |
|
