Chazz6
Active Member
- Joined
- Mar 4, 2021
- Messages
- 270
- Likes
- 179
A tube preamp feeds my Class A power amplifier. Does the preamp add audible distortion? It's a Van Alstine Transcendence RB 10. I haven't found distortion measurements for it, but I did for their FET Valve CF preamp, which came out about five years earlier than the RB 10. A review reported what appear to be careful measurements:
- For a 1 kHz sine wave at 2V RMS, THD+N measured 0.00381% with the first harmonic being 90 dB below the test tone. Bumping the output to 5 Volts (14 dBV) RMS, THD+N rose to 0.00862% and the first harmonic was 83 dB below the fundamental.
- The Intermodulation Distortion test was done with signals at 60 Hz and 7 kHz. The measured IMD at 6 dBV (2 Volts) came to 0.0028%.
- The response is within 0.25 dB of flat from DC to 20 kHz. From there to 90 kHz the response is 1.4 dB below the 1 kHz level.
- –https://hometheaterhifi.com/reviews...fet-valve-cf-vacuum-tube-preamplifier-review/