| Stereo 20 | ||||||
| Long-Tailed-Pair Distortion | ||||||
| (LTP driven direct from oscillator, output into 242kOhm load) | ||||||
| Some power supply filtering added to minimise PSU hum & noise. | ||||||
| ECC83, Phillips Miniwatt, Dual Triode | ||||||
| Output | THD and Noise, % | |||||
| Volt-peak, into 242kOhm | Triode Section #1 | Triode Section #2 | ||||
| 2 Vpeak | - | - | ||||
| 5 Vpeak | 0.05% | 0.05% | ||||
| 11 Vpeak (=9 Watts Output) | 0.12% | 0.12% | ||||
| 20 Vpeak | 0.45% | 0.40% | ||||
| 30 Vpeak | 1.00% | 1.00% | ||||
| 40 Vpeak | 1.90% | 1.90% | ||||
| ECC83, AWV Radiotron, Dual Triode | ||||||
| Output | THD and Noise, % | |||||
| Volt-peak, into 242kOhm | Triode Section #1 | Triode Section #2 | ||||
| 2 Vpeak | - | - | ||||
| 5 Vpeak | 0.05% | 0.05% | ||||
| 11 Vpeak (=9Watts Output) | 0.12% | 0.11% | ||||
| 20 Vpeak | 0.38% | 0.38% | ||||
| 30 Vpeak | 0.95% | 0.95% | ||||
| 40 Vpeak | 1.90% | 1.90% | ||||
| Stereo 20, Overall Distortion | ||||||
| LTP driven from oscillator, output into 15 Ohm resistive load | ||||||
| Left Channel | THD and Noise, % | |||||
| NEC 6BQ5's | ||||||
| 9 Watts Average, Open Loop | 0.80% | Corresponds to 11 Volts-peak output from driver | ||||
| 9 Watts Average, Closed Loop | 0.05% | |||||
| Right Channel | THD and Noise, % | |||||
| AWA Radiotron 6BQ5's | ||||||
| 9 Watts Average, Open Loop | 1.30% | Corresponds to 11 Volts-peak output from driver | ||||
| 9 Watts Average, Closed Loop | 0.11% | |||||
| TL/10 | ||||||
| Long-Tailed-Pair Distortion | ||||||
| (LTP driven direct from oscillator, output into 242kOhm load) | ||||||
| Some power supply filtering added to minimise PSU hum & noise. | ||||||
| 6SN7, Super Radiotron (Aust), Dual Triode | ||||||
| Output | THD and Noise, % | |||||
| Volt-peak, into 242kOhm | Triode Section #1 | Triode Section #2 | ||||
| 5 Vpeak | 0.07% | 0.10% | ||||
| 10 Vpeak | 0.08% | 0.15% | ||||
| 20 Vpeak | 0.16% | 0.30% | ||||
| 6SN7, RCA (USA), Dual Triode | ||||||
| Output | THD and Noise, % | |||||
| Volt-peak, into 242kOhm | Triode Section #1 | Triode Section #2 | ||||
| 5 Vpeak | 0.15% | 0.12% | ||||
| 10 Vpeak | 0.22% | 0.17% | ||||
| 20 Vpeak | 0.35% | 0.50% | ||||
| TL/12 | ||||||
| Long-Tailed-Pair Distortion | ||||||
| (LTP driven direct from oscillator, output into 242kOhm load) | ||||||
| Heavy power supply filtering added to minimise PSU hum & noise. | ||||||
| 6SN7-GTA, Super Radiotron (Aust.), Dual Triode | ||||||
| Output | THD and Noise, % | |||||
| Volt-peak, into 242kOhm | Triode Section #1 | Triode Section #2 | ||||
| 10 Vpeak | 0.10% | - | ||||
| 20 Vpeak | 0.14% | - | ||||
| 30 Vpeak | 0.15% | - | ||||
| 35 Vpeak (=approx 10 Watts) | 0.17% | - | ||||
| 6SN7-GT, RCA (USA), Dual Triode | ||||||
| Output | THD and Noise, % | |||||
| Volt-peak, into 242kOhm | Triode Section #1 | Triode Section #2 | ||||
| 5 Vpeak | 0.10% | - | ||||
| 10 Vpeak | 0.12% | - | ||||
| 20 Vpeak | 0.16% | - | ||||
| 30 Vpeak | 0.22% | - | ||||
| 35 Vpeak (=approx 10 Watts) | 0.32% | - | ||||
| 50 Vpeak | 0.40% | - | ||||
| TL/12 Output Stage and Driver/Input-Stage Distortion | ||||||
| Complete amp (EF37A, 6SN7, 2xKT66) measured, output into 15 Ohm resistive load | ||||||
| Power Out | THD and Noise, % | |||||
| 12 Watts Average, Open Loop | 1.50% | |||||
| 12 Watts Average, Closed Loop | 0.10% | |||||
| * All THD measurements at 1kHz, and filtered below 250Hz to reject power supply ripple. | ||||||
| S.Spicer, May 2002. | ||||||