Wrap up of my amplifier
-For a decade, I have been spending days on direct heating, triode transmitting (plus bias) tubes amps.
-For reference purpose, built a 801A x 3 in parallel (negative bias and non NFB) to monitor plus bias amps for
comparison.
-No tangible differences observed between amps to use grid current flowing and conventional 801A with negative bias.
-For my B&W N-802 SP-system, more than 30W power is desirable to drive I feel....
-Finally, it is my pleasure to be able to participate in ETF 2008, and could have a lot of valuable discussion
with group members, Arigato and thank you all.......
| Tube name | 811A | 100TH | 838 | 8025A | 801A X 3 |
| Power Output(W) | 22 | 30 | 35 | 12 | 17 |
| Distortion( % at 1 KHz) | 2 | 3.4 | 4.3 | 3.6 | 5.3 |
| Plate Efficiency(%) | 43 | 42 | 43 | 44 | 40 |
| Plate DC Input(W) | 51 | 72 | 81 | 27.5 | 42 |
| Grid bias Voltage(V) | 18.5 | 39 | 26.6 | -18 | -58.5 |
| Grid exiting Voltage(RMS in V) | 43 | 82 | 74.5 | 33 | 56 |
| Grit current(Resting / Max. in mA) | 13 ~ 18 | 21~ 48 | 11 ~ 21.5 | 0 ~ 6 | 0 |
| D/F(on/off method at 1KHz) | 2 | 2.85 | 1.6(local NFB)4.0 (global NFB) | 4 | 2.6 |
| Plate Dissipation(W) | 45(CCS)65(ICAS) | 100 | 100 | 30No air cooling | 20 X 3 |
| Filament(V / A) | 6.3 / 4 | 5 / 6.3 | 10 / 3.5 | 6.3 / 1.9 | 7 / 1.25 |
| Amplification factor | 160 | 38 | 50 | 18 | 8 |
Data sheet
Audio room
Ham shack & Service Bench