Ampdog
R.I.P. 23 June 2022
I apologise for the removal of the previous thread through a communication gap.
This is a serious valve amplifier called the "Hall?", after Sir Charles Hall? (1819 - 1895), the founder of the famous British orchestra. [This orchestra survived several periods of serious financial difficulties, at present still performing excellent music. The most famous conducter was probably Sir John Barbirolli].
While getting a few photos in order (some will simply not believe without seeing
....), here the characteristics aimed at and to my mind achieved:
Maximum continuous power output: 100W per channel
Frequency -3 dB response at 1W output: 6 Hz - 200 KHz
Power response -3dB points: 30 Hz - 22 KHz
Global NFB: 22 dB
Output loudspeaker load: 8 ohms and 4 ohms (set by internal links)
Damping Factor: >100
Input voltage for 100W output: 500 mV into 370 K.ohm input impedance
Zero-signal mains power consumption: 305 W
Main internal h.t. supplies: 600V raw for 6L6 anodes; 500V regulated for the rest
Mains voltage selector: 220V, 230V, 240V, 250VAC
Delayed power application: 37 seconds after heater voltage application
Delayed signal application: 43 seconds after heater voltage application
Auto bias correction for power stage current draw
Valves per channel: ? ECC85, ECF80, E182CC, 4 x 6L6GC in push-pull-parallel
Weight: 26 Kg
The first version was the one in my avatar; layout was changed after heat problems (the amplifier runs hot). I humbly believe it compares favourably to anything else in its class.
I am indebted to fellow-formite Charles in helping with measurements, and fellow-formite Timber MG with asistance in potting the transformers and other general help, as well as other members for encouragement.
Details are unfortunately not available for diy construction as performance is dependant on critical construction set-up, component selection and calibration.
This is a serious valve amplifier called the "Hall?", after Sir Charles Hall? (1819 - 1895), the founder of the famous British orchestra. [This orchestra survived several periods of serious financial difficulties, at present still performing excellent music. The most famous conducter was probably Sir John Barbirolli].
While getting a few photos in order (some will simply not believe without seeing
....), here the characteristics aimed at and to my mind achieved:Maximum continuous power output: 100W per channel
Frequency -3 dB response at 1W output: 6 Hz - 200 KHz
Power response -3dB points: 30 Hz - 22 KHz
Global NFB: 22 dB
Output loudspeaker load: 8 ohms and 4 ohms (set by internal links)
Damping Factor: >100
Input voltage for 100W output: 500 mV into 370 K.ohm input impedance
Zero-signal mains power consumption: 305 W
Main internal h.t. supplies: 600V raw for 6L6 anodes; 500V regulated for the rest
Mains voltage selector: 220V, 230V, 240V, 250VAC
Delayed power application: 37 seconds after heater voltage application
Delayed signal application: 43 seconds after heater voltage application
Auto bias correction for power stage current draw
Valves per channel: ? ECC85, ECF80, E182CC, 4 x 6L6GC in push-pull-parallel
Weight: 26 Kg
The first version was the one in my avatar; layout was changed after heat problems (the amplifier runs hot). I humbly believe it compares favourably to anything else in its class.
I am indebted to fellow-formite Charles in helping with measurements, and fellow-formite Timber MG with asistance in potting the transformers and other general help, as well as other members for encouragement.
Details are unfortunately not available for diy construction as performance is dependant on critical construction set-up, component selection and calibration.
