viren bakhshi
Well-Known Member
Lyrita Audio has just brought out another amplifier in its range of single ended tube amps - the 845 SET. This is an integrated stereo amplifier, using a single 845 output tube per channel, with a power output of 15 watts/channel.
Why build another 15 watt amp? Well, the 845 tube enjoys an enormous reputation - I was curious to hear it for myself. Then there were customer pressures, specifically from "heliumflight"! He stubbornly hangs on to his vintage B&W speakers, of average sensitivity. The Lyrita 2A3 SET that he has was being driven to distraction, er distortion, trying to play music through these speakers! And "heliumflight" would have none other than the directly heated triode sound. There was no choice left but to build the 845 SET amp!
Frankly, I am not in the power game. You can get more power out of the 845, if you operate it to its limits. I prefer to run the tube very conservatively, to prolong its life, and to get a better measure of its sound. For me, 15 watts of SET power, with the right speakers, is more than enough in a domestic setup.
So, what does the Lyrita 845 SET add up to. It's a three stage design - the input voltage gain stage is handled by the 5687 tube, RC coupled to the driver stage using the 6V6 tube in triode mode, transformer coupled to the output 845 tube. The 6V6 provides the high current necessary to drive the 845, the interstage transformer provides the right impedance coupling to allow the 845 to run even into A2 mode on peaks. In my view, the interstage transformer is the best way to couple to the 845, and also allows the use of a fixed bias to the tube.
The power supply is beefy, choke filtered. Only tube rectification is used. And, the 845 runs on AC heater voltage. And, no global feedback is used.
Specifications:
Power output 15 watts into 8 ohms
Response 40 HZ to 20 kHz
Tubes
Input 5687 NOS
Driver 6V6 RCA
Output 845 Shuguang
Rectifier 5V4G x 2 parallel
Rectifier 5W4
Regards,
Viren
Why build another 15 watt amp? Well, the 845 tube enjoys an enormous reputation - I was curious to hear it for myself. Then there were customer pressures, specifically from "heliumflight"! He stubbornly hangs on to his vintage B&W speakers, of average sensitivity. The Lyrita 2A3 SET that he has was being driven to distraction, er distortion, trying to play music through these speakers! And "heliumflight" would have none other than the directly heated triode sound. There was no choice left but to build the 845 SET amp!
Frankly, I am not in the power game. You can get more power out of the 845, if you operate it to its limits. I prefer to run the tube very conservatively, to prolong its life, and to get a better measure of its sound. For me, 15 watts of SET power, with the right speakers, is more than enough in a domestic setup.
So, what does the Lyrita 845 SET add up to. It's a three stage design - the input voltage gain stage is handled by the 5687 tube, RC coupled to the driver stage using the 6V6 tube in triode mode, transformer coupled to the output 845 tube. The 6V6 provides the high current necessary to drive the 845, the interstage transformer provides the right impedance coupling to allow the 845 to run even into A2 mode on peaks. In my view, the interstage transformer is the best way to couple to the 845, and also allows the use of a fixed bias to the tube.
The power supply is beefy, choke filtered. Only tube rectification is used. And, the 845 runs on AC heater voltage. And, no global feedback is used.
Specifications:
Power output 15 watts into 8 ohms
Response 40 HZ to 20 kHz
Tubes
Input 5687 NOS
Driver 6V6 RCA
Output 845 Shuguang
Rectifier 5V4G x 2 parallel
Rectifier 5W4
Regards,
Viren
