The 2A3 Amp
Of all the DHTs (directly heated triodes), the 2A3 tube sits at the pinnacle. Introduced in the 1930s, the 2A3 has continued unchanged to this day. Some new production tubes are available, but most manufacturers continue to use new old stock. RCA was a prolific maker of this tube.
Tubes, especially directly heated triodes, have the lowest distortion signature of any amplifying device. Used in simple circuits, the 2A3 tube gives great clarity in music. Its portrayal of musical tone, texture, and harmonics is superb. In a well designed amp, the 2A3 brings music alive.
Lyrita‘s 2A3 amps are single-
Simple 2A3 SET integrated amp -
2A3 SET integrated amp -
2A3 SET power amp -
All DHT 2A3 SET power amp -
The GM70 Amp
To provide a substantial increase in power output, and maintain the signature of
Amp configurations can be customized.
GM70 SET integrated amp -
GM70 SET power amp -
A variation is the power monoblocks, with the GM70 tube operating at very high voltages. This is the ideal operating point for the tube, and it shines in delivering power and an extended response.
GM70 SET Mono power amp -
All DHT GM70 SET power amp -
DHT Line preamp
This line level preamp uses the Russian 4P1L, as a directly heated triode, in a very simple design. Filament bias is used, which aids in simplicity and stability. An audio transformer serves as a load to the tube, as well as isolates the output. This also controls microphonics in the tube. Volume control is on the output.
The sound is rich in tone, with excellent dynamics. A great start to the amplification chain.
Tubes 4P1L, 6C5S
Gain 12 dB
Output Impedance 5000 ohms
Tubes handle low level signals beautifully, with unmatched linearity. They are ideal for the minute signals from the phono cartridge, to amplify and equalize to RIAA specifications.
A new circuit design uses the high transconductance, high gain, dual tube, the Russian 6F12P. This tube brings great clarity in music, with excellent micro and macro dynamics.
The active circuit has enough gain for MM (moving magnet) and high output MC (moving coil) cartridges.
For low output MC cartridges, a step-
Our environment is becoming more noisy electrically, with high levels of RFI (radio frequency interference). The high gain tubes used in phono circuits are very susceptible to RFI pickup. The only way to prevent this is to provide shielding to the entire circuit and tubes. So, the chassis becomes a steel black box.
Tubes 6F12P, 5C4M
Gain MM 54 dB
Gain MC 74 dB with CineMag 1:10 step-
Output Impedance 3000 ohms