Tube Amplifiers

Lyrita Audio

The GM70 Amp

To provide a substantial increase in power output, and maintain the signature of the single-ended tube amp, the GM70 tube is ideal. Its properties are very similar to the renowned 845 tube - though the construction, pin layout, and heater requirements are different. The GM70 is a more robust and reliable tube.

This is available now only as 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. The use of two chassis also allow for better separation between transformers, for lower noise.

GM70 SET Mono power amp -  two stage, interstage transformer coupled.

  Tubes - 6E5P, GM70, 6C5S.     Power output -  35 watts/channel.

Tube  Preamplifiers

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 helps control microphonics in the tube. Volume control is on the output. If a lower output impedance is desired, the volume pot can be moved to the input.

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 (volume at output)

                                   1250 ohms (volume at input)

Tubes -  4P1L, 6C5S.

Phono preamp

Tubes handle low level signals beautifully, with unmatched linearity. They are ideal for the minute signals from the phono cartridge, to amplify and to 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-up transformer is required, ahead of the active circuit. Consider this as part of the cost of a low output MC. Lyrita recommends step-up transformers from CineMag.

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, 6C5S

 Gain  MM                   54 dB

 Gain  MC                   80 dB  with CineMag 1:20 step-up

 Output Impedance    3000 ohms

Why Tube Amplifiers

Tube amplifiers just reproduce music better.

Music has rhythm, melody, and harmony. Instruments have timbre. This rich harmonic content is tied together in amplitude and time. Thus, music consists of very complex, asymmetric waveforms. This complex relationship has to be reproduced faithfully by the amplifier, for music to sound true.

Tube amplifiers do this with higher fidelity. The reproduction of rich tone, and harmonic structure, brings music alive!

Of all tube designs, the single-ended amp is the simplest. This simplicity brings great clarity in music, with excellent dynamics. It involves you emotionally, and takes you closer to the music.

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-ended designs, as originally intended for this tube. SET- single ended triode. The circuits are simple, and use transformers extensively. Amp configurations can be customized for the user.

A new design uses the Russian 6S4P triode in the input / driver stage. This is a high gain, high transconductance tube, which allows for a two stage design. This simplicity gives more clarity in music. This tube reproduces the tonal richness in music very close to that of DHTs, with excellent dynamics.                 

2A3 SET integrated amp  -  two stage, interstage transformer coupled.

  Tubes - 6S4P, 2A3, 5V4G.     Power  output - 3 watts/channel.

2A3 SET power amp  -  two stage, interstage transformer coupled.

  Tubes - 6S4P, 2A3, 5V4G.     Power output - 3 watts/channel.

A more economical version of this amp is available, using smaller transformers and a smaller chassis. The circuit is similar, using the same tubes.

Simple 2A3 SET integrated amplifier -  two stage, capacitor coupled.

   Tubes -  6S4P, 2A3, 5V4G.    Power output -  3 watts/channel.