The driver stage uses 6SL7 tubes in a SRPP topology which feed the KT77 self-inverting push-pull (SIPP) output stage operating in Class A Ultra Linear (UL) mode. The constant current source (CCS) uses an LM317 regulator.
I was most impressed with the performance of the design. The SRPP and Push-Pull outpout stage combine to produce a very low noise floor. Distortion was measured to be less than 1/2% at 12W. The design can be scaled for use with other tubes by simply adjusting voltage and cathode current. My understanding is that KT88 versions of this design are in the process of being built.
For complete information about this project, see the Oddwatt 225 project page - DIY KT77 SIPP (Push-Pull) Tube Amplifier.
Related DIY Tube Amplifier Projects:
- Alex's DIY KT88 Single Ended Tube Amplifier Project
- Bruce's Odd Blocks KT88 Push-Pull Tube Amplifier Project
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