EL34 Push-Pull Mono-Block Power Amplifiers
This amplifier was featured on the January 2003 Issue of the "High-Fidelity
Audio: Radio Technology" by Mr. Tadaatsu Atarashi. The purpose
of designing this amplifier was to drive the B&W Signature 800 with 70W maximum output
derived from EL34 Push-Pull Class B1 fixed bias operation. For this end,
Mr. Atarashi used the largest Hashimoto Push-Pull output transformer, the
HW100-5, along with Hashimoto PT-400B Power Transformer and Hashimoto C-10-200W
Choke Coil.
Mr. atarashi mentioned in his article that EL34 could yield
the most musical sound among the modern high-power tubes. Among several
manufacturers, Mr. Atarashi chose JJ for this project because Mr. Atarashi
thought EL-34 from JJ was very reasonably priced. The basic design of this amplifier
is very traditional; however, in its power supply section, Mr. Atarashi used film capacitors instead of electrolytic ones.
For rectifiers, he used
four Fast Recovery diodes to create a bridge rectifier for the B+ power supply. He
also used two Fast Recovery diodes to rectify the
fixed bias power supply.
By testing with the B&W Singnature 800 speakers, Mr. Atarashi was impressed with the
driving power of this amplifier. Mr. Atarashi was also amazed by the very detailed sound images
that this amplifier can recreate. He concluded, "This is beyond the audio reproduction
(too close to the real sound)."
This amplifier was later used on the
"17 Output Transformers Sound Comparison on the EL34 Push-Pull Mono-Blocks"
featured on the "Tube Kingdom" 2003 Winter issue Vol27.
