EL34 Triode Connection Non-NFB Push-Pull with Hashimoto Transformers -
Project #1
This
amplifier was originally featured on the February 2003 Issue of the "High-Fidelity Audio: Radio
Technology" by Mr. Tadaatsu Atarashi. Mr. Atarashi's goal for this
project was to recreate the later version of Western Electric WE-42 Type Amplifier that was
initially introduced in 1928. The original WE-42 Type Amplifier was
equipped with 205D; however, it was replaced by EL34 in 1958 via Altec Service who took over the
maintenance service from Western Electric. This modified amplifier was
called the 42 AP-1, and Mr. Atarashi followed the basic design of the 42 AP-1 to
construct this amplifier.
As being depicted on the schematic diagram, this amplifier is extremely simple.
Mr. Atarashi called this amplifier a single stage booster amplifier. Besides Hashimoto HW-25-8 output transformer, PT-270
power transformer, and C-15-200CH choke coil, Mr. atarashi used an input
transformer, the P-285Q from P&C in Japan.
Mr. Atarashi used his Studer A730 CD player for the testing input source.
Then, he was planning to drive his Western Electric
WE-753C Monitor
Speakers
with this amplifier although he was not sure which line/power amplifier he could
utilize for this booster amplifier. Therefore, He tested the 16Ohms
headphone output from the Studer A730 CD player directly into the 16 Ohms input. He also tested his mini amplifier that can yield 2.83V,
1W output into 8 Ohms input. In either case, Mr. Atarashi was not 100% satisfied
with the listening result.
Mr. Atarashi ended his article with his promise to feature a line amplifier
that could effectively drive this booster amplifier on the following issue.
However, his actual solution was a little different. That article is explained on
the following section.
