EL34 Push-Pull

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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.   

EL34 (6CA7) Class B Push-Pull Data Sheet

Common grid No. 2 resistor (without decoupling) 750 Ohms
Grid No. 1 bias -36 Volts
Grid No. 3 voltage 0 Volts
Input voltage 25.8 Volts
Load resistance, plate to plate 4000 Ohms
Plate supply voltage 500 Volts
Plate voltage 475 Volts
Grid No. 2 supply voltage 400 Volts
Plate current 2 x 125 mA
Grid No. 2 current 2 x 25 mA
Max. signal power output 70 Watts
Total harmonic distortion 5%

Schematic and Actual Characteristics

bulletSchematic & Harmonic Distortion


bulletFrequency Response & Input/Output


bulletEL 34 Data Sheet from Mullard
bulletEL 34 Data Sheet from Philips
bulletEL 34 Data Sheet from Telefunken

           Data Sheets are from Frank Philips

















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Last changed: 02/01/15

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Last updated: 02/01/15.