Improved Hybrid HeadPhone Amplifier
Published in issue 391, July/August 2009
Jeff Macaulay’s excellent single valve ECC82/12AU7 'Hybrid Headphone Amp' (HHA) published in spurred the author to implement some modifications culminating mainly in an additional input preamp. The resulting project was then slightly reworked In the Elektor Audio Labs and the result is shown here, along with a PCB design to Elektor standards.
Specifications Voltages measured w.r.t. circuit ground T1/T6 base 0.7 V T2/T7 base 1.4 V T3/T8 base 3.8 V T3/T8 Emitter 2.8 V ECC82 grid 4 V T10/T12 Emitter 6.2 V T9/T11Base 0.67 V ECC82 anodes 10 V ECC82 pin 5 9.4 V D2 (across device) 0.8 V T5 VCE 1.3 V R6/R14 (across device) 6.85 V
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Please note. In view of the complexity of international markets, Elektor cannot guarantee the availability of components for this project.
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