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Improved Hybrid HeadPhone Amplifier

Published in issue 391, July/August 2009

Improved Hybrid HeadPhone Amplifier
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.

Extra info, Updates

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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Magazine July/August 2009
UK391 (US $ 11.30)
 

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PCB, bare

Please note. In view of the complexity of international markets, Elektor cannot guarantee the availability of components for this project.

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