• on Audio/Video/Photography
  • Published in issue 11/2007 on page 0
About the article

Headphone Amp with 3D Sound

Sound reinforcement for iPod & Co.

Headphone Amp with 3D Sound
Some audio amplifier designs incorporate ‘loudness compensation’ which boosts the bass and treble frequencies at low volume settings so that the tonal characteristics of the amplifier are perceived as being more linear with respect to the volume setting. The headphone amplifier described here combines a high-spec amplifier IC with a discrete transistor front-end giving additional bass and treble lift together with an audio 3D effect.
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Gerber file

CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor Members can exclusively download these files for free as part of their Membership. Gerber files allow a PCB to be produced on an appropriate device available locally, or through an online PCB manufacturing service. Elektor recommends its business partner Eurocircuits as the company of choice for its own prototypes and volume production in selected cases.

Resistors

(SMD 1206 case)

R1,R21 = 33

R2,R22 = see text

R3,R23 = 15k

R4, R24 = 560

R5,R25,R43,R44 = 33k

R6,R12,R26,R32 = 100k

R7,R11,R27,R31 = 1k

R8,R28 = 1kΩ5

R9,R29,R41,R42,R45,R46,R47 = 10k

R10,R30 = 330k

R13,R33 = 2kΩ7

R14,R50,R122,R222 = 0

Capacitors

(SMD 1206 case unless otherwise indicated

C1,C21 = 22nF

C2,C22 = see text

C3,C4,C5,C7,C23,C24,C25 = 470nF

C6,C26 = 470pF

C41,C42,C43 = 4µF7 (SMD 1812)

C44,C45 = 1µF

C50 = 100µF 16V radial (can-style electrolytic)

Semiconductors

T1-T4 = BC847 (SOT-23)

IC1 = MAX4409EUD+ (14-pin TSSOP; Maxim)Miscellaneous

3.5-mm stereo socket, PCB mount with collet nut

PCB, order code 070393-1 from www.thepcbshop.com

Enclosure

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