Wednesday, November 9, 2011

Headphone amplifier with TPA6120

This is my first SMD circuit. The small size of SMD parts was my problem before. The opinions about TPA6120 is very good on all other related pages, the official datasheet is unbelievable. I have 5 pcs 6120 circuit, so I have to test it with my own PCBs.

The headphone circuit is very simple. With unbalanced balanced converter is much better, but in this first version this feature is missing from these PCB-s. I have design with unbalanced/balanced converter, but for modular mixer only. Now I posting about "independent" headphone amplifiers. Fortunately, this circuit is not the smallest SMD footprint. The distance between foots is 50 mill, the foot width is 20 mill. This size is no problem for homemade prototype.

The main IC is:

This chip have 20 "foots", but the half of these pins are not internally connected. On the bottom, small heatsink available, but this is not only heatsink, this is the GND as 21st pin. Footprint not available, have to be draw on the CAD software. The full circuit without dual power supply, and unbalanced/balanced converter is very simple:

These modifications possible:
  • For both channels (left and right) have + and - inputs for balanced sources. This is optional,
    but maybe the result is better. On this schematic has no input for balanced sources.
  • Separated dual power supplies possible for this one circuit. this is reduces the crosstalk between left and right channel. The dynamics of this circuit on the official datasheet is 120 dB, what is very good if true. Class D amplifier. I have "power filter" circuit to separate power sources of left and right channels, but I don`t want to use this for headphone amplifier because maybe the current source is not enough.

Therefore I have 3 versions of PCBs:

The first is the biggest one, to screw with another preamplifier circuits. The position of rear hole is the reason why this PCB so large:

If the same hole positions are not important between preamplifiers and the headphone amp, then here is the smaller PCB:

Finlay I have smaller. This PCB have separated inputs for balanced inputs of left and right channels, and inputs for left and right powers. this is the reason why volume potentiometer missing, and the power filter capacitors are too:

This is the smallest PCB, but possible to use after unbalanced/balanced converter and with separated dual power supply. But these solutions are required with another circuits.

6.3mm jack input soldered to all of these boards, the 1st and 2nd version of PCB have volume potentiometers too. This volume pot missing from the 3rd version, because the pot must be soldered before unbalanced/balanced converter. The TPA6120 circuit fitted to the bottom layer of all PCBs (this is the reason why this part mirrored), all another placed to to top.

See also:
PCB sales of this project
Module name Size
PDF SCH PCB image Tested Price (US$)
Des./3D Sim.1 Full2 Sim.1 Full2 Man3
TPA6120 headphone amp V:1
16 Ask
TPA6120 headphone amp V:2 55x71
Yes Yes
No 7 15 Ask
TPA6120 headphone amp V:3 55x49
Yes Yes
No 6 13 Ask
Power supply +/- 15V
212x57 69 - Yes Yes
Yes - No
11 20 Ask
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