Home Projects

Projects

Devices

USBHI – USB-interface for headset

by nihtila
written by nihtila

Simple USB audio interface for headset

  • Based on PCM2912A reference design; single IC providing:
    • USB-interface
    • 2-channel DAC and headphone amplifier
    • 1-channel ADC and microphone bias
  • TRRS jack for headset, or headphones and microphone can be wired out separately
    • CTIA or OMTP type jack can be selected with jumper link
  • Not for higher end audio but perfectly adequate for gaming, podcasts, calls, etc.
Continue Reading
5 comments
FacebookTwitterRedditEmail
Modular HP AmpObsolete

HP Buf – High-current buffered amplifier board for HP MoBo

by nihtila
written by nihtila

Amplifier daughterboard for HP MoBo modular headphone amplifier

  • High-power high-performance balanced headphone amplifier daughterboard for HP MoBo
  • Balanced input, balanced output
  • Jumper link for two gain options, default 0/10 dB
  • Jumper link for two output impedance options
  • OPA2134 opamps followed by BUF634 or LME49600 buffers
  • SNR: 113-121 dB A-w depending on the buffer, load, and gain
  • THD+N ratio at 100 mW (LME49600)
    • 300 Ω: 0.0004 % / -108 dB
    • 32 Ω: 0.0007 % / -103 dB
    • 16 Ω: 0.0012 % / -98 dB
  • Max power around 1 W (<0.1 % THD+N)
  • Update: get even higher performance with LM4562 opamps
Continue Reading
0 comment
FacebookTwitterRedditEmail
Modular HP AmpObsolete

HP TPA – Simple IC amplifier board for HP MoBo

by nihtila
written by nihtila

Amplifier daughterboard for HP MoBo modular headphone amplifier

  • TPA6120A2-based simple-IC headphone amplifier amplifier
  • Balanced input, balanced output
  • Jumper link for extra gain option; default 0/10 dB
  • SNR: 116-122 dB A-w depending on the gain and load combination
  • THD+N ratio at 100 mW
    • 300 Ω: 0.0015 % / -96 dB
    • 32 Ω: 0.006 % / -84 dB
    • 16 Ω: 0.009 % / -81 dB
  • Max power around 0.5 W (16 / 32 Ω)
Continue Reading
0 comment
FacebookTwitterRedditEmail
Modular HP AmpObsolete

HP MoBo – Modular headphone amplifier motherboard

by nihtila
written by nihtila

Motherboard for modular headphone amplifier system

  • Motherboard with inputs, outputs, power distribution, and signal routing for amplifier daughterboard
  • Balanced input
  • Balanced and unbalanced outputs
  • Output mute circuit
  • Requires separate amplifier board

HP MoBo is the basis of a modular headphone amplifier design. It provides input and output connections and simple power supply components (external power supply required), and connections for stackable amplifier daughterboard.

Continue Reading
0 comment
FacebookTwitterRedditEmail
DevicesObsolete

miniD Preamp – Tiny miniDSP-based 4-Channel Preamplifier

by nihtila
written by nihtila

This is an updated version of my old miniD preamp from 2014 combining miniDSP and 4-channel DAC-preamplifier

  • Small 4-channel preamplifier with digital signal processor and digital-to-analog converter
    • DSP can be used for crossover for 2-way speaker or between speaker and subwoofer, and/or digital room correction
  • 4 digital SPDIF stereo inputs and one analog input
  • 4-channel unbalanced analog output
  • DSP-solution consists of ADAU1701-based miniDSP-board and applicable software
  • Atmel AVR-based firmware with extensive features such as IR-remote, balance, offset for inputs and outputs, DSP bypass, selection between analog or digital volume control, etc.
  • Main components: SRC4392 SPDIF-receiver and sample rate converter, miniDSP-board, PCM4104 DAC, OPA1662 op-amps and PGA4311 volume control
Continue Reading
0 comment
FacebookTwitterRedditEmail
H-DACObsolete

Addon H-MCU – Microcontroller addon for H-DAC

by nihtila
written by nihtila
  • Provides microcontroller interface to H-DAC jumper-link pinheader
  • Can be made Arduino-compatible with external USB-serial interface board

Addon H-MCU is designed to help use H-DAC in projects where I use microcontroller for selecting input and filter settings. It makes it possible to switch input and DAC filter with external remote signals.

Continue Reading
0 comment
FacebookTwitterRedditEmail
DevicesObsolete

HP Pre 2016 – DAC-preamplifier with headphone amplifier

by nihtila
written by nihtila
  • H-DAC and Addon H-PreAmp encased and used along with PSU Pre 2016 external power supply
  • Very high performance DAC-preamplifier with headphone amplifier
  • Compact and simplified design yet extensive list of features
    • Coaxial, optical, and USB inputs
    • DAC filter response switch
    • Balanced (XLR) and unbalanced (RCA) outputs, approximately 2 Vrms output level
Continue Reading
0 comment
FacebookTwitterRedditEmail
H-DACObsolete

Addon H-Filter – Simple through-hole balanced preamplifier addon for H-DAC

by nihtila
written by nihtila
  • High performance; H-DAC + H-Filter system performance measured with fixed resistors:
    • SNR: 119 dB (A-weighted)
    • THD+N ratio (1 kHz / 2 Vrms): -100 dB
    • Crosstalk: -112 dB at 1 kHz, -100 dB at 10 kHz
  • I/V-stage, filters, output stage, and opamps implemented with through-hole components for easy experimentations
  • Balanced outputs (XLR) on-board, uses unbalanced connectors (RCA) on H-DAC board
  • Potentiometer for volume control to transform H-DAC into preamplifier, or resistors for fixed output level
  • Takes voltage supplies and audio signals directly from H-DAC via pinheaders
  • 5×10 cm 2-layer PCB, through hole resistors and capacitors, placeholders for DIP8 sockets for opamps

Addon H-Filter is a simple filter and output addon for H-DAC with a possibility for a potentiometer to transform H-DAC into a preamplifier. In contrast with other designs of mine, it has been designed with through-hole components to allow easy experimentations with opamps and passive components. It offers high performance with low BOM cost and easy solderability.

Continue Reading
0 comment
FacebookTwitterRedditEmail
Newer Posts
Older Posts