Obsolete

Analog MV8-OP1 clone for Roland MV-8000/8800

by nihtila April 9, 2018

written by nihtila

6-channel analog output module for Roland MV-8000/8800; mimics analog part of Roland MV8-OP1 module
- Digital signal and supply connector with identical pinout to the original
- Same output level as the original
High performance
- SNR: 118 dB (A-weighted)
- THD+N ratio: -103 dB min, -93 dB max
- Crosstalk: -112 dB max

April 9, 2018 6 comments

Modular HP Amp 2017

by nihtila February 4, 2018

written by nihtila

Modular headphone amplifier based on HP MoBo motherboard and changeable amplifier daughterboards:
- HP TPA – simple TPA6120A2-based amplifier
- HP Buf – BUF634- or LME49600-buffered amplifier
Balanced input
Balanced and unbalanced headphone output
Output mute circuit
Part of multi-component system with external power supply

February 4, 2018 0 comment

Modular HP Amp Obsolete

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

by nihtila February 4, 2018

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

February 4, 2018 0 comment

Modular HP Amp Obsolete

HP TPA – Simple IC amplifier board for HP MoBo

by nihtila February 4, 2018

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)

February 4, 2018 0 comment

Modular HP Amp Obsolete

HP MoBo – Modular headphone amplifier motherboard

by nihtila February 4, 2018

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.

February 4, 2018 0 comment

Devices Obsolete

miniD Preamp – Tiny miniDSP-based 4-Channel Preamplifier

by nihtila January 8, 2018

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

January 8, 2018 0 comment

H-DAC Obsolete

Addon H-MCU – Microcontroller addon for H-DAC

by nihtila February 18, 2017

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.

February 18, 2017 0 comment

Devices Obsolete

HP Pre 2016 – DAC-preamplifier with headphone amplifier

by nihtila February 12, 2017

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

February 12, 2017 0 comment

H-DAC Obsolete

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

by nihtila February 6, 2017

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.

February 6, 2017 0 comment

Devices Obsolete

PSU Pre 2016 – External power supply for DAC-preamplifier

by nihtila February 5, 2017

written by nihtila

Dual Trafo Board and SmartPSU3 modules
Two 3-channel power outputs for DAC-preamplifiers, total current capability being approximately:
- +14 V, 250 mA
- -14 V, 250 mA
- +7 V, 500 mA
Over-current, under-voltage, and over-temperature protection provided by SmartPSU3
- Error codes blinked by the front LED

This is the device where Dual Trafo Board and SmartPSU3 were originally designed for – external power supply that is simple yet provides some protection in case something goes wrong in the target device. Its current output capabilities are somewhat limited but enough for small DAC and preamplifier. It was designed for HP Pre 2016 although headphone output power may be somewhat restricted with this power supply.

February 5, 2017 0 comment

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