The Official Raspberry Pi Projects Book - Projects_Book_v4

Review

raspberrypi.org/magpi The Official Raspberry Pi Projects Book 193

JUSTBOOM DAC HAT

A plug-

and-play,

high-

resolution,

digital-to-

analogue

converter

for the

Raspberry Pi

JustBoom

Maker

Says

JUSTBOOM

DAC HAT

he JustBoom range of Pi

products comprises three

main types – DAC, Amp,

and Digi Ğ featuring different sets

of outputs for different uses. Each

is available in full-size HAT and

Pi Zero-size pHAT form, ready-

assembled. Dll are based on the I^2 S

(inter-IC sound) standard.

Here we’re taking a look at the

DAC HAT, which delivers its sound

via an amplified 3.8 mm headphone

socket, or twin RCA outputs

connected to a hi-fi system or

powered speakers. While the KDT

features a 387kKz232-bit DDC chip

(the TI PCM8122), this is limited by

the Pi’s Oinux drivers to 1<2kKz.

Nevertheless, the sound quality

proved mightily impressive in our

tests. Both CD-tuality 19-bit tracks

and 27-bit KD audio files were

played with crystal clarity, even via

a modest Sony mini hi-fi system.

Classical music in particular benefits

from the enhanced clarity and detail.

The DAC HAT comes pre-

assembled, so you just need to

mount it securely on the Raspberry

Pi using the supplied plastic spacers

and bolts. Ds well as slots for

Camera Module and touchscreen

cables, this well-designed HAT

features a full (unpopulated) GPIO

breakout. The packaging includes

an optional IR receiver, for you

to solder on if you want to use a

remote control. There’s also the

option to fit the KDT in a sleek

plastic case (†13 2 '17).

It’s then a case of deciding

which OS to use. D whole host are

supported, including Volumio,

OSMC, OpenEOEC, Roon, and

Max2Play (for which a 30-day

free trial is included). Most are

easy to set up with the KDT. In

Raspbian, it involves commenting

out one line in /boot/config.txt

and adding three, one of which

enables playback from Sonic Pi.

A quick reboot and it’s ready to

use, although we found we needed

to boost the digital volume in

alsamixer for headphone playback.

One final trick up the DDC KDT’s

sleeve is the ability to stack a

standalone Dmp board (†90 2 '7<)

on top, featuring block terminals

so you can connect it directly to

passive speakers. \ou’ll need an

additional power supply to get full

power (30 W RMS) out of it.

Last word

Delivering audiophile sound

at an affordable price, the

well-designed DAC HAT is

an impressive piece of kit. It

offers a huge improvement in

quality over the Pi’s standard

3.5 mm audio jack, and sounds

particularly impressive when

playing back lossless formats.

Music sounds better with a HAT on

T

IQAUDIO

PI-DAC+

Based on

the same TI

PCM5122 chip,

IQaudIO’s HAT

delivers similarly

impressive

sound quality. It

can be stacked

with a Pi-AMP+

to use passive

speakers, too.

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