loads, as well. So, I took THD+N measurements using
both. All the tests were performed at an ambient
temperature of 20°C (the temperature in my shop), which
is a bit lower than the 25°C ambient temperature for
measurements in the chip datasheet. If anything, these
amplifiers might perform a little better at a slightly lower
temperature (Photo 7).
Smallest First
As mentioned, the smallest of the amplifier modules is
the PAM8610. Since it’s just a little bigger than a quarter,
it could fit nearly anywhere. According to the datasheet,
with a 12V power supply the chip can deliver up to 10W
at very low distortion, and 15W at 10% THD+N when
fitted with a heatsink; refer to Photo 8.
The tiny module looks to be fairly close to the
reference circuit provided by the manufacturer (Photo 9).
Except for the onboard filter capacitor, control, and
input/output connectors, the module is entirely surface-mount construction, with entirely 0805 components and
the QFN amplifier chip. This particular module uses a DC
volume control, so it's only a single potentiometer instead
of the dual control used in the signal path of the Dayton
Audio DTA- 2 module, which saves some space. It's small
enough that it could feasibly be integrated with a project
like Craig Lindley's DIY electric guitar to make a self-powered/self-amplified musical instrument. That'd be
pretty interesting to see! (Refer to Photo 10.) It's very
48 March 2015
PHOTO 6. A generic but high quality 12V 10A
regulated switching power supply used to power
the modules. PHOTO 7. Both PAM8610 modules performed very similarly.
PHOTO 8. THD+N vs. power for the PAM8610 chip, from
the manufacturer's datasheet.
PHOTO 9.
The reference
circuit for the
PAM8610 chip,
from the
manufacturer's
datasheet.
