Hello.
The holes on the top of the case can be a solution but indeed the fact that 'things' can get into it leads to reflection.
Other solutions such as a larger size of the heatsink in contact with the
TPA3255 chip and the case are adopted as on
O-NOORUS D4 model for example.
The only 'problem',
which is not a problem in fact, is that the heat transfer by dissipation naturally follows the case and is concentrated in the upper part, normal since the heat rises ('pushed' by the cooler and less dilated air in the lower part), which means that the user may believe in an abnormal heating of the device when it is not the case.
As a reminder, the
TEXAS INSTRUMENTS DATASHEETS indicate a
temperature range of the operating junction up to a
maximum of 150°C.
A
TPA3255 chip powered without any modulated signal dissipates up to 75°C, so it is quite normal and far from the maximum temperature to observe up to around 45°C on the top of the case current models of
O-NOORUS amplifiers related to the 'nature' of the box used for them.
I have carried out all the tests and measurements possible after careful control of the diagrams and
everything is working normally.
I obtained a
maximum of 45°C on the top of the case in its center with a 'laser' thermometer placed exactly 20cm from it.
This measurement was carried out in a room
with an 'atmosphere' at 30°C for 52% relative humidity -> It cost me a lot in heating, LOL
There is therefore absolutely no risk of reliability of its amplifiers which could be heat-related under normal conditions of use
Regards.