RN52 - Integrated Amplifier Driving 8 Ω Speakers
Can we use an 8 Ω speaker with the RN52 module? Does it cause any issue?
According to the module datasheet, it is possible to use the 8 Ω speaker (see the "Speaker Output" section). The speaker output is capable of driving a speaker with an impedance of at least 8 Ω directly. The overall gain of the speaker output is approximately -21 dB to 0 dB in 1.5 dB steps.
Alternatively, you can add an 8 Ω resistor. Note that adding an 8 Ω resistor in series will match impedance correctly and will reduce the voltage to the speaker by 50 percent. This will have the effect of reducing power to the speaker (or headphones) by a factor of four because power is proportional to V².