BC127 / Melody 7.2 / A2DP source Analog audio Low pass


Using bc127 / melody 7.2 as a analog input audio for bluetooth source. It work but for low frequency (under 50 hz) there is a attenuation, like a low pass filter.
Is it possible ? how can i change it ?
I made some test with other source and same sink, and can go down to 5 Hz, when I replace the source with BC127 there is attenuation for low frequency ?


Not sure about your exact setup and I think you might mean ‘high pass’ filter, but here’s what I know.

The analog inputs are capacitively coupled to the chip and this results in a high pass filter. For headset designs it’s common to set the high pass corner frequency around 200 or 300 Hz. This makes sense for phone grade voice band signals. It also reduces wind noise artifacts.

If you’re using a module to run music signals into the analog inputs you might want a lower corner frequency than a typical headset design.

It sounds like you have a couple different sets of hardware that give different results. These might have different coupling capacitor values, which would explain what you’re seeing.


First of all thank, you write i was meaning high pass filter.

This mean,if i use the analog input of the BC 127 with a hifi bandwith, the BC127 reduce the bandwith ?

As you may said is it possible to change (configuration of BC127) the analog filter ?

To have the total bandwith i have to use the digital input or thir is a other solution ?


Hello Patbrun,
BC127 has (very) low value capacitors on analog audio output…
So, even if your load is high impedance… you get a high pass filter

The only solution is to use I2S digital audio.