Hi All,
I have an android car head unit and the external mics are essentially the same as a mic you'd plug into a PC with a dc bias voltage (3v) mono 3.5mm jack. However they have zero filtering on them so you get a lot of road noise and hum.
I've attempt to use a raspberry pi to do some audio processing from an electret mic and do noise reduction and then output the signal down to mic level and plug that into an android car head unit so people can hear me to a reasonable degree. However the original source is just too awful for it to be effective.
I’ve experimented with digital high pass and low pass filtering on the recorded audio with better results.
Is there a little box which basically has a passive band pass filter for say something like 120hz to 5000hz. That people could plug in to improve the general quality of the mic with a mono 3.5mm jack on each side?
or
I’m considering trying to build a circuit for a passive band pass filter however i'm not sure its possible with only 2 wires from the mic port on the head unit.
The oem mic in the car originally has band pass filters on and only 2 wires to the bluetooth module but i know that runs on a lot higher voltage of about 8v.
Any help would be appreciated.
I have an android car head unit and the external mics are essentially the same as a mic you'd plug into a PC with a dc bias voltage (3v) mono 3.5mm jack. However they have zero filtering on them so you get a lot of road noise and hum.
I've attempt to use a raspberry pi to do some audio processing from an electret mic and do noise reduction and then output the signal down to mic level and plug that into an android car head unit so people can hear me to a reasonable degree. However the original source is just too awful for it to be effective.
I’ve experimented with digital high pass and low pass filtering on the recorded audio with better results.
Is there a little box which basically has a passive band pass filter for say something like 120hz to 5000hz. That people could plug in to improve the general quality of the mic with a mono 3.5mm jack on each side?
or
I’m considering trying to build a circuit for a passive band pass filter however i'm not sure its possible with only 2 wires from the mic port on the head unit.
The oem mic in the car originally has band pass filters on and only 2 wires to the bluetooth module but i know that runs on a lot higher voltage of about 8v.
Any help would be appreciated.
The following forum may be a better place to get information on filters.
https://www.diyaudio.com/forums/analog-line-level/
You can look up 'state variable' and 'sallen key' filters. The state variable has an integral bandpass output but it may be too narrow. There are a LOT of calculations for filters. Don't let them intimidate you. Start with given values and scale the values up/down to get where you want to get. The state variable works well with pots to adjust the frequency.
https://www.diyaudio.com/forums/analog-line-level/
You can look up 'state variable' and 'sallen key' filters. The state variable has an integral bandpass output but it may be too narrow. There are a LOT of calculations for filters. Don't let them intimidate you. Start with given values and scale the values up/down to get where you want to get. The state variable works well with pots to adjust the frequency.
i'll look into those, i did put it in analog source as i'm looking to do it on the input rather than output stage, however thread got moved to car audio
Thanks
Thanks
mea culpa
It's me who moved martr post to car audio thread.
I'll move it back in analog line level thread.
George
It's me who moved martr post to car audio thread.
I'll move it back in analog line level thread.
George