One of my friend wanted to build 5.1 system with 5 X LM3886 and One TDA7294 for woofer . He finished his system but he wants to know advice from community regards to low pass filter . I have bunch of ne5532 and njm2068 lying around so I can give him as genuine opamp in India is hard to find . Any thing 60hz to 250hz will do job I guess if I am not wrong
There are several low, high and band pass filters on line. Check at google, and select the proper curve. The opamp here plays a role very poorly important.
If you're using a 5.1 source, I don't think you need any low pass filter as the LFE channel will already be filtered.
However if you want to produce a subwoofer output from a stereo signal, a dual opamp would do the trick nicely
Opamp 1 as a mixer with adjustable gain
Opamp 2 as an adjustable low pass filter
Here is part of the circuit diagram from the subwoofer amp I just repaired, the adjustable LPF stage, the pot is a dual gang. The range of this LPF is 50-150Hz according to the markings on the control.
However if you want to produce a subwoofer output from a stereo signal, a dual opamp would do the trick nicely
Opamp 1 as a mixer with adjustable gain
Opamp 2 as an adjustable low pass filter
Here is part of the circuit diagram from the subwoofer amp I just repaired, the adjustable LPF stage, the pot is a dual gang. The range of this LPF is 50-150Hz according to the markings on the control.
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