Low Pass Filter with ne5532 or njm2068

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
 

ubergeeknz

Member
2018-08-31 12:32 pm
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. Screenshot_20191003_000956.jpg