Low pass filter - TL072

[ch33ta]

I need a low pass filter for my TDA7294 amplifier, found one and it looks very simple

LOW PASS FILTER

please tell me if you have a better schematic (but simple, not too complicated), or if you have a suggestion for the low pass filter above

[Dxvideo]

That works on the same theory but simpler,

[sek]

Depending on what you're aiming for, the website of SL can also never hurt.

[ch33ta]

tnx

can I use TL072 ???
or if you have a better solution tell me

btw. I need to put this on a single power suply if it is possible? (+12V)

[AndrewT]

Hi,
why do you want a low pass filter?
In my opinion it will remove some of your low bass information.

If you are planning to run with large amounts of equalisation to extend the low frequency response of a speaker, then a low pass will protect the speaker from excessive cone travel and the power amplifier from excessive output voltage.

If you are running the speaker near flat then I suggest you use a DC blocking capacitor on the input to your amplifier and set the RC time constant of this filter (-6db/octave- single pole) to about 80mS to 90 mS. That will let all the bass and sub-bass through and get the best out of the low frequency response in the speaker.

BTW
the circuit in post2 will not work with the late information supplied in post4! nor will the linked circuit in post1.

[ch33ta]

Depending on what you're aiming for, the website of SL can also never hurt.

it's like this:
I need a 24dB/oct lowpass filter with changeable frequency (up to 200Hz)

and if it's possible a tested one
I don't like when to build something that probably won't work or if it hasn't been tested

[AndrewT]

Ah!
a low pass to stop the bass getting to your speakers.
I'm afraid your link confused me.

A pair of 2pole Sallen & Key filters cascaded to give 24db/octave.
Do you want Linkwitz Reilly or Butterworth roll off characteristic or something else?

There's a Group Buy and a few spares may be available for a suitable filter (but it's not adjustable).

[ch33ta]

If you are planning to run with large amounts of equalisation to extend the low frequency response of a speaker, then a low pass will protect the speaker from excessive cone travel and the power amplifier from excessive output voltage.

There is definetly huge amount of equalisation
I have a two-band tone control, bass control range is from -19 to +17dB (I love that little button )
So i need a low pass filter because the range of bass control is from 20Hz to 500Hz, and I don't want anything above 150Hz on my subwoofer.

[ch33ta]

Ah! a low pass to stop the bass getting to your speakers. I'm afraid your link confused me.

low pass

This is a simple low pass filter with changeable frequency (30-150Hz).
I just want to know what do you think about this schematic (will it work, and would you make any changes to it ?)

[ch33ta]

I must say I am kind of new at all this, so if you know some better filter please give me a link.

btw. tnx for answering on my newbie questions