Simple low pass filter for Hi-Fi speakers

[seadi123]

Hi everyone

I'm going to build a tiny amp , and im going to use 2 x 2" speakers . Speakers have a 92db sensitivity , and have a frequency range of F0 - 12Khz . Since the normal guitar speakers frequency is 82hz - 5Khz , i was thinking of creating a low pass filter between the amp and the speakers . This could avoid annoying hiss sounds , and make the speakers become more suitable for guitar sounds .

So i was just thinking about the simplest passive filter which is the one below , and using the formula i found that the best values would be 0.01uF for the capacitor and 3k for the resistor . This would not affect the tone , and would set the filter at about ~5.2Khz . This could work on any speaker . What do you guys think ?

[GibsonGM]

I think you should try it...it will eat some signal for sure, but see what you get.    Now, you may also be attenuating some of the harmonics of your 'highest guitar frequencies', so it might not sound that great.   

If this is the case, scale it up (use a 1.5k to make the cutoff ~10kHz....) and see if you can set it to where it sounds good to you.  A pot in that position might be a good idea.     The idea has merit, though   

[Seljer]

If you put that between the amp and the speakers it's going to waste a whole lot of power in that resistor and you won't hear much sound at all!
Your filter would work if you placed it before the power amp, though this means that it doesn't mitigate the nasty sound of the power amp's clipping if you drive it too hard.

You'll probably get better results by coiling up 20 meters or so of magnet wire and just wiring it in series with the speaker(s). If you want to get a bit more fancy you can make it a second order filter with an additional capacitor in parallel with the speaker.
You'd be aiming for 500microhenry to 1mH for the inductor, probably around 5microfarads for the capacitor. You can do some math and such to work out the exact crossover points.

[anotherjim]

At risk of making everyone as lazy as me, I find this site helpful...
http://sim.okawa-denshi.jp/en/CRlowkeisan.htm
I wouldn't put an RC filter on the speaker either. If you're using a chip amp, you can probably build the filter into that easily enough.

[ashcat_lt]

Duct tape.

[GibsonGM]

If you put that between the amp and the speakers it's going to waste a whole lot of power in that resistor and you won't hear much sound at all!
Your filter would work if you placed it before the power amp, though this means that it doesn't mitigate the nasty sound of the power amp's clipping if you drive it too hard.

You'll probably get better results by coiling up 20 meters or so of magnet wire and just wiring it in series with the speaker(s). If you want to get a bit more fancy you can make it a second order filter with an additional capacitor in parallel with the speaker.
You'd be aiming for 500microhenry to 1mH for the inductor, probably around 5microfarads for the capacitor. You can do some math and such to work out the exact crossover points.

+1 I didn't really process the 'between the amp' thing...yeah, you need this in a position that will do more than just 'suck power away', as suggested.