Adding a Sub output... sum the two inputs?

[PaulHilgeman]

I am thinking of adding in a Sub output coming from my gainclone amplifier. Do I simply sum the L and R inputs with a simple opamp circuit?
Thanks,
-Paul

 

[PaulHilgeman]

Or do I use an 'averager'?

 

[GringoAudio]

Use a mixer with Low pass filter

There are lots of Mixer designs on the net. They use summing into an opamp. Just add a low pass filter network on the front end of the mixer and voila you have your mono LOW only output for a Sub amp. For example (but not inluding the lowpass stuff)
http://litec.rpi.edu/LITEC_Tutorials_3_7/Hardware/Chips/Op_Amp__Mixer.html

 

[PaulHilgeman]

How does this look for a dipole sub equalization with the notch filter in it?

-Paul

 

[Helix]

dont you reduce channel seperation with that?

 

[GringoAudio]

Why a notch?nt

 

[PaulHilgeman]

I want to sum the channels so taht I get both L and R coming out of the single sub


The notch is because of the resonance that occours due to the 'D' from the front radiating area to the back. It will create a peak at 290 Hz with the enclosure that I am using.

-Paul

 

[carlmart]

I want to sum the channels so taht I get both L and R coming out of the single sub


The notch is because of the resonance that occours due to the 'D' from the front radiating area to the back. It will create a peak at 290 Hz with the enclosure that I am using.

Yes, what you need is a circuit that mixes both channels and puts a low pass filter to leave out everything that is not los frequency.

You do that before going into the power amp, of course, and you use just one amp as I think you know, and you do this crossover after the preamp or source output.

Why do you want to create a peak?


Carlos

 

[GringoAudio]

Low pass pole at 100 hz or lower for Sub

Make the pole of your Low pass filter at 100 Hz or lower for a sub and then you will have no problems at 290 Hz. It will simply not be there. 290 Hz is not in the realm of sub-bass. Hell its not even bass really. It s low midrange. Kill it.

 

[PaulHilgeman]

Yes, that is true, but this is only a 12dB/ octave low pass XO. If you cross out at 100Hz, that dosnt mean that everything above there is just gone. So if there is a 6dB peak at 290Hz, it will only be about 8 or 9 dB below reference due to the 12dB/octave 100hz XO.

That is why I need the notch.

-Paul