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

PaulHilgeman · 24th February 2003, 09:00 PM

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 · 24th February 2003, 09:22 PM

Or do I use an 'averager'?

GringoAudio · 24th February 2003, 09:42 PM

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...mp__Mixer.html

PaulHilgeman · 24th February 2003, 09:53 PM

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

-Paul

Helix · 24th February 2003, 09:59 PM

dont you reduce channel seperation with that?

GringoAudio · 24th February 2003, 10:52 PM

PaulHilgeman · 24th February 2003, 11:30 PM

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 · 25th February 2003, 12:14 AM

Quote:

Originally posted by 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.

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 · 25th February 2003, 02:44 PM

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 · 25th February 2003, 04:51 PM

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

24th February 2003, 09:00 PM	#1
PaulHilgeman Account Disabled Join Date: Dec 2002	Adding a Sub output... sum the two inputs? 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

24th February 2003, 09:42 PM	#3
GringoAudio diyAudio Member Join Date: Oct 2007	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...mp__Mixer.html

24th February 2003, 10:52 PM	#6
GringoAudio diyAudio Member Join Date: Oct 2007	Why a notch?nt

25th February 2003, 02:44 PM	#9
GringoAudio diyAudio Member Join Date: Oct 2007	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.

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24th February 2003, 09:22 PM	#2
PaulHilgeman Account Disabled Join Date: Dec 2002	Or do I use an 'averager'?

24th February 2003, 09:59 PM	#5
Helix diyAudio Member Join Date: Jul 2001 Location: UK	dont you reduce channel seperation with that?

24th February 2003, 11:30 PM	#7
PaulHilgeman Account Disabled Join Date: Dec 2002	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

25th February 2003, 04:51 PM	#10
PaulHilgeman Account Disabled Join Date: Dec 2002	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

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