Hello Everyone,
To add on to my newbness from yesterday, I have one other part of my design that I am not sure what's going on. I have some suspicions but thought you guys probably could spot it pretty quickly or at least probe at me to look at it differently. I have again attached a setup below. I have multiple audio signals that I have coming into multiple summing amplifiers. Application wise, you can think about headsets. You want your audio to go to everyone else but not to your own channel. I found some information online about summing amplifiers and I thought that I could just leverage that to work the way I want. Probing the design, I fear that what I am seeing is a cascading effect from each amplifier but maybe its something else.
Let's assume all the resistor are the same value so everything is equal for the signals and the feedback. The thought process was to map the signals to combine them into the other channels except its own headset channel.
I put this into LTSpice to get an idea on what should happen. Once I received the circuit I just put in a simple sinewave into one channel to see if the mixers were working for the output. I measured the output and no sine wave. The mixer essentially made the signal disappear. The sinewave comes from a function generator and goes through some preamp and filters before it gets to here. After the filters, I have a sinewave that is about 230mV peak to peak at a frequency of 300Hz. This is not a DC biased signal. That would be the audio input signal in this case. In the simulation world, I would suspect the inverse of that waveform on the output.
Each amplifier should be getting the same signal but since these signals are tied to other amplifiers, is this a no no? That is what I am thinking. If so, what is the best way to isolate the signals and amplifiers to sum these channels like this?
To add on to my newbness from yesterday, I have one other part of my design that I am not sure what's going on. I have some suspicions but thought you guys probably could spot it pretty quickly or at least probe at me to look at it differently. I have again attached a setup below. I have multiple audio signals that I have coming into multiple summing amplifiers. Application wise, you can think about headsets. You want your audio to go to everyone else but not to your own channel. I found some information online about summing amplifiers and I thought that I could just leverage that to work the way I want. Probing the design, I fear that what I am seeing is a cascading effect from each amplifier but maybe its something else.
Let's assume all the resistor are the same value so everything is equal for the signals and the feedback. The thought process was to map the signals to combine them into the other channels except its own headset channel.
I put this into LTSpice to get an idea on what should happen. Once I received the circuit I just put in a simple sinewave into one channel to see if the mixers were working for the output. I measured the output and no sine wave. The mixer essentially made the signal disappear. The sinewave comes from a function generator and goes through some preamp and filters before it gets to here. After the filters, I have a sinewave that is about 230mV peak to peak at a frequency of 300Hz. This is not a DC biased signal. That would be the audio input signal in this case. In the simulation world, I would suspect the inverse of that waveform on the output.
Each amplifier should be getting the same signal but since these signals are tied to other amplifiers, is this a no no? That is what I am thinking. If so, what is the best way to isolate the signals and amplifiers to sum these channels like this?
