This is a design for an active ABY pedal with the option to mix the A and B signal with a second switch. The signal is completely buffered.
SW1 toggle between A and B changing the color of a 2 color LED.
SW2 Activate the A and B mixing option. it will mix the 2 signals.
The switching is not by changing the path like a passive true bypass ABY box but by sending one signal to ground (muting one).
The Extra opamp is used as a buffer for Vref (1/2 Vsupply).
SW1 toggle between A and B changing the color of a 2 color LED.
SW2 Activate the A and B mixing option. it will mix the 2 signals.
The switching is not by changing the path like a passive true bypass ABY box but by sending one signal to ground (muting one).
The Extra opamp is used as a buffer for Vref (1/2 Vsupply).
Last edited:
That's certainly an unusual design to have such a low input impedance. Did you design it to be used at the output of a pedalboard?
If that means you are actually planning to plug a guitar into it, I think you need to substantially redo the design so that the opamps are non-inverting for higher input impedance, and also you need to terminate the inputs so it doesn't oscillate. Don't reinvent the world; look at a published ABY design.
I'm sorry, that makes no sense to me. Are you basing this on an inverting mixer schematic? Mixers don't have to invert. Better to just take an ABY schematic and modify as needed.
From: "https://sound-au.com/articles/audio-mixing.htm"
"3.0 - Active Mixing
The biggest issues with passive mixing are interaction between channels, crosstalk (important for stereo mixers) and noise. The voltage from each channel is attenuated by the number of channels plus one - so a 24 channel mixer has a signal attenuation of 25 for each individual channel. 1V input gives a 40mV output for a single channel. While this is not a major issue because a low noise amplifier can recover the signal easily, interaction and crosstalk cannot be tolerated in a professional mixer.
Imagine the result of using a passive mixer, but rather than simply connecting the mix resistors together, they are all connected to earth (ground). Crosstalk is no longer possible because the mix output voltage is zero. Likewise, interaction is equally impossible because all mixed signals are shorted to earth. Shorting out the mix bus (to earth/ ground) is not useful, but what if we could use a virtual earth that could make use of the current flowing from each mix resistor?
Active mixing relies on exactly that principle. The idea is to use a current amplifier (aka transconductance amplifier), with an input impedance of close to zero ohms. The amplifier relies only on the current through the mixing resistors, and because the mixer amplifier is a virtual earth (hence the name 'virtual earth mixer'), there can be no crosstalk or interaction between channels. Each input resistor connects to the virtual earth, so there is almost no voltage present at the mixing point."
That's very nice, but you're not even truly mixing in your proposed schematic, you are just summing A and B. None of what you are worrying about even applies.
That circuit is a well know form of mixer with opamps. You get reduce vol using the non inverting input.
Here is the AMZ jack orman mixer.
But what does that have to do with your circuit? Is either of your 2 inputs comprised of multiple instruments? If not, it is simply irrelevant.
Most ABY switchers are intended to switch one instrument between two amps or into both at the same time...what are you trying to do with this?
Mike
Mike
Hahaha ok ok. I did not Understood the assignment. Then...
Same concept 1 Guitar to Two Amps.