Hello,
hello I have built this circuit and another with similar output mixing and am looking for an alternative to the current output mixing on this schematic.
the reason being its is harder to dial in the best impedance range on both channels with one balance pot.
I was thinking maybe to remove the pot and have two individual controls though i know in that position they will still effect each other and probably drag the other signal to ground where the resistance is least?
Possibly looking at a way to maybe control the gain individually on each half of U2 that wont effect the other halves output signal strength or maybe adding an attenuation pot at each return before the output op?
any ideas or scribbles would be great thanks
hello I have built this circuit and another with similar output mixing and am looking for an alternative to the current output mixing on this schematic.
the reason being its is harder to dial in the best impedance range on both channels with one balance pot.
I was thinking maybe to remove the pot and have two individual controls though i know in that position they will still effect each other and probably drag the other signal to ground where the resistance is least?
Possibly looking at a way to maybe control the gain individually on each half of U2 that wont effect the other halves output signal strength or maybe adding an attenuation pot at each return before the output op?
any ideas or scribbles would be great thanks
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Why do you care what Impedance?
If you do really care, then reduce the pot to like 5K (the opamps will easily pull that), then add the desired resistance after it.
If you don't like that more of one forces less of the other; then yes, you want two pots.
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> why only one return path uses a jfet?
A simple opamp stage is a better input than a JFET.
However, one path needs an optional polarity flip. That flipper works good, except it is a not-so-good input (impedance can be low). So add another opamp? That makes five. There are dual and quad opamps, no quint-amp package. Add another chip? This designer felt a JFET was better.
A simple opamp stage is a better input than a JFET.
However, one path needs an optional polarity flip. That flipper works good, except it is a not-so-good input (impedance can be low). So add another opamp? That makes five. There are dual and quad opamps, no quint-amp package. Add another chip? This designer felt a JFET was better.
Hi
There is a simpler solution: Just use a single opamp wired as a virtual-earth mixer. This inherently isolates the input signals and if the impedance of the inputs matters that much they can be made to look different. Further, you can replace part of the resistance of the two input Rs with a linear pot with its wiper tied to the mixing node. panning one way emphaszes that input; panning the other way emphasizes the other input.
Do you really need mixing instead of switching? Switching is a lot easier to do.
There is a simpler solution: Just use a single opamp wired as a virtual-earth mixer. This inherently isolates the input signals and if the impedance of the inputs matters that much they can be made to look different. Further, you can replace part of the resistance of the two input Rs with a linear pot with its wiper tied to the mixing node. panning one way emphaszes that input; panning the other way emphasizes the other input.
Do you really need mixing instead of switching? Switching is a lot easier to do.
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