When creating a mono channel in a stereo summing unit it is recommended to do this by splitting the mono source, and via resistors connect to both left and right channels. Are these resistors used only to reduce the level to match the stereo tracks, or are they also needed to not compromise the L/R integrity?
I'm asking because in my design I have summed two mono signals together before they are to be split to the L and R busses, so the level may already be about right. If so, can I omit the usual resistors going to the L/R without inducing any problems?
Would be thankful for some input re this!
/T.
I'm asking because in my design I have summed two mono signals together before they are to be split to the L and R busses, so the level may already be about right. If so, can I omit the usual resistors going to the L/R without inducing any problems?
Would be thankful for some input re this!
/T.
Major requirement for resistors is to keep the two amplifiers driving the two different channels from blowing each other up fighting to produce different voltages. Resistors must be above the normal minimum resistance of the op amps or channels. 1 k minimum usually, 2 k better, 10 k totally safe.
If internally the two signals passes through any more amp stages, resistors on their outputs must be used to protect those amp stages too.
Voltage dividing to lower volume is an additional parameter not to mess (lower resistance by parallel rule) with the above protection.
I should have been clearer: this is a balanced 16 channel passive summing circuit that uses 10k input resistors and I will feed it with balanced line signals from EQ's, compressors and DAC's from my studio computer. I want to make a couple of the inputs mono, so this is about what is happening before the signal hits the input resistors of the summing unit.
Since these input resistors are in place there is already no shorting between the L and R channels, right?
I also thought that I could make a simple 3-way pan switch with something like 30% to the L, 30% to the R and a middle position, but by testing this found out that after the split of the mono signal, there need to be isolation between the L and R or I cannot reduce one channel without affecting the other... I think I need transformers for this (I don't want to start messing with OP amps).
What transformers should I get? Balanced signal, will I need four transformers then for one mono channel? Signal(+) and reversed(-) for both L and R side?
Thanks for the input so far!
/T.
Since these input resistors are in place there is already no shorting between the L and R channels, right?
I also thought that I could make a simple 3-way pan switch with something like 30% to the L, 30% to the R and a middle position, but by testing this found out that after the split of the mono signal, there need to be isolation between the L and R or I cannot reduce one channel without affecting the other... I think I need transformers for this (I don't want to start messing with OP amps).
What transformers should I get? Balanced signal, will I need four transformers then for one mono channel? Signal(+) and reversed(-) for both L and R side?
Thanks for the input so far!
/T.
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