I’ve attached a schematic with which I’ve had excellent assistance from Mooly on diyaudio.
He concluded that I am not breaking any rules and could not see any obvious electrical issues that would prevent it from working.
But it is not working. And I’ve triple-checked my wiring, checked continuity and discontinuity (what should be connected is and what should not be is not).
The aim of the device is mainly to produce three mono outputs from a stereo source:
1. a center channel (mono) output
2. an output consisting of what is unique to either of the stereo channel inputs
and
3. an output consisting of what is common to the stereo channel inputs
In addition, there is a switchable low-pass circuit that can be employed.
Function 1 is simple enough.
Function 2 should contain the sum of one of the stereo channels and the inverted other channel.
The input to this portion is regulated by a linear 2-gang potentiometer acting as a balance allowing the user to pan between the left and right.
For function 3 the outputs of 1 and 2 are combined in a differential circuit (much like done for function 2), essentially producing the opposite of function 2.
The (likely) source unit output is stated as 0.5 volts at 2.2K ohms.
What happens is:
1. The volume seems to be greatly reduced.
2. Neither function 2 nor 3 appears different from the input at all; it’s as if there was no circuitry in place.
3. The low-pass circuit does appear to have some effect.
4. SW2 is a “Break/Make” rotary switch. When I switch between any two positions slowly, thus not making the next connection there is a large squeal. Could someone explain? I didn’t think that an open connection would drive anything nuts.
The schematic and LF353P spec sheet are attached.
He concluded that I am not breaking any rules and could not see any obvious electrical issues that would prevent it from working.
But it is not working. And I’ve triple-checked my wiring, checked continuity and discontinuity (what should be connected is and what should not be is not).
The aim of the device is mainly to produce three mono outputs from a stereo source:
1. a center channel (mono) output
2. an output consisting of what is unique to either of the stereo channel inputs
and
3. an output consisting of what is common to the stereo channel inputs
In addition, there is a switchable low-pass circuit that can be employed.
Function 1 is simple enough.
Function 2 should contain the sum of one of the stereo channels and the inverted other channel.
The input to this portion is regulated by a linear 2-gang potentiometer acting as a balance allowing the user to pan between the left and right.
For function 3 the outputs of 1 and 2 are combined in a differential circuit (much like done for function 2), essentially producing the opposite of function 2.
The (likely) source unit output is stated as 0.5 volts at 2.2K ohms.
What happens is:
1. The volume seems to be greatly reduced.
2. Neither function 2 nor 3 appears different from the input at all; it’s as if there was no circuitry in place.
3. The low-pass circuit does appear to have some effect.
4. SW2 is a “Break/Make” rotary switch. When I switch between any two positions slowly, thus not making the next connection there is a large squeal. Could someone explain? I didn’t think that an open connection would drive anything nuts.
The schematic and LF353P spec sheet are attached.
