LR to SIDE encoder

hej!

i have been drawing on a passive balanced volume controller today and have been googling and thinking about how a mono sum and side encoder could look.

attached is an idea how a side encoder could work.

your thoughts?

Not sure if its any help to you but the Amek Bc3 has both a pan and an image control on the stereo channels ,the image control allows LR at one extreme, mono in the middle and RL at the other end of the travel , the panpot can also double as balance control depending on the mode you set , its very handy to have to check your mono compatibillity ,which is important for radio . Id imagine theres lots going on under the hood to make this all work ,might be a bit of a push to do it all passively.

yes the point is to check mono compability and also whats going on in the difference. no panning or stereo widthening etc.

the controler is fed from a main DA with an out Z of 50-150R.
volume is set by individual sets of matched O-pads with in/out impedance of 1K.
then enabling of mono sum and side is switchable
output goes to speakers/amps with in Z of atleast 10K

theres another way of doing the side but i just thought this was more minimalistic. see pic.

5v333 said:

hej!

i have been drawing on a passive balanced volume controller today and have been googling and thinking about how a mono sum and side encoder could look.

attached is an idea how a side encoder could work.

your thoughts?

Click to expand...

Side is a single signal that does L-R; your schemo shows two signals!...?
It can be done without any additional circuitry, provided the outputs are fully floating, which may not be the case with transformerless outputs.

5v333 said:

theres another way of doing the side but i just thought this was more minimalistic. see pic.

Click to expand...

That second one is more correct; it delivers a single signal and is less demanding on the output stage's CMRR.

abbey road d enfer said:

That second one is more correct; it delivers a single signal and is less demanding on the output stage's CMRR.

Click to expand...

ahh yes the cmrr could be good between hot and cold on one output but between L and R imbalance could possibly be what ever! so thats an achilles heel.

attached is the rest of the controler so far.

the volume attenuator is a 4deck 6pos switch with alot of matched resistors.

the attenuators are O-pads which is also a balanced PI-pad.

i was thinking about naming it "O-pi-um"

catchy?