Hey all, i am new to forum. I am trying yo build a passive box to sum 4 mono 3,5mm jack into 1 3,5mm jack . It all has potentiometer on each. Now;
Signal flowing on ch-1, but when i change other “empty” / “no signal flowing” channel’s pot the flowing channel’s level changes. Every channel has 2k resistor on middle leg of pot. Potentiometer’s are 10k value.
I know i will loose some signal. But need to figure that other resistor affecting system.
What to do?
Signal flowing on ch-1, but when i change other “empty” / “no signal flowing” channel’s pot the flowing channel’s level changes. Every channel has 2k resistor on middle leg of pot. Potentiometer’s are 10k value.
I know i will loose some signal. But need to figure that other resistor affecting system.
What to do?
Thanks, will try virtual earth, but couldnt find schematic for lm4890mm that i got. Newby here 🙂
There will always be interactions in a passive summer circuit. An op amp is required to build
a summing circuit where the input settings do not interact too much.
operational amplifier - Op-amp inverting summer - Electrical Engineering Stack Exchange
a summing circuit where the input settings do not interact too much.
operational amplifier - Op-amp inverting summer - Electrical Engineering Stack Exchange
Last edited:
Thanks for your replies, i figured that out but there is messy noise. I think i can not manage to ground the signal properly. How to solve that
I managed to do a circuit with tl072 on breadboard. But it works really loud humming and noisy. Am i doing sth wrong ?
Dual +- supply ? Try 10k Resistors.
The picture from Rayma shows 0V, but this is Your ground. You still need the + & - supply.
Unity gain Inverter added ? If not reverse speaker wires.
Shorting inputs to ground what happens ?
Are You using dual supplies ?
Pot cases grounded ?
Shielded or very short cables
Try 10k resistors.
What happens if You short the inputs to ground.
Try to learn here. Check the op-amp section. There is also a complete mixer project.
Elliott Sound Products - The Audio Pages (Main Index)
Pot cases grounded ?
Shielded or very short cables
Try 10k resistors.
What happens if You short the inputs to ground.
Try to learn here. Check the op-amp section. There is also a complete mixer project.
Elliott Sound Products - The Audio Pages (Main Index)
Powered opamp with 12v supply , + to pin8 , - to pin 4.
input to 2nd pin. 3rd pin to ground , 2.2 k resistor to feedback loop.
No inverter added.
Shorting input and ground if i am not recall wrong the signal lost. But when even no input
The opamp makes noise just with power pins inserted.
So +12V -12V & ground from the supply I presume, or just 2 wires + &- ?
What capacitors are You using on the PSU ?
I would try 10K for a start (loopback & mixing resistors)
Only 2 wires, +12 and negative side/ only 2 wires. It is normal dc adapter.
The link you gave me is great!! Thanks for that.