Is it possible to sum two mono signals into one stereo?

Are we talking abot the same music track??
And why would you??
Mono means just ONE channel. You can play it on a 15 channel surround system, but you will have every speaker playing the
exact same ting. Maybe I misunderstand you, but I can´t seem to find a reason for you question ;)
 
Just use an RCA Y connector. Mono input RCA jack to two RCA plugs. Also most legacy audio amps and receivers like from the 70s and 80s have a mono switch which will do what you want with a single input.

Newer home theater AV receivers have DSP modes that can simulate stereo from a mono source. But there still is no substitute for a true stereo recording.
 
  • Like
Reactions: 1 user
Moderator
Joined 2011
Wanted to do this passively, DIY. Is it even possible? If yes, do i need resistors of some kind, somewhere?

Technically, two different mono signals played simultaneously (one per channel) ARE one stereo signal.
Many early stereo recordings were made in a similar way.

But if you add them together first, and input the mono result into both channels, you just have virtual center mono,
which is inferior to true one channel/one speaker mono, due to the inherent acoustical problems.

Are you trying to blend separate channels of a voice and an instrument, for example?
 
Last edited:
Member
Joined 2011
Paid Member
Sure, you could use a dual-gang potentiometer (I suggest 100K linear taper) to get
  • OUTPUT_left = (rot% * INPUT_a) + ((100 - rot%) * INPUT_b)
  • OUTPUT_right = ((100 - rot%) * INPUT_a) + (rot% * INPUT_b)
A few delightful facts about this scheme:
  • when rot = 100% you get {OUTPUT_left = INPUT_a} and you get {OUTPUT_right = INPUT_b}
  • when rot = 0% you get {OUTPUT_left = INPUT_b} and you get {OUTPUT_right = INPUT_a}
  • when rot = 50% you get the average of INPUT_a and INPUT_b on both left and right OUTPUTS
  • when rot = 25% you get {left = (25% * a) + (75% * b)} and {right = (75% * a) + (25% * b)}
Of course when INPUT_a and INPUT_b signals have very different magnitudes, the left and right output channels will also have different loudnesses. Which may not be desirable.

I'll let other members have the pleasure of drawing out the circuit schematic, it's pretty simple.
 
  • Like
Reactions: 1 user
Of course when INPUT_a and INPUT_b signals have very different magnitudes, the left and right output channels will also have different loudnesses. Which may not be desirable.

This can be addressed by using two beffer op-amp for input, use resistors at output to cobine both (simple way) or use another opamp as adder circuit,

Many circuits(schematics) are available online, search for "Mono to Stereo circuit" or "op-amp mixer circuit" or "op-amp adder circuit"
 
Sure, you could use a dual-gang potentiometer (I suggest 100K linear taper) to get
  • OUTPUT_left = (rot% * INPUT_a) + ((100 - rot%) * INPUT_b)
  • OUTPUT_right = ((100 - rot%) * INPUT_a) + (rot% * INPUT_b)
.......
This is wonderful :rofl::rofl::rofl:
Thread-starter obviously has no clue what mono or stereo really means and you hit the poor fellow with math model of possible interpretation oh his "question". Delightful !
Thank you Mark, you made my day :up:
 
Last edited:
Wanted to do this passively, DIY. Is it even possible? If yes, do i need resistors of some kind, somewhere?

Thanks.

In Stereo , Vocals, Intstruments are divided into two channels for eg. Drums in one channel, Keyboard in another, Vocal in both. Playing Mono is two speakers is not stereo.
If you have stereo amplifier when you connect mono input chances are there you will hear from one side not other (depending on cable & connector).
If you have two mono outputs connect these to L and R inputs of amplifer.. thats it .