Simple line mixer designs

[Jean-Yvan Fradet]

I have very basic knowledge in electronics.

I am currently looking to build myself a passive simple line mixer. This
is why I read carefully the two pages from Tomi Engdhal at
http://www.tkk.fi/Misc/Electronics/circuits/linesum.html and
http://www.tkk.fi/Misc/Electronics/circuits/linemixer.html. These were
of great interest.

But it raised a few questions. In the section titled "Can I mix more
than two outputs with this kind of circuit ?", Mr Engdhal wrote : "You
you can expand this circuit to more channels if you add one resistor and
one input connector for each new output. Connect them to the circuit in
the same way as the existing inputs.".

If I understood well, a simple line mixer with 3 inputs and 2 outputs
should then look like this :

INPUT 1 -------\/\/\/\---+
---+ R1 10K +------------ OUTPUT 1
| | +----
INPUT 2 -------\/\/\/\---+ |
---+ R2 10K +------------ OUTPUT 2
| | +----
INPUT 3 -------\/\/\/\---+ |
---+ R2 10K |
| |
| (shields) |
+---------------------+

Since my project is to create a passive simple line mixer with 3 inputs
and 3 outputs, I assumed it should look like this :

INPUT 1 -------\/\/\/\---+
---+ R1 10K +------------ OUTPUT 1
| | +----
INPUT 2 -------\/\/\/\---+ |
---+ R2 10K +------------ OUTPUT 2
| | +----
INPUT 3 -------\/\/\/\---+ |
---+ R2 10K +------------ OUTPUT 3
| +----
| (shields) |
+---------------------+

But after reading a few other articles, I guessed it could also look
like this :

INPUT 1 -------\/\/\/\---+
---+ R1 10K +---\/\/\/\-------- OUTPUT 1
| | R1 10K +----
INPUT 2 -------\/\/\/\---+ |
---+ R2 10K +---\/\/\/\-------- OUTPUT 2
| | R1 10K +----
INPUT 3 -------\/\/\/\---+ |
---+ R2 10K +---\/\/\/\-------- OUTPUT 3
| R1 10K +----
| (shields) |
+---------------------------+

My goal is to be able to select to which output a signal would be sent
to. Should it then look like the image below (where -./_- is a switch to
select an output) or with additional resistances before each outputs ?

+--./_--------+
| |
INPUT 1 -------\/\/\/\--+--./_-----+ |
---+ R2 10K | | |
| +--./_--+ | +------ OUTPUT 1
| | | | +---
| | | | | |
| +--./_--------+ |
| | | | | |
INPUT 2 -------\/\/\/\--+--./_-----+ | |
---+ R2 10K | | | | |
| +--./_--+ +--------- OUTPUT 2
| | | | +---
| | | | | |
| +--./_--------+ |
| | | | |
INPUT 3 -------\/\/\/\--+--./_-----+ |
---+ R2 10K | | |
| +--./_--+------------ OUTPUT 3
| +---
| (shields) |
+-----------------------------+

Thanks in advance for your help. And please remember in your responses
that I have very little knowledge in electronics.

Jean-Yvan

 

[Stanislaw Flatto]

I have very basic knowledge in electronics.

I am currently looking to build myself a passive simple line mixer. This
is why I read carefully the two pages from Tomi Engdhal at
http://www.tkk.fi/Misc/Electronics/circuits/linesum.html and
http://www.tkk.fi/Misc/Electronics/circuits/linemixer.html. These were
of great interest.

But it raised a few questions. In the section titled "Can I mix more
than two outputs with this kind of circuit ?", Mr Engdhal wrote : "You
you can expand this circuit to more channels if you add one resistor and
one input connector for each new output. Connect them to the circuit in
the same way as the existing inputs.".

If I understood well, a simple line mixer with 3 inputs and 2 outputs
should then look like this :

INPUT 1 -------\/\/\/\---+
---+ R1 10K +------------ OUTPUT 1
| | +----
INPUT 2 -------\/\/\/\---+ |
---+ R2 10K +------------ OUTPUT 2
| | +----
INPUT 3 -------\/\/\/\---+ |
---+ R2 10K |
| |
| (shields) |
+---------------------+

Since my project is to create a passive simple line mixer with 3 inputs
and 3 outputs, I assumed it should look like this :

INPUT 1 -------\/\/\/\---+
---+ R1 10K +------------ OUTPUT 1
| | +----
INPUT 2 -------\/\/\/\---+ |
---+ R2 10K +------------ OUTPUT 2
| | +----
INPUT 3 -------\/\/\/\---+ |
---+ R2 10K +------------ OUTPUT 3
| +----
| (shields) |
+---------------------+

But after reading a few other articles, I guessed it could also look
like this :

INPUT 1 -------\/\/\/\---+
---+ R1 10K +---\/\/\/\-------- OUTPUT 1
| | R1 10K +----
INPUT 2 -------\/\/\/\---+ |
---+ R2 10K +---\/\/\/\-------- OUTPUT 2
| | R1 10K +----
INPUT 3 -------\/\/\/\---+ |
---+ R2 10K +---\/\/\/\-------- OUTPUT 3
| R1 10K +----
| (shields) |
+---------------------------+

My goal is to be able to select to which output a signal would be sent
to. Should it then look like the image below (where -./_- is a switch to
select an output) or with additional resistances before each outputs ?

+--./_--------+
| |
INPUT 1 -------\/\/\/\--+--./_-----+ |
---+ R2 10K | | |
| +--./_--+ | +------ OUTPUT 1
| | | | +---
| | | | | |
| +--./_--------+ |
| | | | | |
INPUT 2 -------\/\/\/\--+--./_-----+ | |
---+ R2 10K | | | | |
| +--./_--+ +--------- OUTPUT 2
| | | | +---
| | | | | |
| +--./_--------+ |
| | | | |
INPUT 3 -------\/\/\/\--+--./_-----+ |
---+ R2 10K | | |
| +--./_--+------------ OUTPUT 3
| +---
| (shields) |
+-----------------------------+

Thanks in advance for your help. And please remember in your responses
that I have very little knowledge in electronics.

Jean-Yvan

Looking at your suggestions I see a fundamental error. In all diagrams
you have the outputs connected directly (or through switches) to a
single connection where the inputs are 'mixed' by the resistor "mixer".
So you have one point in your design where the inputs combine and how
you extract this info is another story. Resistors in outputs will not
segregate the signals but filters would.

HTH

Stanislaw.