Re: Simple line mixer designs

BobG a écrit :
On Aug 6, 3:50 pm, Jean-Yvan Fradet <jyfra...@xxxxxxxxx> wrote:
I am currently looking to build myself a passive simple line mixer.
===================================================
The 'mixing resistors' keep the low output impedance sources from
'loading down'
the adjacent output channel. Usually a mixer has a volume control to
be able
to actually control the mix. Are you mixing mono or stereo sources?
This design
is a 'passive' mixer. Next level up would use opamps to make a
lossless 'active'
mixer with master output level controls and some gain.

The original design is mono. But I intend to double the design to make
it stereo. I would simply double the channels and link all grounds
together. Buttons and eventual potentiometers would be double-channel
for that purpose.

Yes, I might add potentiometers before the R1 to R3 resistors to control
input level. The design for a passive stereo mixer with pots would then
look like the image at the following link :

http://www.geocities.com/jyfradet/images/Mixer2.png

Note that there is an error on this image. The potentiometers input
connections should be on pin 3 and output on pin 2. Ground remains on pin 1.

Also, I put a resistor after the switches. It would probably be better to put only one resitor before the divide to each output selection buttons...

Still, I need to know if I must add additional resistors or how this
design would be safe.

By the way, if you have a simple design for a do it yourself mixer with
opamps, I might as well go towards that solution.

But the idea behind my initial goal was to avoid adding power supplies
in the first place. It's ok if I lose signal level a bit or if noise is
generated from the resistors. The environment where the device will be
used is noisy anyways...

Jean-Yvan
.