I need a very simple mixer

Lorenzo · Posted: Mon Feb 10, 2014 11:59 am Post subject: I need a very simple mixer

Hi,
I need a simple mixer to mix 2-3 mono lo-fi audio signals.
I need 2-3 line input and the chance to adjust the output volume.
maybe 9v battery...

can you suggest me some schematics?

Actually I made a bodge solding 2 cables in one ouput... it works but... Embarassed

Thank you!

PHOBoS · Posted: Mon Feb 10, 2014 12:25 pm Post subject: Re: I need a very simple mixer

You might be able to get away with a passive mixer dependig on the level of you signals. Just an attenuator on every input tied together with 1K resistors.
Or you could use the attached schematic for an active mixer. (you can add attenuators on the inputs for level control if you want)

mixer (single power, virtual ground).gif

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basic single supply mixer

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Lorenzo · Posted: Mon Feb 10, 2014 12:38 pm Post subject: Re: I need a very simple mixer

PHOBoS · Posted: Mon Feb 10, 2014 1:28 pm Post subject:

It should work fine on a 9V battery Cool

(and you can leave out the 100 ohm resistor or better place it before the diode)

Lorenzo · Posted: Mon Feb 10, 2014 3:32 pm Post subject:

thank you so much!

Dave Kendall · Posted: Wed Feb 12, 2014 1:28 pm Post subject:

You might want to check out the TL061 - it uses quite a bit less current than the TL071, at the expense of some slight increase in noise. In practice any extra noise was not noticable in the one I built for a guitarist, and the batteries last a lot longer.

A couple of notes - the Orman circuit uses a 150K resistor in the opamp's feedback loop to give some amplification when the output level is turned up all the way. If you don't need that, then replacing the 150K with a 100K will give unity gain at the output.

The circuit also has an inverted output - this may not be a problem. If it is, then simply use a TL062, and wire the second opamp to the output of the first, before the 10uF cap, with a 100K series resistor into the - input, and a 100K resistor from the output to the - input. Tie the + input of the second opamp to the same point as the + input on the first opamp. This is the classic dual inverting mixer.

cheers,
Dave

Lorenzo · Posted: Mon Feb 17, 2014 12:06 pm Post subject:

JingleJoe · Posted: Thu Feb 20, 2014 11:55 am Post subject:

I was going to suggest what phobos was saying so I'll add this:

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Lorenzo · Posted: Sat Feb 22, 2014 2:55 am Post subject:

PHOBoS · Posted: Sun Feb 23, 2014 4:20 am Post subject:

JingleJoe · Posted: Tue Mar 11, 2014 1:21 pm Post subject:

that^ right there is how i do most of my signal mixing, nice depiction phobos Wink

you can use different value resistors aswell, to weight the different channels so one input could be louder or quieter Smile

Lorenzo · Posted: Tue Mar 25, 2014 6:02 am Post subject:

col2 · Joined: Feb 15, 2014 Posts: 3 Location: Melbourne Australia

Iv'e used Circuit 3 from this site.

http://www.all-electric.com/schematic/simp_mix.gif

works very well!