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 Forum index » DIY Hardware and Software » Lunettas - circuits inspired by Stanley Lunetta
Trying to design a Simple Active Mixer on sinlge voltage
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acidblue



Joined: Jun 26, 2009
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PostPosted: Thu Oct 14, 2010 2:51 pm    Post subject: Trying to design a Simple Active Mixer on sinlge voltage Reply with quote  Mark this post and the followings unread

I've done lots of googling and reading about op-amps and mixers.
Seems most mixers use dual voltage, +/-12-15v.
Trying to design one that uses single voltage.

Not sure if I got the virtual ground part correct.
Any insight would be appreciated.

This is what I have so far.


Mixer.ps
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rich decibels



Joined: Apr 01, 2010
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Location: Wellington, NZ
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PostPosted: Thu Oct 14, 2010 6:00 pm    Post subject: Reply with quote  Mark this post and the followings unread

http://www.beavisaudio.com/techpages/blocksfragments/

scroll down to the 'mixers' section.

excellent starting point, at least.
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Draal



Joined: May 18, 2010
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PostPosted: Thu Oct 14, 2010 7:55 pm    Post subject: Reply with quote  Mark this post and the followings unread

Check the active mixer (schematic 2) here:
http://www.all-electric.com/schematic/simp_mix.htm

I built it with a few changes. Read my progress from a thread I started a lil' while back. Page 2 has the schematic as well as my substitutions : http://electro-music.com/forum/topic-42776.html

Hope it helps Very Happy !

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acidblue



Joined: Jun 26, 2009
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PostPosted: Thu Oct 14, 2010 10:54 pm    Post subject: Reply with quote  Mark this post and the followings unread

Thanks..
So that will run on a single voltage?
Noticed it's called "virtual earth active mixer", if I read google correctly
A virtual ground is basically a voltage divider on the input,(+) to
cut the voltage in half.

Is that case here?
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Draal



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PostPosted: Fri Oct 15, 2010 5:17 am    Post subject: Reply with quote  Mark this post and the followings unread

Yep, it'll work on single supply. I've used it when I ran my lunetta on a 9 volt battery for a while and it's still loud and proud running on my new regulated 5 volt wallwart.

No bipolar stuff going on here. I have to be more awake to remember the concept of virtual earth though Laughing ! Scroll down to the active mixer section here; it explains it better than I can:
http://sound.westhost.com/articles/audio-mixing.htm

I think it's a very decent active mixer and pretty simple to build.

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acidblue



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PostPosted: Fri Oct 15, 2010 11:24 am    Post subject:   Reply with quote  Mark this post and the followings unread

Cool
Thanks.
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Top Top



Joined: Feb 02, 2010
Posts: 266
Location: California

PostPosted: Thu Oct 21, 2010 6:04 pm    Post subject: Reply with quote  Mark this post and the followings unread

General guitar gadgets mini mixer. Simple one chip mixer, works well.

If you want one with input gains (to plug in guitars or mics), I made a modified version, also with power regulation to run off of a wall wart without humming. If you don't need that and just want to run on a 9v battery, then omit the LM317 and caps/resistors connected to it, and hook the + of the battery to the line where the four 10k resistors are, and negative terminal to the bottom line, which is ground:


Posted Image, might have been reduced in size. Click Image to view fullscreen.

NOTE: if you build it, make those .47uF caps NON POLAR. That was a mistake.

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textual



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PostPosted: Fri Oct 29, 2010 9:29 am    Post subject: Reply with quote  Mark this post and the followings unread

I am using this design from Ray Wilson's site...
I have 2 mixers in my system and this works quite well. Any general op amp will work. I added pots for volume of each input. Log pots are better as well -linear gives less actual 'control' over the difference between loud and soft volumes...


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