Questions on a mixer module for my lunetta

Draal

Can't help but seem noobish on this one, but I'm having trouble visualizing my mixer module. Here's a snippet from Beavis' site. Would this be a good template to follow? I assume I keep the diodes there to keep signals from bleeding together?

If anyone has other layouts/advice for a simple mixer it would be appreciated.

Draal

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-minus- · Joined: Oct 26, 2008 Posts: 787 Audio files: 13

Ah, yes. I built a passive mixer last year. Looks similar to the one you have posted. Here's a link to the DOD Resistance mixer I built:

http://web.archive.org/web/20060630001422/http://geocities.com/worthekik/mixer.html

It's been a very handy device and ultra simple to make. It is the only mixer I have! The only criticism of it is I have problems when plugging this 808 kick drum clone into it. It works, but when I adjust the volume on any of the mixer pots I get a static crackle when they are turned. It doesn't do it when i use anything else BUT the 808. I think it could be that the 808 it +/- 9V and it's having some sort of issue with the other devices... OR it's an inherent problem with the 808 itself.

I think if I used diodes as your schematic does, it may solve this problem. I just haven't got around to fiddling with it yet! The mixer I have linked to and built would be something I will be making for my Lunetta. Either this or one from Ray's Music from Outer Space:

http://www.musicfromouterspace.com/analogsynth/monomixerpage.html

http://www.musicfromouterspace.com/analogsynth/AAA_AudioMixerIndex.php?page=ANALOG

The panning mixer on the link above looks like fun!

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concretedog · Joined: Jun 25, 2010 Posts: 15 Location: UK

I built a passive mixer a while ago thats exactly the same idea as the DOD layout link that minus posted. Really useful little mixer to have around for sure. I got my layout for it from Nic Collins book "Electronic Music, The Art of Hardware Hacking" which has many useful bits in it.

Draal · Posted: Thu Jul 01, 2010 4:21 am Post subject:

Thanks guys! With a new baby coming in 11 days, Keeping it Simple is my new motto. I have to get this lunetta up and running pronto! Laughing

-minus- · Joined: Oct 26, 2008 Posts: 787 Audio files: 13

Build like mad Draal!!! You know how babies can turn your life upside down! Anyway, I won't hold you up.... you have soldering to do! Good luck with the birth too. Thought of any names yet? How about Lunetta for a girl... or CMOS for a boy. Just a thought.... Smile

Draal · Posted: Thu Jul 01, 2010 4:59 am Post subject:

It's going to be a boy...maybe Stan? Now to only convince the wife Wink

!

concretedog · Joined: Jun 25, 2010 Posts: 15 Location: UK

With a 12 week old and a 3 year old...fast lunetta hacking is a must for me also...
I reckon XOR or NAND are good names too!

RF · Posted: Thu Jul 01, 2010 5:45 am Post subject:

Inventor · Posted: Thu Jul 01, 2010 9:52 am Post subject:

I had a cat named CMOS once. She was black and white in color and very intelligent.

Les

-minus- · Joined: Oct 26, 2008 Posts: 787 Audio files: 13

I can see you with a cat named Cmos, Les!

... Did she have 14 or 16 legs? Smile

Draal · Posted: Thu Jul 01, 2010 5:53 pm Post subject:

This thread has giving me a a good laugh Laughing

. Thanks fellas!

Inventor · Posted: Thu Jul 01, 2010 7:35 pm Post subject:

Inventor · Posted: Thu Jul 01, 2010 7:38 pm Post subject:

adamon · Posted: Thu Jul 01, 2010 9:27 pm Post subject:

Hey Draal, try using resistors instead of diodes for a different effect (all the same value). Diode summing tends to get crunch and produces a lot of nice stuff when you're mixing high frequencies. Resistor summing will produce smoother mixing; each voice will stand better on its own in the mix. I've made both versions for my system as I find both enjoyable/useful for different things (of course you can always just use switches to choose either diode or resistor summing).

If you opt for the resistor summing, you may have to play around with values of resistors and pots to keep channels from cutting other ones out when one is turned all the way down (this gave me trouble for a while; eventually I ended up using 10k resistors with 100k pots, and that works well enough). I also use 0.1uf caps for each channel (in line with the resistors) to keep the frequencies from getting shifted when the pot is turned all the way up (not sure exactly why this happens, but the caps seem to take care of it... I need to review my old circuits stuff...).

Good luck!

Draal · Posted: Fri Jul 02, 2010 4:45 am Post subject:

Thanks adamon, I'll be using 100k pots so your tips on that and the resistor/cap values are very helpful.

tjookum · Posted: Fri Jul 02, 2010 5:19 am Post subject:

richardc64

Inventor

Inventor · Posted: Fri Jul 02, 2010 7:57 am Post subject:

adamon · Posted: Fri Jul 02, 2010 9:14 am Post subject:

richardc64, thats why I suggested using a 10k resistor in line with the input. There is still a slight drop in output when one is all the way down, but its minimal enough for me. Any bigger and the overall output starts to get too low (thats with a 100k pot of course).

tjookum, I too started out with the goal of keeping everything simple and powered off a single supply. I would suggest you try out the basic version I've described above; it's worked quite well for my system. One thing to note, if you're using diodes (say 1N914), you won't run into the same problem of cutting channels out when one pot is turned all the way down. Try the following:

input jack -> 100k pot -> diode -> sum all channels -> 100k pot -> output

(the diodes prevent any lower ground from being reached on the first 100k pots)

My wiring for the resistor summing mixer is as follows:

input jack -> 0.1uf cap -> 100k pot -> 10k resistor -> sum all channels -> 100k pot -> output

Ajax · Joined: Apr 05, 2010 Posts: 63 Location: San Francisco

tjookum · Posted: Fri Jul 02, 2010 12:16 pm Post subject:

adamon · Posted: Sat Jul 03, 2010 9:15 am Post subject:

Just remember to put the resistor and/or diode after the first pot (not before, or you won't be blocking the ground created by the pot turned all the way down).

Ajax, I'm not sure what exactly would be going on with your setup to cause that sort of interaction. Diode summing will definitely make the voices cut into eachother quite a bit (intead of "beating" they just kind of cut eachother in and out). You should get more clean mixing with the resistor summing route. Make sure you've got your pots wired up right, and that the resistors are after the pots.

Mikmo · Posted: Sun Jul 04, 2010 12:09 am Post subject:

I build a number of these:

http://www.generalguitargadgets.com/content/view/68/26/

very simle build, runs fine from 9V (even 9V battery).

The design can easily be expanded to more channels, i build both a 6 and a 8 channel version.

-minus- · Joined: Oct 26, 2008 Posts: 787 Audio files: 13

That looks like a great little mixer! I shall be breadboarding one up tonight if I get the time. Thanks for posting that. I think if this works (which I believe it will), I shall be using this in my Lunetta. Unless of course anyone else has some other suggestion...