April 23, 2006

DIY Passive Summing Mixer...

by Chris Randall

So this fellow on Gearslutz by the name of Mitchell decided to make himself a passive summing mixer. This flavor of summing has no make up gain; you use mic pres to bring the level back to line; in this manner you can determine the color of the summing. (The Rolls Folcrum follows this line of reasoning.)

Anyways, there are many more pictures in the pertinent thread. This is actually, as you'll see from the interior shots, a fairly simple project. A lot of wiring, to be sure, but nothing terribly complicated.




Apr.23.2006 @ 11:36 AM
That's very cool looking. The schematic he linked to was all very straightforward.

Shame he seemed to avoid requests for sound clips though in that thread, would be good to hear what it gives to the sound.


Apr.23.2006 @ 3:02 PM
A passive summing mixer is just about the easiest electronic project you can build (in terms of circuitry).

I have built them before, not because they are desirable, but because I am not very good with electronics and they were an easy way to solve the problem. (I created a device with a bunch of old cassette walkmans I got for $10 a piece, mixed together, with the sound being triggered by pressure on a metal plate, which created a percussion "envelope" of sorts on the signal, and then mixed together with a passive suimming mixer... the project only required lots of wire, and several resisters, so i. I put a bunch of weird sounds and noise on looped cassettes... and had a wierd kind of mellotron styled percussion sampler. If that sounds cool to you, it didn't work that well, but I was a broke high school kid, and real samplers cost a lot of money back then. It definitly wouldn't be a worthwile project nowadays).

But back on topic, I don't know what the real appeal to a passive summing mixer is, other than it is easy to build. Maybe there is some niche use for it that I am not knowledable enough to know about, but a google search doesn't turn up much, other than some people want them for mixdown into digital (but, I don't nessisarily see why a passive mixer is better than a real mixer set to sound "dry").


Apr.23.2006 @ 3:32 PM
Chris Randall
Technically speaking, pretty much every mixer out there is a passive mixer; at least, the summing buss is. In this particular context, we're talking about summing mixers that are used for summing stems from a DAW. There are many resources out there on this particular subject, which is certainly a matter of taste and personal experience. You're searching the wrong way, though. You want to search for things with titles like "ITB vs. OTB" and similar.



Apr.23.2006 @ 9:39 PM
Meestor RexRhino...

I'm the guy who built it... the reason I built it was so I could externally sum stems from my audio system, instead of internally bouncing. It's a hotly debated topic, but it definitely sounds better to my ears. The reason you might not want to use your mixer for this is that you might own a mixer that says something like "Mackie" on it and is full of a zillion cheap IC's and op amps that don't sound so swell. My passive summer has nothing but metal-film resistors in the circuit path, and it then gets it make-up gain from my Langevin Dual Vocal Combo which has really nice discreet transistor+transformer based mic pres.

On my budget, it was the easiest thing I could do to make mixes sound nicer.

mitchell sigman




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