PISSbox - Real time noise cancelation (Page 2 of 4)

Yes.  You have to pan everything to one side.  Also, this may not be obvious, but it only works on stuff with stereo output.
In almost every live setting your signal would be summed to mono anyway.

Yeah, and shitty iron. Those "pegs" sticking out of the solder joints are a tell-tale sign of this. I can't stand a 30 W iron that looses its heat as soon as you touch a joint. You need a reasonable quality temperature controlled iron. Something like a Weller or a Hakko. Of course, a lot of it is technique, like preheating the component before applying the solder, applying flux if needed or using flux core wire as well as keeping the tip clean. My preferred method for this is using a brass sponge, rather than a wet sponge.
^ Soldering micro tutorial

Anyway, if I'm understanding this correctly, it's a center tap transformer, where you drive the outer sides with left and right. A couple of thoughts: This is a double sided board right? I'm almost certain it could be optimized to use only one side. However, this probably wouldn't be much use since the jacks you're using are SMD and you want all components on the same side. Are the two sides of the transformer galvanically isolated? This could be an added benefit from using this circuit, if designed properly. Yet another, more expensive idea (both in terms of components and design) is to make the circuit active by using an opamp as a differential amplifier, driven by phantom power.
Or, yet another idea (Sorry for killing this darling early by thinking for a minute) hook up a 3.5 mm jack so that it connects to a balanced input. I guess this is as simple as using a 3.5 mm -> 6.35 mm ("1/8" -> 1/4) stereo cable, given that the mixer has a 1/4 in balanced input jack. So there you go...

My point about single sided boards is that when you have a heavy component like a transformer, you want to place the component on the opposite side of the copper, for mechanical stability. If you have it on the same side, the weight from the transformer could lift off the copper.from the board. So for a single sided board, this limits your choices to having the jacks (SMD) on the opposite side to the transformer.

Anyway, see my idea about galvanic isolation, i.e. not connecting the two sides of the transformer.

Or, replicating basically the same effect as this mod by connecting the stereo output to a balanced mixer input.

save one for me!

HA!  Oh fucking shit, yeah that works too.  Fuck. 

I"ve been trying understand "transformer isolated" but since the transformer is before the summing resistors I didn't think it would be a benefit?

OH so this is a single tap transformer that you're using just as an inverter. Then there's the risk that you'll get a phase difference and/or difference in amplitude between the positive and negative signal. And the tranformer is sensitive to picking up certain noise. In the end, you may get more noise than you started out with.

I'm having difficulty reading the schematic from the board. In part because I can't see the bottom side, in part because the solder mask makes it difficult to see the traces. For example, I can't see that jack one is connected anywhere at all (except for to the big ground plane). No traces as far as I can see, and no vias to the other side. Would you mind providing the schematic?

The possbile amplitude difference is why the pot is on there.
As for the phase differrence, the signals are EXTREMELY close to nulling out completely with the units I've built so I don't think that's an issue (I have to turn every gain I have all the way up to detect anything at all).
Don't know if the transformer might pick up anything else.  I've got cables and amps and crap running all over my workspace and I haven't experienced that.