Matrix Mixer

Talk about music gear for noise music

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xdugef
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Post by xdugef » Mon Jul 08, 2013 4:29 pm

just think backwards

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timdrage
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Post by timdrage » Mon Jul 08, 2013 4:40 pm

RJMyato wrote:just turn it upside down when you use it :twisted:
I'll have to stick it to the underside of the table and operate by touch :D

I can';t actually figure out what i even did wrong... I confused myself but piutting the pots orientated to the in and outputs differently to the diagram but i'm pretty sure i wired it up in a way that was electronically the same... possssibly this is supposed to represent the front of the pots and not the back...?! Image

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timdrage
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Post by timdrage » Mon Jul 08, 2013 4:42 pm

uahh i dunno, i got it backwards vs this at least:

Image

NoizeHack
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Post by NoizeHack » Mon Jul 08, 2013 9:13 pm

I just think of pots as middle is output and the sides are inputs and when you turn in the direction of what is on the side of the input you are turning towards that. or just use alligator clips to connect stuff to make sure it its the right direction before soldering it. I just did this same backwards knobs things on something I built, the knob was for DC offset and the offset was before an inverting opamp stage, so basically it needed to be backwards to be right and I messed it up.

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timdrage
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Post by timdrage » Tue Jul 09, 2013 1:22 am

Yep. I should have actually thought about it more rather than blindly following a schematic :) I think I can rewire without too much effort,.

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timdrage
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Post by timdrage » Wed Jul 10, 2013 1:57 am

Resoldered it last night, works fine now :)

Image
Image
Might somehow reinforce those resistors that are just sticking out with their legs soldered together haha

chaoides
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ACTIVE MATRIX MIXER

Post by chaoides » Thu Jul 25, 2013 8:33 am

Hello!

I am looking for an active matrix mixer (1/4 jack), does anyone know of someone who could do it for me for relatively cheap?

Thanks

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swefn
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Post by swefn » Wed Jan 22, 2014 11:01 am

Hello, I'm new here - mainly because of finding this thread just now.

I did the exact same thing as Mr Drage on my first attempt at a passive matrix recently and got the pot the wrong way around (after following Nicholas Collins schematic/description from his 'hacking manual' and not checking as I went).

I've since made another attempt but seem to be having odd grounding issues whereby I seem to be able to effect the feedback somewhat with the palm of my hand when reaching to turn a knob.
Anyone else have this ?

I've tried a couple of different ways of tracing the path of the ground - one the same as the photos here show and another snaking between each pot and then each jack socket in a long row. I've had the same outcome with each.
Is it just a by product of this kind of circuit?
Am I made of metal?
Any ideas?

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timdrage
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Post by timdrage » Wed Jan 22, 2014 11:13 am

Yeah I dunno, might need building in a metal box for shielding? I had another go at figuring out a setup with mine the toher day and it seemed to make my homemade fuzz circuits pick up christian radio station even louder than they usually do :)

p.s. welcome fellow wrong-way-round solderer :D

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swefn
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Post by swefn » Wed Jan 22, 2014 11:46 am

Thanks! I guess that could be it.
I've got them in Digi-Beta tape boxes from a mate's workplace. They're the ideal size for a 4x4 matrix with 8 jack sockets... a picture would help I'm sure!
Here's one:
http://instagram.com/p/jYpbowHHb8/


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swefn
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Post by swefn » Thu Jan 23, 2014 3:13 am

Cheers!
To clarify, I'm quite keen on the interference! It just seemed more than I had expected and I thought I should check that I haven't done something odd in the build.
Heres a video clip - the first gesture is more indicative of what can happen with certain effects, in the second I touched some of the pots moving them slightly:

http://instagram.com/p/jfHXoHHHTf/
(this is with a KP2 on the harmonic pitch shifter setting)

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timdrage
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Post by timdrage » Thu Jan 23, 2014 4:49 am

Interesting! Hmm you have a bunch of pots somewhat turned up to unconnected in and outputs there right? That might be something to do with it. Interference aside I found the pots interact a lot, if one is turned up but not connected iit messes with the volume of other things in mysterious ways. Some matrix mixers have a switch for each pot to entirely mute unused ones for this reason I guess

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swefn
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Post by swefn » Thu Jan 23, 2014 6:16 am

Yeah that's right, well spotted.
I've done a bit of 'no input' stuff in the past as 'Thaw' (with a friend who processes the no-input stuff using C-Sound and PD). I did this using a Mackie 1202 mixer (that I no longer own) and found that what you have suggested regarding interaction is definitely true in those mixers as well.
BTW you can see a tame example of Thaw here:
http://www.youtube.com/watch?v=P2NIfk2PoLs

When it's something sturdy, off the shelf being re-appropriated for feedback, like the Mackie was - I don't tend to question what's happening inside it but with this one I thought I should ask a 'responsible adult' (sillly I know)- tho' I doubt there's any chance of real detrimental effect to gear or user I thought i'd run it by people here.
I'm guessing that, other than the lack of shielding the ground is open ended.... a friend referred to it as a one-sided circuit, suggesting that it would cause a lot of noise. I'm not even sure what that means to be honest.

Oh yeah - here's a pic of the innards - since this was taken I've tried another route for the ground, to no different effect (apologies if I'm repeating myself):
http://instagram.com/p/jYp7SBnHcQ/

And I keep referring to one in particular - I have made 3 by way of having a clear-out as I had a lot of stuff accumulating in my tool box and a lot of scrapped oscillator - based projects.
I made one with 100k pots and 10k summing resistors
another with 500k pots+47k summing resistors
and a third with 1meg pots and 47k summing resistors.
All 3 work pretty well! - the 1meg version takes a little while for feedback to bleed through and seems to generally behave a bit ... slower, but in a useful way I think.

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timdrage
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Post by timdrage » Thu Jan 23, 2014 8:37 am

Yeah I'm not sure what he means by that either: it looks from your innards photo like everything's grounded to both in and out pots... that's as grounded as anything else I've ever built. :)

I miight try and convert mine into an active one some time; most setups I've tried I needed an excessive number of extra boosts/distortions to get unity-level modulation/pitch etc fx to compete with louder pedals, or to even feedback at all for that matter

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