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I want the ultimate mixer module!
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Author I want the ultimate mixer module!
Argitoth
I really need a mixer module that looks like this:



A = 1 to 2 or 3
B = 1 to 2 or 3
C = 1 to 2 or 3
D = 1 to 1 or 2
E = 1 to 4

OR

ABCD = 4 to 1

OR

Send signal into E, send E outs into ABCD ins, attenuate, send out again.



It's the "Do It All" mixer. You can attenuate, CV attenuate, 4 to 1, 1 to 2 or 3, 1 to 4, attenuate before going out. Does it exist? If it doesn't, how hard would it be to create for someone who knows nothing about circuit boards? Mr. Green
Argitoth


This is better actually. The GUI needs some work, but basically they are separate VCA splitters and mergers. I LIKE VCAs!
flts
I'm guessing you could achieve the same by combining several ready-made modules without having to roll your own, but it might get a bit more complicated.

At very least, E is completely separate from the other parts, so you can substitute a 1 to 4 multiple (maybe a buffered one if you want to avoid signal level loss) module for that without any extra complexity or loss in functionality.

The mixer part would be a 4 to 1 VC mixer with individual post-attenuator channel outputs. Again, you can have a row of multiples to split the individual A, B, C, D outputs to n outputs. So you basically need only one output per channel, plus the sum output.

The closest individual module I can think of in Euro right now would be Plan B model 9, which has a 5 to 1 mixer with individual attenuated outputs, but no VC attenuation. Of course, you could run A B C D thru four separate VCAs for level voltage control, split the signals via multiples at that point and patch one set of outputs to the mixer, and you would be done.
flts
Ah, you'd posted the second picture after I wrote that... It seems I understood the design wrong, so the above will probably not be of much use to you.

Anyway, I'd split it in three separate stages:
1) Everywhere you have 1 to n splitters, just use either passive multiples (just wire a couple of jacks together yourself) or buffered multiples (figure out a simple opamp buffer circuit or a pre-made solution)
2) Think about the level controls as per-channel VCAs with additional manual attenuation (like you probably do)
3) Think about the mixer in terms of which signals you want to combine together in a single stage, and figure out summing the signals (use an opamp circuit again).

I can't give you a ready-made design since I suck at that, but that might help you either hunt down a set of pre-made modules you need, or start thinking about how to design one yourself and ask around for technical help. The second design you posted seems like you'll need a boatload of VCA circuits at least...
Argitoth
Actually, I really want to make this and you know what, I bet I could even start selling it. My dad and I are starting to get into electronics and my dad is also building his first electric guitar.

We ordered this book: http://www.amazon.com/Electronic-Projects-Musicians-Craig-Anderton/dp/ 0825695023/ref=pd_bxgy_b_img_a

That book can probably teach us to create something, but how do I start getting into the eurorack specifics? Like, how can I learn the technical specifications of eurorack so I can produce and sell modules specifically for this brand of modules?

Lastly, my dad sells banjos and parts and so he has a lot of wood working tools. I'm sure someone would appreciate sturdy but ugly and cheap cabinets for their module synths and I'm sure we could also make the cabinets look nice and sell them to those with a little more money.
sandyb
Argitoth wrote:
That book can probably teach us to create something, but how do I start getting into the eurorack specifics? Like, how can I learn the technical specifications of eurorack so I can produce and sell modules specifically for this brand of modules?


a good place for eurorack specs is the doepfer website.
www.doepfer.de then go to the products page and check out "technical details" and "mechanical details."

hth

sandy
flts
Argitoth wrote:
Actually, I really want to make this and you know what, I bet I could even start selling it.


Yeah, that's a good way to go - if you have a good concept and are willing to work for it, it's probably going to be worth it!

It doesn't look like too hard a design to implement once you have the concept nailed .. Multiples/splitters and mixers are some of the easiest audio circuits you can do (aside simple RC/LC filters and voltage dividers), and VCAs aren't too difficult either once you grasp the basics properly and are able to start experimenting.

Quote:
That book can probably teach us to create something, but how do I start getting into the eurorack specifics? Like, how can I learn the technical specifications of eurorack so I can produce and sell modules specifically for this brand of modules?


Sandy beat me to it, check out Doepfer's site. I guess the main things you need to check out would just basically be:
1) The pin config of power connectors and power specifications (+-12V, optional +5V)
2) The standard voltage ranges of CV and audio signals
3) The "horizontal pitch" standard sizes for the faceplates
4) The maximum module depth you can fit in standard cases

The rest is just applying electronics skills to whatever problem you have under those constraints, and when you get a proto finished, testing out that it works properly in a Euro setup.

Quote:
Lastly, my dad sells banjos and parts and so he has a lot of wood working tools. I'm sure someone would appreciate sturdy but ugly and cheap cabinets for their module synths and I'm sure we could also make the cabinets look nice and sell them to those with a little more money.


That's a reasonable idea - there seems to be quite a demand for pre-made no-frills cheap and complete Eurorack cases since the ones by Doepfer etc. are quite expensive. Not everyone can go or wants to go the DIY route. That has been probably one of the reasons lots of people don't go for Euro: getting a case either requires DIYing or costs as much as a bunch of cool modules would already (obviously depending on case size). Check out the discussions here and modularsynth.net about vector rails and nuts, bus boards, linear power supplies, etc., order a bunch of additional stuff, do some measurements, make prototypes and off you go!
Argitoth
now what's stopping someone from using wires with built-in attenuators?:



of course the impracticality of it is that many wires with attenuators might get confusing.
Kwote
i don't think that would be realistic because a good patch can have so many cables stranded together like spaghetti. things would be hard to access and could get accidentally attenuated. not to mention i may not want attenuation on certain things or need different levels of attenuation on both modules connected, etc., etc.
Muff Wiggler
fuck though, that's pretty smart thinking dude. I don't think mounted along the cable would be the best for reasons that Kwote brought up

but - if a dial could be engineered built into the plastic grip/sleeve of the jack, you could buy cables with attenuators on one side, that would be SEX

i'm surprised no-one is making a 'bank of attenuators' module. On a blacet panel you could probably fit 8 if you were crafty. So rather than build tons of attenuators into your module, you build a simple module with matrix mixing (or buy Metalbox's new Matrix Mixer), and use an attenuator bank as a companion module beside it.

now, i know the Matrix mixer doesn't have CV control. No problem. Put another companion module on the other side of the mixer. Yep, bank of VCAs. Problem solved, dream mixer achieved.

----

When I started with modular synths, I was confused why LFOs didn't have depth controls. Later when I learned of the value of VCA for controlling 'amounts' of things within a patch, i was confused as to why modules didn't have VCAs built-in for every input, or at least attenuators.

Then eventually I came to the belief that, for the most part, discreet function is where it's at - it's the whole point of modular synths, and it's why they are different from prepatched synths. Instead of building a module with a ton of discreet functions built in, build a bunch of different modules, each for a function. You get more patch flexibility this way. If you aren't using every channel in your mixer, you end up with spare attenuators and spare VCAs to use in other things.

So I got used to routing my LFO through a VCA to get voltage control over the LFO's depth. It is the way it should be.

Just a thought. Matrix Mixer + buncha VCAs pretty much gives you what you want, i believe....
Argitoth
So Muff, what you are saying is that all you have to do is connect a mixer module somehow to a VCA module? That's how little I know about circuit boards. I thought VC controls HAVE to be built into the circuit board WITH the attenuators. So that's not the case?

So then by what means do you connect modules in this way?

Wait a minute, so does that means you can create a VC module that connects to the resonance amount of a filter if it didn't originally have a VC for the resonance?
Muff Wiggler
Argitoth wrote:
So then by what means do you connect modules in this way?


patch cords. you'll want to get a lot of them if you are starting a modular synth wink I have 200 for my rig.

Argitoth wrote:
Wait a minute, so does that means you can create a VC module that connects to the resonance amount of a filter if it didn't originally have a VC for the resonance?


Absolutely. But you don't have to create a module - you just have to make a patch. Patching in CV resonance on filters that don't have it is one of the first tricks you'll learn when you start getting familiar with modular synths - a very basic building block patch.

On filters that don't have a resonance adjustment you can add it by splitting the output, and mixing some of it back into the input. (filter resonance is just feedback)

You can add voltage control by putting a VCA in the path of this splitter/feedback path and using that to have CV control of how much output gets fed back into the input, giving you VC'd resonance.

This is one of the reasons you often see multiple inputs on filters (like the Mankato - which doesn't have VC'd resonance), so that you can patch up VC resonance on your own and have an input jack to feed it back in. If your filter only has one input, you need to patch a mixer before the input, so you can run the original signal, plus the feedback line, into the filter's input.

Argitoth wrote:
I thought VC controls HAVE to be built into the circuit board WITH the attenuators. So that's not the case?


As you can see, no it's not the case. Modular Synth = Discreet functional blocks, patched together using patch cords. Usually with lots of VCAs - it's one way to add voltage control to the amount of any signal coming from or going to just about anywhere else. You can never, ever have enough VCAs. I have 23 discreet VCAs, plus an even larger number of other modules that can in a pinch be used as a VCA (LPFs, RingMods, etc). And it's not enough.
Argitoth
It's possible that it's not enough because no one has started selling cheap and highly useful VCAs. Might this be the case? If so, then I will surely want to fill this gap.
Muff Wiggler
if you could make a blacet style panel with 6 VCAs on it, each with a lin/log switch, and sell it at a reasonable price, it would be gangbusters.

As a benchmark, the Blacet Dual Lin VCA gives you two linear ones for about $120. The QuadMix VCA gave you four exponential ones for about $165, but has been discontinued.

Six would easily fit on a standard Blacet panel, do a horizontal row for each VCA:

(In/CV_In/Knob/Switch/Out) x 6

If you could make something like that high quality, ROHS compliant and fitting with the size, power format, and visual styling standards of FracRack, and sell it in the sub $200 ballpark, it should be very well received.
Kwote
Muff Wiggler wrote:
if you could make a blacet style panel with 6 VCAs on it, each with a lin/log switch, and sell it at a reasonable price, it would be gangbusters.

As a benchmark, the Blacet Dual Lin VCA gives you two linear ones for about $120. The QuadMix VCA gave you four exponential ones for about $165, but has been discontinued.

Six would easily fit on a standard Blacet panel, do a horizontal row for each VCA:

(In/CV_In/Knob/Switch/Out) x 6

If you could make something like that high quality, ROHS compliant and fitting with the size, power format, and visual styling standards of FracRack, and sell it in the sub $200 ballpark, it should be very well received.


and sell it as a kit for even cheaper as well. Mr. Green
Muff Wiggler
also add a second switch to each vca - to select between +5/+10v needed to fully open the VCA. this combined with the lin/log switch would make for the most useful VCAs in any format.
Argitoth
That would be quite a challenge especially someone who's never wired a circuit board before. But, like I said, I want to learn. No idea how long it will take before I have enough expertise to create a spank-tastic mixer.

Hey Muff, can you go into ms paint or whatever and create an image how you'd want it to look like? That would put it into perspective for me.
Kwote
i noticed you've been mentioning Eurorack format. if you really want to expand business you'll wanna make other formats.

frac rack comes to mind. wink
Muff Wiggler
Argitoth wrote:
That would be quite a challenge especially someone who's never wired a circuit board before. But, like I said, I want to learn. No idea how long it will take before I have enough expertise to create a spank-tastic mixer.

Hey Muff, can you go into ms paint or whatever and create an image how you'd want it to look like? That would put it into perspective for me.


sure



there you go. I don't really think it needs the numbers 1., 2., 3., etc beside each VCAs input, but I figured that would make it more apparent how it worked

aside from proper functionality, sound quality is a big issue in VCAs. Some are noticibly better than others, so you want to make sure your VCA is quiet and can manage the entire audible frequency spectrum. Perhaps consider building the cuircuits as discrete circuits, no IC chips on board. I've heard that discreet VCA circuitry, when done right, performs better than designs using ICs - and as far as I can tell, all the modular options available out there use ICs.

On the other hand, there are IC chips that are basically "VCA-on-a-chip", so if you go this route you don't have a lot of circuitry to build up, probably just power handling and voltage scaling stuff....
Argitoth
this is a good lesson. So what is the 5v / 10v switch for? Is that like bipolar vs unipolar?
Muff Wiggler
Muff Wiggler wrote:
also add a second switch to each vca - to select between +5/+10v needed to fully open the VCA.


MOTM and Euro use 5v, Frac uses 10v. Being able to select between the two would be very handy and make mixing formats much easier.
Kwote
that graphic was cool dood. i'm hurtin for more vca's right now.

knowing this i ordered a Blacet Mixer/Processor Kit instead.
Argitoth
Ok. So how do I start learning what makes things sound better? Will I learn that as I learn to create circuit boards?
Muff Wiggler
good question! I would guess, by a combination of trial-and-error, and by studying the designs of those who have come before you. I think this is the classic way, and the only way.

Start by building a simple VCA around an IC chip that provides VCA functions. Then see what you can do to make it better. Then study some other designs, learn about the shortcomings and advantages of them, and integrate the best parts into your circuit.

After a bit of this, try to build a discreet VCA circuit, without ICs. Compare it to your IC-based one, see where it is better, where it is worse. Find more historical examples, study them and learn from them. Build more refined designs, compare and contrast and listen. Eventually you'll figure out how hard you want to work vs. what you can safely compromise on to get the best you can out of your own circuit.
Argitoth
What is the sign of a good VCA or bad VCA?

Another question, do you ever need to split 1 to 4 signals?

And another, is there a quality difference in modules that are simply in/out without any VC such as mergers / splitters? Is there different levels of attenuation quality? Or is it just VCA?
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