# Math operator unit

proposing this possibly due to my still very humble knowledge about the ER-301 (and i guess some of this is already doable via detours such as offsets, VCAs etc) – but i am thinking:

wouldn’t it be neat to have more “simple” math / boolean operators for signal calculation / manipulation? operators, that can be inserted into signal-paths? possibly even one single “math” unit whose operator (+ - / % > < =! …) can be selected from the lower display?

(edit – coming from max/msp, the “%” symbol is meant to be a modulo… hehe)

1 Like

Yeah, I was thinking something similar recently, actually some simple thresholding units so if an incoming CV went into negative voltage you’d only pass the positive and things like have an upper limit voltage threshold too. That sort of thing…

1 Like

yeah, i guess these simple operators could actually do this and a lot more in a very logical manner…

you could test a signal for being positive (`>= 0`) and use the boolean result (0 or 1) to multiply it, muting all negative voltage (or driving the level of a VCA to 1 or 0, as a matter of fact)

I have been trying not to +1 too many ideas until I actually have my unit and spend some time with it. Seems like some kind of math unit would definitely add a ton of possibilities though.

1 Like

Funny you mention this. Just got my ER301 yesterday and this was one of the first utilities I’d thought it could use for automatically calculating certain variables, e.g. Frequency of Sine waves, similarly to Pd/Max. We’ll see if it’s implimented!

Wouldn’t you prefer to keep the abstraction closer to what you would find in a modular synth?

• multiplication is a bipolar VCA
• modulus is a wavefolder
• threshold is a rectifier
• and so on
4 Likes

That’s a good point. One of the reasons the original idea resonated with me is that the ER-301 is a “Sound Computer”, and a Math unit seems akin to things you might do with a computer. Even though you can accomplish many of those same things as you describe, I guess I tend to equate those to analog circuits (even though many are implemented digitally in various Eurorack modules) more than a computer.

I guess in a way it comes down to nomenclature, presentation, and also to knowledge.

I will show some of my ignorance here and say that some of the equivalents you make in the bullet points aren’t readily apparent to me. “Addition is mixer” - sure. “Modulus is wavefolder” - never occurred to me. Is it? “And so on” - it is possible I might not know what I don’t know! Might be time to further my education.

Yes please! I think it is really important to keep the implementations of ideas as close to the larger modular system outside the ER-301 as much as possible so those skills are directly transferrable without having to translate them.

Although I have to say I only think of a threshold as a rectifier in the loosest sense and not the same as full wave rectification - unless I am really missing something?

I tend to think of threshold as a comparator! Am I wrong?

that indeed is a very good point hehe… maybe i’m looking for something like a codebox? a little unit that lets me stack various math functions and grasp their interplay at first sight? or may i’m just too connected to max/msp!

how ever… i’m sure there’ll be some possiblity to do all this in due course, so i’m glad to be patient.

thinking that i have a sound-computer in my modular, i’m no longer sure about any point of reference (or the necessity of such) as for its implemented functionality, to be quite honest

I am - 100% - no doubt in my mind at all

oooof double nested quotes don’t work in Discourse? That’s a bit lame - first time I’ve seen anything here I really disapprove of!! For the record the first sentence in this quote is mine!!

Comparator/Clamping/Rectification. I tend to just group them all together in my head under the term Thresholding because the implementations are very similar:

Clamp
if x > y then y else x
Half-wave Rectify
if x > y then x else y
Comparator
if x > y then 1 else 0

That might just be me.

Yes, I see where you’re coming from for sure!

If you see my recent example of the Slope Detector custom unit, I had to use the envelope follower to act as a rectifier before hitting the threshold of the sample player due to the negative voltages created by the preceding collections of units, it works almost perfectly, so I think there is a useful difference there.

I’d be very interested in any constructive criticism of that implementation if you get chance to check it out, and perhaps it will help too?

I think that if you were to design a unit that just did a simple math operation like add or multiply then you will inevitably want to add other bells and whistles to get it work well within a typical patch (such as gains/offsets on each of the operands) and then you will almost definitely end up with one of the common operations found in modular.

1 Like

Actually, as soon as I saw your slope detector post I coded up two new units: Rectifier (w/ pos, neg and full wave) and a Fold unit.

6 Likes

heheh … that’s enough of a mission accomplished for me very happy to hear – urgently want to fiddle around with these units. thanks!!!

1 Like

For what it’s worth, I have found the ER-301 to be an incredibly useful teaching/learning aid, the fact that you can see the signals in the scope views is huge! Being able to refer to the functions in exactly the same nomenclature as the rest of the modular means that other folks have immediately been able to start working with the non-virtual equivalents despite losing the scope aspect. It’s magic!

I think introducing different ways of describing the same things in the default firmware would be detrimental to this.

I have absolutely no objection if at a later date there is an add on that implements this way of thinking at all!

I hereby declare the ER-301 as the ultimate in the expression of the modular eurorack meme ‘both’

1 Like

AWESOME!! Thank you so much - total win

1 Like

I was thinking maths operations could be bitwise processing. Break two signals using ADC into x bits and the process the bits using logic functions. And then DAC them back together.

Pretty cool way of making complex logic/control from two very simple signals

You mean like the Xoac Leibniz Binary Subsystem?

In which case yes, that makes loads more sense - great idea!!

1 Like

Don’t that module but I think that’s what it does. I think some of the Waldorf synths have it as part of their modulator processing and the monomachine does it in one way by interlacing an lfo with a fixed value, creating a much more complex shape/pattern from say sawtooth