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Just starting with the ER-301? Ask Your Questions Here!

This is a thread for those of us who are new to the ER-301, or maybe just a little rusty.

If you are feeling stuck, frustrated, or simply bamboozled by the sheer amount of stuff to get your head around - post your query here!

Edit by @odevices: You are of course free to start a separate thread/topic just for your question. Up to you.


I’ll begin. I’m not sure what I would use Containers for. Are they a kind of Mixer? What is a Custom Effect or Custom Source?

The nomenclature here is based on firmware 0.4.25.

A container is just basically an empty shell Unit. A place for you to start creating a chain of units that you’ll likely want to re-use again and again, or even share on the forums. Say you want to create a synth voice, or some effect. You might start with a container unit so that you have something there besides a chain to save it all into.

They aren’t quite like a mixer, because a mixer actually does something on it’s own (mixes the signal coming into it with the signal in its subchain). A container doesn’t do anything until you fill it up with some Units.

The Custom Source unit blocks any input coming into it from the left. It would be suitable for a sound generator. Try placing a Custom Source unit into a chain. Then put a Sin Oscillator in front of it. You’ll notice the sine wave signal disappears and shows No Signal at its output because the Custom Source has blocked it. You’d want to place your sound generating units inside of the Custom Source rather than in front of it.

Now replace the Custom Source with a Custom Effect, and notice that the sine wave passes through it. So this kind of container is more suitable for an effect, like, say a delay or whatever - anything that’s going to process an incoming signal rather than generate its own signal.

There are also some special ones for multi-band. They’re a little more advanced, but they essentially have multiple signal paths that get mixed back together at unity gain before going to the output. You could use these for effects that process a signal in different ways in parallel.

Of course you can rename these containers, as well as add custom controls to them that control the params of the Units inside of them. That way hopefully you (or anyone you share your unit with) only has to pay attention to the top level controls, and can ignore the whole sub-chain of Units inside that makes your creation do whatever it does. Many (most?) of the unit presets tagged “custom-unit” on this forum were built inside of a container.

Hope that helps - feel free to ask for clarification.


Thanks for the comprehensive explanation Joe!

One quick question: is it possible to remove the text “Band 1”, “Band 2” etc? It obscures the very useful graphic display of the waveform.

Thanks for starting this thread! Just what I need. :slight_smile:

I have a few questions:

  • What exactly is the “bump scanner” unit for? I’ve placed it after audio sources for distortion, but I get the feeling it’s for modulation signals?
  • What is the “Rational VCA” for? Or, how does it operate?
  • Is there currently a way to visualize an ADSR envelope while you’re dialling in the parameters for it? I know you can see it after you’ve dialled it in, but haven’t figured out a way to see it while dialling in.
  • The same for a waveform from an oscillator - any way to visualize it while editing the waveform? I could always just connect the output to the Mordax Data, of course, but would be handy to have it inside the box, so to speak.
  • Oh, and the same regarding the EQ, would love to see a visual representation somehow while dialling in. Is it possible?
  • Regarding the convolution reverb - it seems to distort easily. What is the determining factor in that? Loudness of the impulse loaded into it? The length of the impulse file loaded in? I tend to put a limiter before it, but it still very easily distorts.

I also have a lot of question about Joe’s custom units (which are awesome, by the way!), but I reckon information on them should be out there somewhere, so will just have to look a bit more for it. :slight_smile:

Some general questions about the ER-301:

  • Are there many people working on the “middle layer” of it? I love the selection of units available, but would obviously love even more (the state of mankind, innit, more more more, haha) - especially reverbs (I haven’t quite figured out how to build a decent reverb with the units currently available).
  • Also, what do people think opening up the C++ programming part of the ER-301 will add to the table? Would we be able to port open source DSP stuff into it that way (I’m talking 100% out of my ass here, as I know basically nothing about programming)? Do you reckon more people would get involved in making their own plugins?

I’m sure I’ll have more questions once I dive deeper into it. I still don’t understand how a lot of the units work, but I’ll keep experimenting. I’ve already made some pretty interesting patches with this thing, and love doing it. It’s an incredibly inspiring module! :slight_smile:


Also - are there any smart tricks for how to implement dry/wet control for the various effects units? I’ve tried putting a VCA after the effect, but that essentially blocks off the signal flow when it’s closed, so no can do. How can you put a VCA in somewhere, have it closed, and sort of “tap off” it at will, without it breaking the signal flow of a channel? Putting it in a global chain? Or are there other solutions?

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You will need two VCAs for dry/wet control. For the dry VCA, bias it open and set the CV gain to -1. For the wet VCA, leave it biased shut and set the CV gain to +1. Then attach the same CV control to both VCAs!

Your signals will need to run in parallel and be mixed together; a 2-band container would be fine for this purpose.


Not to my knowledge.

Some of these are pretty deep questions, so let me (and/or others) respond a little at a time.

It’s a VCA - just like the linear bi-polar VCA, so it amplifies (or reduces) its incoming signal. What’s special about it is that it’s gain is specified in ratios. Like 2:1, or 1:2, or 4:1, or 3:4 for example. Or another way to write those would be 2.0, 0.5, 4.0, 0.75.

Sometimes specifying a gain amount as a fractional ratio is really handy. One fairly common place is in audio rate modulation, like FM or phase modulation, where the frequency of the oscillators involved (modulators and carriers) are typically specified as ratios of some base frequency that sets the overall tuning.


@desolationjones Ah, sweet, thanks! I’ll try that now. :slight_smile:

@Joe Ah, nice! That makes sense. Thanks for clarifying. :slight_smile: Do you have a short overview of your custom units somewhere? I’ve seen your Accents-post, and have read the descriptions of some of your units in there, but quite a few of your units lack a description. A few of them are self-explanatory, more or less, but a few others are quite mysterious still. :slight_smile:

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The Bump Scanner and Sample Scanner units are CV-addressed curves (transfer functions, if you like). Set the bump shape or load a sample, respectively, and the output will be the Y value of the curve at location X = CV input.

The Bump Scanner is especially useful as a window comparator.

The Sample Scanner is especially useful as distortion / saturation.


Everything I have is in this thread. A lot of the units have videos to help explain them too. Feel free to ask about anything that isn’t clear.


The Exact Convolution unit is very processor-intensive and it’s possible that your distortions are actually stutters from the audio not being ready in time for output. Keep your IRs shorter than 500ms or run the 48kHz firmware to achieve better performance.

(An interesting side note: the built-in recorder will usually record fine even when your outputs are breaking up, since it benefits from being slightly asynchronous.)


@desolationjones thanks heaps! That makes it a bit clearer. I’m not 100% on the terminology, but I do roughly know what a comparator is, and I think I understood your description. I’ve been using a modular synth for 5-6 years, and get along with it well, I think, but the more down to the basics it gets, the more I become aware of how little I know, hehehe. So for the bumper scanner, you basically feed a CV signal into the unit input, and the bump scanner transforms it according to its settings? I tried it just now with a Wogglebug, and it sure does something funky to the incoming signal.

About the convolution reverb - good to know. I’ve been using these “rhythmic convolutions” impulses I got a while back, and all of them are more than 500ms long, so maybe I should try just shortening them down, and see how that goes. Thanks for the tip. :slight_smile:

Regarding the VCA dry/wet trick. I tried it just now, and it does seem to work, but when the VCA is closed (so dry), the signal doesn’t seem to pass the 2 band container - and I guess it’s not supposed to, right? I haven’t completely wrapped my head around the different band containers and how they work, so should probably just look that up. Is there a way to have a completely dry signal just pass all the dry/shut effects/units?

@Joe - thanks! Ah, my bad! For some reason I thought you had gathered all the info on all the units in the first post, but I see now that there are several of the other units described further down the thread. Awesome! That should keep me entertained on Youtube for a while. :slight_smile:

Very much appreciate the input, guys!

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To my knowledge its just me at this point (well, and of course Brian). There might be others who have created things with the Middle Layer but if so they haven’t shared anything on the forums that I’m aware of. Want to get involved? :slight_smile:

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I’d love to contribute, but my programming knowledge is limited to basic html (haha), and I know most programmers wouldn’t even call that programming! :sweat_smile:

Yeah, I probably should consolidate at some point. Maybe as we move from 0.4 to 0.5 would be a good time for that.

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This should work… AFAIK the input of a multi-band container is multed to each band, and the outputs of each band are mixed. I have very little experience with the multi-band containers, though.


Aaah, now I get it! Thanks for clarifying. I had set it up all wrong afterall. Visual learner. Awesome, thanks a lot, that should do it. :slight_smile:

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Oh … is there some way to have one of the granular playback units use the incoming “live” buffer of sound instead of reading from the SD card?

AFAIK, yes. Set a recorder and assign a new buffer to it. Then this buffer should be available in the granular unit.