ER-301 as a polyphonic oscillator module

Hey everyone,

I’m looking for a polyphonic oscillator module and while I was aiming E370, some people told me I should check ER-301 for that. Since I haven’t seen many videos of ER-301 dedicated to that, I’d like to know if someone uses it for the same purpose and if you compared it to other modules, like E370.


I sometimes use it as a polyphonic synth in general, pairing it with the expert sleepers fh-2. Because there are enevlopes, vcas and filters you can make polyphonic voices wholly in the box.

As far as oscillator specifically, there is the capability to do smooth morphing wavetables with single cycle waves, fm, and lots of wave shaping abilities, though that can get complicated. It has four outputs so you can send four separate voices for individual manipulation.

The one downside is control and immediacy. You have to bring your own methods of controlling the parameters in the 301. Also because there is no preexisting structure you have to build your own. This can get a little complicated with polyphony, but is totally achieveable, and very fun. Also because it is a digital environment you can make quicksaves and get back to a previous state.

The device is extremely reconfigurable, which is amazing to get a variety of sounds. It can take time to build up patches, since the building block units are often simpler than similar eurorack modules and aren’t necessarily tuned for a specific sound or use.

Also consider it’s capabilities outside of oscillator/synth voice duty. It has some good effects, delays in particular, the built in reverb is just okay, granular synthesis, sample playback, looping and up to 12 track recording.

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I wanted to add to this a bit, because it’s obvious to those of us that have ER-301s but maybe not to someone who doesn’t yet. You can spin up and mix more than four oscillators internally and send them out any/all of the four outputs as you choose. So really, the number of voices is mostly limited by available CPU.

CPU usage varies by the type of oscillator or unit. But to give you some kind of finger in the wind, I was able to spin up more than 20 variable speed sample players at once on the most recent firmware. (That’s more than I’ve ever needed in practice - it was a stress test). The granular players tend to use a bit more CPU than the variable speed player, for example, so you wouldn’t be able to spin up as many of those.

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Very cool!

I’m just kind of afraid of that “limited by CPU”, because I have no idea how far it can go.

For primarily oscillator use you shouldn’t have an issue as oscillators are one of the more lightweight units. I inserted 20 single cycle units (an oscillator that can take multiple single cycle samples and morph between them wavetable style) and am only using 40% of the CPU.

The only time I ran into CPU issues with oscillator related activities was when I did an additive voice with 9 sin wave oscillators per voice, and that was on a previous firmware that had slightly less cpu headroom.

I could see running into issues if you are trying to do more than 4 voices. Even if you make a super complex patch that takes more CPU than you have for polyphony you can sample your monophonic patch and use sample players to play it polyphonically.

That’s very cool. I’m probably getting one instead of an E370. I just have to look for alternatives to know I’m making the best decision.

The biggest thing that seems to not agree with some people is the learning curve on the ER-301. It’s very powerful, very customizable. That depth comes at a cost of some complexity.

If you don’t mind spending some time getting familiar with it (which personally I’ve found very rewarding and fun, but some don’t and that’s ok too) then I don’t think you’ll find its equal.

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I’ll go ahead and weigh in here as well just to add that if you were to JUST use the ER-301 as a sound source, and not doing any other processing internally (filtering, vca, envelopes) that you could probably go much higher than 20 voices. I’ve never tried it, just because I don’t need it, but I think you’d be pleased.

One of the cool things about doing it like this is that you could run all of your voices through a single filter, etc. which in the case of micro systems gives you a lot of big in a tiny space.

The 301 is just very flexible. It is whatever you need it to be.


Looking at the e370, which I’m not familiar with, one thing you might finding wanting about the ER-301 is knob per function controllability like the e370 has. The ER-301 has 16 bipolar inputs (audio or cv) as well as i2c which you can use control the internal parameters, but you have to bring your own method of control. In my case I use a quadratt and will soon have a 16n faderbank that can communicate over i2c with the 301.

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That’s not a problem for me, actually. I rather not do much knob controlling while “playing”. I leave it to LFOs, envelopes, etc.

My main concern is just sound.


I agree with everything that has been stated before!
And I’d also highly recommend to get yourself an er301.

But as for polyphonic modules I would also add the following to your list.

  • synthbox Firmware for 1010 musics bitbox
  • flame 4vox

I was interested in synthbox, because of that changeable firmware capability and because it’s much smaller than E370. Have you ever tried them both to tell me about how they differ soundwise?

4VOX was not on my radar. I’ll check it out.

Never tried an E370. so can’t compare them. (Though i’d love to :slight_smile: )
only can give you information on the synthbox and the 4vox. just ask away…

There’s not much to ask, I just wanted to know if you like the way they sound.

What they are capable of seems to be pretty clear from the manufacturers pages.

Sound wise the synthbox sounded surprisingly good!
Loved both, the clean as well as the dirty sounds on it.
And for what it is, they ui feels great, too.
(Unfortunately, it had to leave town in order to make place for a hydra)

The 4vox sounds great, especially if you manage to get your own wave tables on it. The factory tables are known to have, well let’s say character. (See muffs for that feature) I love the factory ones, too.
Mostly used them through lp and bp filters so I was always able
To get rid of the character if I didn’t want it. Might not help you either.

Since we are already here, how has it been with Hydra? People talk about its character too.

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:slight_smile: i feel trapped. for if i would give any judgement of its character
(which would be ‘delightful’) then i would be one those people, too. right?

Haha. Not exactly. There are many who likes its sharo highs character and many who don’t.

fair point (for those people). i can see why its character (we’re still onto its sound, right?)
is an important talking point. but to me that point feels pointless until you have the chance to hear it on your own system… (do you have one? or just thinking about it?) and then you’ll like it or not.

or: how has it been with the er301?
i think that is the right question to ask about the hydra as well as about the er301!.
there was an answer about the hydra on some youtube stream of consciousness which
i think is pretty much true for both, at least for me it is:
“it doesn’t dissapoint”.
as for my taste: it’s just that i have quite a diverse taste in synth sounds,
sometimes i like it clinically dry aged. sometimes i long for plenty of
heavy dirt. and what the manuals had promised me was this: they let you
do all that, everything inbetween and all this even in a continuous (i.e. non-discrete)
way. hey, i would even say that both are perfectly capable to translate your character into a sound :slight_smile:
gems in - gems out. garbage in - garbage out :slight_smile:

and there’s one thing i’d like to add to the disappointment equation.
both are full of surprises in two respects. of course there’s the firmware updates that
bring you new stuff. but then there’s also my belief that with both it’s rather impossible to
get the full picture of what they are actually capable of based on the manuals.
you might get an idea of it but since both are fine examples of something somebody once called
adjacent possible: you’d be surprised, no matter how fantastic your imagination might be.
sometimes i think it’s worth to take a look on what they can’t do?

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we’re still onto its sound, right?

Yep, it’s about it.

Well, I must say you sold me flawlessly.