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Interface modules for the ER-301?


Don’t forget that there is a modulation gain parameter and you can always get even more gain by inserting a VCA unit in the path and setting the level to something greater than 1.


I’m a bit late to the party on this - so this will be a DIY kit type of thing?


Just tested using WMD Quad-anti-aliasing filter to input more audio sources using the A-B-C jacks as audio jacks, the QAAF removes aliasing so you get smooth audio in!


You filter what with the wmd anti aliasing filter?


I am slightly confused though, aren’t the ADCs after the inputs?


Filter audio and then take that output into the “CV” inputs in the ER-301, those lack a anti-aliasing filter before the ADC’s so if you don’t filter those inputs beforehand you get aliasing.
The QAAF is a perfect match for this purpose because it’s small (4hp) and provides 4 filters which were built for this type of duty


Ehm no, this way you just remove aliasing of the module you put into the er301.
So if you have a module which has aliasing, you can remove this aliasing with your filter, before it goes into the er301.

You can not remove aliasing done by the er301 by filtering before… just by removing some high frequency’s of the material going into the er301 you don‘t remove the aliasing IN the er301… think about it, that’s not logical.
but no worry, the abc inputs don‘t have wild aliasing…(At least I think so, actually never tried sampling with those inputs. But did a lot of audio rate modulation…:-)) so you are fine using those with or without filter.


Actually, this isn’t really how input aliasing works, you need to remove every frequency which is above half the samplerate of the inputs, or you get aliasing…
Sorry, don’t want to sound like a jerk about this, this article explains it well:

If you look at this picture, you see that inputs labeled IN have a 4th-order butterworth anti-aliasing filter before going into the ADC, this is exactly what the QAAF does:

I think the QAAF doesn’t pass DC well though, so you would loose up to for CV-inputs but gain the same amount of audio inputs. It


@veqtor, i think you phrased it a bit confusing when you wrote
"…the QAAF removes aliasing so you get smooth audio in."
the term anti aliasing filter is a bit strange anyway, it can imply that
it is able to remove aliasing artifacts after the dac. it’s “just” a low
pass filter with an extremely steep curve isn’t it?

anyway it seems to be quite a handy filter for this!


@veqtor is correct. If you want to use the ABCD inputs to record or process audio with substantial energy above 30kHz then putting it though a low pass filter will help prevent your audio from aliasing at the ADC. However, there is another resampling process (60kHz to 48kHz or 96kHz depending on the firmware) after the ADC that might re-introduce some aliasing again. Which is perhaps what @Evs is referring to.


sorry, you are not sounding like a jerk at all, i was sounding like one, so please take my excuse! :slight_smile: and what you say is absolutely right, don´t know what got into me, i´m happy to stand corrected!


Ahhh, I can finally post about Mutable Stages. You can use it as 6 offset generators, 6 LFOs, 6 decay envelopes, n-stage step sequencer, some combo thereof…


Following on from the 16n post above where the Telex expanders for Teletype are mentioned I have been thinking of going down the TXi > Teletype > ER-301 route as a way to intelligently provide interface controls for the ER-301.

I haven’t tried this yet, but I have confirmation that the TXi should be able to act as simple controls for any parameters, but also be processed via the Teletype for custom control too.

If anyone has this setup and has tried this, I would be very interested to hear how something like this works in practice:



Using TXi this way is a very cool idea I hadn’t even considered. Honestly, between Stages, TXi, Neonach, etc there are a crazy number of good options for interfacing with ER-301 right now. :smiley:


This works fine. How well it actually works depends on how busy the teletype is and how fast you can run this script - since it’ll only update the parameters every time the script runs and even short intervals will introduce a noticable amount of stepping. You can work against this problem by adding some slew (either on the analog outputs of the teletype or inside the ER-301, depending on how you use it).

I’ve used the knobs of the txi for simple offsets in this way a few times before when my other offsets were all in use and it works well enough. But most of the time, I prefer to use them to control parameters of the teletype that don’t depend on such fast polling.


Thanks @x2mirko - so perhaps not the magical solution I thought it might be!!



Nice looking system ! I have no interest in the new Mutable modules but Marbles and Stages must definitely be powerful w/ the 301.

I’m so ready for the next 301 batch…