Looper and sample player unit behavior with external audio input

hey brian,

here is the scenario i’m using and apologies for the long explanation… i’m running my nord piano into an external mixer and then a line level aux send from that mixer is feeding input 1 on the er-301. i’m able to boost the input using the preamp setting in the admin section and all is good there.

i then have created two mixer units. mixer 1 contains a dub looper and input 1 (the piano) is the source audio for that looper. mixer 2 contains a sample player which plays back the same buffer that the dub looper is using. i have the level control on mixer 1 (looper) at 0 and the level on mixer 2 (sample player) up so that i only hear what I have just recorded into the looper buffer. the issue is that when i punch in on the looper the live piano audio is coming through on the sample player unit on mixer 2.

i remember using this same setup back when i first received the 301 and do not recall the 301 behaving like this. might you have any suggestions on what i could try to remedy this situation?


Oh my. I just realized that I never got back to you on this. :bowing_man: Are you stilling having this issue?

The only thing that I can think of is that the play head on the sample player just happened to be right behind the record head of the looper so that it just seemed like you were hearing the piano live without delay.

FYI, I recreated the chain that you described, using a 16s buffer, and was able to confirm that the live input was not being passed through.

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thank you for getting back to me on this Brian and testing on your end. i will recreate the issue in a video this evening and send it your way when completed.

Hey Brian, late on the reply but hope you are having some well deserved time away!

Here is a short video about the problem I am having and hopefully it will explain it a little clearer.

A side note I forgot to mention is that the view now available in the grains player is SO good! It really is helpful to be able to visualize the actual grains playing as you move through different sections of the buffer.

Not sure of the best way to get a video to you as it will not let me attach the video file even if I try to upload it as a .zip?

Link to my dropbox and hopefully you are able to download it from here: https://www.dropbox.com/s/6dqks65ivdnu0yu/looper%3Aplayer%20issue.MOV?dl=0

I haven’t forgotten about this!

Thanks Brian, hopefully the video explains what is going on.

Hey Brian,

Just checking back in to see if you’ve had any time to reproduce the issue I demonstrated in the video?


Sorry for not getting back to yet! I’ve have been looking at this and analyzing it. I haven’t come up with a fix for it yet which is why I’ve been slow to report back.

I pretty much understand why it is happening and it is essentially related to the known issues around playing back from a buffer that is simultaneously being recorded. Most people have reported this issue as a sort of clicking sound which normally happens when the play head (from a sample player) collides with the record head (of a sample recorder) because the play head is either going in the reverse direction or it is faster/slower than the record head. If the play head and record head are going in the same direction with the same speed then typically you would not expect them to collide and hence there would be no problems.

However, in your case, static-like sound is coming from the fact that your punch-in timing is pretty good so that you have the record head right on top of the play head, continually clobbering it as they both move along together writing and reading the same spot in the buffer.

Based on the above, there is a workaround (more like a hack). The goal is to get the play head away from the record head even if just a little bit. Now, I assuming that you are using the same gate from the Digitakt to reset both the player and the looper. The temporary workaround is to insert a uDelay (Micro Delay) in the player’s trig sub-chain and set the delay to 2 or 3ms. This will cause the play head to lag behind the record head by 2 or 3ms. That means the play head will be behind the record head and thus include the newly dubbed material as you are playing it.

If you instead put the uDelay in the reset sub-chain of the looper then the record head will lag behind play head. This will also fix the static-like artifact but now the playback will not include your live dubbing but rather play the undubbed sound since the record head will be writing its new material behind the play head. You can choose where to put the uDelay based on which behavior you would like.

A proper fix for this type of shared buffer scenario is coming but it requires some fundamental changes in the internal signal routing and DSP scheduling which should happen sometime in v0.4.

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By the way, would you mind if I made this thread public? Your video explanation of the issue is excellent and the workaround might be useful for others until I get a more permanent fix.

If you would prefer that it not be made public, then please do not hesitate to say so. I will understand :wink:


Thank you for taking the time to look into this and provide a temporary solution which I will give a try this evening.

No problem here if you want to create a thread on the subject if it might help others :wink:

Thanks again!

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Do you mind if I just turn this thread into a public one rather than create a new one?

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whatever is easier sure no problem


This is great - thanks for sharing, really good explanations and good to know a more considered fix is coming!



can confirm both of these options (using the second) work like a charm. Thanks!:muscle:


I know this thread is old…does uDelay still exist.

I have CV coming in from VCV Marbles, and ER301 is not staying on the locked loop.
I figured it may be fluctuation in the MIDI converting to CV in my FH-2, but in the DATA it never changes.

so it seems like the ER301 doesn’t keep up? if uDelay is gone, what else can I try OR…id it exists, where is it? I can’t find it.


naturally I little while later, I found an even OLDER thread, 2012, where micro delay was suggested.
:+1:t6: :+1:t6: :+1:t6:

I think you mean micro delay? where you can specify a number of m/s of delay? for me it’s under delays and reverb.

No I meant uDelay because Brian suggested it
“ If you instead put the uDelay in the reset sub-chain of the looper then the record head will lag behind play head.”

Top of the thread, but in a thread from 2012 I saw Micro Delay mentioned. So ya that werks.

But I did mean uDelay, but, also Micro Delay :wink:
So ya.

uDelay and Micro Delay are the same unit.

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Is that indicated somewhere or is that just something you are supposed to know.

I’m not the brightest :wink: