201 Pocket Piano audio input

In his recent YouTube review of the 201 Pocket Piano, loopop says (in the section on IO):

And then you have got, officially, a single monophonic audio output jack. Unofficially, if you use an insert or stereo breakout cable, you also get a monophonic audio input – so you could theoretically use this as a vocoder or monophonic audio processing unit, but there’s no official synth engine that was made available to test this yet.

Has anyone yet experimented with audio input into the 201 PP? Is anyone (C&G or otherwise) working on a mother patch/synth/etc. that makes use of it? I have had a 201 PP in my hands for only one day, and I’ve been playing with Pure Data for barely longer than that – so I have lots more about the stock PP to explore – but this is intriguing, and offers yet another field of exploration! Or has no one done this yet because there is some technical limitation in the 201 PP that means that processing audio input is impossible or difficult to do?


The 201PP has an audio input??? Intriguing…

Definitely can see some use cases for this. Granular synthesis here we come!

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This, from someone who has form in developing great patches for the PP, is very promising. I had assumed that everyone knew about this and was either already working on it or had dismissed it for some technical reason (sounds as if loopop had an insider conversation with someone). Glad I asked the question, anyway! Now, back into those YT French university lectures on Pure Data…

a while back it was asked here about stereo possibilities with the 201, to which Owen replied that only one channel is wired into the jack. It is a TRS / stereo jack, so it seems like an unfortunate and shortsighted design decision to not even have the connection inside ::// Although it is specifically in reference to output, and not the possibility of input on that other channel, it seems doubtful.



Nov 5

Anyone know if the 201 is capable of producing stereo audio? I vaguely remember seeing something in the kickstarter about it, and I’m pretty sure the 1/4 output is stereo and not mono like the original 201. Would a mod to the mother patch do the trick, or is it more complicated than that? I know that 5 moons recently got a firmware update, is there anything similar in the works for the 201? I think it could really elevate the instrument, specifically patches with effects like Hammond.


Nov 5

Unfortunately no, there is only one channel wired to the output jack.

loopop sounded pretty certain about what he was saying, and it would be uncharacteristic of him to make an assertion like that spuriously. Has anyone done a teardown of the 201? (I haven’t been able to find one documented.) It wouldn’t prove anything, of course, but it would be interesting to know if anything is wired to the second channel.

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Interesting - I hadn’t seen the Loopop video yet. I’m not sure where he came up with the TRS breakout cable comment, with no context it seems apropos of nothing.

I’ve had my 201 apart several times - here are photos of the output jack on the both sides of the board. I don’t know quite enough about what I’m looking at to offer any analysis…

as nice as a breakout or TRS option might theoretically be, it seems like it could be troublesome in actual use. i.e., if it’s in a mode to use a TRS / in + out, what happens when a TS mono plug goes in there?

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Thank you for those internal shots! I am not an electronics fellow (I do code (other), but I don’t do hardware very much), so I can’t interpret them properly. What I find interesting is that in line with the jack plug appear to be two microswitches (S2 and S3), while on my 201 I see just one switch there, the power switch. Are there two microswitches serving the power switch, or is one doing something else? Maybe I’m just getting the wrong end of the stick. I think I will have to open mine up and probably invalidate my warranty.

Anyway, I wish you and anyone else reading this at these advanced hours on the last day of the year – a happy new year!

A quick update on this: I was able to access the audio input using a TRS insert cable and the adc~ object in pd. Unfortunately, the resulting signal was pretty much unusable: very quiet and a significant roll off in high frequencies. I’m hoping that this is a firmware/software thing that our pals at c&g are working on, but it does feel like a hardware limitation. My best guess right now is that there’s either a capacitor or something in the input signal path that is affecting frequency response or the 201 is expecting something other than a line level signal. It’s worth stating though that I’m nowhere near a professional when it comes to this stuff.

Also, @sgotb if a TS cable were plugged into a TRS input/output then I’m pretty sure the input would just be shorted to ground (muted). Same as if one were to plug in headphones (TRS) to a headset socket (TRRS).


that is extremely interesting!
I just commented on the loopop youtube video asking him about the comment ::))

I think you’re correct about the TRS / TS shorting in that scenario.

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Yes there are two switches - I noticed it when I had it apart and thought it unusual. but not as unusual as yours only having one :thinking: I got mine in the first Kickstarter batch, maybe some changes happened in following production.

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aaaand I finally just watched through the whole loopop video - he highlights patch storage stuff by @twang69 and my more synth modes ones too :+1:

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Oh no, I meant that on mine there’s one power switch on the outside, so I didn’t understand why your photos seemed to show two microswitches underneath it on the inside. I haven’t opened mine up yet, but I imagine that it’s the same as yours on the inside.

Oh cool, loopop answered you already! For the convenience of anyone else reading this thread, he says:

I plugged a 1/4 TRS to 1/8 adapter and noticed that it didn’t turn off the speaker, which made me suspicious that something was going on (in a good way…) so I asked C&G and they confirmed the input, but they had no official patch to release at the time of the making of the video. I tried a test patch and breakout cable and there’s definitely an ADC there passing audio into the 201, but levels weren’t right and I didn’t have time to explore it further

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It is true, there is audio input on the 201! It is connected to the ring on the TRS jack, so you need a breakout cable. Currently there is an issue with using it which is why it didn’t make it into Loopop’s video. Basically the input is wired to the left line input, but the software is currently configured to use a mic input which isn’t wired to anything (you are able to hear a tiny bit of the signal bleed through.)

We made a vocoder patch to test it, and it works great once the audio is configured correctly which can be done with a couple of commands. The patch attempts to run these commands from Pd, which was working for me, but not for Loopop. So we have to figure out the best way to do this, maybe a software update to the mother patch.


Thanks – it’s so good to get confirmation from the horse’s mouth. I am really looking forward to seeing the input working on the 201! Now, in the meantime, to sort out a suitably portable mic with a built-in preamp, given that the C&G one is out of stock everywhere.

@oweno would it be possible to post these commands to the forum? I know a factory patch/update is in the works but in the meantime I’d love to tinker with the audio input, and I’m sure others would as well.

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Let me think out loud: this mean we could theoretically use the internal speaker for hearing the others pieces of gears of a live setup, right? But that would mean preventing the 201 to cut the speaker when a jack is inserted… This would be a great feature for couch jammers!

You can accomplish this by chopping off the tip of the adapter. The jack functions as a simple switch, when tip is inserted, the connection to the speaker is broken…but make sure you have an extra. I tried this, and now I don’t have a way to get the line out until I get a new adapter haha

@internetbreakup Sure, the commands are:

    amixer sset 'Input Mux' 'Line In
    amixer sset 'Line' cap

First one sets input to line in, the second one enables line input capture. It should be possible to run these from a patch by using the shell object (which is not built into Pd, but a copy of it can be found in the pd/lib folder on the 201 disk). I think the problem when I tried initially is the underlying operating system is also configuring the audio when it boots up, so the patch would make the config, then the OS would change it back or something, just need to investigate that …

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It would be cool if I could use the 201PP to audition effects pedals with the built in speaker, simply by plugging in an insert cable. :sunglasses:

Just got the adc to work properly! The only hiccup is that you have to do a soft reset (High E F and G + Shift) to hear it. I think this is because of the OS thing Owen was talking about. Happy to report that it sounds great, especially with the C&G mic :wink:

Also worth mentioning that you can access the audio input without muting the speaker by plugging in a standard 1/4" TS instrument cable about halfway into the socket. You’ll feel it click a few times; you want the second click.

For anyone who wants to try for themselves, here’s what I did:

  1. Make a [loadbang]

  2. Connect [loadbang] outlet to [t b b] inlet

  3. connect left outlet of [t b b] to [del 0.5 1 sec] inlet. This delays the second message by 500 ms and may or may not be necessary.

  4. Connect right outlet of [t b b] to a message box containing the first message: [amixer sset ‘Input Mux’ ‘Line In’] without brackets

  5. Connect [del 0.5 1 sec] outlet to a message box containing the second message: [amixer sset ‘Line’ cap] without brackets

  6. Connect outlets of both message boxes to the [shell] object’s left inlet. If you’re like me and don’t have the [shell] object installed then you can create a dummy object like [+] to make the connections and then rename it.

  7. Exit edit mode, save the patch, and quit pd.

  8. Hold the rightmost “white” keys (E, F, G) and press shift to restart the mother patch. You should now be able to access the audio input via the [adc~] object.

Please note that powering down the 201PP currently resets/disables the audio input. However, as long as this code exists in either mother.pd or the currently selected synth mode all you need to do to reactivate it is repeat step 8 (soft reset).

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