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Messages - mario

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Ah yeah the card slot is a pest :( There is a simple trick to it though, check this out.

People often ask why is it designed this way - well, all models use the same PCB and it is not feasible to have 2 versions of them (further explanation here). Besides that, the wooden model is being phased out (it's too time consuming and problematic to make), and the plastic version that we plan to continue with, does not have this problem. I also have a halfway finished "sync" software (for downloading the recorded material to PC but I only know how to program for Windows, so it is not a complete solution for everybody). Still much easier to use the tape trick as suggested by Alex. 8)

General Discussion / Re: Question on input leds and B4 (V2 03/2021)
« on: March 20, 2021, 09:43:44 AM »
Good catch! ;D And you're right, this is how "off" is currently indicated. The manual has been printed a while ago and then I probably changed the indication, because seeing no LEDs was confusing. And forgot that it results in this inconsistency. I'll probably fix it online, even though it will become inconsistent with the paper version.

Hi and welcome! :)

Thank you for interesting questions. This indeed needs some explanation and I don't remember it being discussed anywhere yet.

Quote lower the mix of the soundscape (through the S2 sensor+ setup menu) : OK but complicated AND lower is not enough, mute is better.

If the background soundscape is completely muted, everything ends quiet. That's because of how the subtractive synthesis sound engine works. The chord progression (and melody line, if present) controls a chain of low-pass or high-pass filters. If there was nothing coming in, either white noise (as in any of the "wind"channels) or a sound of water, rich in frequencies, there would be nothing to filter. To hear the chord progression on its own we'd need to let it control some other kind of engine (FM, wavetable etc...), that can generate sounds on its own. Or at least supply some sound into it all the time, via mics or line input. Or is this what you wanted to achieve, to have no background at all, only filter incoming signal? The lower limit for sample volume could be easily changed to zero, or we could add a "background off" button shortcut to accommodate this.

Again on chord progression I read in the V2 channels documentation, channel 111 "...where the progression is accessible by other channels". I could find only Channel 31 and 1111-1114 that use the chord progression.

Yes, there are only those 4 "soundscape" channels that can make use of the custom defined chord progressions, as there are only those 4 soundscapes, and the granular sampler is polyphonic so it can use it too. By the way with use of a SD card, the "water" background sample can be temporarily replaced with a vaw file from the card, by pressing the awkward combination of SET+RST (hold SET, press RST shortly while something plays), but this is not finished yet with regard to choosing a file and adjusting its sound levels, and therefore not documented.

I believe that no other sound engine currently implemented can make any use of "notes" at all. Dekrispator (#33) can use the melody line, but the necessary controls are not there yet, it's one of those neglected channels based on a 3rd party sound engine that need more attention (MI Clouds being the other one, it has more parameters internally than what is accessible through Gecho's limited user interface or MIDI implementation, the only way remaining is to download the config file to SD card and edit it). I plan to expand some of this in the next fw update.

suggestion 1: create a channel (say 1115  :o, I mean 2111) that play slot 0.

OK so if I understand you correctly, you meant this new channel to play chord progression on its own, which as explained above will not work, but it might make sense to have such a channel just for verification that all notes are defined well (sometimes it is hard to hear it all when other noises are involved). This could use a simple FM or sample based synth engine.

suggestion 2: for every channel with two digits, and for these that make sense, create the counterpart starting with 21xx that mix the current chord progression

That's a good idea, and plenty of space for this kind of shortcuts. This could be even user definable by editing config file [channels] section; I doubt that the current format supports "slot 0" as a chord progression source but it's very easy to add.

Thanks to Mario for creating this unconventional device.

Thank you for your support, much appreciated, mainly in these times - we could not keep doing this without enthusiastic people like you!

Feature Requests and Feedback / Re: granular sampler
« on: March 06, 2021, 09:41:54 PM »
Hi Jean-Luc, thanks again for the feedback, very happy to hear it works well and you are enjoying it!  8) (I don't have SQ1 so it's good to know there are no compatibility problems). I just got hold of a MIDI controller that has 16 knobs so will try to implement controls for more parameters, for example in Clouds channel it will make easy to access them all.

General Discussion / Re: Firmware upgrade roadmap status?
« on: December 03, 2020, 01:28:51 PM »
Well, I'd want to finish the firmware at least up to the point where it matches descriptions on front panel... (sync/cv is not there yet - more info here at the end).

The sources repo is there also to attract collaborators, but still waiting... perhaps there is not enough units out there in the wild yet 8)

Hardware Questions / Re: Clicky/glitchy Playback from SD card
« on: November 23, 2020, 11:46:38 AM »
That's great - thanks for the update!

If you still need this in future - I am not sure either what equivalent of PuTTY works best on Mac, but there seems to be a ported version available. Anything that can talk to a COM port without triggering the RTS line (as the hw handshake signal) should work.

I hope the loopsynth will help you to stay creative during the lockdown. Cheers! :)

General Discussion / Re: MIDI overview for Gecho Loopsynth?
« on: November 18, 2020, 09:10:18 PM »
Hi Jean-Luc,
That's great! At first I haven't realized that it works out of the box, assuming it was just another USB-host board that requires external circuit to drive it, but it is actually a complete solution, fantastic! I'm ordering one of these too - will be much easier to use it to upgrade my controller than using the Arduino shields :)

Hardware Questions / Re: Clicky/glitchy Playback from SD card
« on: November 14, 2020, 05:18:04 PM »
Hi and welcome! :) Happy to hear you are enjoying the lizard synth.

So far I've heard from 3 other people about the same problem. In one case it turned out to be too slow / not genuine card, bought on eBay. In other cases the card seems good enough but for some reason still does not perform well - the problem is that until I get hold of the same problematic card I can't really debug the issue.

Your 2GB card is likely to be just a little bit too slow. Is it Class 4? If yes, that would explain it. I've been using SanDisk Ultra Class 10 (U1) 8GB and 16GB cards without any problems. The other guy who has encountered this problem has used the same type of card, only it was 32GB (which should not make any difference at all so it is quite a mystery, unless the sector size is different and it plays some role - I'll need to get one of those and try, as currently I only have a 32GB Extreme which works well).

If you want to see how your card performs, there is channel #3142 - SD Card speed test, it outputs the result over serial console and you can use PuTTY to see the result. The test writes and reads 2MB of data, with my cards this takes cca 3-3.5 sec to write and 1.5-1.7 sec to read (the read info will show up only when running second time as the file needs to exist on the card first, things are done in this order to rule out any possible cache effect).

The sampling rate of 50.780 kHz is what the loopsynth uses internally. This odd value is simply a result of architecture, the ESP32 chip is driven from 26MHz crystal and the master audio clock is normally derived from it using a PLL (phase locked loop) circuit that gives very stable and low jitter signal.

But then not all values are possible, for example when requesting 48kHz from the I2S controller, 50781.250Hz comes out - this is a consequence of I2S bus timing, where MCLK (master clock) frequency is a nice number, precisely 13MHz (half of the xtal's 26MHz). Without PLL it is possible to obtain exactly 48kHz but that requires MCLK to be an odd / fractional value where the I2S controller uses some tricks to achieve that, and the clock is not smooth. This results in additional "quantization" noise added to the output signal (more theory here if you are interested).

This of course results in whatever is recorded to SD also getting encoded in 50.78 kHz. I personally did not find this to be much of a problem as the software I used to edit audio or video was able to resample the tracks behind the scenes. PC has a lot more power so the algorithms to manipulate audio give a lot better results than if this was attempted in the synth's own small CPU (which would also need to be done in real time).

Some 3rd party sound engines - like Clouds - use 44.1kHz as they require more CPU power and need to squeeze the last bit of it, but where it was possible I decided to keep the ood sampling rate as it sounds noticeably better.

About the card formst - the default format with which the card comes from the shop is usually good. We use FatFS library that supports FAT16, FAT32 and exFAT too - but there is still a limitation in Gecho because of the older ESP-IDF version used, which limits the card size to 32GB - I believe this is because larger cards are SDXC and use exFAT (this will likely be fixed in future firmware once I get time to port the code base over to the new version of the framework).

For best results and especially if you plan to use the material later, it is not advisable to record to SD, rather just take raw audio and record with external device, as from time to time glitch may occur and ruin the recording, for example when the card times out while erasing sectors, or something like that. Of course for the channel #222 to run well, this problem needs to be eliminated.

General Discussion / Re: MIDI overview for Gecho Loopsynth?
« on: November 09, 2020, 12:19:02 PM »
I just received this little card to interface a Craftsynth V1:

 I have to find time to plug it in but the card is pretty cheap and I'm hopeful ...maybe....

Hi Jean-Luc, haven't seen that one - hope you will figure it out and let me know! It seems to use a different chip to what I've got - this Arduino shield and also this board and found library and some discussion about them here and here.

General Discussion / Re: MIDI overview for Gecho Loopsynth?
« on: November 09, 2020, 11:54:04 AM »
I have made a sort of poor mans solution to the problem, with a javascript solution that works in a smartphone browser..

Very cool! I did not know this was possible. If also virtual COM ports can be handled in a similar way then we could implement MIDI over USB in Gecho (not much work on firmware required, redirecting the data from one USART port to another is trivial). The question is if there is an equivalent browser object / if smartphone has support for that kind of device.

It would also enable a simpler update mechanism - over the USB cable, which is currently only supported in Windows but if it was in browser then it should work everywhere.

General Discussion / Re: MIDI overview for Gecho Loopsynth?
« on: October 27, 2020, 07:28:30 PM »
That's a nice keyboard! And it has true MIDI, great. I was looking for something simpler / that takes less space and still has 8 knobs or faders, but all seem to only have USB MIDI. Well, I guess it is time to hack the generic USB controller that I have (by adding Arduino with USB host shield).

About sustain - is that not achievable by the "MIDI Polyphony" setting?

I guess SUSTAIN_CHORD is close to what you want? (except that the sustain will be there all the time, but from my experience that is good enough in most channels).

Of course, better to have an external pedal to control this. The modification for the firmware would probably just be as simple as "ignore note-off messages while the pedal is pressed, release all notes when pedal is released"... or, if you want to just tap the pedal shortly to sustain the chord, then "ignore note-off messages from now, until another note-on comes in, and release all previous notes then". what do you think, would that work?

Hardware Questions / Re: Buzzing sound when recording
« on: October 27, 2020, 07:08:12 PM »
Ah, good to hear it was just that!  8) Thank you for the update!

Hardware Questions / Re: Buzzing sound when recording
« on: October 27, 2020, 10:40:41 AM »
Hi! Is the buzzing now present in recordings? If yes, can you send me an example wav? (via email or upload it here, short files should work). Also, can you try another SD card, to find out whether the problem is related to current state of the card (might need to be reformatted) or the firmware. You can also try to revert back to old firmware to be sure that the problem arises only in the new version

General Discussion / Re: MIDI overview for Gecho Loopsynth?
« on: October 25, 2020, 11:01:42 AM »
Hi Michel, happy to hear you are enjoying the loopsynth!

I've only tested it with Arturia Keystep, which transmits on CC1. And it is usually tied to the most interesting parameter / the one effect of which is most prominent in the sound - so you're right it's amount of voices in granular, and the pitch bend control is linked to de-tune.

Is there an official MIDI specification somewhere? I couldn't find it anywhere, but maybe I overlooked something?
No I haven't got to do that yet - thanks for reminding, I need to update channel list with more details about MIDI controls where it was recently added.

I like the sensors, but I think it would be awesome to be able to use MIDI CC to control the sensor effects.

The other cc numbers are ignored, but it would be easy to link them to the other 3 sensors. And in Clouds engine they could directly control the 8 most useful out of the 10 parameters available.

And maybe use sensors in conjunction with CC, so they add up...
That is certainly possible too.

What controller do you use - does it have more wheels or does it rather allow to select what the one or two wheels do?


Programming Questions / Re: JTAG or USB for programming
« on: September 21, 2020, 01:27:01 PM »
Hi and welcome! :)

The easiest way is to connect via USB, that's what I use when developing the firmware. And it is supported by official environment.

But indeed JTAG offers more comfortable debugging, if you want to use it you'd need to hi-jack pins that are currently used for SD card:

Maybe there could be an adapter in the form of micro SD card to wire them out.
If reset signal is needed, it can be taken from the pad on top right of the board - top pad is RST, bottom is GND:

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