Happy New Year everyone! Hope you all had a good holidays. I’ve been thinking about doing another revision to my Pedal Hardware design (still 125b sized). Any wishlist items from the community?
There are a few things bothering me about how it’s assembled (rotation of the bottom 3 pots, having through hole stuff under the pots, etc) that I think I may finally have an idea of how to solve. I’m also thinking of removing the assembly of the jacks from the PCB so that if people want to do alternative layouts for the enclosure it would be easy to do so (top jacks instead of side, separate L/R jacks for audio instead of TRS, etc).
It’s sorta a big undertaking to re-layout the whole board so I figured now is the time to ask.
Yes, to both of you. My current top priorities include what you’ve mentioned:
Rework the layout so the pots can all be rotated the same way. Currently pots 4-6 are upside down compared to 1-3 because that was the only way it would fit with the existing layout.
I plan to remove all of the jacks that are PCB mounted (MIDI, TRS Audio, Power). Instead I will provide through hole pads on the PCB where you can connect whatever enclosure mounted jacks you want. This will make it easy to make variations on where the jacks are on the enclosure. So this would help the requests that @Manysounds and @KnightHill mention. For instance, instead of using TRS single jacks for stereo audio in /out, you could opt for separate L/R jacks. Or you could do top mounted jacks instead of side mount, etc.
Expression Pedal support, this should be fairly easy and makes for a nice option.
Here are some other ideas folks have tossed around:
RGB Indicator Leds
Additional buttons for the screen UI.
Larger screen (no idea how this would fit)
S/PDIF Digital Input/Output (not really sure how feasible this is, might be better to create SPI connections between pedals)
Toggle switch to bypass input / output buffers for line level mode
Toggle switch to indicate if TRS input is in Mono or Stereo mode
Seed2 DFM integration (very little information on this yet, so not sure if possible)
Hi Keith,
thank you very much for sharing your project!
As I don’t have kicad I was not able to have a look at the schematics. Is there a possibility to have that as pdf?
I too want to use Daisy Seed for Guitar effects and have now begun to dive into this. You have written, that you use schematics of the petal board?
In my opinion it is probably better to use a preamplifier with some gain to use as many bits of the ADC as possible and a low pass filter for low noise to suppress radio. At the moment I experiment with Gain=10 and f.hip= 10kHz at the input. Have you done some experimenting here too?
The second thing, that astonishes me, is that neither Petal nor Terrarium have an output low pass filter, while the datasheet of PCM3060 says: “…This filter is not enough to attenuate the out-of-band noise to an acceptable level for many applications in general.” - When I have a look at the output signal with my oscilloscope I do have the impression, that this is true. Therefore I think for Guitar use an output RC-Filter 10kHz (10k + 1n5) is a good thing to add. I would be interested in your opinion here too?
Cheers Christof
Well, if you want to have no colouring of the sound in the preamp here then a circuit with negative feedback like a typical opamp circuit is the way to go.
There are very nice circuits with njfets which do not need a daisy seed to emulate a Guitar preamp. A favourite of mine is Son of Ben. Son of Ben Preamp - PedalPCB.com
For the “effects-suite” you’ll have to use the bootloader to load to SRAM, which I thought was going to be complicated until I actually did it, and it turns out to be super simple, here’s the docs for it: libDaisy: Getting Started - Daisy Bootloader
Interesting, I think the input / output stage buffers could be improved in this design. After talking with ES, they also might be the reason there is some extra noise when using Rev7 seeds. I’m not an EE, I mostly just cobbled together this design from other schematics and designs, so it’s a bit out of my league to know how to improve upon the buffer design. If you have any ideas, I’m definitely all ears! I’ll have to PDF the full schematics later, but here are some screenshots of the Input / Output buffer circuits. These designs are the same as from the ES Daisy Petal reference designs.
Hello! Just wanted to thank @kshep as well for open sourcing this project! I finally got the chance to complete this first build last night.
I didn’t catch that you could order the DC/DC converter through JBL before ordering assembly, so I ended up purchasing this separately, and soldering the part with an iron. I forgot how difficult it is to hand solder at a smaller smd pin pitch Otherwise, the build was smooth for most part (it was a definitely a tight squeeze for soldering some of the components), I made some mistakes with getting the pots/lcd screen flush with the case, but this was my first pedal build ever, and I have 4 more pedals to build where I can improve
For this pedal, I am using the Rev 4 daisy with the original audio codec and am happy to say that, the noise level was astonishingly low, if not negligible. At least this is the case when I feed line out from my audio interface to the input, I’m sure that signal from my guitar or bass will have a different impact as the signal has a much smaller magnitude.
I can’t wait to implement some FX ideas that I have been looming on for the past year and I’m so excited that I was able to get this up and running without many hiccups. Thanks again for releasing this platform and reigniting my interest in audio DSP!
I bought the Petal years ago intending to build something but saw recently that it’s no longer available and the only docs are under Legacy Products . So I wasn’t sure where to start with it and have been looking around recently because I want to build pedals now. I’m so glad you made this awesome platform, well done!
@Transient Awesome, glad you were able to get one built! I feel your pain on hand soldering the DC/DC converter, that can be really tough. I did that on a my first few ordered before I could figure out how to get JLC to assemble them. Glad to hear you got everything working and I look forward to seeing what you do with it!
@eno Thanks! That’s one of the reasons I started this project was because the Petal wasn’t available any more. Your Daisy Petal should still function just fine though. There isn’t really any thing much different in developing for it vs my pedal. You could probably pretty easily even create a Daisy Petal hardware definition for my Software platform get some effects up and running quickly.
I’m currently implementing a stereo delay (currently a multi tapped delay with pitch shift control on each tap because I saw there was already an extensive reverb/delay module), and have a rough demo working but would like to expand more and flush out some details before sharing.
I have a question regarding the knobs parameter/adc scaling resolution: I can see that these are scaled from 0 to 127.
Is this design choice for ease of implementation to fit in the MIDI CC value range, or due to preserve accuracy in the ADC, or some limitation (or simply to accommodate the default value) in libDaisy with getting 16 bit resolution from the ADC?
If this is simply ease of integration into MIDI spec, I would like to propose an extension to the parameter type definition to give the option to specify parameters that occupy 2 midi CC slots and scale for 14 bits. Let me know if this makes sense and if you’d like to me make a PR to suggest an implementation to accommodate this feature and maintain current behavior so that no end user needs to change their effect classes?
Otherwise, the build was smooth for most part (it was a definitely a tight squeeze for soldering some of the components), I made some mistakes with getting the pots/lcd screen flush with the case, but this was my first pedal build ever, and I have 4 more pedals to build where I can improve 
. So I wasn’t sure where to start with it and have been looking around recently because I want to build pedals now. I’m so glad you made this awesome platform, well done!