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Messages - Randall (Admin)

#226
Good questions.  Here are my answers:


- Can I use SPST toggle switches in place of the 3 footswitch buttons at the bottom?
Any switch could be used in place of a footswitch, but a “latching” switch like a toggle probably wouldn’t work the way you intend without a slight modification to the pi-Stomp software (https://github.com/TreeFallSound/pi-stomp/blob/master/pistomp/footswitch.py). It expects a momentary signal to change bypass status. Each time the GPIO input is pulled low, the bypass status is toggled. Step on it, the effect is bypassed, step on it again, it’s enabled. A latching switch like a toggle (without a software change) would toggle each time you turned it “off”.  The software change would be almost trivial though.

- Do you sell a complete kit with only a bare case, meaning all drilled just not painted/printed?
Not officially.  I do however have one which was my first CNC prototype.  I'd be willing to give you that for half price ($16 instead of $32).  email: sales@treefallsound.com

- Are there any extensions / hacks that could be done at built time to address the 3 concerns at https://treefallsound.com/wiki/doku.php#warnings_about_powering_pi-stomp - maybe a fuse for #3, some diodes for #2?
The design does include a resettable poly fuse, but the reaction time could be a half second or more.  Damage to sensitive components can occur within milliseconds, so the fuse is mainly there to prevent fire.  Additional diodes (even low dropout) still drop the voltage.  Since the pi wants 5v, and every power supply I tried actually measured slightly less than 5v, I couldn't warrant the extra drop.  Bottom line, use the wrong supply, it might fry.  But given the fuses in the pi and pi-Stomp, it likely won't catch on fire.  To greatly lessen the likelyhood of using the wrong supply, the power connector chosen is a less standard barrel connector with a 2.5mm center pin instead of the more common 2.1mm pin.  This prevents the otherwise likely scenario of using the standard 9v supplies ubiquitous for guitar pedals.   

- Is line level input supported?
By “line level” you probably mean -10dBV (aka “Consumer line level”), roughly 1v pk-pk.  The input buffer has about 2.4 volts of headroom, so yes, it can handle consumer line level or 0dBu Pro Ref Level, but not +4dBu Pro Line Level.  For that you’d at least need to attenuate it before feeding it to the pi-Stomp.  For fine adjustment, you can control the input gain of the digital mixer via the System menu, but if the analog input is too hot, it's already clipped by the time it's hit the digital mixer.

- How are DIN and USB MIDI related? Can they be freely routed in software?
The MOD host allows MIDI learn for mapping controls (pi-stomp footswtiches, "Tweak" knob, expression pedal, and any DIN MIDI or USB MIDI CC messages to plugin settings.  MOD leverages ALSA and Jack for MIDI and Audio.  So, yes, anything you can do with those is possible.  The pi-Stomp and MOD software do not "own" the MIDI ports, they can be routed/shared by whatever software is configured to do so. 

#227
Using pi-Stomp / Other audio software works on pi-Stomp!
February 02, 2021, 02:10:20 PM


pi-Stomp has always intended to be a platform. One of its main advantages over commercial units, is that it runs Linux, and thus can run additional software.

I just committed some minor software changes to allow the hardware to work independently of the recommended MOD software. So now, you can use pi-Stomp hardware with other audio plugin hosts!

You can even MIDI-map the pi-Stomp controls and footswitches to control effect parameters in the host.

I’ve tested two such hosts so far. They both work great.

Rakarack â€" an awesome (Free) guitar oriented virtual pedalboard


Carla â€" a Free, full featured modular audio host. It can run multiple plugin formats including LADSPA, DSSI, LV2, VST2, VST3 and AU, plus SF2 and SFZ sound font files!


For more details and installation instructions, check out https://treefallsound.com/wiki/doku.php?id=other_software_running_on_pi-stomp_hardware

We’ll likely eventually add improved support for software like these so that the LCD and rotary encoders can be used to change settings, presets, pedalboards, etc.
#228
Building pi-Stomp / Re: Input buffer
December 03, 2020, 03:56:32 PM
If by "not playing nice with the 5v supply", you mean noise, Yeah, I know all about that!  The 5v rail is likely to be extremely noisy.  Not just with typical ripple, but pop-corn burst noise.  Even a good low pass RC or LC filter won't help much.  I found I had to regulate the supply - kindof a bummer cuz you loose headroom to the voltage drop of the regulator, but the only other low noise solution I found was to battery power it.  Since it would be weird to require a battery in a digital multi-fx pedal, I used a  AMS1117-3.3 on the 5v rail with input and output caps.  For the buffer itself, I use this https://www.mouser.com/ProductDetail/579-MCP6292-E-P with unity gain (2 resistors, 2 capacitors per channel).  I tried 5 different dual op-amps and settled on that one because it was the quietest and supports rail-to-rail input/output which is important when you don't have headroom to spare. 

#229
Although this Forum Topic is open for discussion of bugs/issues/feature-requests etc., formal reporting and tracking should be done in the github project(s). 

For pi-Stomp software go here: https://github.com/TreeFallSound/pi-stomp/issues
#230
General / Forum Rules of Conduct
September 27, 2020, 11:05:30 PM
This forum is provided to discuss DIY musical effects.  It is not intended as a general "Lounge" type forum, so please don't use it for topics that aren't in the general realms of music, instruments, effects, electronics, DIY, etc.

We hope it'll serve as a very open, good natured, helpful forum and not require moderation.

Abuse on this forum will not be tolerated.  The administrator reserves the right to delete any posts which are considered offensive, harassing, racist, sexist, etc. and to suspend the account of anyone for any reason.

Like Bill and Ted taught us, Be excellent to each other!