Audio processing using Phantom Power?

Which Arduino board would be best for doing a bit of low-latency audio processing using only the power provided by the Phantom Power of an audio mixer?

I want to do a bit of EQ, gating and compression to a vocal or instrument input with a simple pitch tracker for practicing in the studio on headphones (the headphones would be powered through the audio mixer). The signal can't have too much latency or it will be too disturbing or even unusable...

Would the analog audio output of the DUE be high enough resolution to sound ok? Also, I believe Phantom Power is 48V @ 14mA although I've heard that it can safely be more than 14mA, that's just an average. Thoughts?

MOderator removed crosspost in other section.

An Arduino is a microcontroller, it's used for controlling LEDs, motors, small displays, reading inputs from sensors and buttons ... It is not suitable for digital signal processing.


It’s not suitable because it can’t do it? Or because it isn’t what Arduino boards are generally meant for?

It doesn't have a decent ADC nor DAC. For audio, you need at least 16 bit, preferrably 24 bit, at a sample frequency of at least 48 kHz. That's an insane amount of data. An 8-bit AVR Arduino will just choke. There are ARM Arduino's available, that may be able to keep up. Applying digital filters and effects to the signal takes a lot of processing power at that rate. It will require complex programming approaches using DMA etc.
There is a reason why commercial effect processors use dedicated DSP hardware.

what about the Arduino DUE? and if this isn't problematic to ask... what about one of the Raspberry Pi units? Or some other unit I can get for under $50?

As I said, it might work with a Due (ARM Cortex-M3), but it is going to take an enormous amount of time and effort.
Do you have any background in real-time audio processing and DSP? What experience do you have in the Arduino field? Do you know any programming? What languages?

A Raspberry Pi is a completely different beast. It's a real computer, it is much, much faster, has 10,000 times more RAM, runs an actual operating system. I'm pretty sure that it can do some real-time audio processing, but there is no way that you can run it off of a 14 mA supply.

I have almost no qualifications of any kind. My plan was to do as much research as possible on my own, find some possible solutions and present them to an expert who can lash it all together and make it work for some fee. -that’s another quest I’ll be going on, to find such a person...

My best shot so far is my brother who taught himself Python last year, so he was planning on giving it a go using some translator? Programming Arduino with Python? He and I both have a sound engineering background.

Python is an interpreted language and so is much slower than C/C++ which is a compiled language.
The problem with the Pi is that the operating system is not real time so audio processing is much more difficult involving pipes and DMA and other advanced concepts.

Your chosen project is way way over your head and if you want to do this on the Pi I would suggest you have at least a year of study in front of you before you can begin to tackle it. Mind you if some one have done it before and published something on line you can reproduce then that makes it much simpler.

However if someone has managed to get this to run on 14mA, or even 140mA which might be possible with a buck regulator down from the phantom power, supprise would be insufficient and I would have to resort to astonishment.

I wouldn't advise putting a switching regulator on your mixer's phantom power, that'll risk inject loads of noise into any phantom powered microphone on the same mixer!!

Phantom power is designed for one purpose only, FET preamps in a microphone - trying to reuse it
for a DSP system sounds deeply problematical.

This is exactly the same reason that my engineers gave when they told me that I should not use a switching regulator in an RFID reader. This proved a totally unfounded fear when I actually ordered one to try it.

For now, I'd forget about using phantom power. You've got a lot of learning, experimentation, and development to do before you can start thinking about the power supply...

My best shot so far is my brother who taught himself Python last year, so he was planning on giving it a go using some translator? Programming Arduino with Python? He and I both have a sound engineering background.

That's good. Once you know one programming language, it's a lot easier to lean another one. The important concepts (mainly loops & conditional execution) are the same. And when programming a microcontroller, you're using special functions & libraries specific to the particular hardware, so you're not using much Standard C/C++ (or Python) anyway.

There is a FREE online DSP book called [u]The Scientist and Engineer's Guide to Digital Signal Processing[/u], By Steven W. Smith. The book isn't specific to any particular hardware or language. I believe the examples are pseudocode. So you could "play around" with Python or C++ on the computer before getting any particular hardware.

I'm not saying you can't do it, but DSP is generally considered "advanced programming" and if you were taking Computer Science in college, you probably wouldn't take DSP until your 3rd or 4th year. (And by that time you'd also have lots of math under your belt.)

On the hardware side, I'm not sure if the Raspberry Pi can handle it or not. You'll probably want to run it without the operating system. The BIG PROBLEM with "regular computers" is the multitasking operating system, which is always multitasking even when you're running one application. That means you need buffers, and buffers are delays. There are "tricks" to minimizing latency and obviously some people are using PCs & Mac's for real-time audio but getting the latency down can be a pain and it usually takes a powerful computer. (The faster the computer can finish the other tasks, the faster it can get back to reading/writing/processing audio, so you can use a smaller buffer.)

I don't know if you need one, but there are specialized DSP chips and you can get a development board so you can start testing & writing software before building the hardware. (I don't know what the DSP chips cost but last time I looked into this, the development boards were several hundred dollars... Apparently not meant for hobbyists.)

Is that this sort of synthetizer you want to build ( Arduino DUE Inside)?:

Is that this sort of synthetizer you want to build ( Arduino DUE Inside)?:

Groovesizer TB2 - All Twelve Bits [DEMO] - YouTube

Who's talking about synthesizers?

Ok everyone, here's really my question in all of this: Where do I go to find someone (ideally someone local I can meet with in person) whom I can pay to just figure this all out for me and build a prototype? I have money to spend on it, but it is difficult to find such people.

Sites like Upwork and Toptal are problematic because you have to pay up front for the time spent explaining the project to the would-be designer, and I don't want to do that. The reason I was digging around here in this forum was because I figured I might just have to do enough of my own research to present a more finalized solution to an hourly engineer on TopTal.

I really want to find someone who is willing to be creative with me and build a prototype which I'll purchase from them for an amount that also satisfies their time invested in the project, not this strict hourly stuff I keep finding online. I don't work hourly, and so I don't like paying hourly. I think in terms of projects and negotiated rates. Any ideas?

ideally someone local I can meet with in person ....... Any ideas?

Given that this is a global forum and you haven't said where in the world you are then no.

This is not a quick project even for people experienced in this sort of thing, you will be talking about months of work and several thousand dollars, at least. It is unlikely you will meet anyone to do it for the money, your only hope is to engage someone who wants to do it as well.

I'm in Portland, Oregon. Several thousand dollars sounds about right to me, but I just don't know where to find people. I've tried contacting computer science students in the local universities, but nobody has time, no matter what the pay.

Try contacting a local hack space or Fab Lab.

I believe Phantom Power is 48V @ 14mA although I've heard that it can safely be more than 14mA

It might also be 12V or 24V, probably limited by some series resistance.

If you want this to work only on your particular mixer, that's ok - just measure the output and see what you have.

Designing something to use phantom power from any mixer... I'd say it's a non-starter.