The Eerie Sounds Of Ioalieia: An ESP32/Valve/Analog Hybrid Circuit Sculpture

We’ve not had a circuit sculpture piece for a while, so here’s “ioalieia” a lovely hybrid digital-analog sound sculpture by [Eirik Brandal] to dig into.

Tidy straight lines. Nice job!

The host of the show is the ESP32 module, which generates audio frequency square waves, which are fed into a MCP4251 digital potentiometer. From there, it is fed into a AS3320 Voltage controlled filter (VCF), from Latvia-based ALFA (which is new to us, despite them being manufacturing electronics for sixty years!) This is an interesting device that has a four independently configurable filter elements with voltage controlled inputs for frequency control and resonance. The output from the VCF is then fed into a 6n2p (Soviet equivalent to the 12ax7) twin-triode vacuum tube, which is specifically aimed at audio applications.

The suitably distorted filtered square waves then pass into a Princeton Tech Corp PT2399 echo processor chip, which being digitally constructed, uses the expected ADC/RAM/DAC signal chain to implement an audio echo effect. As with the VCF, the echo depth can be modulated via the digipot, under the ESP32’s command. For a bit of added bling, the vacuum tube output feeds back into the ESP32, to be consumed by the internal ADC and turned into a light show via some PWM controlled LEDs. Lovely.

The final audio output from the echo chip is then fed into a speaker via a pair of LM380 amplifiers giving a power of about 5 W. It sounds pretty good if you ask us, and software configurable via Wi-Fi, giving this sculpture plenty of tweakabilty.

Of course circuit sculpture come in all shapes and sizes, and it wouldn’t do to not mention at least one sculpture clock project, and while we’re on it, here’s last year’s Remoticon circuit sculpture workshop.

18 thoughts on “The Eerie Sounds Of Ioalieia: An ESP32/Valve/Analog Hybrid Circuit Sculpture

  1. Hmm maybe, a few months ago, IIRC, I went down a rabbit hole learning about ALFA.
    Something on Hackaday probably triggered that excursion. A comment perhaps?

    1. Does anybody know a distributor for ALFA or do they sell direct? Can’t find their parts on octopart, and there’s no info on buying on their website – i see a few synth companies reselling in quantities of 1, but interested in knowing what kind of pricing they have for medium quantities (10-500).

      1. You mean….no one to hold my hand and keep me from dangers assuming me to be some simpleton?! But….then I’ll have to consider my surroundings and be responsible for my own actions! And if I’m too busy paying attention to myself like that I won’t be able to judge everyone around me for engaging in lifestyles I’ve heard implied are bad and therefore must lecture those people to be a better milksop⁶, as they are obviously simpletons. They need to llive a boring, bland, uninteresting life like me so I can justify my own lack of substance in a life I allowed myself to be told to live , avoiding any semblance of thinking for myself less I inadvertently enjoy something the Zezeitgeist of doesn’t….. I mean, if no one is holding my hand like that …. How will I eat my kale chips?!?!!!

  2. Just for info: ALFA produces clones of the (in the synthesizer world) very well known chips from Curtis semiconductor that came up in the 80ies; with dedicated chips for all core synthesizer functions (VCO, VCF, ADSR, VCA). With the revival of analog synthesizers the ALFA chips found a broad acceptance.

  3. Nice build. Hopefully he us using 45v anode voltage and no 250v… One thing that nags me a lot is the tendency to put a led underneath a tube. For me that is the same as the cheap steampunk thing to hotglue cogs to a hat.

    1. I generally find that the glow from the filaments visible through openings are enough. Especially the bigger hotter tubes are bright enough.

      But i can understand if one wants to highlight them a bit with lighting. Just wish they would pick something that fits like Amber coloured leds that match the warm nature/aesthetics of tubes, instead of nearly always going for Blue or RGB. That is just plain tacky if you ask me.

      1. I was going to say the exact same thing. As long as it matches the orange/amber glow, heck even if it has a bit of ramping to the brightness for shiggles, an LED under the tube is fine. But I agree, just a bright ass blue or RGB cycling through unnatural (for a tube), and garishly against any semblance of aesthetic, color patterns is absolutely awful. It advertises the lowest form of both understanding of why tubes are cool, and of effort on behalf of the builder/designer. Honestly, IMHO, it does nothing but go against any possibilty of seeing any positivity in a piece, art or otherwise. It is that rank fugly to me.

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