Auto 808

[Marshall Arts]

Can anybody explain to me, why the two of the most iconic devices in music electronic have an "808" in their product name? Anyway, the "Auto 808" is referring to the TR-808 Rythm Composer, not the TS-808 Tube Screamer ;-).

Background story: I sometimes play a foot stomp with my acoustic guitar (basically a number plate with a bass pickup below it) to add some "four on the floor" beats. However, I was always looking for something more automatic, where I tap in the tempo and the thing keeps going... Than I saw the documentary "808 - the heart of the beat that changed music" (https://en.wikipedia.org/wiki/808_(film)) during vacation and thought, that an 808 bass drum and some arduino control might do the trick. I designed taprecise (a tap tempo control for PT 2399 based delays, http://www.madbeanpedals.com/forum/index.php?topic=22653.0) before, so I knew that this would not be too complicated. Initially, I wanted to build the analog bass drum circuit from the 808, but than I found out, that you can use the PWM output to play samples. And somebody had already designed a polyphonic (!) arduino sample player with 808 samples (https://hackaday.com/2016/02/23/a-slew-of-open-source-synthesizers/). The sample quality is not brilliant, but it's absolutely ok for the purpose.

The Auto 808 has a white tap tempo button and a blue "mute" button. Tempo can be tapped while the thing is muted, the LED will indicate the beat. Once the tempo is set, I can unmute the Auto 808 and it will start straight on the press of the blue button.

When the switch is set to the left, the device is in manual mode - the white button will trigger a bass drum sound each time it's pressed (so, basically it will work like a foot stomp). There is no latency (the samples are played via interrupt).

Output is a mono 3.5 mm jack, as it will be connected to the AUX in on my "TC Helicon Play Acoustic Live" (which is also 3.5 mm, so I don't need an adapter cable).





I liked the breadboard version from this morning so much, I decided to build it straight away and not make a PCB for it. With only a few offboard components, it may not look nice from the inside, but it's a great practice tool and a powerful bass drum companion.

[dawson]

Neat!

[Marshall Arts]

Quick demo

https://youtu.be/41t1CaPrlF4

[jjjimi84]

That is such a brilliant idea, berry berry kewl.