Headphones and line out for 1-bit Arduino sound

Shiru · 2017-02-14 17:00:55

Shiru
1-bit Wizard
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From: Russia, Moscow
Registered: 2015-07-01
Posts: 502

Topic: Headphones and line out for 1-bit Arduino sound

Alright, I had enough of crappy sound coming from an old trasistor radio that has been used for testing for Octode and Phaser1 ports, which made quite difficult to judge if the sound is even correct. It became apparent that I need a better control, especially if something more complex or tricky than these engines considered, so I came up with a very simple schematics that may come handy if you need something like this too. Note that I'm not an EE, it may have mistakes in the design, but at least it something that works. It can be used to connect headphones (volume is not too bad even without amplifier), line input, or an amplifier.

R1 and C2 here are the low pass filter, the values calculated for ~16 KHz cutoff to avoid possible hiss artifacts that is typical for the 'interleaving' 1-bit enignes.

C1 is a coupling capacitor to block the DC offset. Potentiometer R2 allows to change the output level. The values for these were chosen just because I didn't have anything else. These together actually act as a high pass filter, but the cutoff is ~1.5 Hz, so it should not affect the sound. Volume range is good as well, smooth transition from zero to max.