Electronic music DIY - some simple ADCs and DACs

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Audio in and out

ADCs

MCP3008, SPI, 8-channel, 10-bit (fewer-channel variants: MCP3004, MCP3002, MCP3001) (EUR1.5)

MCP3208, SPI, 8-channel, 12-bit (fewer-channel variants: MCP3204, MCP3202, MCP3201), (EUR2.5)

ADS1015, I2C, 4-channel 12-Bit ADC (EUR1.0)

ADS1115, I2C, 4-channel 16-Bit ADC (EUR1.5)

(...4 and ...3 variants just have fewer channels)

AD5593, I2C (EUR8)

8 channel, each usable as a 12-bit DAC, 12-bit ADC, or GPIO

PCM186x, I2S

The above tends to choose the most-channel variant Note that some of these can be used in differential mode, halving the effective number of channels.

DACs

TLC5620, SPI, 4-channel 8-bit (~EUR3)

MCP4728, I2C, 4-channel 12-bit (EUR0.5)

MCP4725, I2C, 1-channel 12-bit (EUR0.5)

MCP4921, SPI, 1-channel 12-bit (EUR0.5)

MCP4922, SPI, 2-channel 12-bit (EUR1.5)

MCP4822, SPI, 2-channel 12-bit (EUR3.0)

TDA1543, I2S, 2-channel 16-bit (EUR0.5)

PCM1710, I2S, 2-channel 16-bit (EUR1.5)

DAC8551, , 1-channel 16-bit EUR5 (e.g. in Braids)

PCM5102, I2S, 2-channel 16- or 32-bit (PCM5101 and PCM5100 are very similar, but with slightly lower dynamic range and SNR)

DAC08, DAC0800 and similar, 8 boolean input pins to one 8-bit channel output (EUR0.5)

TLC5940, 16-channel 12-bit PWM (not DAC) (EUR1.5)

Earphones / small speakers amps

There's a bunch of ICs that you can use on a line out that can also deal with headphones (not all op amps are happy driving them directly) and tiny speakers.

Many of these are effectively op amps with larger power stages

which is why you can one of these amplifiers as an audio op amp (the specs aren't so useful beyond audio)

and why you can build your own from an op amp and a transistor pair

...essentially a simple Class A amplifier.

choice of op amp (e.g. TL072) may imply bipolar power, which is impractical unless you happened to have that already.

In-ears headphones only need a few milliwatts(verify), while chunkier headphones up to maybe a few hundred milliWatts (depends on their sensitivity, which is sort of their efficiency: dbSPL @ 1mW)

Some options:

• LM386

an audio amplifier IC -- basically an op amp with a larger output stage

Ouput power varies with package, lowest is ~100mW and highest is ~800mW.

4~12V supply, or 5~18V, depending on package

gain is 20 (default) up to 200

and bypass

• LM380

similar to LM386, but up to 2.5W

10~22V supply

• TDA7052

...or others from that family, like TDA7050

4.5~18V supply

differential output

higher output (~1W)

apparently a little lower noise

from 3V?

• TDA2822

1.8~15V supply

2* 110mW

gain: 39dB (~90), fixed

two channel

• PAM8403

Class D (most of the above is class AB)

3~5V supply

3W output

https://electro-dan.co.uk/electronics/pam8403speakers.aspx

Microphone (pre)amp

✎ This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

Main jobs:

increase signal level

not introducing noise

A lot of op amps qualify for that.

In practice you have further constraints from

a specific mic's impedance (things are harder if it's higher, like piezos)

a specific mic's sensitivity, typical mic placement

40dB of gain covers a lot of uses

some amount of padding (attenuation) is sometimes also useful

voltage level of what you're driving into expects

use of phantom power

not pick up mains hum (or other EM noise) because increasing any 40dB is probably audible. Probably meaning shielding.

There are a few specific helpful ICs, e.g. with externally tweakable gain, like

• MAX9814

autogain threshold and attack/release configured via external components

designed somewhat towards electets

and you may not want automatic gain control in various cases.

https://www.homemade-circuits.com/small-amplifier-circuit/

Depending on what you're driving into, some BJTs, or FETs,

Most op-amps (or headphone amps, LM386 seems common in examples) with at least moderate gain, and moderately low noise.

This is more about circuit design.

• If electret, you want an offset (resistor to high rail) and then probably isolate that from the input with a capacitor

• switch-mode power is likely to introduce noise, so instead want battery power, or linear regulation,

When you can, put this closer to the mic, though in practice this matters for very quiet mics.

Sensor pre-amps in general can be classified as

current sensitive

charge sensitive

parasitic capacitance

I've seen circuits with LM386, LM358,

https://www.homemade-circuits.com/small-amplifier-circuit/

http://www.thatcorp.com/datashts/AES129_Designing_Mic_Preamps.pdf

Combinations

DAC and amp

MAX98357 - I2S, 1-channel, 3W amp

CODEC - ADC, DAC, and sometimes more

• SGTL5000 - I2S

• AK4556 - I2S

• PCM3060 - I2S

ADC, DAC, and amp

WM8731 - I2S