Sound Pack Creation Guide for Midicircuit

Since launching Midicircuit v2, a few of my musician friends — 7th Wonder and Luke Elliot — along with myself have been contributing sound packs to the app. Through that process and experimentation, we put together this guide for anyone who wants to create and submit their own sound packs for Midicircuit.

What Is a Sound Pack?

A sound pack is a collection of audio samples that users play on Midicircuit. There are three types:

Type	What It Is	Pad Behavior	Examples
Drum	Collection of one-shot hits	Each pad plays a different sample	808 Kit, Boom Bap Kit, Lo-fi Kit
Melodic	A single pitched instrument	Each pad plays the same sample at a different pitch	Piano, Synth Lead, Rhodes
Bass	A single bass instrument	Same as melodic, tuned for lower range	Analog Bass, Sub Bass

Audio Specifications

All samples must meet these specs:

Spec	Requirement
Format	WAV
Sample Rate	44.1 kHz
Bit Depth	24-bit
Peak Level	-1 to -3 dB (normalize if quieter)
Channels	Mono or Stereo

Checking Your Levels

ffmpeg -i sample.wav -af "volumedetect" -f null /dev/null 2>&1 | grep -E "max_volume|mean_volume"

If your samples are too quiet, normalize them:

ffmpeg -i quiet.wav -af "loudnorm=I=-14:TP=-1:LRA=11" normalized.wav -y

Quality Checklist

Every sound pack should pass these six criteria:

Punch — Does it hit hard and feel immediate? Transients should be crisp.
Body — Does it have weight and fullness? Samples shouldn't sound thin or hollow.
Character — Does it have a distinctive sonic identity? Avoid generic, stock sounds.
Consistency — Do all samples in the pack feel like they belong together? Matched in tone, processing, and vibe.
Dynamics — Does it respond well to velocity? Samples should sound musical across the volume range.
Tail — Is the decay/release clean? No clicks, pops, or abrupt cuts at the end.

Creating a Drum Kit

Drum kits contain up to 16 individual samples, each mapped to a pad on the grid.

Drum packs don't have to be strictly drums. Hip-hop producers often include melodic chops, chord stabs, vocal samples, vinyl loops, or instrument one-shots alongside kicks and snares. Think of it as a sample pad — anything you'd want to finger-drum or chop with works here.

Sample Count and Layout

The pad grid is 4x4 (16 pads). For a traditional drum kit, aim for a balanced layout:

Sound Type	Suggested Count	Grid Position
Kick	2	Pads 1-2
Snare	2	Pads 3-4
Rim / Side Stick	2	Pads 5-6
Clap	2	Pads 7-8
Hi-Hat	2	Pads 9-10
Shaker / Tambourine	3	Pads 11-13
Percussion / FX	3	Pads 14-16

You can use fewer pads — not every kit needs 16 samples. The existing "Analog Rytm 808 Drums" kit uses 12.

Naming Your Drum Samples

Name samples descriptively. If you want automatic GM-standard ordering (recommended), include the sound type in the filename:

KICK_01.wav
KICK_02.wav
SNARE_01.wav
SNARE_02.wav
RIM_01.wav
CLAP_01.wav
HIHAT_CLOSED.wav
HIHAT_OPEN.wav
SHAKER_01.wav
PERC_01.wav

We recommend ordering them in this order: KICK → SNARE → RIM → CLAP → HIHAT → SHAKER → PERC

Tips for Drum Samples

Keep kicks punchy: 100-300ms is usually enough
Snares and claps: leave a natural tail, but no longer than ~500ms
Hi-hats: closed hats should be tight (50-150ms), open hats can be longer
Avoid reverb tails — the app adds its own FX. Dry is better.
Remove any silence at the start of each sample (zero-latency trigger)

Creating a Melodic Instrument

Melodic packs use a single sample that the app pitch-shifts across the pad grid to create a playable instrument. The quality of that one sample matters a lot.

Record or render a single sustained note at middle C (C4)
Length: 2-7 seconds. Trim longer samples and add a fade-out.
Clean, dry samples pitch-shift better than heavily processed ones
Avoid heavy vibrato — it sounds unnatural when pitch-shifted
Slight detuning or chorus is fine and can add warmth
Export with a medium-long release for a natural decay

Creating a Bass Instrument

Same as melodic — a single sample, pitch-shifted — but tuned lower.

Record at C2 or C3
Keep it punchy: 1-3 seconds is usually plenty
Balance sub and harmonics — sub-heavy samples lose definition when pitched up
A slight attack transient helps the note cut through in a mix

How to Create Your Sounds

You don't need expensive gear. Here are several approaches:

Option 1: Software Synths (Free)

Use free VST/AU synths in any DAW:

Vital (vital.audio) — Modern wavetable synth, excellent for pads, leads, bass
Surge XT (surge-synth-team.org) — Powerful hybrid synth
Dexed (asb2m10.github.io/dexed) — DX7 FM synth for electric pianos and bells

Workflow:

Design your sound in the synth
For drums: render each hit as a separate WAV
For melodic/bass: render a single sustained note as WAV
Normalize and export at 44.1kHz / 24-bit

Option 2: Hardware Recording

Record hardware synths, drum machines, or acoustic instruments:

Record direct (line-in) or with a microphone
Export each sample as an individual WAV
Trim silence from the start, clean up the tail
Normalize levels

Option 3: Sample Processing

Start with existing royalty-free samples and process them:

Layer, pitch, filter, or resample to create something new
Make sure the result is original enough to avoid licensing issues
Export as WAV at the correct specs

Option 4: Field Recording

Capture real-world sounds for experimental/lo-fi kits:

Record with a portable recorder or phone
Edit and process in a DAW
Trim, normalize, and export as WAV

Delivering Your Sound Pack

What to Provide

Organize your files in a folder:

My Sound Pack/
├── KICK_01.wav          # For drums: individual samples
├── KICK_02.wav
├── SNARE_01.wav
├── ...

Or for melodic/bass:

My Sound Pack/
├── SYNTH_C3.wav         # Single sample

Include with your submission:

Pack name — A descriptive, creative name
Category — drum, melodic, or bass

What Happens After Submission

Quality review — We check against the quality checklist above
Technical validation — Verify specs and app compatibility
Integration — Sound pack is added to the app
App testing — Verified on both iOS and macOS

FAQ

How many samples should a drum kit have? Between 8 and 16. The grid is 4x4 but not every pad needs a sound. 12 is a solid number.

Can I use samples from sample packs I've purchased? Check the license. Most commercial sample packs allow use in music production but not redistribution as a sample library. Since Midicircuit ships the raw WAVs, you need a license that permits redistribution or embedding in apps.

What if my sample is in MP3 or AIFF format? Convert to WAV first:

ffmpeg -i sample.mp3 -acodec pcm_s24le -ar 44100 sample.wav

Can I include velocity layers? Not currently. The app uses single-layer samples with velocity controlling volume. This may be supported in the future.

What's the maximum file size? Keep individual samples under 5MB and total pack size under 20MB. Shorter, well-trimmed samples sound better and load faster.