Home Recording Reference Charts: Frequencies, Modes, Cables and Levels
Eight reference charts covering the numbers a home studio needs at hand: instrument frequency ranges, axial room modes by dimension (1130 divided by twice the dimension, so 12 ft gives 47.1 Hz), cable and connector types, buffer size to latency (128 samples at 44.1 kHz is 2.90 ms), microphone polar patterns, dB reference levels, monitor size by room size and treatment coverage.
Definition: An axial room mode sits at the speed of sound divided by twice the room dimension, so a 12 foot wall resonates at 1130 divided by 24, which is 47.1 Hz, and again at every whole multiple of that.
These are pages to bookmark rather than read through. Each one is a dense table of figures you will want repeatedly and will not remember, surrounded by enough explanation to know what the numbers mean and, importantly, where they stop being reliable.
- Acoustic Treatment Coverage Chart: How Much, Where and How ThickAcoustic treatment coverage chart by room use and surface, with absorption coefficients for 1, 2, 4 and 6 inch mineral wool from... Open →
- Cable and Connector Types Chart: Every Studio Connection ExplainedComplete studio cable chart. XLR, TRS, TS, RCA, S/PDIF, ADAT, USB, Thunderbolt, MIDI and speakON compared by balance, signal level... Open →
- dB Reference Levels Chart: dBFS Targets and Real World SPLComplete decibel reference chart. dBFS recording targets, 0 VU alignment, bit depth noise floors, and real world SPL levels from a... Open →
- Instrument Frequency Range Chart: Fundamentals, Harmonics and Problem BandsComplete instrument frequency chart for recording. Fundamental range in Hz, the harmonic region where character lives, and the... Open →
- Microphone Placement Distance Chart by InstrumentMicrophone placement distance chart: starting distance and aim point for vocals, acoustic guitar, amps, drums, piano and more, with... Open →
- Microphone Polar Patterns Chart: Nulls, Rejection and Proximity EffectComplete polar pattern chart. Omnidirectional, cardioid, supercardioid, hypercardioid, figure of eight and shotgun compared by null... Open →
- Monitor Size by Room Size Chart: Matching Woofers to Cubic FeetStudio monitor sizing chart. Woofer diameter matched to room floor area and volume, with realistic low frequency extension... Open →
- Room Modes by Dimension Chart: Every Common Room Size, CalculatedRoom mode chart for every dimension from 7 to 20 feet in half foot steps, with four orders of harmonics, plus the lowest mode and... Open →
- Sample Rate and Latency Chart: Buffer Size to MillisecondsComplete latency chart for every buffer size from 16 to 2048 samples across 44.1, 48, 88.2, 96, 176.4 and 192 kHz, with round trip... Open →
Which chart answers which question?
- "Why does this bass note disappear when I sit down?" The room modes by dimension chart, and then the room mode calculator with your own three measurements.
- "What frequency should I cut to fix this?" The instrument frequency range chart, which lists the problem band for each instrument alongside its fundamental range.
- "Why does this cable hum?" The cable and connector chart, which covers balanced versus unbalanced and the specific trap that a TRS jack can mean either balanced mono or unbalanced stereo.
- "Can I drop my buffer without dropouts?" The sample rate to latency chart, and then the latency calculator for your own hardware overhead.
- "Where do I point the microphone to reject the room?" The polar patterns chart, which gives the actual null angles rather than the assumption that the null is directly behind.
- "How loud should I be recording?" The dB reference levels chart, and then the gain staging calculator.
- "Are my monitors too big for this room?" The monitor size by room size chart, which is the single most commonly ignored constraint in home studio buying.
- "How many panels do I need?" The treatment coverage chart, and then the treatment calculator.
The figures worth memorising
Most of what is on these pages should be looked up rather than remembered. A small number of figures come up constantly and are worth knowing by heart.
| Figure | Value | Why it comes up |
|---|---|---|
| Speed of sound at about 20 C | 1130 ft/s, 343 m/s | Every acoustic calculation on this site |
| Sound travel per millisecond | about 1.13 ft | Turns a latency figure into a distance you can imagine |
| First axial mode | 1130 / (2 x ft) | What your room does at low frequencies |
| Wavelength of 100 Hz | 11.3 ft | Why thin panels do nothing to bass |
| Quarter wavelength at 100 Hz | 2.8 ft | Why bass traps go in corners, not flat on walls |
| Latency from a buffer | samples / rate x 1000 | Every time a session starts feeling laggy |
| Tracking level target | -18 dBFS RMS | The digital equivalent of 0 VU |
| Dynamic range per bit | 6.02 dB | Why 24 bit makes headroom free |
| Level drop per doubling of distance | 6 dB | Microphone distance is a gain control |
| Listening triangle setback | spacing x 0.866 | The number people get wrong with a tape measure |
The one on that list that changed how I work is the third from the bottom: six decibels per doubling of distance. It reframes microphone position as a gain control rather than as a framing decision, which means the fix for a quiet singer is usually to move the microphone rather than to add preamp gain, and the fix for a preamp running out of headroom is usually to move the microphone back rather than to reach for the pad. Once you think of distance as a knob, half of the gain problems in a home studio become placement problems instead.
Where these charts stop being reliable
Two of these pages are exact arithmetic and six involve real-world variation, and it is worth knowing which is which.
Exact: the sample rate to latency chart, and the room mode figures. Both are pure arithmetic from stated constants, and the only variable is that the speed of sound changes slightly with air temperature, which shifts mode frequencies by a fraction of a percent across a normal indoor range.
Representative rather than exact: absorption coefficients vary between manufacturers and mounting methods, instrument frequency ranges vary between instruments and playing styles, polar pattern figures vary between capsule designs, and published monitor low frequency specifications are measured at thresholds that differ between brands, which makes cross-brand comparison approximate. Each of those pages states its assumptions in the table caption, and where a figure is a rule of thumb rather than a measurement, it says so.
Related sections
- The calculators: the same arithmetic, applied to your own numbers
- Guides: what to do once you know what the numbers say
- Comparisons: several of these charts underpin a comparison
- Interface spec database: preamp counts, connections and sample rate ceilings
- Complete builds: three fully priced studios with the room included
Frequently asked questions
What frequency is a room mode for a 12 foot wall?
The first axial mode is 47.1 Hz, from 1130 divided by two times 12. The same wall also resonates at every whole multiple of that figure, so 94.2 Hz, 141.3 Hz and upward. A rectangular room runs three of these series simultaneously, one per dimension, and the frequencies where two series land close together are the ones that will boom rather than merely lift.
How many milliseconds is a 128 sample buffer?
2.90 milliseconds at 44.1 kHz, from 128 divided by 44,100 times 1000. At 48 kHz the same buffer is 2.67 ms and at 96 kHz it is 1.33 ms, because the same number of samples represents less time as the rate goes up. That figure is one direction only, and the round trip you feel is roughly double it plus 2 to 6 ms of converter and driver overhead.
What is the fundamental frequency range of a bass guitar?
A standard four string bass in E standard tuning has a low E fundamental at about 41 Hz and a top G at the twelfth fret around 196 Hz. The character people identify as bass tone lives well above the fundamentals, mostly between 700 Hz and 2.5 kHz where the string attack and finger noise sit, which is why a bass can be audible on a phone speaker that reproduces nothing below 200 Hz.
What level is 0 VU in the digital domain?
Minus 18 dBFS is the common alignment, and minus 20 dBFS is the SMPTE standard used in post production. Analogue gear was built around a nominal 0 VU operating level with roughly 18 to 20 dB of headroom above it, and converter manufacturers matched digital full scale to that headroom so the two systems could be patched together. Every analogue-modelled plugin inherits that calibration.
Which microphone polar pattern rejects the most from behind?
Hypercardioid has the deepest rear null relative to its pickup angle, but its nulls are at roughly 110 degrees rather than directly behind, and there is a rear lobe at 180 degrees. Supercardioid nulls sit at roughly 126 degrees. This is the detail people get wrong when aiming a microphone to reject a monitor: pointing the back of the microphone at the speaker is not the null.
How much acoustic treatment does a room need?
Between 15 and 25 percent of total surface area for a mixing room and 20 to 30 percent for a room you also record in. A 12 by 14 foot room with an 8 foot ceiling has 752 square feet of total surface, so 20 percent coverage is about 150 square feet, which is roughly nineteen 2 by 4 foot panels. Corners come first, then first reflection points.
Working out your own room and signal chain? The Home Studio Build Planner is the paid version of these pages: 8 printable worksheets you fill in with your own numbers, plus the full PDF, $29.