Reference · Tiles
TILEEVERY ENCLOSUREΩImpedance
The electrical load each design puts on the amplifier, in ohms, at each frequency. Its peaks show where the box and port are tuned, and its lowest point is the load the amplifier has to drive.
- Shows
- The electrical load the amplifier sees, in ohms, at each frequency: its size only, not its phase.
- Healthy when
- The peaks sit where the box and port are tuned, and the lowest point is a load your amplifier can drive.
- If it is not
- Check the box volume and tuning, and plan the amplifier for the lowest point rather than the nominal rating.
The tile#
Impedance
Ω
- Sealed, 15 L40.4 Ω at 54 Hz
- Vented, 55 L at 32 Hz22.8 Ω at 19 Hz
The sealed example peaks at 40.4 Ω at 53.6 Hz. The vented example has two peaks, at 19.1 Hz and 49.9 Hz, and between them a dip to 4.63 Ω at 31.6 Hz, at its 32 Hz tuning. Higher up the vented example falls to 3.53 Ω at 191 Hz, below its driver’s 4 Ω rating; the sealed example bottoms out at 4.06 Ω at 182 Hz.
- Open the sealed example or the vented example in the simulator, then hover the curve for the ohms at a frequency.
- Each visible enclosure draws one line in its colour. The value is what the amplifier sees: the drivers as they are wired, plus the Series resistance and any Series capacitor.
- A multiple-entry horn draws its throat driver as the main line and each other driver as a dashed line, named D2, D3 and so on in the legend, because each driver has its own amplifier channel.
- The curve is the size of the impedance only. The Phase tile shows the phase of the sound, not of the impedance; Compare can plot Electrical Phase beside impedance.
- The Headroom tile’s Amp pane lists the same curve’s Min impedance and Max impedance beside the Nominal load, with the voltage and current your target level needs.
How to read it#
- A peak is a resonance. On its own in free air a driver peaks at its Fs; in a sealed box the air behind the cone stiffens it, so the peak moves up. The Dayton Audio DCS205-4 has an Fs of 32.3 Hz and peaks at 53.6 Hz in 15 L.
- A vented box splits that peak in two. The dip between them sits at the port tuning, where the port does the work and the cone barely moves: 31.6 Hz for a box tuned to 32 Hz. Neither peak is at the driver’s Fs (29 Hz for the Ciare 12.00SW).
- Above the peaks the curve settles close to the coil’s resistance, Re, plus the series resistance, then rises slowly as the coil’s inductance takes over. The vented example bottoms out at 3.53 Ω at 191 Hz (Re 3.30 Ω).
- The lowest point is an important amplifier-load check: the nominal rating is a label, not a floor. A tall peak is not a problem in itself; the amplifier delivers little current there.
- Power and EQ do not move the curve. They change how hard the design is driven, not the load: the vented example’s curve is the same at 1 W and at 100 W.
What each enclosure looks like#
| Example | Peaks | Dips between them | Lowest point |
|---|---|---|---|
| Sealed, 15 L | 53.6 Hz | None | 4.06 Ω at 182 Hz |
| Vented, 55 L at 32 Hz | 19.1 Hz, 49.9 Hz | 31.6 Hz | 3.53 Ω at 191 Hz |
| Passive radiator, 10 L | 30.1 Hz, 54.9 Hz | 37.4 Hz | 3.55 Ω at 205 Hz |
| Bandpass 4, front tuned to 59 Hz | 36.5 Hz, 95.3 Hz | 57.6 Hz | 3.47 Ω at 226 Hz |
| Tapped horn | 22.6 Hz, 47.5 Hz, 105 Hz | 39.2 Hz, 80.6 Hz | 6.18 Ω at 221 Hz |
- A sealed box has one peak, at the resonance of the driver on the air in the box.
- A vented box, a passive radiator box and a fourth-order bandpass box have two peaks. The dip between them is the tuning of the port or passive radiator.
- A horn has a peak for each of its own resonances, so its curve is busier.
What moves it#
| Change | Effect | Why |
|---|---|---|
| A smaller sealed box | Peak from 53.6 Hz (15 L) to 68.1 Hz (8 L); 44.2 Hz in 30 L | Less air is a stiffer spring behind the cone. |
| A lower port tuning | Dip from 31.6 Hz (32 Hz tuning) to 28.0 Hz (28 Hz) | The dip follows the tuning. |
| More drivers | Parallel lowers the load, series raises it | Set by Number of drivers and Wiring. The peaks move too, because the drivers share the box. |
| Series resistance | Adds to the whole curve | Cable and amplifier resistance sit in series with the drivers. |
| A Series capacitor | Rises steeply at the bottom | The capacitor’s own impedance grows as the frequency falls. |
| Power or EQ | No change | They set the drive, not the load. |
What to try#
| Try | What it changes |
|---|---|
| Find the tuning | A vented box draws two peaks with a dip between them. The dip sits at the port tuning, so it checks the box does what you meant. |
| Read the lowest point | Above the peaks the curve falls close to the voice coil’s resistance, often below the nominal rating. That is the load the amplifier has to drive. |
| Change the wiring | With several drivers, Number of drivers and Wiring set the load: parallel lowers it, series raises it. |
Ask your AI#
Ask your AI
Your assistant runs the same solver on your own designs through the 00 Simulator connector.
Using 00 Simulator, simulate every enclosure in my open workspace and read its impedance from 10 to 400 Hz. For each one, tell me the frequency and ohms of every peak, the dip between them, and the lowest impedance, and compare the lowest point with the driver’s nominal rating.
Connect your assistant so it can open your designs.