Foundation Course — Audio & Product Basics

# Foundation Course — Audio & Product Basics

Every concept below is anchored to a real, documented value already in this project (Master Data field or ) — not a general textbook explanation. Where a requested topic has zero project source (e.g. the physics definition of a term), it is marked PENDING VERIFICATION rather than borrowed from outside knowledge, per this phase's explicit rule.

## Signal

'Signal Input Range' / 'Signal Output Range' are documented per-SKU for DSP units, e.g. FP-8A: RCA input 2Vrms, High level input 9Vrms. This project defines Signal operationally as these real input/output voltage ranges, not as a generic waveform concept.

## Frequency

`frequency_response` is documented for 52/52 SKUs, e.g. FX-4: '10Hz - 75kHz(-3dB)'. This project's working definition of frequency is the documented per-SKU response range.

## Voltage

Documented as `power_consumption` / operating voltage per SKU, e.g. FX-4: '9-16 VDC'. FP-8A: 'DC 9V~16V'.

## Current

FP-8A: 'Standby Current: ≤0.1mA' (only current value documented anywhere in this project). PENDING VERIFICATION for operating (non-standby) current on any SKU.

## Resistance / Impedance

`impedance` documented for 49/52 SKUs. Real values: FX-4 supports 2Ω/4Ω speakers (4-8Ω bridged); FP-8A input impedance Low Level 15KΩ / High Level 22Ω.

## Power

`power_output` documented for 52/52 SKUs — always as a Max/Nominal pair, e.g. FX-4: '230W x4 RMS @2Ω / 460W x4 Max @2Ω'.

## RMS vs Peak/Max

FX-4 (real, from manual ): every power spec is given as both an RMS figure (continuous) and a Max figure (peak), e.g. 'Rms Power @2Ω: 230W x4Ch' vs 'Max. Power @2Ω: 460W x4Ch'. This project's working definition of RMS vs Peak is exactly this documented pairing — RMS is the lower, sustained number; Max/Peak is the higher, short-duration number.

## Sensitivity (Input)

FX-4: Input Sensitivity 380mV-7.5V. FP-8A/FP-12A: RCA input 2Vrms/1.2Vrms, High level input 9Vrms — these ARE documented.

## Sensitivity (Speaker, dB/W/m)

PENDING VERIFICATION — no `sensitivity` field exists anywhere in Master Data for Speaker/Subwoofer SKUs (confirmed in ``). Do not teach a generic dB/W/m definition without a real per-SKU value to anchor it.

## Speaker basics

PENDING VERIFICATION for construction/driver-type detail — see ``: no local manual exists for any Speaker/Subwoofer SKU. Only real, documented facts: SKU names/taglines (e.g. 'Coaxial', 'Component' where present in product names) and whatever `impedance`/`frequency_response` fields are populated.

## Amplifier basics

Class AB vs Class D distinction is real and documented per SKU tagline (13 Amplifier SKUs, see ``). Real wiring/power-supply/protection-circuit content exists for FX-4 only.

## DSP basics

Input types (High Level, Low Level, Optical, Bluetooth, USB), EQ, crossover, time alignment, and phase are all real and documented for FP-8A/FP-12A specifically — see ``. Other DSP SKUs: Master-Data-level only (input_type field, no deep-dive detail).

## Vehicle basics

MOST (digital fibre-optic bus) and OEM DSP/Amplifier (Burmester) are real and documented for 2 Mercedes-Benz C-Class trims only — see ``. No vehicle in this project has a confirmed A2B value. **No vehicle-to-Freude-product recommendation exists anywhere** — this is the most important Foundation-level fact for anyone in a customer-facing role.