Audio

Last updated: September 18, 2024

Audio System

2021+ Model X only comes with the Premium Audio standard, and there is no Base Audio option. This vehicle comes with 24 speakers total, 2 amplifiers, and 1 Audio Digital Signal Processor (ADSP). Of the 24 speakers, 22 are for the sound system, 1 is for the Pedestrian Warning System (PWS), and 1 is the emergency speaker for AutoPilot. The speakers are powered by the Media Control Unit (MCU) amplifier located on the Infotainment Board and the external amplifier located behind the right rear trunk trim. The emergency speaker is controlled and powered by the Autopilot board, and not the MCU.

There are 2 separate sets of microphones used for the Telephony and Active Noise Cancellation (ANC) subsystems. The Telephony microphones are located on the headliner, and the ANC microphones are located in the front seats.

The Music, Movie, Gaming, Telephony, and ANC audio processing is completed by a dedicated ADSP located on the Infotainment Board.

Audio System Architecture

A high-level architecture diagram of the inputs and outputs to the ADSP is shown in the image below. The external amplifier is located in the trunk of the vehicle, while the MCU amplifier is a collection of 3 amplifiers located on the Infotainment Board.

Audio System Architecture

Speakers

2021+ Model X contains 24 speakers. The diagram below outlines the placement of the speakers and their amplifier configuration.

Speaker Placement

Speaker List

Qty	Image	Size	Type	Frequency Response	Location	Amplifier
1	Center Channel	100mm	Midrange	200Hz-13kHz	Instrument Panel	MCU
2	Left & Right	100mm	Midrange	200Hz-13kHz	Instrument Panel	MCU
2	Left & Right	25mm	Active Tweeter	3.5kHz-20kHz	Mid A-Pillar	MCU
2	Left & Right	60mm	Midrange	200Hz-13kHz	Upper A-Pillar	MCU
2	Left & Right	200mm	Woofer	50Hz-200Hz	Front Door	External
2	Left & Right	80mm	Midrange	200Hz-13kHz	Front Door	MCU
4	Left & Right	160mm & 30mm	Midwoofer & Passive Tweeter	60Hz-3.2kHz / 3.2kHz-30kHz	Rear Door	External
2	Left & Right	60mm	Midrange	200Hz-13kHz	Rear Headliner	MCU
4	Left & Right	80mm & 30mm	Midrange & Passive Tweeter	200Hz-13kHz / 3.2kHz-30kHz	Liftgate	External
1	LFE Channel	200mm	Subwoofer Enclosure	30Hz-90Hz	Rear Quarter	External
1	Mono	80mm	PWS	300Hz-5kHz	Aeroshield	MCU
1	Mono	67mm	Emergency Speaker	250Hz-4kHz	Front Passenger Footwell	AP Board

Note

The midwoofers and passive tweeters in the rear doors are connected to the same input signal (one input signal per side). Similarly, the midrange woofers and passive tweeters in the liftgate are also connected to the same input signal, separate from the speakers in the rear doors. As such, these speakers make up a single row in the Speaker Placement table shown above.

Note on Serviceability

The connections for the A-Pillar tweeter and A-Pillar midrange speakers are only differentiated by the length of the cable. If force is applied to the cables, it is possible these connections could be swapped, which will damage the tweeter over time. It is important these connections are established correctly, and the connections can be tested with a multimeter.

Shown below is a table of the correct mapping of the connectors, pin numbers, and respective speakers.

Connection (Positive / Negative)	Harness Placement	Speaker
AMP1_1_P / AMP1_1_N	Left Lower A-Pillar	Tweeter
AMP2_1_P / AMP2_1_N	Right Lower A-Pillar	Tweeter
AMP3_2_P / AMP3_2_N	Left Upper A-Pillar (Headliner)	Midrange
AMP3_4_P / AMP3_4_N	Right Upper A-Pillar (Headliner)	Midrange

Amplifiers

As mentioned previously, 2021+ Model X has a single Premium Audio trim. The vehicle still contains 2 amplifiers: 1 located on the MCU (MCU amplifier) and 1 located in the trunk (external amplifier). Together, these amplifiers drive the 22 speaker sound system plus the PWS speaker. When determining the output channels from the amplifiers, there are some important aspects to note:

• The 30mm passive tweeters (4) do not require their own driven input channels and are wired in parallel with their respective paired drivers.
• The subwoofer is counted as a single speaker, but it requires 2 driven inputs.
• The emergency speaker is driven and controlled separately by the autopilot board.

This results in a total of 21 output channels, 12 from the MCU amplifier, 8 from the external amplifier and 1 from the AutoPilot amplifier.

MCU Amplifier

The MCU amplifier has 3 Digital to Analog Converter (DAC) amplifiers (4x40W output power) accounting for a total of 12 channels. The layout is given below:

• 2 midrange on the front doors (1 for each door)
• 3 midrange on the instrument panel (left, center, and right)
• 4 midrange on the upper A-Pillar trim and rear headliner
• 2 tweeters on the front lower A-Pillar trim
• 1 pedestrian warning speaker on the aeroshield

External Amplifier

The external amplifier is an additional audio amplifier located behind the trunk trim and was formerly known as the Premium External Amplifier. It contains 2 DAC amplifiers, which account for 8 channels. It has an A2B chip (slave) for communication. The layout is given below:

• DAC Amplifier (4x40W output power):
  • Connected speakers are located at the left (1) and right (1) rear doors, as well as the left (1) and right (1) sides of the liftgate
• DAC Amplifier (4x80W output power):
  • Connected speakers are the left (1) and right (1) front door woofers and the subwoofer (1) in the trunk

External Amplifier Location

Note

It is important to point out that the system is not reliant on the A2B Bus or the external amplifier for chimes or other critical audio.

A2B Audio Bus

2021+ Model X contains 2 A2B audio busses: A2B Bus A and A2B Bus B. The A2B Bus A is used for the main audio system, and connects the Infotainment Board to the headliner mics and rear external amplifier. The A2B Bus B is used for the ANC system, and connects the Infotainment Board to the seat microphones and accelerometers.

A2B Architecture - Bus A (left), Bus B (right)

Antenna / Radio Tuner

2021+ Model X uses the same tuner found in the previous generation of Model S/X vehicles. Power is provided to the tuner module via the right vehicle controller (VCRIGHT). Communication to the Infotainment Board is made over a 2-wire Ethernet connection housed in the same connector. The radio tuner contains FM, HD Radio, and SiriusXM Satellite Radio (for North America).

Radio Tuner Located in the Liftgate

The SiriusXM antenna is located on the C-Header. The FM and DAB antennas are on the backlite and are connected to 2 FM antenna amplifiers, which are found on the left and right sides of the liftgate.

Microphones / Active Noise Cancellation (ANC)

2021+ Model X contains 4 digital Micro-ElectroMechanical System (MEMS) headliner microphones, 4 digital MEMS seat microphones, and 4 3-axis accelerometers. The 4 MEMS headliner microphones are used for Telephony (calls and voice commands), while the 4 seat microphones and 4 accelerometers are used for the ANC subsystem.

Microphone Module in the Headliner

Active Noise Cancellation (ANC)

The ANC System consists of 2 pairs of digital MEMS seat microphones (4 microphones total), 4 ANC sensors (accelerometers), the ADSP, and speakers. The high-level concept of the ANC system is to cancel any unwanted audio signal (like road noise) by adding an additional signal of the inverse phase.

It may seem counter intuitive to be adding more noise to achieve less overall sound, but this concept takes advantage of a physics phenomenon called destructive interference. Essentially, when two waves of the same frequency meet, they sum together, and the resulting wave is what is heard. If the two signals are the inverse phase of one another, they will cancel each other out completely, leaving silence in an ideal world and reduced noise in practice.

For the 2021+ Model X ANC system, the accelerometers act as the input for road noise. The ADSP then inverts the phase of the unwanted sound wave and outputs the inverted wave from the speakers to cancel out the unwanted noise inside the cabin. Since it is difficult to cancel out higher frequencies without precise microphone / speaker relative to ear placement, the 2021+ Model X ANC only works up to about 300Hz.

The ANC accelerometers are located at each wheel and can be seen in the A2B bus diagram in the A2B section. The ANC seat microphones are located in the headrest of each seat, which have 1 microphone on each side of the passenger. The microphones are located here so they are as close to the customers' ears as possible, allowing the ANC algorithm to best tune for the "quiet zones" around the customers heads.

Since the algorithm is optimized for these localized "quiet zones", if the passenger moves their head around the cabin or slouches in the seat, the ANC effect will be less prominent, and they may hear more of the undesired road noise.

Active Noise Cancellation (ANC)

Note

The ANC microphones are only located in the headrests of the front seats. This means the ANC system is only active for the front seat passengers, not for the rear seat passengers.

Audio Serviceability

Replaceable Components:

• All speakers
• External amplifier
• Tuner
• Antenna amplifiers
• ANC accelerometers
• Telephony headliner microphones
• Front seat ANC microphones

Non-Replaceable Components:

• ADSP - part of the Infotainment Board
• MCU amplifier - part of the Infotainment Board

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