Zen Audio POWER9 Network Amplifiers

For many years, automotive sound systems risked system noise and distortion due to a tortuous signal path for low-voltage analog preamp signals.

OEMs addressed this with dedicated infotainment digital networks and amplifiers with built-in digital processing. This approach means that the only analog signals come from the amp, and have already been heavily processed: Active Crossover filters, Delay, EQ, Phase manipulation, Compression and Limiting, and Upmixing have been added to the original signal. 

There are also non-entertainment sounds handled by the sound system which are injected into this audio output. Some of those we need, but some we don’t. 

Chimes, handsfree calling (phone calls and emergency telematics), and navigation prompts are essential to retain.

Active Noise Cancelling (ANC) and Fake Exhaust Note are important to eliminate from high-performance sound systems. 

 

OEM Networked System Architecture

 

The traditional way to integrate with these systems has been to use the amplified outputs, convert them to digital, add more processing to reverse the previous audio processing, convert them back to analog, and then re-amplify them. When ANC and/or fake exhaust are present, they must be disabled in some manner (often requiring wiring or software modification). All analog signal transfers require careful gain matching by the installer to realize full power while avoiding noise issues.

Traditional OEM System Integration

 

Zen Audio networked preamps have changed this equation significantly. Zen preamps connect to the infotainment network in the vehicle, decode the digital content, and include the non-entertainment sounds we need, while eliminating the sounds we don’t. Then Zen preamps deliver that content to the aftermarket sound system in either high-fidelity analog or SPDIF digital. Zen Audio network preamps are part of high-fidelity sound systems around the world.

OEM Integration with a Zen Audio networked preamp

 

Zen POWER9 Amplifiers

 

OEM Integration with a Zen Audio network amplifier

 

Zen POWER amplifiers take this approach several steps further. Nav-TV still takes the digital stream from the infotainment network. The Zen Digital Signal Processor performs the acoustic tuning functions in the digital realm, before the signal is amplified. There is no risk of ground loop noise or gain mismatches. The entire signal path is internal to the amplifier until it is ready to drive speakers! The Zen DSP also constantly analyzes the music signal, instantly notifying the Zen POWER Regulated Supply if headroom is needed.

This architecture is a great opportunity for amazing sound.  Nav-TV included several advanced technologies in the Zen Power amplifiers:

  • Class H variable-rail amplification delivers power when it’s needed
  • Zen POWER’s staggered output design lets you put the power where it’s needed
  • Advanced performance chipsets deliver Class D amplification with low noise
  • The Zen POWER Regulated Supply ensures consistent, reliable power delivery in modern vehicles
  • Multi-stage thermal management with both forced-air and convection cooling

 

Zen POWER9 Power Specifications 10-24V DC

  • Four 70 watt RMS channels, less than 1% THD
  • Four 150 watt RMS channels, less than 1% THD
  • One 500W RMS mono channel, @1% THD
  • One RCA-out preamp channel 
  • SNR ~ 105db, THD+N <0.005%
  • *2025+ Ford applications add four “ACM” 25W channels

 

Zen POWER Regulation 

With loosely-regulated power supply amplifiers, output power increases as the voltage from the battery increases - up to the limit of the operating range. 

Unfortunately, output power also decreases as the battery voltage decreases. 

With loose regulation, output power is directly dependent on input voltage

 

Good amplifiers using loose regulation will have usable dynamic headroom.  (Dynamic headroom is defined as power output above the rated power, into a constant load, for a minimum of 20 milliseconds - this is long enough for “peak power” to improve musical performance in most cases, and make the amplifier sound like a different, more powerful amplifier when playing music.). 

Stiffly-regulated power supply amplifiers have the same output power regardless of the battery voltage - as long as the voltage from the battery is within the operating range. These amps do not have dynamic headroom in the sense of delivering additional power into a constant load - if the load is constant, the power delivered is constant.  

With loose regulation, output power can briefly rise above the constant output 

 

Stiff regulation costs more to manufacture, and doesn’t deliver dynamic headroom - so why did Nav-TV use this approach? Partially because cars using today’s “smart” alternators don’t work the way cars did 30 years ago. It used to be that the alternator voltage went up when the engine RPM’s went up, and the voltage went down as more electrical devices went to work (headlights, rear-window defoggers, and aftermarket amplifiers would all cause voltage drop). That meant your sound system had slightly more power when you stepped on the gas, and slightly less when you turned on the headlights. 

Nowadays, the charging system  is dynamically managed by a computer. When RPM’s go up, the alternator output decreases (often it completely shuts off ) to slightly reduce the parasitic drag on the engine during acceleration. 

When you turn on more devices and increase the load, the alternator output increases. This is exactly backwards from what many of us in car audio expect from the vehicle’s electrical system! So there are benefits to having a stiffly-regulated power supply - consistent operation, unaffected by the voltage management in the vehicle. 

With stiff regulation, Zen POWER9 amplifiers always sound great

 

But stiff regulation doesn’t give us dynamic headroom, and we like headroom- it lets amplifiers sound more powerful. So Zen POWER uses a Class H power-supply design with variable internal power states operating at different voltages.

The DSP processor analyzes the incoming musical signal, and selects the most appropriate voltage level.  This means Zen POWER provides the functional equivalent of dynamic headroom - more power for musical peaks - but for even longer periods of time!

With Class H "look-ahead", management, output power rises for musical peaks

 

Class D operation

The single largest differentiator in Class D amplifiers is the central Class D IC. There are a number of different IC suppliers and models to choose from, and they deliver varying degrees of performance. The Zen POWER9 uses the same model Class D IC as many of the highest-performing audio amplifiers in car audio - the TI 3255. You’ve heard this chip in many renowned car-audio amps.

THD + Noise for the Zen POWER9 Network Amplifier

 

This is what allows the Zen POWER9 to deliver clean power without audible noise or distortion - the technology is built into in the Class D chipset.

 

In Conclusion 

The Zen POWER suite of technologies - DSP-managed Class H power supply, stiffly-regulated for consistent and dependable performance - paired with a great-sounding Class D output stage - delivers performance like you've never heard before. Listen to it to learn for yourself!