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Power Conditioner for Audio. It's real advantage? [Article]

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Audio Basis - educational articles

Power conditioner is one of audio equipment, whose action can be demonstrated easiest way. But what about the conditioner’s impact to sound quality?
Read below what happens into audio module with and without the power conditioner.

Power conditioner audio

 

I'm want to tell right now: there is no simple univocal answer. Because each case is individual.
At each home or studio, personal work should be done. There are many variables. I suppose, even careful big research results don’t cover all cases.

 

Abbreviations

AC - alternating current

DC - direct current

PSU - power supply unit

PWC - power conditioner

UPS - uninterrupted power source

 

 

Power conditioner using

 

Ideal alternating current's electrical wave form is pure sine.
Distortions and ambient noise are added to the sine in wire spread. Electrical motors, transformers and other generate pulses when this equipment are switched.

"Dirty" alternating current come from electrical outlet to home devices.

In general:

Power conditioner (PWC) is device to suppressing the noise, spreading via electrical network.

 

Electrical power conditioning

Electrical power conditioning

 

At the picture waveforms (top) and spectrums (bottom) are shown. Waveforms and spectrums are not real and intended for demonstration purposes only.

PWC is connected to electrical network outlet.

At the PWC's output outlet, alternating current is filtered (purer sine). The current intended to feed heterogeneous home equipment, including musical ones.

 

Power conditioner using

Power conditioner using

 

  • Auto voltage regulation is very desirable functionality for music equipment, sensitive to voltage out of allowable range.
     
  • Impulse protector defend music equipment against damaging by big voltage pulses into the network.
     
  • Noise filter remove different air (caught on wires) and other interferences.
     
  • Also isolation transformer may be used to electrical noise suppression via galvanic isolation of AC circuits. The transformer break so called ground loops [1], causing additional currents (we can consider it as noise) in the line. The transformer, as coil, may improve surge suppressing, theoretically.
     
  • The conditioner may remove constant part of input voltage, that cause additional heating of electrical transformers into power supply unit of an audio device.

 

However, still there is no standard definition of "power conditioner" term.

As conditioner may be considered various devices from pulse protector, auto voltage regulator to very sophisticated uninterrupted energy source with synthesis of output voltage sine form.

So a the conditioners may have different functionality.

If you choose the conditioner, check its specification.

 

Audio devices are connected to output outlets of PWC for more qualitative power supply.

 

 

How power noise could affect to sound quality

 

Sound quality is noise and distortion level at analog output of a musical device.

Theoretically, noise from AC can penetrate to audio output and add noise and/or modulation of the musical signal.

Below we will learn an audio system structure to better understanding how it can work.

 

 

Noise spreading in home and studio audio system

 

Noise is spread 2 ways:

  • electrical power wires (more significant way),
  • air.

Electrical noise spread

Noise spread

 

 

Power conditioned system structure

 

First, let's consider simplest system: the conditioner feed single device.

 

Power system structure

Power system structure

 

"Dirty" electrical voltage come to the conditioner from AC power line.

Impulses with big voltage are suppressed by impulse protector. It allow to avoid damage of defending audio device.

Auto voltage regulator try normalize long-term voltage changes.

The noise filter suppress other noise.

In emergency case (super high voltage levels or extremely low quality) the conditioner can break connection with input line. It allow to defend audio device and the conditioner against damage.

Power conditioner can synthesize sine output voltage. Or output voltage may have waveform close to square.

The PWC may have internal accumulator battery. In emergency case the conditioner may switch audio device's supply to the battery's DC/AC converter. Such PWC are called as uninterrupted power source (UPS) [2].

 

Approximate functional design of switched
uninterrupted power source

Switched UPS

 

As alternative, DC/AC converter can feed audio device without switching.

 

Approximate functional design of permanent
voltage generation UPS

Permanent voltage generation UPS

 

PWC don't guarantee sine at conditioner's outlets. But some models can do it.

 

It's important to remember, that it is not mandatory functionality of power conditioner.
There are many different schemes and decisions.
Read carefully PWC's specification or manual.

 

 

Noise spreading through power supply system

Noise and changes from power network pass the conditioner with suppression.

 

Noise spreading thru power system

Noise spreading thru power system

 

Power supply unit (PSU) into the audio device convert high voltage AC to low voltage DC.

Noise pass thru the PSU partially and come to low voltage line (DC).

Power supply unit is noise source itself. So there are need to separate external noise (from AC input) and own PSU's hum.

Further the cumulative noise come to digital and analog part thru internal DC power buses. Digital part is noise source too.

When musical signal come to analog part, this part can also affect to low voltage line. Because transistor/tube switching cause currency changes, that may cause power bus voltage changes.

 

Therefore, power supply system is comprehensive thing with several noise sources and feedbacks.

Total noise in low voltage power line (including external AC noise) affect to audio output.

So, first, we must check noise spectrum and level at analog output of the audio device.

 

Measurement of the conditioner impact to sound quality (noise level)

Measurement of power conditioner impact to sound quality (noise level)

 

We can compare noise at the analog output with and without the PWC.

If the difference is invisible, we can use the conditioner as additional protection against probable surges into AC network.

If we protect audio system via the conditioner, we should check analog output of the system.

Read details below.

 

As rule PSU have functionality like the the conditioner, shown at this picture:

  • impulse protection,
  • auto voltage regulation,
  • high frequency noise filtering.

However:

  • some power supply units may have input voltage range issues,
  • power conditioner may have better implementation of impulse protector.

So the conditioner can provide more optimal mode for power supply unit, placed into the audio device.

 

Power conditioner may be checked via special device - power line noise meter. You can plug it into home and conditioner's outlets and compare both noise values. If the conditioner work properly, noise at PWC's outlet will lesser, than at home power line.

 

Video: One of check kind of power line noise meter

 

But, noise suppression at AC input of the audio device is not final aim.

Final aim is audio quality increasing.

 

So we must check noise level at analog output first.

After it, we can learn voltage spectrum of power lines inside audio module, at audio device's AC input, etc.

 

To interaction reducing of the analog device parts thru the low voltage power buses, line isolating filters are used.

 

Power system structure with noise isolating filters

Power system structure with noise isolating filters

 

Power line noise, impacting to analog output, may be reduced via line isolating filters.

These filters suppress noise from audio device's power line, coming to supplied part.

Also filter can block noise from the part to avoid the noise penetration to the analog device's power line.

 

Same filters may be implemented into the conditioner to reduce the noise penetration between the devices.

 

 

Conclusion

 

  1. Sound quality is defined as noise and distortions at analog output of an audio device.
  2. Single way to estimate impact of AC power supply quality to sound quality is noise measurement at the analog output of the audio device or system.
  3. "Clean" AC, coming to audio system is not aim in itself.
  4. Both, power supply unit of audio device and the conditioner, have same functionality.
  5. But power conditioner may have wider range of AC parameter deviation and provide better AC power line conditions (keeping proper electrical mode, surge protection) for the PSU.

 

Author Yuri Korzunov

 


References
  1. Bill Whitlock. Understanding, finding, & eliminating ground loops
  2. High-Availability Power Systems, Part I: UPS Internal Topology

 

 

 


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