How To Choose The Right Linear Power Supply

Why the Power Supply Is Foundational

From an engineering perspective, power delivery sets the baseline for noise, reference stability, and clock behavior across analog stages, digital logic, and timing circuits. A “real” DC rail always contains ripple, high‑frequency noise, and load‑induced disturbances, so the question is not whether noise exists, but how it couples into critical references like ground, voltage references, and clock oscillators.

What Power Supply Noise Really Is

The output of any practical power supply is a combination of DC voltage, low‑frequency mains ripple (50/60 Hz), high‑frequency switching/EMI components, and transient disturbances caused by dynamic load currents.

In audio systems, the audible impact is driven less by the total noise number and more by the noise spectrum, how it couples into the circuit, and whether it pollutes sensitive reference nodes.

Core Engineering Challenges of SMPS in Audio

Switching power supplies (SMPS) operate with high‑frequency PWM, fast current edges, and dense wideband harmonics, which are inherently harder to fully isolate from sensitive audio circuitry.

Even when an SMPS meets regulatory limits, high‑frequency noise can still propagate via PCB power planes, ground returns, cables, and connectors, often landing exactly where DACs, clocks, and reference sources are most vulnerable.

• Ground Reference Modulation
  • In mixed‑signal and high‑speed digital systems, ground is not an ideal zero‑volt node; currents flowing through ground planes create voltage drops that modulate digital thresholds and analog reference points.
  • Because ground is part of the signal path in audio, this modulation increases common‑mode noise and can degrade both measured performance and perceived clarity.

• Power Noise → Phase Noise → Jitter
  • Clock oscillators are highly sensitive to supply noise, which is converted into phase noise inside the oscillator loop and appears as jitter in the time domain. For DACs, this jitter is not a bit‑level error but a loss of sampling‑time accuracy, which directly compromises timing precision and micro-detail.

Engineering Advantages of Linear Power Supplies

Linear power supplies (LPS) avoid high‑frequency switching, operating instead at mains frequency, so their noise spectrum is narrower, more predictable, and easier to manage with conventional filtering and layout techniques.

By presenting cleaner rails and more stable ground references, an LPS gives analog stages, clocks, and voltage references a more consistent operating environment, even when downstream PSRR is limited.

• No High‑Frequency Switching Source 
  • Because linear designs do not rely on PWM, they avoid the wideband harmonic “spray” characteristic of SMPS and reduce the risk of unpredictable high‑frequency coupling into sensitive circuitry. The resulting **noise** profile is more benign and easier to control through good transformer design, rectification, and filtering.

• Cleaner Power and Ground
  • A well‑designed LPS achieves a lower wideband noise floor and more stable ground return paths, which directly benefits clock oscillators and low‑level analog stages. This stability helps the entire system operate closer to its original design intent, rather than constantly compensating for fluctuating supply conditions.

• Linear Transient Behavior
  • Oversized transformers and large reservoir capacitors give LPS designs lower, smoother output impedance and more linear transient current delivery under dynamic loads. This is especially important for analog output stages and precision clock modules, where current pulses must not collapse or modulate the supply rails.

Why Digital Audio Devices Also Benefit

“Digital” does not mean noise‑immune; logic thresholds are defined by analog voltages, and clock systems remain fundamentally analog oscillators. Power noise erodes timing margins and increases susceptibility to jitter, so devices like Streamers, DACs, DDCs, Master Clocks, USB/SPDIF interfaces, and network audio gear are all highly sensitive to supply quality.

Audible Differences, Explained Technically

Listeners often report a lower perceived noise floor, improved focus and coherence, and more stable imaging when moving from a noisy supply to a well‑engineered LPS. These subjective impressions correlate with reduced noise coupling, a cleaner jitter spectrum (especially close‑in phase noise), and more stable power and timing references across the system.

LHY Audio’s Design Philosophy

LHY Audio treats linear power supplies as infrastructure components whose purpose is to minimize their own “participation” in the sonic signature rather than act as tone‑shaping devices. The design focus is on noise spectrum over efficiency, prioritizing stable, low‑noise power that improves consistency across entire HiFi systems.

How to Choose the Right LHY Audio Linear Power Supply

Selecting the correct LHY Audio LPS starts with your device’s original adapter label: check output voltage (V), rated current (A), and DC polarity.

The output voltage must match exactly, the LPS current rating should be equal to or higher than the original adapter, and the polarity must be correct for safe operation.

• Voltage, Current, and Polarity Basics
  • Always match the specified DC voltage and respect the simple relationship Power = Voltage × Current (W = V × A) when considering total load. All standard LHY Audio linear supplies ship with center‑positive DC output (inner positive / outer negative), so devices requiring center‑negative polarity need explicit support or a polarity‑reversing solution arranged with the manufacturer.

• Why Current Headroom Matters
  • Running a supply at or near its maximum current rating increases thermal stress, noise, and ripple, so generous current headroom is recommended for audio use. Extra headroom improves transient response, promotes a more relaxed, natural presentation, and enhances long‑term reliability of both the LPS and the powered device.

As a rule of thumb, if your device requires 12V / 2A, choosing an LPS rated for at least around 2.5–3A ensures comfortable headroom and better sonic stability.

For digital audio, clocks, servers, and switches, a “too large” supply is rarely a problem; an oversized, low‑noise LPS tends to run cooler and more relaxed while delivering more consistent performance.

Our Two Cents

The core value of a linear power supply in HiFi is not magic but reduced system uncertainty: lower, better‑behaved noise and more stable references across the signal chain. 

By matching voltage and polarity correctly, allowing generous current headroom, and choosing an LHY Audio LPS sized to your real‑world load, you let your audio gear perform closer to what its designers intended in the design lab.

Explore LHY Audio's LPS lineup here