Power supplies
Power supply labels are useful, but they are easy to overread. This page separates construction facts from the conclusion people often jump to: good implementation beats the buzzword.
Linear supply
Transformer, rectifier, reservoir capacitors, and often regulators. This is the old-school default for many analog components.
Why it matters: Simple, quiet when designed well, physically large at high power.
Gotcha: Linear does not automatically mean quiet; transformer field, grounding, rectifier noise, and regulation matter.
EI-core transformer
Laminated iron transformer with separate E and I stampings. Older and still common where cost, leakage behavior, or mechanical packaging fit.
Why it matters: Can be robust and serviceable; usually larger and can radiate more magnetic field than a comparable toroid.
Gotcha: Not a quality downgrade by itself. Implementation and shielding matter more than the silhouette.
Toroidal transformer
Doughnut-shaped core popular in hi-fi because it is compact and has low external magnetic field when used correctly.
Why it matters: Common in power amplifiers, DACs, and preamps. Often marketed heavily because buyers recognize it.
Gotcha: Toroids can pass DC on the mains poorly and can hum mechanically if the line is dirty.
R-core / C-core transformer
Alternative core geometries used where low leakage flux, low mechanical noise, or packaging is the design goal.
Why it matters: Seen in some Japanese and specialist gear, especially source components and preamps.
Gotcha: Less common does not automatically mean better; current capacity and regulation still have to match the circuit.
Choke-input or choke-filtered supply
Uses an inductor/choke as part of the high-voltage or reservoir filtering path.
Why it matters: Classic tube-amplifier technique; can lower ripple and change supply behavior under load.
Gotcha: Bigger, heavier, and costlier; not every choke in a product means a full choke-input supply.
Regulated linear supply
A linear supply with active regulation after rectification/filtering.
Why it matters: Common in low-level analog, DAC clocks, digital boards, and phono stages where stable rails matter.
Gotcha: Regulator type and layout matter; "regulated" is not enough to predict noise.
SMPS
Switch-mode power supply. Rectifies and switches at high frequency before filtering/regulation.
Why it matters: Small, efficient, universal-voltage friendly, and common in Class D, streamers, TVs, and modern compact gear.
Gotcha: Bad SMPS designs can be noisy, but good ones can outperform casual linear supplies.
External PSU
Power transformer/regulation lives in a separate box or upgrade module.
Why it matters: Can move magnetic fields and heat away from sensitive circuits; common in Naim-style ecosystems and some turntables/phono stages.
Gotcha: External PSU covers very different things: a real second chassis, a turntable motor controller, or a commodity adapter brick. Use PSU form and PSU brick to separate them.
Separate PSU chassis
A dedicated outboard enclosure for transformer, rectification, regulation, or high-current reservoir stages.
Why it matters: Often part of two-box preamps, flagship streamers/DACs, and upgrade ecosystems where isolation, noise, heat, or serviceability matters.
Gotcha: A second box is not automatically better; it may also add cabling, connector losses, and upgrade-path cost.
External adapter / brick
A wall-wart or inline AC/DC adapter supplies low-voltage power to the product.
Why it matters: Compact and practical for streamers, DACs, phono stages, and small turntables, especially when universal mains input is useful.
Gotcha: This is the kind many buyers want to filter away. In compare views, add the PSU brick column and set it to No.
Battery supply
Runs all or part of the circuit from battery power.
Why it matters: Can isolate from mains noise in low-power circuits such as phono stages, DACs, and portables.
Gotcha: Battery management, output impedance, charging noise, and age still matter.