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VALAB Vishay HEXFRED Full Bridge Rectifier VALAB Vishay HEXFRED Full Bridge Rectifier
A direct-replacement audio power-supply upgrade using four individually selected ultrafast, ultrasoft-recovery diodes.
Vishay VS-HFA08SD60S-M3 600 V 18 ns Typical Recovery Pure Copper Pins Fully assembled VALAB bridge rectifier module. Terminal functions are clearly marked on the PCB. Why Build a Discrete Bridge When Standard Bridges Are Everywhere?
Because the rectifier is inexpensive, but it is not sonically insignificant.
In an audio power supply, the bridge rectifier repeatedly switches the transformer secondary into a reservoir-capacitor load. That charging action occurs in short, high-current pulses. The reverse-recovery behavior of the diodes, together with transformer leakage inductance, wiring and PCB layout, can generate narrow current spikes and high-frequency ringing.
A carefully chosen soft-recovery diode does not magically create musical information. Its practical purpose is to make diode commutation more controlled and to reduce one possible source of high-frequency disturbance in the power supply.
In our listening tests, the change was heard as more clearly exposed detail, quicker and cleaner transients, and a more refined overall texture—transparent, but never sterile.
Listening impressions are subjective and the result will depend on the complete circuit, transformer, grounding, reservoir capacitance, snubbing and system resolution.
Built with Vishay HEXFRED Diodes
Each module uses four genuine Vishay VS-HFA08SD60S-M3 diodes. This device is a HEXFRED ultrafast, ultrasoft-recovery silicon diode selected for low recovery charge, low peak recovery current and reduced EMI/RFI in demanding switching applications.
It has also earned an excellent reputation among experienced audio builders for combining speed and clarity with a natural, musically convincing presentation. That balance is why VALAB selected it for the power supply of a new amplifier project—and why we decided to make the same part available to other DIY builders.
Important terminology: VS-HFA08SD60S-M3 is not a Schottky diode. It is a 600 V HEXFRED ultrafast soft-recovery diode, which is the appropriate technology for this high-voltage bridge. Four discrete DPAK diodes on a compact PCB with heavy pure-copper terminals. Small Investment, Meaningful Upgrade
- Four discrete Vishay HEXFRED soft-recovery diodes
- Common four-terminal bridge layout: DC+ / AC~ / AC~ / DC−
- Pure copper terminal pins for robust, low-resistance connection
- Compact physical format intended to replace many standard flat bridge modules
- No external heatsink required in VALAB's intended low-to-moderate-power application range
- Suitable for amplifier power supplies, DACs, CD players, preamplifiers and other audio DIY projects when voltage and current requirements are compatible
This is the kind of upgrade that requires little money and only a small amount of work, yet it addresses a component through which every charging pulse of the power supply must pass.
Technical Specifications Module topologyFull-wave bridge rectifier, four discrete diodes Diode manufacturer / modelVishay VS-HFA08SD60S-M3 Diode technologyHEXFRED ultrafast, ultrasoft-recovery silicon diode Repetitive reverse-voltage rating600 V per diode (manufacturer component rating) Continuous forward-current rating8 A per diode at TC = 100 °C (manufacturer rating under specified case-temperature conditions; not the assembled PCB's continuous-current rating) Single-pulse forward current60 A per diode (manufacturer component rating under specified conditions) Reverse-recovery time18 ns typical at IF = 1 A, dIF/dt = 200 A/µs, VR = 30 V, TJ = 25 °C Forward voltage1.4 V typical at IF = 8 A, TJ = 25 °C Terminal orderDC+ / AC~ / AC~ / DC−, as marked on the PCB Terminal materialPure copper pins VALAB application recommendationAudio equipment below approximately 200 W, subject to the actual transformer secondary current, capacitor charging current, ambient temperature and installation conditions Package contents1 × fully assembled VALAB full bridge rectifier module
Headline diode ratings come from the Vishay component datasheet. The finished bridge module is limited by the PCB copper, terminal pins, solder joints, airflow and installation—not only by the rating of one semiconductor.
Rear view of the compact PCB. Designed as an Easy Replacement
The board, terminal spacing and overall layout were designed around the familiar flat four-pin bridge-rectifier format. For compatible equipment, replacement is straightforward.
- Unplug the equipment and fully discharge all power-supply capacitors.
- Confirm the original bridge's four-pin spacing, available clearance and exact polarity order.
- Install the VALAB module according to the PCB markings: DC+, AC~, AC~, DC−.
- Recheck every connection with a meter before applying power.
Do not assume that every four-pin bridge uses the same orientation. “Pin compatible” applies only when the original component has the same physical spacing and the same terminal order. Please compare and measure before purchase and installation. Power and Thermal Guidance
During development, a prototype module was operated in a VALAB amplifier test environment of approximately 300 W without noticeable temperature rise at the rectifier. This demonstrates useful efficiency in that particular circuit; it is not a universal 300 W module rating.
Amplifier wattage alone does not determine bridge stress. Transformer voltage and current, reservoir-capacitor value, conduction angle, turn-on surge, chassis temperature and airflow can make two “200 W” amplifiers place very different demands on a rectifier.
Our conservative recommendation: use this module in audio applications below approximately 200 W, where the actual rectifier current and temperature remain moderate. In the intended application range it should work reliably without an added heatsink.
For high-current supplies, very large capacitor banks, severe surge conditions, motor drives, inverters or industrial power conversion, please use a bridge and PCB specifically engineered for those loads. If this module becomes significantly hot in operation, disconnect power and select a higher-capacity solution.
Where It Makes Sense
- Replacing an ordinary molded bridge rectifier in a compatible audio power supply
- New amplifier, preamplifier, DAC and CD-player DIY projects
- Builders seeking lower-recovery-noise rectification without designing a discrete bridge PCB
- Systems where fine detail, transient articulation and power-supply refinement are worthwhile goals
It may be one of the least expensive parts in the power supply, but it is certainly not the least important. The rectifier is a small component with a direct role in every reservoir-capacitor charging event.
Please Read Before Purchase
- This product is intended for experienced audio DIY builders and qualified technicians.
- High-voltage power supplies can retain lethal energy after power is removed.
- Verify voltage, current, polarity, pin spacing, clearance and thermal conditions in your own circuit.
- Do not exceed the ratings of the diode, PCB, wiring, transformer or other power-supply components.
- Sound descriptions are VALAB's subjective listening observations, not guaranteed results in every system.
If you’re purchasing multiple items, we’re happy to offer a special price in addition to the savings from combined shipping.
Please contact Kevin through Messages before placing your order. He’ll be happy to put together a great offer for you.
If you’d prefer to complete your purchase right away, please feel free to proceed with checkout. Kevin will refund any excess shipping charges afterward.
Thank you for your support!
VALAB Components selected by listening, engineering judgment and real amplifier development. A practical upgrade for builders who care about every part of the signal and power path.
