JS-4 Triple-Regulated Power Supply

After more than 2 years of development and testing, the JS-4—UpTone's new triple-regulated, dual-output, 100% isolated, 2.1A/4A linear power supply is entering production! Build and delivery will be limited to about 40 units per month initially, beginning late-June, 2025.

While all the JS-4 units being assembled in June have been committed to clients, we are happy to accept additional reservations. PLEASE CONTACT US TO ORDER YOURS AND TO RECEIVE A CUSTOM SHIPPING QUOTATION.

DC cables are not included with the JS-4; Please look at our SAPPHIRE Silver-Plated, Star-Quad DC Cables —with Neutrik SpeakON plugs to fit JS-4—and request to order one or two to be included with your JS-4 shipment. UpTone presets each unit to operate in 100/115/120V or 220/230/240V countries (user can adjust afterwards)

Ships via insured Priority Mail 2~3 day service ($25~$55) in the US. Outside the US via door-to-door FedEx International Express ($95 to most countries; $65~$75 to Canada).

INTRODUCTION & DESIGN

The UpTone Audio JS-4 is a sophisticated regulated linear power supply. It may produce surprisingly audible sonic improvements in fine music systems when used with equipment which is able to operate from an external DC power supply within the JS-4’s current capability and output voltage range.

Besides delivering truly state-of-the-art performance, the JS-4 offers a great deal of flexibility in usage so you are likely to find applications for it with various components as your music system evolves.

Our primary goal in designing the JS-4 was to offer a wide range of user-adjustable output voltages without any sacrifice to performance. This has been accomplished via some of the techniques detailed in the Technical Highlights section below.

Digital audio devices draw current in very high frequency bursts. As important as ultra-low output noise is, ultra-low output impedance and the “speed” of regulation response to transient loads can have an even larger impact on sonic performance. Every aspect of the JS-4’s topology, circuit design, and parts selection are focused on delivering “fast,” highly regulated, ultra-low noise DC to your connected components.

The JS-4’s two output channels are 100% isolated from each other, so this supply can be ideal for powering devices on opposite sides of an isolation barrier. UpTone’s own award-winning EtherREGEN switch is a prime example, for while it creates a special active-differential isolation “moat” for Ethernet components, powering both an upstream and downstream device requires fully independent power supply rails so as not to defeat the EtherREGEN’s isolation feature.

Each of the JS-4’s two output rails can deliver 2.1 amps continuous current (with instantaneous peak ability above that) at any of 8 user-adjusted voltages (3.3V, 5V, 6V, 7V, 9V, 12V, 13.5V, and 15V). If 2.1A is not sufficient for a connected component, the JS-4 has a MODE switch to activate custom circuitry which internally joins the two channels—to deliver up to 4 amps continuous current to one output jack (In this mode the other output jack is turned off and the JS-4 operates as a single output supply).

For users who have equipment with even higher current requirements, two separate JS-4 units can be connected together to produce either a single 8A output (both MODE switches set to 4A/Single mode) or one 6A output plus one 2.1A output (one unit set to Single mode, the other to Dual mode). This feature requires a coaxial SMA cable to properly parallel the units along with a custom ‘Y’ cable—both offered for purchase directly from UpTone Audio.

Since the JS-4’s outputs are both fully “floated” from AC mains ground and isolated from each other, it is even possible to fabricate a custom cable such that a single unit’s two outputs deliver bi-polar (+/-) supply voltages. Applications for such a bi-polar supply include analog preamp circuits or some rare digital devices that require a plus/minus supply—typically for their analog output stages. Contact UpTone Audio for advice on creating a custom “bi-polar wired” cable for the JS-4 if you have such an application.

During manufacturing, each unit has been carefully tested to assure reliable performance. The JS-4 is coverer by a 2-year warranty. UpTone offers prompt, personal, and professional support to all our clients for all our products.

TECHNICAL HIGHLIGHTS

• Two separate channels of highly regulated,100% isolated, ultra-low noise, ultra-low output impedance DC. Each output rail can deliver 2.1 amps continuous current (with instantaneous peak ability above that) at any of 8 user-adjusted voltages (3.3V, 5V, 6V, 7V, 9V, 12V, 13.5V, and 15V).

• Mode switch with custom circuitry to internally parallel the two channels to deliver 4 amps continuous current to the DC-1 output jack (DC-2 jack presents no output in this mode).

• Coaxial SMA jack—combined with an optionally ordered SMA cable and a custom SpeakON ‘Y’ cable—permits two JS-4 units to be paralleled together to produce either a single 8A output (both MODE switches set to 4A/Single mode) or one 6A output plus one 2.1A output (one unit set to Single mode, the other to Dual mode).

• Custom 60VA dual-primary/dual-secondary R-core transformer with shielding between primaries and secondaries as well as copper outer shield. Objective and subjective performance of this R-core transformer exceeds that of even very expensive toroidal types. Mechanically this R-core transformer operates silently in both 50Hz and 60Hz AC mains frequency countries.

• Special 6th generation Cree silicon-carbide Schottky diodes for AC>DC rectification; 4 for each JS-4 output channel. Objective and subjective performance of these parts is greater than typical Schottky diodes.

• Three distinct stages of high-performance voltage regulation in each output channel, with custom filtration sections between each regulation stage. First stage utilizes a specially controlled, highly efficient (97%) DC-DC regulator operating at 800KHz; Second stage is a high-current, low-noise Micrel linear regulator; Third stage consists of 4 Linear Technology LT3045 ultra-low noise (0.8µV RMS), high PSRR, ultra-low output impedance regulators.

• Unique “hierarchy of charge” design techniques are used to employ filter capacitors—before and after each regulation stage—sized to maximize “speed” and filtration for output, while also reducing AC current-draw peaks by conducting throughout a higher percentage of the AC waveform. This avoids ringing and saturation of the transformer core and thus nearly eliminates any noise going back to the AC mains.

• Seven 1-Farad/2.7V super-capacitors used in series (per channel) to provide 143,000µF of filter capacitance between second regulation stage (Micrel) and final third stage (LT3045s). This large super-capacitor bank handles load fluctuations down to below 1Hz. Fancy, large and expensive “audiophile” electrolytic capacitors are not needed because most all high frequency ripple is already eliminated beforehand—coming off the middle-stage Micrel regulators.

• Carefully chosen arrays of Murata X7R ceramic capacitors are used before and after the final stage of LT3045 regulators, whose job it is to filter any remaining minute amount of high frequencies and to superbly handle high frequency load transients presented by the equipment being powered by the JS-4.

• Logic circuitry associated with output voltage selection adjusts both the input and output voltage of each voltage regulation stage. This allows each regulator to receive an input voltage just 0.7V above the voltage it is set to regulate to. The result is optimum noise performance, low heat dissipation, and the ability to offer a wide final output voltage range without compromise.

• All circuitry is built onto a single large 4-layer PCB with expertly optimized trace widths, thickness, routing, and impedance control. Even the DC output jacks, switches, and AC inlet/fuse/switch module are all right-angle PCB through-hole soldered directly to the circuit board. Elimination of wiring is a performance advantage. [The large R-core transformer is mounted separately to the JS-4 chassis’ bottom plate and wired to low-resistance terminals on the PCB board.]

• Ultra-low resistance (≤2mΩ) 4-pole Neutrik SpeakON DC output jacks are used for secure and electrically superior connections.

• Assembled with all stainless-steel hardware in fine-finish aluminum casework sitting on machined aluminum feet with anti-slip rubber rings.