The World’s Best Audiophile Linear Power Supplies

UpTone Audio JS-2

Price: $925 (dual output)

Product

About UpTone Audio

Our mission is to keep introducing affordable audio components and accessories that produce clearly audible improvements in fine music systems. [UpTone will never sell audio “snake oil.”  The engineering and sonic effects must be real, otherwise we won’t bother.] Our goal is to grow and conduct our business with personal and professional integrity, and to enjoy interaction with audiophiles worldwide.

I, Alex Crespi, am the sole owner of UpTone Audio and I coordinate all product design, production, and operations. The circuits of UpTone Audio products are engineered by John Swenson, and we work closely together on a range of groundbreaking projects. I have known John for almost 17 years, and feel privileged to be able to work with him, to co-create and produce products from his inspired circuits and concepts, and to count this brilliant man as my dear friend.

John Swenson on the benefits of a choke-filtered linear power supply:

The traditional cap only filter (transformer, diode bridge, big cap) produces raw DC with a sawtooth riding on top. That sawtooth produces lots of high frequency components that the regulator has to deal with. Traditional regulators do very well at low frequencies, but have lousy characteristics at high frequencies which means a fair amount of those high frequency components from the cap-only filter get through to the regulator. Fancy discrete regulators do well at blocking the high frequency components, but add cost and complexity to a PS. Our approach is to use a properly designed choke-based supply whose ripple is a perfect sine wave, no high frequency components, thus a traditional regulator works very well. The discrete regulator is not needed to deal with the high frequency components, since there aren’t any.

All diode types except Schottkys emit a burst of ultrasonic noise as they turn off. This noise can go forward into the load circuit AND it can go back into the AC line, and it can also excite the transformer resonance. The “slow” diodes still have this ultrasonic noise. Schottkys are the only type which do not have this noise. Schottkys also usually have about half the voltage drop of other diode types and are usually faster. Which type to use depends a lot on what your supply looks like and what you are trying to optimize for. 

With a traditional low voltage design with a large cap right after a bridge you get large current spikes, these produce a large amount of high frequency noise which needs to be filtered by what comes after the cap. In this type of circuit the slow diodes can help cut down on the extent of the high frequencies generated by the sharp high current pulse. BUT they still generate the ultrasonic noise.

This is another reason why we like to use the choke-based design. With the choke there is no steep high current pulse, so no disadvantage to Schottky diodes. You get the advantage of no ultrasonic noise, lower voltage drop (so lower power consumption in the diode) and no big massive current pulses.

Build & Specifications

Superficially, the UpTone Audio JS-2 is probably the most sumptuous power supply in this review. Compared to the other power supplies, I personally prefer the look of this one with the subtle orange LED. But it’s not only aesthetically pleasing, it feels well built and robust.

• The JS-2 is capable of continuous current output (from either rail) of:4.3A at 5V, 5.5A at 7V6.8A at 9V7.4A at 12VThose maximums are reduced when both independently-regulated outputs are used simultaneously, depending on voltage setting and loads at each.
• Upon special request (at no extra charge) we can provision the DC2 output rail to have a 15V setting (client chooses which stock setting, 5/7/9/12V to trade away for the 15V setting). At 15V the JS-2 can deliver 4.4A.
• Wait time for someone ordering a JS-2 is always only 1-3 weeks (quoted at time of order) as we consistently build 25 units every 6 weeks. There are now more than 1,000 JS-2 units in the field worldwide and it is incredibly robust and reliable.
• The JS-2 at $925 comes “free” with one of our custom 1.5m Oyaide/Belden 15awg shielded, star-quad DC cables–always with 5.5mm x 2.5mm plug at the power supply end, and client choice of 5.5mm x 2.5mm or 5.5mm x 2.1mm at the device end. A second cable can be included for $75 more—again with choice of device end plug size (but always 1.5m length).
• Dual-output, choke-filtered linear power supply with four user-selectable DC output voltages.
• Guaranteed current capability is 5 amps continuous from either output at any voltage setting.  Up to 7.0 amps split between outputs, depending upon DC voltage combination; Instantaneous capability of up to 10A.
• Outputs: 2
• Transformer: Electrostatically shielded 100VA R-core
• Voltages: 5V, 7V, 9V, 12V
• Dimensions: 9.0 inches wide x 9.1 inches deep x 3.3 inches tall (with feet).
• Weight: 10.5 pounds
• Warranty: 3-year parts and labor (excludes shipping costs after 90 days).

Overview

When I first gave the JS-2 a listen, I really enjoyed it. It didn’t draw too much attention to itself but I was satisfied with what I was hearing. This power supply is one of the more “energetic” and balanced ones in this comparison. It doesn’t try to tilt too heavily towards any specific sonic character. There’s great rhythm and brilliance across the entire spectrum.

On subsequent listens, the recurring theme was “Not bad at all. I like it.” The JS-2 has a good balance of all the technicals and doesn’t overdo or artificially hype anything. Details and texture are real-ish. And it’s a clean sound with good extension and a very broad soundstage.

I could hear what it was missing relative to the other supplies (mostly meatiness and articulation), but I think it has enough drama, power, and verity to please most ears. It’s not the smoothest or the most controlled, but it organically etches out some finer grain details. It also outperforms most of these power supplies in the treble region. Stringed instruments in particular have an abundance of air, sparkle, and speed. And notes are held with the right amount of sustain and intent.

Overall, the JS-2 is a fun and exuberant power supply. Its avidity produces vitality with a touch of gold. You’ll get a clean and transparent sound with a wide soundstage. Most importantly, it preserves the essence of the recording. This truthfulness is a rarity in many power supplies (and audio gear in general).

The Sound

Although the bass won’t split the floor open, the JS-2 is fast and punchy. It has appropriate cadence and confidence. Just enough to build an emotional connection to the music – and keep the listener engaged. The JS-2 is all about that free-spirited romance.

The soundstage is broader than it is deep. Meaning the frontal and back distances are closer together. Also, the spatial definition sits more in front of you than around you. You’re basically listening from a few rows back. Highlights aren’t glossy but have true texture and material. As such, the JS-2 is capable of beautifully reproducing the timing of reverbs and decay.

Just Right

The midrange is decently fleshed out – and is surrounded by collective bags of insight. It’s lucid but in a more informative and expressive way rather than being embellished.

Although aural shaping isn’t the JS-2’s best strength, it has better texturing and tonality than even the much pricier Sean Jacobs DC4. Resolution and air are also another nice quality. But above all, I think it reproduces treble very truthfully. Woodwinds and sopranos sound more like the real thing.

As far as tonality, the JS-2 doesn’t come off neutral or overly warm. More of a tepid tone – but still organic. Sometimes it sounds warm enough for my ears. And I’m glad it steers clear of being colorless and gray. It’s an enjoyable, even-handed tone that is luminous when needed.

Tradeoffs

The biggest drawback of the JS-2 is probably its lighter amount of fullness and body. It’s not a very meaty-sounding power supply. But it isn’t unbearably thin either. It’s just more lightfooted and tactile than it is tangible.

The JS-2 also doesn’t have razor-sharp delineation. You won’t get that precise, pinpoint imaging. But it’s far from sounding smeared. It still has a good balance of weight and provides enough musical connective tissue. When the track gets busy, however, the JS-2 does get a little soft and loses a bit of grip. It’s still able to convey the mood and momentum of the music very well. Just not as precisely.

Who Should Buy the UpTone Audio JS-2 Linear Power Supply?

Get this power supply if you enjoy a more uppity and fun power supply. It doesn’t have the most molded sound, but it’s transparent, organic-ish, and the tactility in the treble region is hugely addictive. Also for such a small power supply, dual-rail with four adjustable voltages, you get a lot of flexibility and value for your money.

Comparisons

vs. Mojo Audio Illuminati v3

• The JS-2 isn’t as analog sounding, but offers more shine and vibrancy.
• The JS-2 is thinner and not nearly as dense as the Iluminati v3.
• The JS-2 has more texture, transparency, and detail. Also tighter imaging.
• The JS-2 has more grain and roughness while the Illuminati v3 is meatier and smoother.
• JS-2 has more accurate treble but Illuminati has much beefier bass.

vs. Sean Jacobs DC4

• The DC4 has far better separation and contouring.
• DC4 layers out the music much better.
• The DC4 is much smoother.
• JS-2 is much quicker, cleaner, and more transparent.
• JS-2 has a much larger soundstage.

vs. Paul Hynes SR7

• The SR7 has far better separation and contouring.
• SR7 layers out the music much better.
• The JS-2 is leaner than the SR7. Not very dense.
• JS-2 has much higher energy, good detail, and more accurate treble.
• JS-2 has a larger soundstage.
• JS-2 has more natural tone.
• SR7 articulates the “fabric” of the music more granuarly.

vs. JCAT Optimo 3 Duo

• The Optimo 3 Duo is darker and meatier.
• Optimo has much better quality and more present bass.
• JS-2 is more elevated and has truer top-end reproduction.

vs. Farad Super3

• JS-2 has more dimension, depth, and a sound that will tickle you. The Super3 is slower and more compressed.
• The Super3 is more balanced and doesn’t really overemphasize anything. The JS-2 is more fun and engaging – but is more aggressive.

vs. Plixir Elite BDC

• These two have very good treble.
• The Elite BDC has more detail while the JS-2 is more tangible.
• The Elite BDC has a cooler tone.
• You could hear the shape and dimensional space of the music more with the Elite BDC
• Elite BDC has far better bass output. Both in weight and tightness.
• JS-2 has a more natural tone in comparison. Which makes it enjoyable for most of the music I listen to (Hip hop, R&B, pop, acoustic).
• JS-2 is meatier and more congealed.
• Elite BDC has more inner resolution.

vs. Fidelizer Nikola2

• The Fidelizer has truer tone.
• The JS-2 skews towards the brighter and airy side