Light Harmonic LightSpeed USB cable test review


In digital audio, we’ve come a long way from the early eighties, and the rise of Redbook CD playback. Many media have changed in between, but the refinement of the gear and everything associated took the same route as analog accessories. It's unfair to put a stamp of “defunct” on digital, if you're an avid analog fan. I'm one of those, but I've always used digital playback of some sort as a necessity of audio life. It would be a heresy to say one cannot enjoy the true potential of digital playback, especially with the amount of gear created last few decades. Some managed to pinpoint the problems of digital audio in early years, and some have addressed their views and technical solutions in the past few years to a great extent. The digital revolution has affected our lives not only in high-end audio society, but on a larger scale.
Digital paraphernalia have become an integral part of digital front ends, and as important as audio signal cables. We might argue all day and night for weeks how cables matter, or don't. I don't even waste my time anymore in convincing "unbelievers". From time to time, I deliberately swap the cables and watch the reaction. It’s funny to see the internal and external change after the sublime "experiment" has been revealed.

Cables matter, and always will. Just look at other fields of industry: there can be a healthy question of price and the level of dedicated system integration, but one thing is clear. Cables perform differently, and affect the audio signal at levels dependent upon the complexity and replay standard of the audio system.

I didn't use the Light Harmonic LightSpeed with entry-level DAC's or USB to SPDIF converters. It's a bit too far out in trying to address $2000 USB cable with DAC's of the same or lower price. Among others, the Lampizator Level 4 DAC and Audiobytes Hydra USB converter were on hand during the review.


Supposedly, not all USB cables meet the USB Audio 2 high speed industry standard specification. If we look at high speed signal protocols being used for very fast digital data transfers they also don't come cheap when high performance is needed. For data rates at 15 GHz and above you'll quickly have to look into 1k price range.

Looking at it from a basic point of view and connecting the dots, the importance of digital cables might seems even more logical then the use of expensive audio signal cables. I believe they all make sense in setups that can reveal the differences.

So the real question with such high specifications of USB cable is how much benefit will there be in actual performance?


Light Harmonic already established themselves with the Da Vinci DAC. This DAC turned around quite few minds about the real ability of digital to analog conversion. From the same company now comes their dedicated USB cable. I've asked Light Harmonic's Larry Ho to answer a few questions and convey his understanding of USB cables and the need for a high-end audio version in digital audio:

Why make a dedicated USB cable?

USB cable is one of the most essential digital cables in a high-end system, we feel.

A capable USB cable should be able to transmit high speed 480M bps signal bit perfectly and with precise timing.

In past few years we saw a dramatic rise of computer based digital audio playback systems. LIke with great analog, it feels that every part of digital audio playback system become not only important, but crucial part of well balanced system?

Yes. A common mistake is thinking that "a digital cable is immune to noise because there are only '0' and '1' there".The truth is that a high-speed digital signal is highly sensitive to noise, and it is easy to let 1 become 0, or 0 become 1 in the impedance-mismatched, noisy environment.

The 'timing' of the arrival of each 1 and 0 greatly impacts the decoding engine and the resultant digital playback.

You were involved in the USB 2.0 Audio Class-standard formation. How did that affect your vision of USB cabling in general?
Well, that experience, along with my previous 7 years of experience of USB high-speed transmission
(including transceiver IC design, software/driver implementation, high speed 32/384K DAC engineering), provided a lot of interesting facts and insights. I used all these facts and insights in Lightspeed USB cable's design.

What length is efficient?

The longest USB cable is 5 meter. But usually I would suggest a shorter one, so as to avoid issues with noise and impedance mismatch.

WIth Lightspeed everything seems to be designed out of the box, even to the small details. Why the dedication?

Yes! All of Light Harmonic's products are "outside of the box". We will not make anything that is 'me-too'! What's the point? ;->

Too often we hear that zeros and ones are simple and logical to transfer. But in practice, can we actually hear the difference in performance of cables?

Of course! Like I wrote before, timing is important and 0 or 1 could be reversed during noisy environment. Please remember: Computers are noisy.

How does an analog and vinyl lover come to digital cables :)?

This is a good question. Could I call it FATE? I listened to vinyl and analog sources all the time before I designed my own stuff as a hobby.
The progress of both Light Harmonic and high definition digital audio is bringing digital sound closer and closer to the sound of analog sources.

What is important in the construction of USB cables?

Impedance-matching, high bandwidth and separating the USB power-noise from the signal.... Remember, the original USB cable designer put both 'POWER' and 'SIGNAL' wires into one CABLE for convenience, not for performance.

Performance vs bling?

We designed the LightSpeed USB cable for maximum performance, not to be "audio jewelry". We hope people find it to be attractive, but we consciously avoided the trap of using wraps and connectors which can actually damage performance. To us, designing a USB cable is more like racing than being in a beauty contest!

Tell us more about Ultra-high Speed Differential topology...

Ultra-high speed differential topology is primarily focused upon USB differential signal transmission. We use this special topology to make sure the overall bandwidth is 20 times of 480M, more than 10G bps. This topology requires very special tooling and high-precision routing and testing machines, which drive the manufacturing costs sky-high! But for this performance, it's worth every penny.

What are in your view are the most-common mistakes made by other USB cable manufacturers?

'Dress' the cable like other analog cables. Make it so thick that it has so much capacitance that it actually SLOWS down the signal, and makes the 0 to 1 transit become highly distorted.

How could you achieve a 20 times wider bandwidth and for what reason?

With our USDT technology, we achieve 20x bandwidth. The reason is simple to understand:

Imagine there is a highway (USB cable): if you design it to run 480M bps at most, and you want a lot of cars that can drive at 480M bps as well, it will have traffic jams, just like in the real world. It will be impossible to achieve the highest speed.

Our design is to make the highway 20X (20 lanes), so every car has quite a lot reserve space and bandwidth to run. So it could drive as fast as its design will allow.

What is exactly bit perfect audio playback?

Bit-perfect and Timing perfect means: 0 is 0, 1 is 1, and every bit arrive at the exactly the timing it was designed to be.


Now what exactly can a high-end audio USB cable translate to?

Let me dig deeper...

My review sample of Light Harmonic LightSpeed USB cable came as a standard split power and signal line cable with a shared connector on both sides.

As with all the gear I'm getting under the scope LightSpeed went throughout the 300+ hours break in. And boy, this had an effect on the performance! Usually with audio cables there are different degrees of the change after burn in. It can be anything from a dramatic to slight changed character what happens afterwards. With LightSpeed the change was far beyond what I'm used to experiencing with interconnect and speaker cables. Level of noise, the depth of the space and soundstage. They all benefited far beyond small scale.

I took Larry Ho’s advice and broke in LightSpeed additionally via USB 2.0 external Hard Drive. As suggested on the net copying the large files back and fort helps speeding up the process. I still kept at my standard hour count, but this might speed up the process and help preserving the nerves of the few audiophiles, that cannot wait that long :).

There is an additional "trick" to play with two headed white

version of LightSpeed, that use one USB connector head for needed power. As USB receiver IC demands a 5V power voltage to get visible power half is needed.

After the computer recognizes the connected USB device you can actually "de-plug" the power USB connector. The benefit? Music goes on without a power loop… Now call this uninteresting! Wish I could try this myself. 

Comparing to the Elijah Audio, Entreq USB and few other costlier cables, the absence of noise level was most evident along other positive attributes. This brought out the musical improvements being noted in the paragraph below.


I have literally tons of digital files in numerous formats, from FLAC, Wav, Aiff etc. All the digital stored music quickly starts to pile up and some sort of library system is then needed. Computers became gatekeepers of our musical treasures, and outboard devices have a mandatory role in quality high-end replay.

As always, my late night listening and notes are my best friends when it come to finishing reviews. I've watched the LightSpeed "morphing" over the time. As mentioned, a lower noise-floor brought out a clear perspective of music. Little nuances I've somehow missed in the past seem to come out with the blacker backgrounds.

Morten Lindberg’s 2L label has already established a reputation of its own. With high-resolution files of music in almost all formats, they bring the remarkable musical event to the worldwide music-loving public.

I own quite few of their recordings and know a dozen by heart. With LightSpeed USB cable I’ve become immersed into the music with more involvement and feedback than ever before, compared to other USB cables. Not truly sure if those packets of data were being carried in a more proper manner, but many things changed with the playback. And yes, for better. Much better.

Not only the instruments and a sense of three dimensionality was pushed forward, but listening involvement avidly struck me.

I often say there are right and wrongs with high-end audio. With the potency of LightSpeed the rights were prominent to the max.


Being a cable junkie and prolonging my addiction to USB family doesn't makes me less wicked at all I guess :). With Light Harmonic LightSpeed USB cable my points regarding cables differences, a must burn in period and actual sound impact were only getting their hard proofs signed underlined.

Light Harmonic LightSpeed is a different USB "beast." It's packed different, it's designed different, it looks different and it performs on different level.

In the ultra high-end audio world where even little changes can create a dramatic performance boost, LightSpeed takes the USB domain to a grand new scale. To call LightSpeed performance a small change would be an understatement. 

I believe this is the cable that proves my points of view in creating ultra high-end digital reproduction system. A real balanced digital audio system is even more complex then vinyl playback rig. We thought we figured out digital audio long time ago, but each year a new turn bounces us back to the unknown.

Light Harmonic LightSpeed USB cable brings the unknown a bit closer to understanding and extend the Light Harmonic philosophy to the USB cable product that shook many grounds already. Mine included.

Highly recommended!

Technical Specifications

Conductors Signal: 0.51 mm silver plated 99.9997% pure copper
Power: 0.6 mm 99.9997% pure copper
Connectors USB-A: 30µ 99.9% Gold Plated A Grade Phosphor Bronze
USB-B: 30µ 99.9% Gold Plated A Grade Phosphor Bronze
Dielectric Construction Layer 1: 0.55 mm Gas Injected Polytetrafluoroethylene
Layer 2: 0.08 mm Biaxially-oriented Polyethylene Terephthalate
Layer 3: 0.32 mm Gas Injected Tetrafluoroethylene
Layer 4: 0.08 mm Biaxially-oriented Polyethylene Terephthalate
Layer 5: 0.35 mm (+/- 0.1) Polyvinyl Chloride
Final dimensions: Square-shaped, 3.5 mm (+/- 0.1) X 5.0 mm (+/- 0.1)
Rated Bandwidth 10.083 Gbit/s

Price: 0.8m = $999, 1.6m = $1,399, 3.8m = $1,999

Manufacturer comment from Larry and the crew:

Matej, Thank you so much for the time and effort you put into
your review of our LightSpeed USB cable. It is always rewarding to
read a review in which the writer discovers, understands and explains the
product's strengths and benefits, as you have done here with LightSpeed.

As you are well aware, any discussion of cables can be emotional, and
perhaps even more so in the case of USB cables. Like you, we prefer to
avoid pointless debates, and simply let the performance of LightSpeed
speak for itself.

We hope that your readers will have the opportunity to hear the benefits
LightSpeed provides when used with a leading-edge DAC such as our DaVinci DAC
and DaVinci Dual DAC!

Sincerely, Larry Ho & Gavin Fish, Light Harmonic
Matej Isak. Mono and Stereo ultra high end audio magazine. All rights reserved. 2006-2013. ..:: None of the original text, pictures, that were taken by me, links or my original files can be re-printed or used in any way without prior permission! ::..