I’ve been holding this review now for several months, not because it was hard to write – in fact, it’s a short review – but because I’ve been unclear about what exactly to say. And I’m not unclear what to say because I didn’t like the X-Link – I liked it right off the bat – but because this is the second product that I’ve reviewed and have no real idea how it works. As a non-engineer, I can repeat the explanation given by the designer, but despite researching the topic of “ground planes,” my brain isn’t understanding the technical concept behind the product or why it makes the difference that it makes. Writing about anything other than my purely subjective impressions will probably subject me to criticism and/or ridicule, but what the heck…
Vogel makes a line of interconnects and speaker cables that have been positively received. However, in addition to interconnects and speaker cables, Vogel Cable makes several products which are designed to improve sound by addressing ground plane and magnetic field stability. These products are said to have a cumulative effect, but I only tested the X-Link which improves ground plane stability by addressing minute eddy currents that are ever-present in the ground plane.
Eddy currents in the ground plane? What’s that? I racked my brain attempting to recall all my prior experience with grounding of audio systems, but nothing helped with the concept of “eddy currents in the ground plane”.
What problem we talking about?
Most audiophiles have dealt with the dreaded ground loop, which creates a very audible hum in your audio system. How does that happen? Let’s talk about grounding.
I’m definitely not an engineer, but I can fake my way through a few electrical/electronic explanations. Chassis ground is any conductor which is connected to a unit’s metal chassis. Three-conductor line cords connect the chassis to earth ground when plugged in to a properly wired AC outlet. In units with a two-conductor line cord, the chassis does not connect to earth ground. However, the chassis is normally connected to the internal ground of the component enclosure in both unbalanced/consumer and in balanced/pro equipment. This internal ground is called the audio signal ground. It is the internal conductor used as the ground reference for the internal electronics. In high-end electronics, it’s often further split into digital and analog ground sections, but it is important to remember that all divisions of signal ground connect together in one place. Connecting these divisions is usually called a star grounding scheme. Star grounding is also a term used to describe the more macro process of connecting a series of components and electrical circuits. The point is to connect everything to a single ground, as opposed to multiple grounds with different potentials.
Connecting multiple devices together with interconnects ties the signal grounds of the multiple devices together in one place through the conductors. Ground loops occur when the grounds of the devices are also tied together in another place. This creates a circuit through which current may flow in a closed “loop” from one unit’s ground out to a second unit and back to the first. When this current flows through a unit’s audio signal ground it creates the hum. Balanced interconnects were developed to be immune to these noise currents, which can never be entirely eliminated.
Hopefully, as a non-technical person I’ve described that correctly. However, assuming I described that correctly, it’s my understanding that this is not what Vogel Cable is trying to address with its ground plane stability products. So what else can it be?
Even without a ground loop, a little noise current always flows through every interconnecting cable. It is impossible to eliminate these currents entirely. Moreover, the internal PCBs of today’s electronics have their own grounding and noise issues. According to the ubiquitous Wikipedia:
A ground plane in PCB assembly is a layer of copper that appears to most signals as an infinite ground potential. This helps reduce noise and helps ensure that all integrated circuits within a system compare different signals’ voltages to the same reference potential. It also serves to make the circuit design easier, allowing the designer to ground anything without having to run multiple tracks; the component needing grounding is routed directly to the ground plane on another layer. Ground planes can also be placed on adjacent layers to power planes creating a large parallel plate capacitor that helps filter the power supply. Ground planes are sometimes split and then connected by a thin trace. This allows the separation of analog and digital sections of a board or the inputs and outputs of amplifiers. The thin trace has low enough impedance to keep the two sides very close to the same potential while keeping the ground currents of one side from impacting the other.
OK – so I don’t really understand this, or why there’s always some noise current flowing through the interconnects. However, all of this suggests that ground planes not only exist in each component, but that signal ground planes can exist between components. Assuming that I’ve got this right, my next question is whether this small amount of noise current audibly affects the performance of the audio system. Chris Vogel says it does and that he’s come up with some products that improve performance by addressing these minute currents. He’s not the only one. BAlabo (Bridge Audio Laboratory) also provides a signal ground plane connection lug on its DAC, preamp and amp.
The Vogel Cable Solution
Most connections between components simply provide a simple conductive path between the ground planes of components, like the connection of a simple copper or silver wire. In an effort to improve the ground plane between components, some manufacturers provide parallel wire connections between each chassis. Many of us have had components which incorporate this feature, but in my case I was never able to detect any clearly audible improvement.
The X-Link is different. It is a single cable that connects between any two components by utilizing any free (unused) RCA jacks. It connects only to the groundside of the RCA jacks. This means the X-Link only provides an inductive coupling – not a conductive coupling – between components. As a result, the plugs on the ends of the X-Link do not require a center pin. Center pins are incorporated into the plugs only for ease of use and to add stability – the X-Link does not require them to perform its function.
Chris Vogel says that the X-Link uniquely addresses dynamic artifacts and eddy currents that diminish the musicality of virtually any music system. He says that it does this by improving the ground plane that the components share. Further, he indicates it’s not merely the connection itself, but the addition of certain proprietary treatments that enhance the X-Link’s ability to work with minute currents. As I understand it, many of these improvements were made in early 2010, and that X-Links manufactured after that time provide much improved performance (older users can get upgrades).
Vogel Cable gives a 45-day satisfaction guarantee. Chris was very pleasant to work with and was very helpful in explaining the general concept without specific design secrets relating to the X-Link.
All of this is nifty in theory, but how does it sound? As I mentioned above, other than proper grounding of my electrical circuits, I’ve never been able to discern any audible improvement from connecting components via their chassis grounding lugs. Well…read on.
Though the instructions encourage you to experiment, they also state that the X-Link is directional, so I put it in as indicated by the directional arrow between my Lessloss DAC and my Lyngdorf RP-1. The effect was immediately noticeable. The soundstage became significantly deeper and more layered and enveloping. The 3-dimensional improvements were unmistakable. The soundstage also seemed a bit narrower, but mostly because it now felt like a horseshoe rather than a flat soundstage. Over the course of the next three days the effect was replicated on every piece of music I played, but by the third day the “horseshoe” became wider and was now the width of the entire room. During this time I took the X-Link in and out of the system several times, and in each case the effect was the same.
Sometimes I review an audio component which sounds interesting at first, but over time becomes fatiguing, or artificial, or some other undesirable characteristic. None of these issues manifested themselves with the X-Link, so I thought it was time to get some other opinions. I’ve got a group of friends who are not audiophiles, though they swear they’d like to be, who come over for some fun listening every 8th or 9th Thursday. They were due in a few weeks, so they became my guinea pigs. They have provided a reality check for my impressions of new audio toys, and when both of them are in agreement, then I have reliable confirmation that the ordinary music-lover hears a clear improvement in the music.
When they arrived that evening I made no mention of anything different in my system. In fact, they asked and I denied the presence of anything new. They commented that the new music I was playing sounded very good, and I left it to that – new music. After about an hour of listening, I told them that I wanted to put something new in the system and get their opinion. I did not let them see what I was doing, and removed the X-Link. Within 5 minutes each of them firmly stated that the “new thing” I added actually made things sound less live and less natural. I then reinserted the X-Link, again without letting them see what I was “removing.” They both confirmed that everything sounded better without that “new thing.” I asked them to describe what was better about it, and they each indicated that the “new thing” had flattened the soundstage and reduced the dimensionality of the presentation. Less firmly, they also opined that there was a loss of detail. Only then did I reveal to them that I had not added, but had in fact removed, a single cable that was not even in the signal path. After some extended discussion, we concluded that the wrap-around effect of the X-Link created in my system the impression of at least five feet of additional soundstage depth. We also concluded that the presentation had more clarity, much like the use of improved power conditioning.
Over the course of the next several weeks I substituted several different interconnects for the Silent Source Music Reference XLRs that were connected between my DAC and room correction device to determine whether and to what extent the X-Link’s effect was affected by the other interconnects used between the components. In all cases the X-Link rendered its improvements, even when I used the mighty Tara Labs Zero Gold interconnects (review to come).
The X-Link between other components and in a mid-fi system
Chris Vogel told me that the the X-Link was designed to work between the source and a preamplifier, but since I don’t use a preamp I connected it to my room correction device, and as you know, that worked quite nicely. I did, however, have the Pass Labs XP-20 available and confirmed that using the X-Link in a source-to-preamp connection produced the same beneficial results. I did not get any material improvements when I used it between my reclocker and DAC or between my music server and reclocker, and Chris confirmed that those were not good uses of the X-Link. Consequently, you can experiment with other uses, but source-to-preamp is the best place to start, with other connections downstream of the source also possible. Vogel’s website states that typical positions where an X-Link may be placed are: phono preamp to linestage, CD player to preamp, CD player to integrated amp, DAC to preamp, preamp to amplifier.
Interestingly enough, the X-Link consistently improved high-end systems when used downstream of the source, but was less consistent in mid-fi systems, improving most, but making very little difference in some. There was an excellent improvement when it was used between a Pioneer Elite DV-38 DVD-A player and a Sony SPD-EP9es digital preamp, but not much when used between a Direct TV satellite receiver and a Denon receiver. Your mileage may vary, but it’s worth experimenting.
I really had not doubted my own impressions of the X-Link, but the confirmation from my buddies make it clear that the effect wasn’t too subtle for non-audiophile ears, and that’s really the main message of this review. Significant improvements occurred whenever the X-Link was added between components that were located downstream of the source, and it often seemed that the improvements were most noticeable when it was added to a high-end system. Highly recommended, given that Vogel has a 45-day return option and you have nothing to lose if you don’t get the improvements I experienced.
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