[note: this review is a work in progress.  Most recent edit 2/13/14.I will be adding to it as I get more seat time with the device, and as I read up on and try to better understand the technology involved.  If there are specific things you would like me to address, please mention them in comments.]

“Yeah, right.”  If you’re like most folks in the audio hobby, that was likely your initial reaction when you first heard or read about the BSG Technologies qol “Signal Completion Stage.”  I have a clear recollection of ducking out of John Atkinson’s review of the qol when it appeared in Stereophile in early 2013 after reading this:

Superficially, there seemed to be an increase in volume of 2–3dB; more significant was that individual objects in the soundstage—the solo voice in "Hotel California," the piano in the Brahms—didn't get louder. It was the surrounding space that gained in volume. With both pieces of music, the sound definitely improved with the Signal Completion Stage doing its stuff.

Skeptonometer pinned; on to the next review.

I’ve still never heard the qol in action, and there continues to be widespread skepticism about it.  However, both Atkinson and Robert Harley of The Absolute Sound have reviewed it quite favorably, and silly me, that gets my attention.

Fast-forward to early 2014, and the qol has a little brother, called reveel; battery powered, compact enough for portable applications, and priced at $120.  Time to see what the fuss is about.  Online ordering is well executed (it amazes me how many e-commerce sites still can’t get this right), and three days later a box arrives.  Inside the box is a blister-pak, and inside the blister-pak is (1) reveel, (2) a USB-A to USB-micro-B cable used to charge the unit (it fully charges in 2-3 hours using an Apple iPhone AC adapter), (3) a 3.5 mm to 3.5 mm analog stereo cable used to deliver a signal from source to reveel (whatever reveel is doing, if anything, is done in the analog domain), and (4) a couple of small adhesive-backed Velcro squares that you could use (were you of a mind to do so) to attach reveel to a portable source.

It’s a tiny thing, somewhere between round and octagonal in shape, measuring 6 cm high by 5.5 cm wide by 14 mm deep.  Photo 1 shows it with a current Apple iPod Touch and a Resonessence Labs Herus, to give an idea of its relative size.



Photo 2 shows the “south” end, with a USB-micro-B charging port and an LED that shows the charge state. 



Photo 3 shows the “north” end, with a 3.5 mm headphone output, a 3.5 mm input, and a slide switch labeled “bypass” at the left end.  When the switch is in the “bypass” position, no processing takes place; move it to the right and the reveel is engaged.



My initial listening was done using my curr ent primary portable rig, an Apple iPad Air connected via the Camera Connection kit and a short USB cable to a Resonessence Herus.  Using the ¼ inch-to-3.5 mm adapter that came with my Ultimate Ears Reference Monitors, I ran a cable from the Herus to the input of the reveel and plugged my UERM into the reveel’s output.

In evaluating new gear, I nearly always listen first to the first movement of the Dvorak “New World” Symphony, in the Naxos recording by the Baltimore Symphony conducted by Marin Alsop.  It’s a fine-sounding recording of a familiar work, and it puts extensive demands on any piece of gear’s abilities to accurately convey instrumental timbres, resolve complex ensemble playing, and deal with fairly extensive dynamic range.

So, here we go.  Push the bypass switch away from “bypass,” and …

Whoa!  Two changes are instantly apparent.  First, there is a perceived increase in loudness (about which more later).  Second, there is a perceived increase in soundstage width and depth—and within that wider and deeper soundstage, instruments lock perfectly into their normal positions on stage (for example, trumpets slightly behind and to the right of French horns, and trombones centered and behind both).  Whatever is causing it, it’s a pretty remarkable effect.

“Fat Mountain,” from Russ Barenberg’s album When at Last, challenges for a different reason.  Russ’ Word War II-era Gibson J-45 has a very distinctive sound; it was constructed with maple back and sides rather than the mahogany or rosewood used in most flat-top acoustic guitars, and is noticeably brighter throughout its range as a result.  It’s also prone to some fret noise, as it is set up with the action pretty low.  With two guitars in the mix, the reveel makes it easy to tell which is which; some reputable portable gear I’ve heard struggles to get that right.

With “A Matter of Minutes,” from Shawn Colvin’s Live, something happens that, on first hearing, is a little disconcerting.  Colvin’s acoustic guitar stops being a point source. Fret noise and finger slides are distinctly to the left of the instrument’s primary output, which seems weird—but on reflection, that’s actually correct reproduction of how the instrument sounds in real space.  Playing a guitar right-handed, fret noise and finger slides emanate from a location that is 18-24 inches to the left of the sound-hole.  It’s as though reveel has put the guitar in your hands.

I should also note that on the same Shawn Colvin track, bringing reveel into the signal path causes Colvin’s voice to move distinctly to the right within the soundstage.  Once you get used to it being in a different location, there is little or no difference in how it sounds; and again, I think this is correct localization.  Playing a full-size acoustic guitar in an unamplified setting, your head is typically directly about the sound-hole, and that’s where reveel places the voice.

By now, you should be getting the idea that I’ve rejected the null hypothesis.  This is not snake-oil or confirmation bias. I may not be able (yet) to tell you how reveel is doing what it’s doing, but it is absolutely doing something.  And I'm still some distance away from having an answer to the most important question, that is, "do I like it?"

added 2/13/14

Now, about that perceived increase in loudness.  It's real.  And some primitive measurements with a SPL meter and a Beyerdaymic DT 1350 in place of the UERM shows it to be mostly around 2-3 dB, as Atkinson noted in his review.  With that knowledge in hand, I tried to roughly level-match (not easy given the imprecision of the volume slider in the iOS 7 Music app) in my subsequent listening.  As a general rule, the reveel effect is independent of volume, but it's more easily perceived with t hat additional gain left in the signal chain.

I listened to a wide variety of piano music, from sonatas to solo jazz to classical and jazz trios to concertos.  In nearly every case, reveel gave the recorded piano more of the physical presence that a piano has in a live setting.  To cite only one example, the dissonances that are characteristic of Thelonious Monk's playing ring more clearly (or, if you prefer, are more jarring) with the reveel engaged.  The lower octaves are more of a physical presence.  Ironically, the reveel showed me something about one of my favorite solo piano recordings that I hadn't really noted previously: Boyd Lee Dunlop's The Lake Reflections was mixed "backwards," with the left hand predominantly in the right channel and vice versa.

As noted above, the reveel effect includes a broadening and deepening of the soundstage of nearly every recording I've listened to with it engaged.  Within that broader and deeper soundstage, individual instruments find individual spaces.  Some reviewers of the qol used terms like "spotlighted" and "lit from within" to describe this effect.  I'm not sure either of those terms really get to the essence of what's happening.  But when it happens (for example in the case of Louie Perez' jarana at the beginning of "Cumbia Raza" from the Los Lobos album This Time), your ability to hear into the mix is enhanced.  You go from knowing that he's playing to knowing what he's playing.

I'm still not completely sold.  The reveel listening experience is significantly different from any prior headphone listening experience I've had.  You may reject it as "artificial."  But so far, I am finding that it enhances my enjoyment of recorded music--and that's what this hobby is about, ain't it?

The only way to know if you will like it, is to try it.  Set your preconceived notions aside and go for it.  The only thing you have to lose is $120 (well, and another few hundred for a second one and the additional cables you will need to put it in your desktop system).