BSG qøl Signal Completion Stage

I walked into BSG's room at the Newport Beach Show in June 2012 unsure of what I was going to hear. I was well aware of this new company's qøl Signal Completion Stage ($3995), but didn't know if it was a genuine step forward in audio reproduction, or just another example of the hokum found on the fringes of our hobby. I took my listening seat, and BSG's CEO Larry Kay, cofounder and erstwhile publisher of Fi magazine, performed A/B comparisons with the qøl's processing in and out of circuit.


As I wrote in my show report, the difference between bypass and process was enormous on both the Eagles' "Hotel California" and Leon Fleisher, George Szell, and the Cleveland Orchestra's recording of Brahms's Piano Concerto 2. 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.

I asked for a review sample.

Signal Completion
The obvious question to be asked is "What does it do?" From BSG's website:

"BSG Technologies has developed a method of retrieving sonic information from audio signals that provides a realistic and complete rendering of the original acoustic event. . . . Instead of 'adding' a host of processing techniques intended to create 'effects,' we have simply found a way to extract information already present in recordings, but otherwise hidden in conventional reproduction. Our technology enables complete capture, transmission, and reproduction of such information, including elements that, until now, have remained hidden and buried in electronics, and unavailable to the listener. The result is an audio experience with fullness and richness beyond comparison and one which carries essentially all the dynamic, tonal, and spatial content of a real sonic event. . . . We call it 'qøl(tm).'"

The Signal Completion Stage uses technology developed by BSG's Barry Stephen Goldfarb, who has taught audio engineering and acoustics at the university level. BSG and Goldfarb applied for two patents on qøl, one of which, US Patent 8259960, was granted last fall. That patent refers to "phase layered" treble and bass signals as well as antiphase signals, but I found it difficult to see from the circuit diagrams included in the patent what was actually being done to the input signal. However, looking at the application for the other patent, US20110158413, I found the following two paragraphs:

"8: The objectives and advantage of the present invention may also be achieved through an audio signal reproduction method that involves, among other things, selecting a discrete signal source having left and right signal inputs, summing the left input signal and an inverted right input signal to produce a left–right difference signal, summing the right input signal and an inverted left input signal to produce a right–left difference signal, and summing the left and right input signals to produce a left+right summed signal. The method and circuit further involve adjusting the gain of the left+right summed signal, adjusting the gain of the left–right difference signal, and adjusting the gain of the right–left difference signal. Still further, the method and circuit involve summing the gain adjusted left+right summed signal and the gain adjusted left–right difference signal to produce a left audio output signal, where the ratio of the gains associated with the left+right summed signal and the left–right difference signal at least approximates the golden ratio [1 plus the square root of 5 divided by 2, or 1.618, equivalent to 4.18dB]. Similarly, the gain adjusted left+right summed signal and the gain adjusted right–left difference signal are summed to produce a right audio output signal, wherein the ratio of the gains associated with the left+right summed signal and the left–right difference signal at least approximates the golden ratio.

"9: The audio reproduction method of claim 8, wherein the gain of the left+right summed signal is asymmetrically adjusted relative to the gain of the left-right difference signal, such that the ratio of gains is within 10 percent of 1.618; and wherein the gain of the left+right summed signal is asymmetrically adjusted relative to the gain of the right-left difference signal, such that the ratio of gains is within 10 percent of 1.618."

Ah-ha! This looks like a variation on something with which I am familiar: the Blumlein Shuffler, which allows adjustment of a stereo soundstage's width and dates back to the 1930s. By converting a conventional stereo signal into Sum and Difference signals and amplifying or attenuating the Difference signal before rematrixing these signals to produce left and right outputs, the stage width can be reduced or expanded. And if you change the spectral balance of the Difference signal, you can selectively alter the stage width at some frequencies but not others.

I had experimented with shuffling when I produced one of the tutorial tracks on Stereophile's Test CD 3 (Stereophile STPH006-2). I took a choral stereo recording I had made with distant, almost-coincident cardioid microphones, converted it to Sum and Difference signals, then applied a low-frequency boost to the difference signal before reconverting the recording to left- and right-channel signals. My goal was to both compensate for the bass rolloff typical of distant cardioid mikes and widen the stage in the bass. The result was successful, though I found that getting the correct degree of equalization was difficult: too much, and the recording sounded phasey; too little, and the improvement in stage width was minimal.

BSG Technologies
3007 Washington Boulevard, Suite 225
Marina del Rey, CA 90292
(310) 827-2748

guitarist8's picture

This certainly seems like an interesting product. However, reading through this review it reminded me of the BBE Sonic Maximizer that I have used in many live sound applications. Any experience with this, much cheaper, piece of gear in a hi-fi environment?

cgh's picture

I heard this device at RMAF11.  I could clearly hear the dB gain and a widening of the stage during the A/B session they gave us.  The people representing the company indicated they really were not into audio -  my inference was that audio was some derivative use.  As someone with a background in research level physics my BS detector normally goes off in these situations, especially when I start hearing unsubstantiated magic beanisms like "quantum" or "tunneling" or or some other high voltage torture that results in the sound being different .... I only remember them talking vaguely about phase.  My BS detector didn't go off.  They seemed genuine, excited about their product - almost giddy - curious about audiophiles, and not really too  aware of the technical details.  I was curious.  

Segue to the latest issue and I got the answer to my question.  This product, regardless of price point, will not be for everyone, especially purists (aspiring?).  But it is nice to have some transparency.  All too often some product is introduced that changes the sound; but is it for the better?  Or do people just get excited when they can hear a change and the marketing sets the stage for its reception being perceived as an improvement?  So thanks to Mr Atkinson and BSG for the transparent and well-written article.

(Edit: p.s. I have a funny picture from their room I saved that is two 'scopes comparing a signal with the device on and off.  Makes sense in retrospect :-)

OneMic's picture

I just had to comment that this is one of the best reviews I have read and frankly I am really glad to see a review of this caliber on Stereophile.   This type of educated and informing review is what myself and many of your readers have been waiting for on these type of "tweak" or enhancement products.  

JA you did a standup job cutting through the manufacture's frankly B.S. copy of "not being an effects box but digging deeper into the recording and uncovering hidden and secret information through our proprietary processing technology".   You explained in relatively understandable terms that this is precisely an effects box with a singular well known effect.  

While being an effect box is not a bad thing, I am just glad that someone at Stereophile is finally calling a spade a spade and not just ignorantly regurgitating the manufacture's fraudulent marketing speak. 

JA, I anxiously look forward to more of these kinds of articules as they do a great job of shining a light of truth on the dank and dirty world of tweaks. 

pwf2739's picture

I am not an engineer nor a designer of reference level audiophile components. I am one who very much wants to hear the reproduced music as lifelike, detailed, natural, involving and as close to live music as possible. Towards that end I have devoted a substantial sum of money to achieve what to me sounds engaging and makes me enjoy the music. 

I frankly don't really understand much of what was written in the article. I mostly skimmed through the reprint of the patent application. I certainly don't have a great sense of what a Blumlein Shuffler is, what it does, or how it may be applicable in today's high end components. I'll leave that for those far more learned than I am. 

However, I have owned a BSG qol Signal Completion Stage for eight months now. I have had professional musicians, recording engineers, audiophiles and friends in to hear my system. In each and every case, the most discussion centered around the qol unit. And each and every person who has heard it, including wives of friends were amazed at the difference it makes. 

When my friends inquired about the qol unit, we did not discuss a Blumlein Shuffler or a patent application. I simply told them that it brings much of the recorded sound to the front that may be ordinarily hidden or obscured. I told them that it made the music sound so much better. Everyone was astounded at the difference it made. Simply put, it makes the music sound more lifelike. Not in the way a graphic equalizer on a mid-fi surround sound receiver does but actually more lifelike. Your hear so much more music with qol. The proof is in the bypass button on the remote- you can actually hear what you are missing without qol. 

I don't really care if my system costs $200,000, $2,000,000 or $2.00. I can tell you that any high end system I build will have a qol Signal Completion Stage as part of the components. 

Patents, Blumlein Shufflers, equalization, this, that- all are fine discussions. For me, I'll take the music. Because qol works. 

neogeo's picture

Next time, please don't make it so obious that your comment was paid for by BSG :)

russtafarian's picture


Your article inspired me to try this out for myself.  After reading your description of the Blumlein Shuffler, I tracked down a free mid-side VST plug-in ( ), installed it in Jriver (music playback software for the PC) and played around with mid-side levels.  I found that a small increase in side level (between 0.8 and 1.2 with this plug-in) did help the soundstage bloom on many recordings.  Too much level and it sounded too phasy and exagerated.  But when set to a tasteful level, it really works!

I heard the BSG unit in a friend's system a few months ago and really liked what it did.  He listens almost exclusively to vinyl so an analog solution like the BSG is ideal for him.  For those of us who have computer audio setups, we have an alternate path to get to the same place.  Thanks for cracking this nut for us.

prerich45's picture

You are correct!!!! You do hear more instruments when cautiously applied! Biggest thing, it  was FREE!!!!  Listening to it in J River now! 

Et Quelle's picture

indecisionIs the variation on already known techs enough to justify the cost.Is it any better choosing effects on a receiver. Buy it if your wealthy, looks cool?