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Blue Circle Audio SB100S Solid State Stereo Amplifier Review

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Blue Circle SB100S Solid State Amplifier

For the Dagogo readers unaware of Blue Circle Audio and its founder and Chief Architect, let me fill you in a bit.

Gilbert Yeung founded Blue Circle Audio approximately 20 years ago in Innerkip, Ontario, Canada. Upon meeting Gilbert you will find a very dedicated audio engineer who takes his craft very seriously. He is direct, no nonsense and all about business. This stern appearance masks the heart of a natural-born entertainer and clown. Upon getting to know Gilbert on a personal level, you will find someone who is completely and totally self effacing, especially if it gets him a laugh.

Nothing represents that light-hearted view on life and the importance of maintaining the solid sense of humor that Gilbert possesses more than the infamous “Mary Lou.” No, she is not his girlfriend nor his wife but a whimsical mistress of sorts. She is not a fantasy at all but very, very real. Those who have met Mary Lou are always smitten and enjoy listening to her, always marveling at her delivery. You see, Mary Lou is not a person at all but rather a stereo. Yes a stereo, but not in the common or even normal sense.

Mary Lou started life as a purse housing a preamp and a pair of high heel shoes housing mono-block amplification. As a natural effect of introducing her to the masses, there were always suggestions on how to improve Mary Lou’s assets. The last time I was in her presence, she sported the addition of a very nice sun dress with two Gallo Nucleus speakers strategically placed in the, uhm, chest area! She was seductive to be sure and unflappable in her delivery of her musical message. I am still waiting to see her with the addition of a nice subwoofer strategically place in her bum. I cannot think of any better way to sum up Gilbert’s take on high audio art than Mary Lou! Yet at the end of the day when it comes to his craft, he is completely serious and creates high quality and highly musical electronics. For some years now I have been using his BC86 MKIII Power Pillow power line filters in conjunction with full on power conditioners which results in an even cleaner power with a total absence of noise.

A few years ago, I did a review for another publication highlighting the Blue Circle BC100 and BC101 amp and pre-amp. I summed up my review of those two components in this way – “you will have yourself a very satisfying system that will keep you enjoying the music for a long time. This setup will give you all the punch of solid-state, coupled with a lot of the sweetness of tubes without any of the hassles. Of course it won’t be Mary Lou, but it may be a whole lot easier to get past your significant other.”

I thoroughly enjoyed my time with the 100 and 101. Alas they are no more. Gilbert decided to cease production, which brings me to this piece. I spoke with him at the Rocky Mountain Audio Fest and we decided it would be a good follow up to review the SB100S solid state amplifier.


The Blue Circle SB100S is a fully solid-state stereo amplifier pushing out 100 watts per channel into 8 ohms. If you open the SB100S, it has a toggle switch named TUBE WARMTH SWITCH; its purpose is to smooth out the high frequency a bit. This feature becomes extremely useful when you are in a “bright” room or you are using a digital source that is a bit harsh or perhaps not of the best quality. In Gilbert’s words, “It’s almost like using a different tube in a tube amp to tune the sound.”

The review sample was supplied with the optional Blue Circle BC62 power cord. This cord uses some pretty hefty 10-gauge high quality copper wiring and actually the same cord could, in effect, be used as a speaker wire; the quality is that good. It also is incredibly flexible, which is unusual for such a stout chord. The BC62 in itself sells for $300 as an option. The SB100S comes with a more mundane power cord. Strongly recommend the upgrade.

The unit is very compact and elegant looking. It measures 16 inches deep by 17 inches wide and only 3 inches tall. The sturdy black case is fronted by an elegant black acrylic face plate with the Blue Circle logo in the middle. This is a fairly radical departure for the Blue Circle units as they are generally faced with some type of metal plate, the most popular being stainless steel and any control knobs are usually large natural wooden knobs. The SB100S has a very different vibe and more contemporary look that is much easier to blend in with most decors.

The Blue Circle logo deserves some special mention here. When I reviewed the BC100 I noted that my wife, Paula, had mentioned that it was a shame that the blue circle did not light up with a nice rich blue color. She felt that it was somewhat weak. She mentioned that it would be nice if it put off the same light that the blue LEDs of some of our other equipment. When I opened the case I found that the logo was backlight by a small incandescent bulb giving off a bit of a yellow glow. We mentioned this to Gilbert at the following CES. I was astonished when I walked into his room at RMAF this year and saw that the logo was wicked deep blue and jumped out of the case. Gilbert told me that after Paula’s comments he later altered the lighting and switched to LED. It made a huge difference in the aesthetics of the unit. People never doubt the importance of the scientific Wife Acceptance Factor in your audio equipment. Gilbert certainly understands the importance of the aesthetic appeal. Paula is still on cloud nine for the response to her critique.

The amplifier weighs in around 32lbs and is easily placed anywhere you want it to go. One of the most interesting features that I first noticed was the binding posts. Since we cannot seem to agree on standard sizes for all spades and other ancillaries in this industry, there is sometimes a problem with speaker wire spades being too big to work with some WBT type of posts and too small for others. The Blue Circle posts look almost primitive by comparison to the WTB; but in the real world they work better and easier than anything else I have worked with. The posts are about an inch long with hex head nuts of the same length. They are easy to turn and can be removed if needed and all you have to do to really tighten them up is a box end wrench to really get a strong, solid connection. Not particularly pretty but exceptionally practical and no one sees the back of your equipment but you anyway! (Unless they are really nosey of course.)

So what does this all mean in terms of sound and quality? Well quite a bit. First, the amp sounds much bigger than it is. By that I mean that in general terms when I have been in the presence of a solid-state amp in the 100-watt-per-channel range that sounds this good, it is twice the physical size and twice to three times the price. There are few exceptions that I have heard, most notably the Usher 125 and Gilbert’s own BC100. As a matter of fact, the SB100S struck me as more powerful and improved upon the BC100. I do not think it was just because it had 50 watts per channel or more, and it was more than just the additional headroom. There was a difference in the presence this amp provided that could not be so easily explained. The black arts of audio if you will!

I thought it would be good to use the exact same tracks to review the SB100S as I did with the BC100. I lived with it long enough to have a pretty strong memory of how it performed. Straight up I can say that, left in its normal mode, it sounds less tube-like and definitely more solid-state.

The SB100S produced a solid and punchy bottom-end with plenty of grunt and superb control. In critical listening what really jumped out at me was that it produced music in direct relationship to the scale of the work, just as the BC100 did but with more authority. The bass was deep, musical, full of air and never overwhelming. It could not match my Music Envoys for scale and power but they lacked 100 watts per channel in comparison, and that can provide for a lot of additional head room.

In the midrange, the delivery allowed for emotional involvement that I rarely have with solid-state equipment. Being a musician, albeit a poor one, I am familiar with the way a group of instruments should sound like, and the SB100S presents most instruments accurately and handles the micro-dynamics better than most amps I have listened to in this price range.

In the area of vocal presentation, it provided all the detail and none of the harshness. Sibilants were neither elevated nor diminished but delivered in a very natural sense with the appropriate amount of air propelling them from the vocalist’s lips. A great example of this is on Jane Monheiht’s Live at the Rainbow Room (NCODED MUSIC NC-4249-2), the opening cut “Somewhere Over the Rainbow” with the acapella. It is a great test for the vocal presentation of any amp.

As for the top-end, it was right there where I wanted it to be. Not too bright or too relaxed but just at the point where I got all of the sparkle and shimmer and none of the edge and glare that I usually associate with all but the best solid-state pieces, usually costing three time the price of the Blue Circle! The decay of things like cymbals was up there with some of the best, which surprised me. The cymbal would bloom and then decay at a very steady rate and even towards the end the shimmer was still with you. Hit a cymbal sometime and take a very deliberate listen to how it decays and you will get the sense of what the Blue Circle captures.

It is no secret that I am not a huge authority on classical music, but I do have some classical recordings that I like to use for reviews. Most notably is Symphony No. 9 by Antonin Dvorak as performed by the Royal Philharmonic Orchestra, under the direction of conductor Jascha Horenstein (Chesky CD31). Creating a grand sense of scale was not a problem for the SB100S. I was able to get quite satisfying sound levels. One of the things that I liked during this part of the review was how well the amp presented the transitions from full impact to low level passages with a sense of ease. The sense of detail remained the same. The transients were lightning-quick but maintained a little bit of a laid-back subtlety. I immediately noticed that the high frequencies were more pronounced and seemed to decay longer than I am used to.

As an example of what I mean, the shimmer of a cymbal seemed to linger a bit longer and a bit clearer than in my regular system. It was not a startling amount of difference but just enough to be noticeable. The same was true on Holst’s The Planets (Deutsche Grammophon 445 860-2), especially during “The Warriors” and on the shift from “Mars the Bringer of War” to “Venus, the Bringer of Peace”. I was able to listen quite satisfactorily at moderate levels without ever touching the remote volume, and all the detail was presented in a concise and consistent delivery.

On Pink Floyd’s “Comfortably Numb,” a long time favorite of mine and a great test track from the live Pulse CD (Columbia CK67096), it put me right in the middle of the music. What I really enjoyed was the delivery of the vocals and David Gilmour’s guitar solo, which I happen to think is one of the greatest guitar solos ever written. There was an absolute lack of glare and edge. The air around the guitar is just stunning. Gilbert is actually gifted in his design work as he gets this right on every solid-state piece of equipment of his that I have had the pleasure of listening to.

On “Papa Was a Rolling Stone.” from Lee Ritenour’s Overtime CD (Peak Records HPKD-8531-2), which was recorded live in the studio, I was treated to the feeling of a small and intimate setting: Right there in the middle of the circle in which it was recorded; up close and in the close proximity of the band. Once again, I felt that Chris Botti was actually standing to the side of me as he played. The sense of scale was exactly what I would have expected had I actually been in the studio during the recording.

Unlike its predecessor, the SB100S seemed more comfortable with metal and headbanger genre of music. On some of the tracks, such as Audioslave’s “Gasoline” from their debut, self titled album (Epic/Interscope EK 86968), the sound was more coherent and held together better than the BC100, which was not always comfortable with that type of music. The music was consistently enjoyable and there was never a single glitch with the amp. It produced a lot more slam and impact. Where it really stood out in this music was in the impact of the bottom-end: Kick drum in your face and a whole lot of air moving in the room. The slam was to write home about!

I tend to listen to a lot of older jazz recordings on vinyl before the engineers started on the trend of putting things into their proper perspective as to placement of the musicians. In other words, more of a right-and-left than a true soundstage, like those being created in most of today’s recordings. That being said, the soundstage was still quite involving just without as much center-imaging. The placement of Chet Baker on “The Touch of Your Lips” from the same-title album (Steeplechase SCS 1122) gave a sense of air around him that I generally only seem to get with tubes, or the pricier solid-state amps. He was out front a bit from the other musicians and the delivery was very smooth. Even when Chet bobbled a bit, which was prone to happen closer to his death, thanks in no large part to the loss of a lot of teeth during his heroin addiction, there was no missing it. Whatever was presented to the SB100S, it delivered without much of its own coloration.

This amp was very easy to listen to and mated up well with all three speakers I hooked up to it. It sounded great with the Usher 6311s and really cooked with the Von Schweikert Unifield 3. As I have stated before, Gilbert Yeung and Blue Circle Audio are the real deal. If you have a small to medium room, the Blue Circle SB100S would be a great anchor for an affordable and very satisfying system. This amp will give you all the punch of solid-state, coupled with some of the sweetness of tubes in an easy-to-live-with package that takes up little space and fits in with just about any decor. As I stated before: Of course it isn’t Mary Lou, but it may be a whole lot easier to get past your significant other.”

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