February 2000Wyetech Labs Topaz Amplifier
by Doug Schneider
I know of no amplifier topology that generates more controversy than the single-ended designs. On the one side of the fence are those who proclaim that single-ended is the ultimate in simplicity and signal purity. Then there are those, usually proponents of solid-state designs, who see single-ended as nothing more than a distortion-producing amplifier anomaly that may sound good but usually has inferior technical specifications, including low power efficiency and poor compatibility with loudspeakers.
Some criticisms certainly ring true. For only a few hundred dollars you can get a solid-state amplifier that will run circles around the power output from a single-ended tube amp. Furthermore, for the price of a cost-no-object single-ended tube job, like this unit from Wyetech Labs, you can get a solid-state amplifier that will drive just about any speaker on earth and then some. Based on this criteria, single-ended amps can hardly be called great value. However, experienced audiophiles know that power is only part of the equation.
Even for those who criticize single-ended designs, most wont dispute that these amps can sound very good. However, why they sound good will again produce disagreement. One side will likely proclaim the superiority inherent in the design that results in greater accuracy; the other side will likely claim that is not necessarily due to the accuracy of reproduction and more to do with producing a pleasing, often described as euphonic, sound. In other words, theyll say it is some anomaly in the loudspeaker/amplifier combination that just happens to sound good, but it is a coloration nonetheless. Still another argument can be made that when you hear the stellar sound that some single-ended amps are capable of, is it important to ask why it sounds that way. After all, isnt it the music that really matters?
Canadian-based Wyetech Labs, lead by president and designer Roger Hebert, produces the Topaz single-ended stereo amplifier. When Wyetech introduced the Topaz a few years back, it was the companys only offering. Now theyve added two line-stage preamplifiers, the Opal and Jade priced at $8400 and $4200 respectively. A new but lower powered amplifier will be coming in the future.
The construction and parts quality of the Topaz, and the rest of the Wyetech line, are an interesting example of audio esoterica and engineering practicality. These products reflect Heberts personality and his views on audio. After talking to Hebert at length, I can attest to the fact that when you buy a Topaz amp, you buy a bit of Roger too.
The Topaz is a single-ended, class-A design using 211 output tubes to deliver 18Wpc continuously into 4 and 8 ohms and can swing short-term peaks of up to 50Wpc. There is no local or global feedback. The tubes are self-biasing, making user intervention minimal. Audiophiles will recognize many parts, including Solen capacitors and Holco and RCD resistors. Binding posts are high-quality pieces by WBT. The hallmark in the design is the Audio Note output transformers that are finished in polished chrome and 24-karat gold plating.
The chassis is of 12-gauge steel and assembled very solidly to help reduce vibrational effects. The Topaz is a substantial beast measuring 16" wide by 10" high by 22" deep and clocks in at a back-breaking 106 pounds. Luckily it has handles to lift it in and out of its packaging. No reference is made to the brand of internal wiring used; however, the manual states that "Teflon-coated OFHC copper wiring is used where appropriate and silver solder is used throughout." Wyetech supplies a standard 18-gauge off-the-shelf power cord that should have been something a tad better in my estimation. Im not one for recommending superfluous add-ons, but for a product in this price range, other options should be considered, particularly if you can get a further improvement in sound. While I rarely hear the enormous differences some claim power cords can make, I was surprised at the improvement the JPS Labs Power AC cord made, which Ill get to later.
The amplifier color, which does make it unique, will find an equal number of admirers and detractors. Many will describe it as light purple. Surprisingly, my limited survey sample showed women greatly approved of its color while men were mixed. Could women be getting tired of the black and silver we see everywhere else?
Ergonomically the Topaz seems designed for function over form. The circuit is laid out for the shortest signal path possible and the best sound quality. As a result, there are some peculiar aspects to the Topaz's design, including input jacks and output posts on the front panel and a power switch on the back-bottom corner. With this layout, its easier in many systems to turn the amp backwards and hook it up that way (mind you, the back panel of any product isnt the most attractive thing to look at). Used properly, facing forward, you have to ensure your cables are long enough to reach and bend around. Its a bit of a hassle.
The only other real quirk is the 4/8-ohm-tap switch, which is placed right between the tube and it respective output transformer. Given that these tubes run HOT, you have to be careful when switching taps not to touch the tubes. For the average consumer who sets the amp up once and leaves it, this wont be a problem. For someone reviewing it and switching back and forth to determine the performance, its a bit of a pain. On the other hand, there is a convenient feature in this switch since it has a third middle position that places the amp effectively in standby mode. No output will hit the speakers, so you can change wires without powering off and on.
Since Wyetech Labs and I live in the same city, Roger Hebert lugged the Topaz to my listening room and set it up. The amplifier performed flawlessly without a single hiccup or burp in the months I auditioned it. Once the amp is powered up, there is not much more to do other than wipe it free of dust every once in a while. When it left my room, its weight left a substantial dent in the carpet, but I was able to brush it out.
You may not get much power out of this type of amplifier, but you sure do get a substantial product. The price for all this is a pretty hefty $9800 -- not cheap by any standard. But the Topaz is intended as a reference-grade product, and according to Roger Hebert, it pains him to recall the lengths had to go to "do it right." Tubes have a one-year warranty, while the amplifier itself comes with a three-year warranty that can be extended to 20 years at no extra charge by simply mailing in your registration card.
Without a doubt, there are some serious considerations when matching an amplifier like the Topaz to speakers. At numerous shows Ive been to, Tannoy has mated their extremely large, high-efficiency Churchill loudspeaker with the Topaz with outstanding, high-volume results. I didn't have such high-efficiency speakers on hand. Instead, I tried a number of regular speakers, with mixed results. Besides the power limitation, I found early on that the Topaz has an up-front and lively character with nicely fleshed-out bass and midrange frequencies. While its not traditionally tubey sounding, it does have a robustness, fullness and warmth that many will associate with tubes (Ive heard solid-state amplifiers with similar attributes, so thats why I dont call such traits necessarily tube-like). As a result, speakers that already exhibit a similar warmth or fullness, particularly in the midrange, proved to be a little too much of a good thing. Furthermore, if the speakers are too difficult to drive, other problems are exacerbated. I had to try a few speakers before I got the right match.
I ended up using the Cliffhanger Audio CHS-2/W-2 combination. These speakers can be considered close to a full-range speaker since they have strong bass down to 30Hz or so. They are 88dB efficient and present a nominal 6-ohm load that drops a little below 3 ohms at higher frequencies. This is a borderline case for use with an amp like the Topaz, but both Roger Hebert and Cliffhanger Audios Ian Smith thought all should be fine. "Its worth a try," they agreed. Sure enough, in my mid-sized room (12' wide by 14' long by 9' high) the Topaz provided more than enough power to drive the Cliffhangers to loud listening levels with no loss of bass response or dynamics. I tried both the 4- and 8-ohm taps and found that although there was no night-and-day difference, the amplifier sounded better and performed without strain to my ears on the 4-ohm taps. Ian Smith listened to the combination and felt that the amplifier was driving the speakers with no trouble, meaning the amplifier was getting a fair shake in my system.
Other components included the Blue Circle Audio BC3 Galatea preamplifer and either my Theta Data Basic transport, Camelot Dragon Pro2 Mk II jitter reducer and Theta Prime II DAC as a separates-based digital source, or the Audio Aero Prima single-box CD player. All cabling is Nirvanas S-L series interconnect and speaker wire. My regular amplifiers are the Blue Circle Audio BC2 mono amplifiers that retail for $6300 per pair, and I used these for comparison. The all-wood BC2 amplifiers are single-ended too, but they are hybrids, meaning that they use a tube input stage and transistor output. With their transistor stage, they can deliver higher power -- 75Wpc at 8 ohms. The amplifiers get plugged into a Brick Wall Series Mode Surge Filter specially made for high-current amps, and the rest of the components are plugged into a Power Wedge 114.
Although it takes a bit of time for the Topaz to warm up -- about an hour of play is when it starts to sound its best -- I could tell right off that this was no sloppy, mushy amp as Ive heard from some other single-ended designs. "Single-ended syrup" is the term some use to describe the woolly and indistinct sound that some amps have, but it just doesnt apply here. Providing it's matched to the correct speakers, the Topaz is full through the bass, midrange and high frequencies, but is not fat or bloated. Despite its low power rating, its surprisingly dynamic with a gutsy sound that can fill a room. It sounds a whole lot more powerful than its 18Wpc rating would indicate.
In terms of bass response, always a concern with amps like these, the Topaz portrays the low end with tightness, authority and control. Frankly, its hard to believe that this amplifier only puts out 18Wpc. It certainly sounds like much more. Dont get the idea, though, that its bass will rival or eclipse that of beefy solid-state amplifiers. Some people, when they hear a single-ended amp that can do good bass, get excited and forget what a solid-state amp can do. Listen to the high-power amps from reputable solid-state manufacturers and you can find an almost bottomless pit of power. Instead, what you hope for here is deep, tight and controlled bass that is respectable. Thats what the Topaz delivers -- and does so surprisingly well, in fact. Kickdrum is tight and fast, which gives good rhythm and drive to music. There is no apparent overhang or slowness to the sound either. Music with fast-paced percussion is rendered with excellent speed and clarity. The amplifier doesnt sound like it's huffing and puffing trying to catch. The low end of a piano has a rich tone with fullness and weight and sounds exceedingly natural. On "When I See You" from Greg Keelors Gone [WEA CD 17513] there is some well-recorded room ambiance that plumbs the bass depths with a wealth of detail. The Topaz plows it out beautifully, giving dimensionality to the recording.
Where amps like the Topaz really seem to shine, however, is in the midrange, where they can portray an almost holographic presentation. Done right, there is a liquidity and fullness that blossoms with startling realism via voices and instruments like piano and guitar. It can be so real its almost spooky, and Ive never heard other amplifier designs do it to the same degree. The anti-single-ended camp may argue that what were hearing is coloration, but what I hear is something that sounds very real and natural. The epitome of this is what I heard from Marc Mickelsons system when he inserted the incredible Lamm ML2 amplifiers. Granted, these amps run almost $30,000 for the pair for their 18Wpc of power, but there is an almost touchable realism to their midrange sound. Unfortunately, I dont have the resources to have a pair of amps that cost what the Lamms do in my system for any type of direct and meaningful comparison, but I can tell that the Topaz has a similar kind of presentation.
To get an idea of what the Topaz does with vocals, I pulled out plenty of favorite recordings, but due to space limitations in this review I will only mention a few. "Use Me While You Can" from Bruce Cockburns Breakfast in New Orleans [True North TND 0183] opens with the sound guitars placed apart and distinctly in the stage. A minute of so into the song Cockburns deep, resonant voice appears rock-solid in the center, and he speaks for the next couple of minutes. Its very well recorded with a beautifully delineated stage in terms of width, depth and specificity of the performers. The drums sound recorded in a different venue, but they are placed with realistic size back in the stage. The Topaz places the images with rock-solid specificity and brings a full and dimensional sound to the voice and guitar that has an almost resonant quality. And just like it is with live music, the presentation of the singer and the instruments is not flat-sounding like it is through many amplifiers. While the performers may be placed left, right, front or back, there is also the space they occupy that the Topaz reveals very well. The presentation is vivid and up-front without being forward or aggressive, which results in a rich, robust and involving sound.
My favorite song from this same disc, "Mango," combines Cockburns voice in harmony with Jonell Mosser. Cockburn sounds almost center, just a touch left with Mossers angelic voice right beside his. An overused word in the audio lexicon is palpable, meaning fleshed out, so that you can almost touch it. Im forced to use it here because thats exactly what you hear with these voices so well delineated and fleshed out in space. Once again, its an almost spooky sense of realism; its hard to believe it's coming from two-channel audio.
Comparing the Topaz with my BC2 amps proved interesting because both present the upper bass through midrange frequencies in a different way. The Topaz is almost bulbous sounding with a stage that projects into the room. Imaging depends on the recording, of course, but in general vocals sound like they are at or forward of the speaker plane and the images seem almost carved out in space. The Topaz is very revealing and can display excellent width and depth, but it does not exaggerate depth. You can hear the back of a room, but it is just not necessarily as far back as I sometimes hear it. On the other hand, the BC2 does not bloom in the midrange to the same degree, but presents a tad more texture and detail in this region.
The BC2 amps seem to go subjectively deeper than the Topaz, resulting in a weightier, more fleshed-out sound. The slam of the BC2s is a bit stronger --they have more thunder in the lower regions. Whether this is a result of the design or the increased power is hard to say. The BC2s also have a tad more detail in the upper-bass region and exhibit a slight bit more texture and control, at least through the Cliffhanger speakers. In summary, the BC2s are a tad weightier and more full-sounding, the Topaz tight and lively with good impact. Given the Topazs power rating, what it does in terms of impact is highly respectable. Single-ended slop it is not.
Voices are exceedingly clean but not quite as liquid-sounding through the BC2s and are not as carved out in space to the same degree as with the Topaz. Instead, it is slightly drawn back in comparison, but there is an almost endless sense of depth. I would not say the BC2s exaggerate depth, but are simply able to display some of the finest sense of depth from any amplifier Ive heard, providing it is in the recording. Overall, its nearly impossible to say whether one amplifier is more accurate or more correct than the other; they are just different, and each listener will have his own opinion on what he prefers.
The high frequencies of the Topaz are, as expected, smooth and clean, just like those of my BC2s. Unlike with tube amps of yore, there is no rolled-off character with the Topaz that makes for a forgiving sound. Both the BC2s and the Topaz have sound that's as clear and extended as the best Ive heard. There's not a hint of grain or grunge up there. Like the midrange and bass regions, there is a vivid character to the Topaz's treble. The result is almost bell-like clarity that is never bright or edgy. On the other hand, the BC2s seem to have a tad more sparkle, but similar to their midrange performance, they are a tad more laid-back. Once again, what you prefer will be a matter of taste.
The differences between the Topaz and the BC2 amplifiers proved interesting because a few months back I reviewed the $9800 Blue Circle Audio BC2.1 amplifiers. Their sound is somewhere between the BC2 and the Topaz in terms of vividness and palpability. The BC2.1s have a bit more bloom in the midrange than the BC2 and even a touch more detail. In other respects, they sound closer to the BC2, probably because they are both based on the same design. Something worth noting about all these amplifiers, despite their sonic differences, is just how relaxed and easy they present the music. There is an uncanny sense of musical coherency and realism that Ive heard with only a handful of amplifiers. The common thread among these three, of course, is that they are all single-ended amps. Coincidence?
A small change of plan
Although I believe in keeping a component in its stock form so that a review is representative of what the average consumer will hear, I did make one change that had results worth mentioning. I replaced the stock 18-gauge power cord with the 8-gauge JPS Labs Power AC cord ($459), and the resultant sound was somewhat surprising. The Power AC reduced the overall bloom of the amplifier just a notch, but turned out a higher-quality presentation in terms of bass impact and weight. As well, there was a slight bit more openness to the sound, and more soundstage transparency and detail too. I didn't experiment with other cords to any great extent, but for existing owners or prospective buyers of the Topaz amplifier, some experimentation is probably worthwhile.
The Topaz is a high-quality amplifier both in terms of build quality and sound. It presents a vivid, lively and full-bodied presentation with excellent resolution and is able to project a stage with rock-solid stability. Properly set up, it is capable of playing music with an almost uncanny sense of realism. But despite this praise, it is, of course, not the amplifier for everyone. It sounds a whole lot more powerful than its power rating would let on, but there are still obvious limitations as to what it can do. This isnt so much a criticism of the Topaz as it is of single-ended amplifiers in general. Proper speaker matching is paramount because a low-power amp must be mated with speakers of sufficient sensitivity and that do not present too tough a load to drive. Furthermore, I recommend matching such an amp with high-quality speakers that dont have any exaggerated sense of warmth or bloom themselves.
However, even given its limitations in terms of power, the Wyetech Topaz can do things that are magical. There is a sense of immediacy to its sound that, once heard, is hard to find elsewhere. Ive never heard a solid-state or push-pull tube amplifier render vocals the way the Wyetech Topaz can. For those who favor this type of amplifier and have the speakers to match, the Topaz produces top-class sound that should be heard.
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