March 2000GW Labs 270 Amplifier
by Ken Micallef
In recent years -- heck, in recent months -- availability of advanced levels of digital audio products has gone through the roof. A look back at the SoundStage! archives reveals all manner of upsampling DACs, super-duper CD players and killer-for-the-money DVD players. But is the same rate of change happening in the world of power amps? You can make the obvious argument that there are more quality tube amplifiers around than ever before. That also holds true for the wacky world of low-powered SET amps. The fact is, while there are still umpteen opportunities to spend kazillions on high-end audio (is that what we still call it?), you can easily assemble a very good, and I mean very good, rig for a reasonable sum that won't ruin your marriage (or whoopee in the marriage bed). But while digital audio remains the new frontier, even among some power amps, tube amplifier designs have not really changed since the 1960s. Right! That's why tubes still rule and NOS supplies are getting thinner day by day.
The GW Labs 270 power amplifier is another new kid on the glowing tube block, straight outta San Francisco. Selling for $1800 USD, the 70Wpc 270 fits comfortably within a broad range of tube amps near its price. So you could say that the 270 has its work cut out for it.
What a shame about me
Before detailing the GW 270's specs and features, let me relate a small tale of woe. When I first received the GW (hmmm, that reminds me of an old friend I had in my southern youth whom we always called "GW") Labs amp, the first thing I did was unplug my Cary SLM-100 monoblocks and replace them with the 270 on top of three big sorbothane feet. The GW Labs amp has plastic thumb-screw covers on its dual set of three gold-plated binding posts, which allow you to attach speaker cables to either a 4- or 8-ohm tap. Very cool. The Carys don't have such a feature. My Audio Physic Virgos are a 4-ohm load, so I screwed down the plastic one marked "4" on the JPS Labs Superconductor+ speaker cables. I hit the front-panel-centered power switch, waited while the tiny glass eye above the switch went from red to green (soft-start delay circuits warming up), and then instantly popped in a CD. Sat back. Damn! Wait a minute! This bugger has better bass control than my $4995 Cary monoblocks. What the heck!
A call to Kirk at Cary Audio back in my home state of NC explained the dilemma. The Carys are wired for an 8-ohm load, so bass delivery with the 4-ohm Audio Physic speakers was going to be a little soft. It's not that the sound lacked warmth -- oh, the Carys are warmth champs, with sweet highs, a see-through midrange and ample, if slightly euphonic, bass. Kirk suggested I send the Carys down for a switch that would enable me to choose between 4- and 8-ohm taps. He also ran the idea by me of having the SLM-100s outfitted with a paper-in-oil caps and another switch that would make their KT88 tetrodes run in triode mode, cutting the power to 60 watts, but upping the sonic merriment factor. So I shipped off the Carys and proceeded to get it on and get it started with the GW Labs 270. Does the 270 stand up to the Cary amps? I will tell you that my opinion of the GW Labs 270's marvelous overall articulation and smoking jump factor never changed.
Gold in them thar hills!
A not unpleasant cosmetic design that recalls a Golden Tube Audio amp, the GW Labs 270 has subtle visual appeal, its streamlined silver front plate matched by a black brushed-aluminum chassis and transformer cover. Weighing in at 31 lopsided pounds (the back of the amp is heavier than the front because of the transformers), the 270 measures 15.5"W x 7"H x 14"D, uses triode tubes (four Svetlana driver 6550s, two Phillips 12AX7s, and two12AT7s), which are biased by easily accessible top-mounted pots. Also onboard are carbon-film resistors, WIMA coupling and Solen bypass capacitors, and most unusually, double C-core output transformers.
An ad for the GW Labs 270 in Vacuum Tube Valley online states: "With few exceptions, most vacuum tube power amplifier manufacturers use lesser quality and inefficient EI-core output transformers. The Model 270 uses super quality double C-Core output transformers. Not only is a C-core technically better than an EI-core, a properly configured C-core like the ones in the Model 270 have a much improved sonic performance."
Not being a tech-head, this bit about EI-core vs. C-core transformers could be a load of hooey. But perhaps the C-core explains some of the very good sounds made by the GW Labs 270.
OK, so I got the souped-up Carys back, and sure enough, the bass performance was now much more coherent, extended and even a tad lower in pitch when required. I could hear bass and midrange notes more clearly, with better articulation and slam. The Cary paper-in-oil caps replaced Hovland Musicaps, so the Carys' trademark lushness was even a bit more so now. The triode switch opened a window into regions of treble extension I had not previously known.
But you're wondering how the GW Labs 270 sounds. For me, some similar priced (to the GW Labs 270) tube amps, even the ones made by well-known industry leaders, often sound more like solid-state than tube designs. Not so for the GW Labs amp. The 270 is warm as a tube amp should be, but with well-controlled bass. Its midrange is nicely uncolored, and with good presence, while the treble range is free of grain.
The first thing I played through the 270, after marveling at the Carys a bit, was Steely Dan's Two Against Nature [Giant 24719]. I must tell you, the GW Labs 270's best qualities are its coherency and clarity. On "Jack Of Speed," which features a plucked bass line and a trademark Steely Dan horn section riffing overhead, the 270 performed like a champ, letting me quickly relax into the music. Everything from Donald Fagen's classic New Yawk whine to Walter Becker's searing guitar yelps were delineated with superb timing and tonality. Next up was Pat Metheny's latest Trio 99-00 [Warner Bros. 47632-2]. Here, Larry Grenadier's bass, which was bulbous and a mite tubby on my original Carys, sounded about the same on the GW Labs amp. It lacked the bass weight and authority of the newly revamped Carys. But Metheny's guitar was equally liquid and, again, coherent. Bill Stewart's cymbals lacked the uppermost shimmer that the Carys supplied so eminently, but the GW Labs amp is so musical, the nitpicking is mostly slim. It's just remarkably easy to get caught up in the sound the 270 makes.
I wouldn't call the 270 forward, but it is not as open and sweet as the more-than-twice-as-expensive Cary monoblocks. It is very slightly closed-in, with an occasional reedy quality to the treble. But it is highly resolving and mostly easy on the ears nonetheless. This may be due to the 270's democratic range. No area of performance is especially highlighted over another, a sign that perhaps the aforementioned C-core transformer is an important factor in the performance of the amp. On acoustic music such as the Metheny disc or Terence Blanchard's Wandering Moon [Sony SK89111], the GW Labs amp grabbed me and refused to let go, even with the minor quibbles I may have had.
Quiet and energetic, the 270's jump factor easily equaled that of the Carys. Popping in Beethoven's Fifth Symphony (John Eliot Gardner and Orchestra Revolutionnaire Et Romantique [Archiv 445 994-2]), I was again struck by the 270's stereo separation, vibrancy and generally animated character. I am new to classical music, but this had me caught up in all the splendor of the Ludwig Van's great Fifth, with all its harmonic delicacy and nuance. Oddly enough, the GW Labs amp casts a smaller soundstage here than do the Cary monoblocks, but it does the channel-to-channel spatial thing better. What does this mean? Instruments seem better defined -- if less three-dimensional. There was more separation, but less front-to-back depth. Everything was on the front plain, even if it was very well presented.
Ditto for Frank Zappa's Yellow Shark Orchestra [Ryko 40560]. A recording with amazing energy, layered instrumentation, and great dynamics all within a complicated score, the YSO is a workout for any rig. On the GW Labs amp, though, while the energy and clarity were top-notch, transients on bells, temple blocks, and brass sounded slightly hard. Over to techno land: Chemical Bros' "Setting Sun" single [Astralwerks] features a house-wrecking bass riff that sounds like a tornado boring into your skull. Same as before: On the GW Labs 270, the sampled, whirling sitars sounded mean, as they should, but a touch hard.
It is often easy, and comforting, to get caught up in our own biases. After all, we have spent a lot of money on our rigs, and we don't like to have that fine balance upset by some upstart we have never heard of. The GW Labs 270 was good at surprising and challenging me, I must admit. It has its little weaknesses to be sure, but it is also good at making music, simply, accurately and relatively cheaply. And I haven't even tried NOS tubes with it, which are a must for any new tube amp. GE and Sylvania NOS 6550s are easily available (Tungsol too, if you have the cash) and will almost certainly outperform the stock Svetlanas.
Let's see how the GW Labs amp performs with a pair of ProAc Tablette 2000 Signature minimonitors, which may more accurately represent the speakers with which it might be paired. Steely Dan's "Jack Of Speed": Bass was nicely weighty and punchy while transients sounded more reedy than before, but this could also be a case of the amp accentuating the bell-like clarity of production. The ProAcs have great bass extension for minimonitors, but they are nowhere near as invisible as the Virgos. But back to the GW Labs 270's brilliant clarity: I was now hearing small bells and a harmonica on the Steely Dan track that I had never heard before with the Carys. And on the Metheny disc, Grenadier's bass was now better defined, though the drums lost their spaciousness. But the guitar was still wonderfully liquid.
Hey GW, what do you think?
The GW Labs 270 Amp had me applauding, but with a little gibing along the way. It does many things well, especially for a $1800 tube amp. It is a bass champ in a small package. While I missed the absolute low notes, roundness and lovely rendering of the Carys, I could not deny the 270's ability to punch it out with the best of them. The GW Labs 270 doesn't cast a soundstage as big as Everest, but what it does achieve it does exceedingly well. It has contagious energy, good articulation and sharply defined imaging. It's very coherent, and it makes the most out of any music you give it. Problems with treble that resulted in occasional hardness, reediness, and a very slight closed-in feeling were its drawbacks, but don't forget the cure-all known as NOS tubes -- as well as the 270's modest price.
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