The high gloss white GLOW Audio Amp Two is a charming EL84 integrated tube amplifier. It also comes in gloss black as well. With modern looks, tube cage and the tiny DAC included, it is a very good starting point for building a serious sound system around high efficiency loudspeakers. Have laptop or other digital source already? Just add GLOW Amp Two and you are ready for tweaking audiophile speakers. The village of the GLOW Amp Two is populated with two driver and four EL84 power tubes. The Amp Two requires four power tubes because it is a push-pull design. The signal for each channel splits with each tube handling half the signal. GLOW uses Beijing EL84s because they are the best available in China. The EL84 (also 6BQ5 in North America) tube is popular in amplifiers. It was intended as an inexpensive alternative to larger EL34, 6L6, and KT66 power tubes. In the late 1950s, popular Dynaco, Eico, Mullard and Fisher manufacturers were using them. Popular guitar amplifier maker Vox based incredibly popular stable based around the EL84. A slightly higher power version, the 7189 and 7189A, became the standard power tube in Scott tube audio amplifiers.
In this push/pull configuration, GLOW avoids the
graininess that seems common among such amplifiers in this price range, for
example, with EL34 tubes. Most of the low-powered, vintage tube integrated and
power amplifiers from the 70s are an incredible value for tweaking audiophiles
today. Pick them up cheap, get them refurbished with new engines and sidewalls,
and then drive any high-efficiency loudspeaker with pride. After drooling over Don
Garber’s 1.5 watt X-shaped Fi amplifier, I was also smitten this year
by the new Nelson Pass, low-powered SIT-2 with its revolutionary Static
Induction Transistors. That solid-state amplifier provided a huge 10 watts,
which is easily enough power for mid and upper range horns in my Big Ole Horn
But Tang Is Okay
Tang heard his first stereo in Hong Kong when his
dad bought a German record player that had two detachable speakers. "I was in
the second grade. My brother just bought a Beatles album, in stereo. I was blown
away by the recreation of the soundstage from this little stereo. That is how it
all started. My love for music was reinforced when I went to live with my
grandmother in Gulfport, Mississippi, and she took me to hear a New Orleans
style jazz band playing by the pool at a nearby hotel. I was 8 years old. I
stood there transfixed right in front of the drummer soaking it all in, it was
magic. He was working the snare with some brushes, the horns were blowing.
Another "a-ha" moment."
"I made money in high school buying trade ins from the local hi-fi store in Nashville TN and putting together systems for friends. I did a lively business buying low and selling high, got to hear and audition all kinds of gear, and learned what people liked and didn't like, and why. Later when I lived in Taiwan teaching English, I worked with a local Chinese audio guy to develop a line of speakers based on small satellites and using subs. There were import restrictions on finished goods in Taiwan at the time, and there was a lively business importing or manufacturing raw drivers and copying the best designs available at the time. This was 1984, and the notion of using a dual voice coil sub to augment the bass for smallish speakers was pretty new. Everything I learned from buying and selling ARs and KLHs and JBLs and Linn and KEF speakers, I put into those designs. We developed a beautiful line of speakers and subs, but this was before the internet, and I had no idea how to market or export them. Being a poor student, I didn't have the money to start a business of that nature, and I picked a business partner who was just as poor as I was. I ended up abandoning the venture and going to law school. I still have one surviving pair of those bookshelf speakers that I developed back in 1984, and even today they still sound excellent!"
Better Than One
The glossy white of the sample model was a
refreshing change to the row of black boxes that adorn the audio rack. Plus, the
tubes light up from the bottom with a blue GLOW, while a pale blue ring around
the Volume knob lets you know the amplifier is on, even in daylight. Tang says
he "didn't want to use a blaring LED," so they went with a subtle blue ring. In
addition, there is a glowing red Power toggle on the right side. The blue
back-light on the tubes toggles on or off with a rocker switch, also on the
right side. With four sides occupied, only the flat bottom and the left side are
bare. The visual effect is charming and intentional. It gives the Amp Two an
uncluttered and simple Apple look. I love the clean white Apple looks of this
amplifier with its tubes glowing. In addition to high gloss white, high gloss
black is available. (Tang asked "what other colors would you like to see?")
"About 40% of our customers are non-audiophiles (women, architects, musicians, etc.)," Tang said, "and they have a design aesthetic that favors simplicity. We wanted to avoid the "bristling with buttons" look of so many audio components." Plus, the Amp Two currently ships with a modest DAC, the size of a cigarette pack. It is perfect for the electronic conversion juncture between iPod, iPad and laptop to the Amp Two.
"We wanted a sound signature similar to the Amp One; a family resemblance, if you will. We chose the EL84 power tube because of its inherent sound qualities. This means that at 15 watts per channel, our amplifier is not as powerful as the EL34 driven push-pull amps that are so common today. But the EL34 push-pull amps typically sound quite aggressive and grainy. We chose instead to use the EL84, because of its inherently sweet sound, gorgeous and detailed mid-range, and superior high frequency capabilities."
To improve the bass and treble, Tang said there
are a number of decisions that have to be made in designing such an amplifier at
this price point, for instance how much negative feedback is sufficient to
provide adequate bass response with lower impedance speakers, how much money
should be put into the transformers, etc. The Amp Two design is nothing radical
or novel. It is a push-pull amp. The art is in selecting the right components
for the circuit design that has been chosen, and "tuning" the amp
accordingly, based on the characteristics of the particular components chosen.
It takes a lot of knowledge and judgment to make those critical decisions.
"There is a huge subjective aspect to this," Tang says, "and we spend a lot of time voicing our gear. In the case of the Amp Two, it took several years to get it the way we wanted it to sound. Typically, we will survey what is out there now, and what has been made before (the classic Eico, Fisher, and Dynaco amplifiers for instance), and settle on the several amps that we find to be the best sounding. Then we figure out what it is that makes them sound the best. We determined early on that performance and price are not that closely correlated. In other words, there are some amplifiers under $2,500 that sound as good or better than amps that cost over $5,000. We then turned it over to our engineers to build prototypes based on the criteria we selected. There is a lot of back and forth at this stage, as the engineers attempt to adjust the sound."
Original Amp One
Because it was their first effort, designing the
Amp One in 2007 was a much more involved process. Before deciding what to build,
Tang took nearly two years listening to all manner of amps. He listened to
classic Scott, Dynaco, McIntosh, JoLida, nOrh, Consonance, Spark, and other
Asian offerings. Then he decided to get various custom samples from Chinese
manufacturers interested in manufacturing amps for him. Tang got all manner of
amps; 300b SETS, EL34 push pulls, you name it. Then he took considerable time
auditioning them, all the while communicating with the engineers to determine
whether they were simply copying another amplifier, or thoughtfully selecting
circuit designs and components.
Tang has relatives in China who manufacture electronics, and although they are not involved in audio, they assisted him in making sure he had the right contacts, and were able to get him the best pricing on parts and components. The various amplifier manufacturers Tang contacted were told to give him the best, cost is no object, "kitchen sink" samples. "Some of them were monsters that weighed 50 pounds," he says. "The ones who got it right, were then told to make the amplifiers smaller, with hand wound transformers, quality components, and point-to-point wiring. And hardest of all, the amplifier had to be very affordable, which in 2007 dollars meant a retail price point of around $500. Via this process of elimination, was born the Amp One." Despite this process, there were speed bumps along the way. One manufacturer sold out to another company in the middle of production. "We had to reject all of the amps. The new company made unauthorized changes that were unacceptable. Quality control is our primary focus." According to Tang, the GLOW Amp One has been a huge success, and is now in its 4th version. But the company began looking to expand its amp offerings and in 2010, started focusing on an Amp Two.
Birth To The Amp Two
in American Expertise
Tang met Chaffee when Tang was rolling out the Amp One, through a mutual friend, Randy Bankert, recently deceased founder of Sonist Audio. Chaffee is one of those rare individuals who knows her stuff, and is willing to help a friend in need. She offered several suggestions to improve the Amp One; Tang kept in touch. To improve the pre-production samples, Tang reached out to Chaffee. "She graciously agreed to consult with me; she made a number of modifications to our pre-production samples that made a huge difference- tighter imaging, improved bass, and a non-fatiguing presentation reminiscent of our acclaimed Amp One."
The Amp Two is thus not a "copy" in the sense that it is not a re-badged or re-branded product; it is completely new from the ground up. A lot of amplifier manufacturers cut corners, using off-the-shelf transformers and printed circuit boards to save money. The transformers are critical of course. Valve (tube) amplifiers usually use an output transformer to match the high load impedance requirement of the tubes (several kOhms) to a low impedance speaker. And printed circuit boards can degrade the sound quality. "This is apparently something Tannoy engineers concluded after considerable testing as early as 1985," Tang said, "when Tannoy quit utilizing PCBs in their speaker components." Tang plans other amplifiers. Another single-ended and another push/pull amplifier are on the drawing boards. They are also discussing the possibility of developing monoblocks and a phono preamp, but that is further down the road. And, he says they have some interesting new speakers to be unveiled before long.
Ultimately, it is the audible performance of the
amplifier that reveals whether the transformers are properly designed and
matched. "I am aware of a budget push-pull EL84 amplifier that weighs about a
third as much as our amp," he said, "and sells for about half the price. Unlike
most amps in that range, it is well designed and sounds quite nice, given its
price, but it is lacking in the lower bass, and the amplifier's distortion
increases considerably at its limits. The budget amplifier might be fine for
casual listening, or with unchallenging source material. But the limits
resulting from the use of cheaper transformers means it cannot perform as well
as an amplifier with more expensive, better matched transformers."
amplifiers are challenged by the impedance of the woofer, what can amplifier
designers do to overcome that challenge?
"Judicious use of negative feedback helps to address the flabby bass syndrome common to zero negative feedback designs," he said. "The trick of course is to minimize reliance on negative feedback for this purpose, using just enough to provide sufficient low-end control, without affecting the overall sound."
He recommends 50 hours to break-in the amplifier,
though I did not notice any
significant difference after warm-up. He says "one might notice an increase in
the smoothness in the sound beyond 50 hours." Replacement tubes are not a
problem. GLOW has a stock of replacement Beijing EL84/6P14 in matched sets, as
well as the driver tubes for the Amp One and Amp Two, and will be posting
pricing and availability of the tubes online soon. Although pricing is not yet
finally determined, Tang expects tube prices will be competitive with other tube
Tang lives in Hercules, California, a sleepy little bayside town 25 miles from San Francisco, 20 miles from Napa and the wine country, and 10 miles from Berkeley. He has a small number of retail dealers. Orders are mailed out within three business days, "but if there are intervening holidays, or if we are simply very busy, then it may take up to five business days." GLOW is at most audio trade shows and will likely be at CES (January). GLOW offers a full, money back 30-day trial period; "so far no customer has sent an Amp Two back!"
GLOW sells amps to customers all over the world. Tang notes, "That is the one of the joys of this business. I get questions from folks in Germany or Finland or Singapore or South Africa, and sometimes we talk about where they are from, and they will send pictures of their part of the world. When they purchase an amp or some of our speakers, it is nice to know that someone so far away is enjoying our products. The world is a big place, and I would never otherwise know about half these places. But the best sale was when we got a customer from Hercules, this little coastal town in California with barely 20,000 residents, a little pin prick on the map, and the same town I live in. And I have no idea who this bloke is. With 7 billion people on the planet, what are the chances of that happening?"
On the four different systems I auditioned the charming GLOW EL84 integrated amplifier on, it was always enjoyable listening.
Incredible Beginner Bargain
Although my Blue Note scores seem harsh, this is an excellent little amplifier for very efficient loud speakers, like single drivers and Big Ole Horns. It is a very good value for the money and a great starter amplifier for beginners. Just add laptop. In my own category, enjoyment, I must award this amplifier four Blue Notes also. It may not be the last word in tube amplifier power for most cone speakers, but this is a sweet, enjoyable amplifier at a very attractive price.
As of this writing, while the Philippines recover from a super-typhoon, GLOW is offering a pair of bookshelf speakers with their Amp Two! Got a source? Simply add their combo and you have yourself a sweet little system with many tweaking audiophile qualities. Hard to beat that value.