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Still Audio EL84 Integrated Amplifier: Affordable Handcrafted Exotica!

09-16-2018 | By Jeff Day | Issue 99

When Mark Still contacted me in June about reviewing his handcrafted Still Audio EL84 integrated amplifier (below) I was immediately intrigued, particularly when Mark urged me to give it a try with my pair of vintage Altec 832A Corona loudspeakers, whose visceral musicality I adore.

Still Audio EL84 Integrated Amplifier

I was impressed with Mark's chassis design for his Still Audio EL84 integrated amplifier, which evokes Don Garber's artful Fi chassis designs that I have admired so much over the years (below).

Then there's the EL84 vacuum tubes in the Still Audio EL84 integrated amplifier, which are one of my favorite tubes for audio, being full of vibrancy, color, and articulation that makes recorded music come alive in an exciting and life-like way, and it doesn't hurt a thing that EL84s are one of the most affordable high-performance vacuum tubes when it comes time for refreshing them!

Still Audio EL84 Integrated Amplifier

I've always enjoyed EL84 amplifiers, and a well-designed, high-quality, high-performance EL84 amplifier—like the Still Audio EL84 integrated amplifier—provides a great balance of musicality and audiophile-style sonic performance that is hard to beat at any price, but in this case it's an affordable $2895 USD.

Mark Still of Still Audio

It's become my custom for Positive Feedback articles to introduce you to the designer behind the audio component under review with a bio overview, in this case Mark Still of Still Audio, because I think that gives you a glimpse into the person who has such a great passion for music and audio that it has led them into the realm of designing components for your enjoyment, and how their personal background and unique talents & insights informs their audio designs.

Photo courtesy of Mark Still

It just so happens that there is an excellent bio of Mark on the Still Audio website, so rather than write a new one from scratch like I usually do, Mark has been gracious in letting me borrow from what's written there for you.

"When Mark was six years old, his Grandmother would take him to thrift stores to buy record players by the dozen. He would take them home and begin assessing what needed to be fixed or how to take parts from one and make them work on another. He then sold them to friends and family. Mark has always loved music, and as a young child liked to watch things work, like turntables going around, and the tubes glowing."

"Mark always had the best (and most complex) audio systems on the block. His friends would always ask, what does that component do, or how do you know how to hook all this stuff up? He also converted a lot of records to cassette for people using his equipment."

I didn't read Mark's bio until I was writing this article, and it helped explain a number of things for me, like the fact that Mark is a musician, which goes a long way in explaining why Mark's EL84 integrated amplifier sounds so musically natural and "right". More about that later in the article.

"He played baritone in a brass marching band with his brother, then moved to the bass guitar, playing in various bands around town. He eventually started playing rhythm and then lead guitar. He maintained all his amplifiers and equipment himself, sometimes modifying them to create his own unique sound."

"In high school, he had a recording studio and a 4-track tape machine where he recorded all the local bands and events, mastering them down to 2-track. Mark was in a band and eventually recorded an album that was cut to vinyl. At the same time, he was asked by one of the guitar teachers if he would tour with them as their sound and recording engineer. He spent that last summer in high school touring with that band. The guitarist was from the band Stephen Wolf."

"Mark's family owned a machine shop, so engineering came natural to him and he has a passion for mechanical design and engineering." 

"At that point, Mark transitioned to testing, fixing and repairing computer boards from IBM and DELL at the dawn of the computer age. The money in computers was great but looking back he says he should have stayed with audio-based electronics."

"Mark moved from the electronics side of computers to designing and writing software where he could release his creative side of design and engineering."

"Feeling the passion, Mark got his recording certification from Oak Grove Recording with the renowned Joe Laquidara, who wrote and produced hit songs for the band Boston. Mark is now a certified recording engineer."

Photo courtesy of Mark Still

"In 2010, Mark took a year off to rediscover his passion for audio and music. That year, he designed a single-ended amplifier that he took to Rocky Mountain Audio Fest, where it was received positively driving a pair of Rethm loudspeakers."

"Once Mark did this, it unleashed his passion and desire to design, create, and build audio equipment that competes with the best equipment available today. His passion for quality and design work are unmatched. He says he is not done with a design until he has exhausted all other possibilities. Only then does he know he has the best design possible." 

"Mark is building and selling his equipment in very limited quantities out of his home electronics laboratory. It is exciting to see what Mark is creating today and in the future."

"Each and every one of Mark's products are hand made one at a time using the best parts available today.  Mark designs his products to last forever, considering every last detail before the final prototype is put into production." 

Certainly, Mark has all the personal attributes for making a stellar audio product, as he has a love for music and audio electronics, is a musician, understands engineering and industrial design, is a mastering engineer, has experience developing audio amplifier circuits, and has a passion for developing an innovative and quality product.

The Still Audio EL84 Integrated Amplifier

It's really rather incredible how much goes into designing and developing an audio component like the Still Audio EL84 integrated amplifier.

Still Audio EL84 Integrated Amplifier

There's a lot involved from getting from the designer's vision for an audio component to realizing a final product that will meet the needs and desires of its intended audience. There're the technical skills needed in laying out a high-performance audio circuit, the informed choices of the components that make up that circuit, the artistry involved in voicing it both musically and sonically, and the crucial development of its industrial design that refines the component's scope and performance, optimizes its features, appearance, and value, all in ways that benefits the customer and makes a statement for the designer.

I asked Mark about his design goals for the Still Audio EL84 integrated amplifier, and he told me:

"I started designing this amplifier in January 2017. I wanted to build an integrated type amp that would fit into spaces that most high-end amplifiers wouldn't. I also wanted it to have a good amount of power, more than a typical SET amplifier could deliver. I wanted to create something that didn't currently exist and could win an industrial design award. It had to be a work of art and it had to be very high quality."

Still Audio EL84 Integrated Amplifier

"The shape of the amp was of prime concern. I have always been a fan of amps that were long and thin like the Quad, some of the old Fisher's, and others. That is where the initial shape idea came from. Some other aspects of the design were inspired by the late and great Don Garber. What a great designer, he will be missed!"

"Modern day systems don't require a lot of inputs, and a good majority of modern systems only use two inputs for a DAC and a phono stage, so that's what I did, and provided two inputs. I wanted to keep it simple and easy, and to fit today's system's needs. For outputs I chose to include 4 Ohm, 8 Ohm, and 16 Ohm outputs, because a lot of speakers favored by those with low-powered amplifiers are either 8 Ohm or 16 Ohm. There's very few 4 Ohm loudspeakers out there, but I chose to offer all the modern speaker impedance options."

I asked Mark to elaborate a little on his circuit design for the Still Audio EL 84 integrated amplifier:

"The input stage consists of a 12AU7 phase inverter. The 12AU7 was chosen because of its high current capabilities which can easily drive a pair of EL84s to full output. Because of this it's a great tube for phase inverter duties. The output stage consists of a pair of EL84 pentodes connected in ultra-linear (UL) mode to the output transformer, and no negative feedback is applied. This requires a very high-quality transformer, so Hashimoto transformers where chosen for the job. Each channel is idling at approximately 81mA, with each of the EL84's cathode biased at 39mA and the 12AU7 at 3mA. This circuit can output 10-watts in UL operation. While the EL84 is capable of 15-20 watts the distortion goes up significantly when UL operation is not used. I chose this mode because I wanted very low distortion. All of the tubes are running at or below spec, so vintage tubes can be used without worry of burning them up, and they all should last for a very long time."

"The power supply uses a large 300mA transformer, into the 5AR4 rectifier tube that has output capability of 220+ mA into the choke that is capable of 300mA. From there each channel is split off into its own set of low ESR reservoir caps to supply each channel. I chose to use "banks" of smaller caps, 47uF or 56uF, rather than a very large single cap because they are capable of filling faster with each mains cycle. There are no resistors in the power supply for the output stage. Only one to drop the voltage and separate the phase inverter that also has its own reservoir cap. This gives the power supply very low impedance contributing to the amplifiers speed and agility. The power supply can supply both channels at full output and run at about 50% giving it a good amount of head room."