Raven Audio Nighthawk MK2 Integrated Amplifier Review

The advantage of integrated amplifiers is the preamp and amplifier sections are built into one chassis, resulting in shorter signal paths. It takes less space and eliminates the need for another set of cables.

All Raven Audio integrates and amplifiers are self-biasing; you never have to adjust tubes for a perfect match.The chassis is manufactured of sturdy 14-gauge carbon steel with an aircraft-grade aluminum face plate. The handles are made of schedule-20 carbon steel with knobs machined from aircraft-grade aluminum.

So there I was, perusing some audiophile sites on Google when I came across this post from Raven Audio’s Dave Thomson. He was claiming that his new integrated would perform as well or better than similar products that sell for twice the price:

“If you do not think your chosen Raven Audio product is the absolute best amplifier or preamplifier you have ever heard in the price range AND up to double the price, we will refund your investment, no questions asked. We want every single Raven Audio customer to be 100% satisfied with their purchase.”

Usually, I hear this kind of boast from cable manufacturers and I don’t give them a second thought. Still, this was interesting, so I decided to take him up on the challenge because: 1) I had never heard of Raven Audio, 2) I like integrated tube amplifiers and 3) I love a challenge. I picked up the gauntlet, contacted Dave, and within a few weeks the Nighthawk “flew” in from Texas to my home in New England. Dave even sent me some extra tubes to try out to allow me to tailor the sound to my liking.

The Nighthawk MK2 comes in a silver colored baked enamel. With solid aluminum handles, a folded carbon steel chassis and solid aluminum remote, the overall solid feel of quality construction was undeniable. Self biasing tubes certainly make for easy set up (virtually plug-n-play), but what of the sound quality? And at 20wpc, can it really do some musical heavy lifting?

On the back, the speaker terminals allow you to optimize the speaker choices with 4 ohm and 8 ohm configurations as well as a sub out. No digital source inputs can be found on this device as there is no DAC on board.

When my unit arrived, I had to install the tubes which were carefully packed in bubble wrap and boxes. The instructions for installation were easy to follow and I had the tubes plugged in no time.

As a precaution, I used gloves when handling the tubes. Oil from your fingers could cause the tube to heat unevenly and crack the glass. Plus, if the tube broke while it was being pressed into place, the finger you save could be your own.

People ask me about “self biasing” and what purpose it serves. I can try to explain it in laymen’s terms as such:

The best way to understand bias is to think of it like the idle setting on a car. The fuel and air mixture is adjusted so that the motor runs smoothly; too much of either and the motor won’t run very well or even possibly not at all. The idea is to find the perfect balance for optimum performance. When it comes to tube amps the idea is similar, however, instead of fuel and air we are dealing with electrical current.

The purpose of setting the bias of an amp is to find the optimum setting for the flow of current when the amp is idling.

Too much and the life of a tube is significantly decreased and in extreme cases failure can occur; this is also referred to as “biased hot.” Too little and unpleasant distortion (crossover distortion) is produced; this is referred to as “biased cold.” The correct setting is crucial for an amp to perform at its best both functionally and sound wise.

Obviously, if there is an optimum setting, why not just set the bias to that point and leave it? Well, it’s not really that simple. It’s more like a moving target and not an exact setting. Think of it as an acceptable range, not one single point. The reason for this is that each set of tubes is going to have different performance characteristics that will affect how the bias should be set.

Even within a single brand of tubes you will find one set that may vary wildly from the next in terms of its operating characteristics. Unfortunately, that is one of the realities of vacuum tube production. For this reason, when changing power tubes in a tube amp it may be necessary to set the bias on the amp to make sure it is optimized for the new set of tubes and not the set you just replaced. Without getting too technical, basically through a series of design characteristics – mainly a resistor – these amps balance themselves against the current draw of a given set of power tubes. For this reason, they will normally function pretty well with a wide range of tubes without needing any adjustment. It’s just “plug -n- play,” however; I would still recommend buying a matched set of tubes for optimum performance. (Replacement tubes can be purchased from Raven Audio and many NOS tubes can be purchased off of the internet, though caveat emptor).

Of course, all of this is academic if in the end the Nighthawk doesn’t sing like a Nightingale. Terms that usually describe tube sound range from “warm and mellow” to “less harsh” than pure digital sound. They introduce second harmonics distortions that most people find euphonic. Tubes generally have a soft treble roll off that reduces the edginess in some recordings.

I’ll try to describe specifics in my music review section. In my set up, I ran my Oppo 103 analog outs into the Nighthawk. My interconnects were Kimber Cable PBJ’s, 1 meter lengths.

I played a variety of music through my Revel F12s and a pair of Legacy Audio Silhouettes that I had on hand for a review. Both of these speakers have moderately good efficiency (over 89). The higher a speaker’s efficiency, the less power you will need to drive them to louder volumes. Keep this in mind if you are contemplating a 20 watt tube amp. To go higher in SPL, get more efficient speakers or purchase a tube amp with more output (such as a Raven Audio Shadow MK2 50wpc stereo amp, for instance).

When powering up the Nighthawk, I noticed the sound quality of my music improved over time. The music sounded thin and the sound stage was flat. In time, I learned to let the unit warm up for at least 10 minutes before I would sit down for serious music listening. Solid state devices are usually ready to play music the second you turn them on.

With tubes you need to be a bit more patient. I often do my more serious listening at night in a very dark room. I find light, in general, too distracting for my listening habit. In the case of listening to the Nighthawk in a darkened environment, I had the added benefit of seeing the soft glow from the compliment of tubes…and I found that somewhat mesmerizing and soothing. Seriously. Glowing tubes look cool! I can just about guarantee that anyone that walks into the room during your music session is going to notice them and say something. As a tube owner, you should take pride in that it draws the eye.

Now on to the music. I have eclectic tastes and play everything from Bach to Flaming Lips. Most of my music is in a hi-rez format. Feeding the Nighthawk hi-rez is a great idea. (GIGO: garbage in, garbage out applies here). Now I don’t want my descriptions here to imply that tubes “loose” some sort of sound quality. They definitely affect the sound, but not in a bad way…unless you are some purist who demands the sound be exactly what the recording engineer captured (whatever that means).

On the Nighthawk, it lost its edginess and became quite listenable. The slight tape hiss that you could normally hear was diminished and the sound stage depth improved, making it sound less 2 dimensional. And this change in quality was not subtle. In fact, I found that most of my music that was mastered off of analog tapes (especially recordings from the 50-60’s) sounded smoother and less over sibilant. It wasn’t that they lost detail, but they sounded more natural and relaxed.

The soundstage was often improved and the sound became less tiring to listen to over long listening periods. This is what tube lovers like about these devices. Musically, they are just very natural sounding. Jazz music also sounded good. I listened to Dave Brubeck, Hiromi and Miles Davis…all of which sounded musically sweet on the Nighthawk.

THE RAVEN AUDIO NIGHTHAWK MK2 is a High Performance Amplifier.

After several weeks of auditioning the Nighthawk MK2, I can say that it is musical, natural sounding, easy to operate, and has a major “coolness factor” with its array of glowing tubes. With the right speakers, you will never feel you lack power and you just might pull out some music that you shelved because the recordings sounded harsh.

Raven Audio has quite a selection of preamps and amplifiers, and the Nighthawk MK2 is reasonable priced for the quality of construction and sound it offers. If you are interested in getting into tubes for the first time, the Nighthawk MK2 is a great choice. The fact that it is self biasing means you can “set it and forget it”. The Nighthawk MK2 will give your music wings!