Secrets of Home Theater and High Fidelity - Best Of Awards 2015
The 20wpc Nighthawk Integrated is Raven Audio’s entry-level amplifier, your taste of tubes on a budget. It handles digital and analog with a wideband, smooth, detailed, and accurate sound.

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.

Raven Audio Nighthawk MK2 Integrated Amplifier

Highlights

Raven Audio Nighthawk MK2 Integrated Amplifier

  • “Self biasing” for ease of use
  • More than enough power for all but very inefficient speaker types
  • Wonderful, smooth, 3D sound you’d expect from tubes
  • Very solid construction with beautiful enamel finish
Introduction

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.”

RAVEN AUDIO INTEGRATED AMPLIFIER REVIEW SPECIFICATIONS
Design:

Tube Integrated Amplifier

Output:

20wpc

MFR:

20Hz – 20kHz

Speaker Terminals:

4 and 8 Ohms

Inputs:

6 Single-ended RCA

Recommended Speaker Sensitivity:

87dB – 96dB

Dimensions:

6.5” H x 15.5” W x 14” D

Weight:

35 Pounds

2 x 12AT7:

Preamplifier Stage

2 x 12AT7:

Power Amplifier First Stage

2 x 12AU7:

Phase Inverter/Driver

4 x 6L6GC:

Power Tubes

Self-Biasing
MSRP:

$2,595

Company:

Raven Audio

SECRETS Tags:

Raven, Raven Nighthawk MK2, Preamplifiers, Power Amplifiers

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.

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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?

Design and Setup

Raven Audio Nighthawk MK2 Integrated Amplifier

The Nighthawk is a US-made (Texas), 20wpc, 10 tube (4 x 12AT7; 2 x 12AU7; 4 x 6L6GC), self-biasing design. Offering six single-ended inputs and both 4 and 8 ohm speaker connections. It weighs in at 35 lbs., partially a result of the carbon steel chassis and uncluttered aluminum faceplate. It sports dual top handle bars made from extruded aluminum which allow for easy lifting while offering some protection for the tubes. The front panel has three knobs; power, volume and source selection. The silver enamel is a baked enamel such as you would find on autos. The power cord was a custom made, one meter length that was as thick as my thumb.

Raven Audio Nighthawk MK2 Integrated Amplifier

The whole piece exuded quality construction. The unit also comes with a small, but solidly built aluminum remote to control the volume. I wasn’t sure that the Nighthawk even needed a remote, but over the course of my review, the ability to control the volume from your seat and not having to get up all of the time was a real bonus.

The volume knob on the Nighthawk is motorized, but because it is not illuminated, you really can’t see what position the knob is in from across the room.

When the Nighthawk is powered up, a tiny green light by the power knob glows faintly. From across the room, you can barely see it. The tubes of course glow as well, but in a day lit room even the tubes are hard to see if they are glowing or not. Also, be aware that the tubes do not have a cage around them, so if you have kids, be sure to not let them get near the tubes as they are hot. The selector knob allows you to chose up to five analog sources.

Raven Audio Nighthawk MK2 Integrated Amplifier

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.

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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.

Raven Audio Nighthawk MK2 Integrated Amplifier

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.

Raven Audio Nighthawk MK2 Integrated Amplifier

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.

Raven Audio Nighthawk MK2 Integrated Amplifier

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).

In Use

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.

Raven Audio Nighthawk MK2 Integrated Amplifier

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).

Art Garfunkle

Art Garfunkle “Simply The Best”

Listening to Art Garfunkle singing Bright Eyes, I noticed a few things immediately. I love the song, but it always sounded thin and somewhat “brittle” to me. Is it because it is an older recording? It’s a crummy digital transfer? Perhaps an inferior studio environment? I have no idea. All I know is it’s a bit thin a tizzy sounding in the digital format.

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.

Antol Dorati

Antol Dorati

Classical music was bit more mixed. Old recording on the Mercury label sound very good, but some of the stuff on the Telarc labels seemed to lack impact. Antol Dorati playing music from Bartok in the late 50’s fared well with smoother sound than the same SACD off of the Oppo. For the most part, bass, such as the thwack of a timpani seemed to lack a bit of impact and bite compared to what I got from playing it digitally through my pre/pro (Emotiva UMC-200).

Erich Kunzel

Erich Kunzel “Classics at the Pops”

Not a big difference, but a noticeable one all the same. For instance on the Telarc disc, Erich Kunzel playing Copeland’s Fanfare for the Common Man, the Nighthawk could not quite give me the controlled deep bass line that this music demands. In fairness, I was asking a 20 wpc tube amplifier to play something I usually listen to with 200 watt monoblocks, so it is not really an apple to apple comparison.

Paul McCartney

McCartney & Wings “Band on the Run”

Interestingly enough, I did not notice the lack of impact in some old school rock-n-roll. I played The Who, McCartney & Wings and The Doors.They all sounded great. Now I realize that even the bass guitar of John Entwistle can only go down to about 45 hz and an orchestra with organ can go considerably deeper. My advice? If you are a banging “bass head”…you are probably not in the marketing demographic that tube manufacturers are shooting for.

Raven Audio Nighthawk MK2 Integrated Amplifier

Go for a big solid state amplifier and pummel your ears. However, if you love and respect your musical interludes and sound quality trumps sheer volume, the Nighthawk is a good choice. Of note, I never felt I lacked volume for any of the music I was playing. I was able to drive the Legacy and Revel speakers to comfortably loud levels and never felt I was straining the Nighthawk. Most of us listen to music at enjoyable levels that are often far below 20 watts, so don’t over look this integrated because you think it is too wimpy.

Now I also listened to a few movies in stereo with the Nighthawk. Honestly though, using it for the purpose of listening to a movie is like cutting up your wife’s mink stole to make ear muffs. You can do it if you want to…but why? Tubes are for music. Let’s just leave it at that.

Conclusions

THE RAVEN AUDIO NIGHTHAWK MK2 is a High Performance Amplifier.

Likes
  • Quality, solid construction
  • Wonderful natural (self biasing) tube sound
  • Enough power to make most speakers sing
Would Like To See
  • Volume knob light
  • Headphone jack in front

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!

  • John Johnson

    I’ve listened to Raven Audio tube amplifiers at serveral shows over the past couple of years, and the experiences have always been very positive. These are well built amplifiers, and they are built in the USA.

  • Raven Audio

    Thanks John!

    And thanks to Jim Milton for a great and completely honest review.

    Offering all the quality of a fine vacuum tube product like the Nighthawk MK2 (or any product in our Avian Series actually), and being able to install really good NOS preamp and driver tubes into it, especially an “American Built” product that can be sold in stores, all at a price point that people can hopefully afford is a major endeavor these days. It was NOT easy.

    We hope that people will understand what we are trying to do, and could NOT do this without people like the “Secrets of Home Theater and HiFi” team allowing us a chance to be reviewed like this.

    Again, thanks to everyone at “Secrets” – so very much!

    Most Sincerely,
    Dave Thomson
    Raven Audio

  • alex rothman

    i am the proud owner of raven audio amplification. “THE RAVEN” a 300b tube based integrated amplifier. There can be no better amplification in the world. You see right thru the music. Your are drawn into it. All the details of the recording are there.Is there colorization by the tubes? Not sure.i can only tell you the music sounds exactly as intended and as natural and neutral as can be.It is rated at 15 watts per channel..Some may not understand. Raven audios 10 watts,is another tube companies 40 watts and solid states 80 watts. It is in the power supply and voltage regulation that all the power of god on earth is unleashed. The power is more than enough to fill my 20x 20 room with blasting clear,warm glorious sound. I have owned mcintosh,krell ,NAD AND MARK LEVINSON. There really isnt anything but maybe my old mac that sounds even close to the raven(and thats because i have a soft spot for my first tube amp over 40 years ago). andy rothman sharethemusic@aol.com

  • Joe Frances

    Alex, thanks for your comments. As a prospective buyer not sure which unit to purchase, could you tell me what speakers you are using with The Raven?

  • Joe Frances

    Dave, One of the issues that I see as a prospective buyer is the growing shortage and cost of NOS tubes. I have read somewhere in my current research that your equipment really benefits from NOS replacements. I just saw that a quad of 6550s cost about $1,200; and other smaller tubes are going up a lot. Also, there is a bias I think (legit or not) against newer Russian tubes. How are you addressing this issue? How should a customer think about this. I think is a big issue. Thanks,

    Joe

  • Raven Audio

    Hello Joe,

    While we can – we do plan to keep installing a nice blend of NOS and excellent tested old stock preamp tubes. We have however, always and ONLY supplied new generation power tubes in all of our power amplifiers.

    Relying on old stock “power tubes” would be a large – and therefore very costly mistake. Even the old preamp tubes have been troublesome from time to time due to the fact that so many can lose their reliability with improper storage and even during rough shipment since most have spent half a century stored on some dark warehouse shelf before being shuffled endlessly for only a few weeks until I find and grab them. They I suspect can suffer from some shock due to that sudden difference in handling.

    We do know, and have always known, that eventually we must go to installing new preamp tubes as original equipment, and that (as I have said often for the last year or so) will probably occur before the end of the (2017) year unfortunately as our brand recognition and popularity grows.

    The use of fine old preamp tubes has always been a personal choice of mine because I really love to at least “try” to give my customers the best that I know how to give when it comes to audio. Admittedly, this has not always gone 100% according to plan though, and as stocks grow smaller and more expensive, some of these great old tubes have turned out to be a little noisier than expected. We are I expect now scraping the bottom of the tube barrel.

    As most of us admitted “tube-heads” know, it sometimes takes a few weeks or months before they start to go a little wacky, and no amount of testing ahead of time can help to protect my customers from this unfortunate occurrence. As a result I have usually ended up shipped replacement pairs as a result. So the time is absolutely coming soon. Unfortunately.

    As far as the bias against Russian or Eastern European tubes go, that is probably going to eventually subside as they get better at it. Hopefully this will keep happening and they will keep getting better and better with time.

    The tube suppliers – as example: New Sensor – manufacturers of preamp (ECC-88, 81, 82, 83, etc.) & all of the various power tube types have “raised the bar” so to speak, in both sonics and reliability as time has gone by. Still, problems exist periodically, mainly in the reliability arena. Unfortunately when they do blow, usually with a great short-lived light-show, they can take some tube socket resistors along with them – most of the time requiring a trip back to the manufacturer or repair shop.

    Preamp tubes on the other hand will almost never damage an amp in any way. You just lose your initial tube-cost investment.

    So, we do what we can as tube-loving audio enthusiasts to be patient when this occurs. The tubes will always be the weakest link in this chain of “tube-audio” love~! And I will always try my very best to get my customer’s amps back to them as quickly as possible. Because one thing is for sure…. yes, an antique Tung Sol 6550 power tube may be built like a tank, and have the reliability to match, the current $250-300 ea. price tag is usually out of our budget. So we really have no choice. In the end 95+% of the new ones will last 7,500 hours under normal design conditions. That’s usually a LONG long time… do the math.

    We have supplied almost of our amplifiers with current made (Svetlana, Mullard, Tung Sol, Gold Lion etc.) power tubes for years now. We also periodically test (and are currently in the middle of testing for 2017 by the way!) all of the available (power, rectifier, regulator and preamp tubes) so we can at least actively “attempt” to provide our customers to the best of our knowledge.

    We do wish we could obtain some of these tubes from a USA manufacturer, but alas we can only say that we buy them from a USA owned “supplier” instead. Hopefully we will not go to war with Russia anytime soon – or ever for that matter~!!!!!

    I do suspect that tube amp owners will always be in search of those old gems while they exist though… I know I will~! And NOBODY is getting my ultra-top cherished old treasures. Well… I have been known to have my arm twisted occasionally…

    Peace~!
    Dave