My dad never liked gravy. “You don’t need it,” he’d say, whether we were having turkey, roast beef or meatloaf. He liked the taste “unadulterated.”
I, on the other hand, used to put gravy on everything: meat, mashed potatoes, bread, even my green beans.
My mom made good gravy, but it was standard fare — mostly jus, with a little flour. A family friend, though, made gravy to die for. She’d put pieces of meat in and tripled the flour-to-jus ratio. Then she’d add some more seasoning, including black pepper. She’d simmer this heavenly concoction until it was so thick it would stick to an upside-down spoon.
That gravy was sooooooo good. My mouth still waters at the memory. But as awesome as it tasted, there was a downside. It was so rich, you could practically feel it instantly clogging your arteries. It also filled you up to the point where you had to almost force down dessert on top of it. And all you wanted to do 20 minutes later was groan and take a long nap.
What’s more, to get back to my dad’s point, if someone asked later how the meat tasted, you wouldn’t have a clue. The actual main course could have been a couple of pieces of cardboard. The gravy obscured the taste you paid for at the butcher shop or grocery meat counter.
Some audiophiles are a bit like gravy lovers. Whether they will admit it or not, they like something extra when feasting on their favorite music. Call it harmonic richness, bloom, glow or whatever high-end term you want to apply, but there is definitely a crowd that savors this recipe.
The current popularity of single-ended, flea-watt tube gear driving high-efficiency speakers bears this out. Even the staunchest tubeophile wouldn’t argue that they are getting a coating of second-order harmonics on the meat of what they are listening to. These individuals, though, would contend that — like gravy — they enjoy this byproduct in cooking up whatever tunes they’ve selected. It stirs something in their audio palates. It tastes goooooooood. And like drinking fine wines or driving European coupes, most people choose a high-end hobby for the pleasure it brings them. So, what’s the harm of a little distortion, if it’s the “right kind?”
Well, there’s also that quest to try to reproduce music at home the way it sounds live. And, as tummy-rubbing satisfying as that tube-amp rig may be, at some point you’ll catch a listen of a top solid-state amp — maybe at a show or your local dealer — and the resolution, pacing and bottom-end control will have you wondering, “Do I really need the gravy after all?”
This can cause a malady known as audio nervosa, a particularly troubling and all-too-common affliction. It’s the idea that something better is out there. You’ll see — the more you listen to that solid-state system, the more you’ll find aspects that are inferior to your original components. Maybe it’s even something you can’t put your finger on — a lack of emotional connection, possibly. That gravy was pretty good after all, you think. But yet….
That brings us to the subject of this review: the Merrill Audio Advanced Technology Labs Thor monoblocks. The Thors are the result of a stereo connoisseur trying yet another recipe. Will it be the one that satisfies both your taste buds and your soul? Read on.
With the Thors, chief cook Merrill Wettasinghe (see sidebar, below) says he wanted to build an amplifier that competed with the best, but was relatively affordable. He’d already turned heads with his 400-watt Veritas monoblocks, but they sell for $12,000 a pair. So he came up with the Thors, also monoblocks, which offer 200 watts per channel for $4,800.
The Veritas, although expensive in absolute terms, can arguably hold their own with monoblocks costing twice as much. In this approach, Wettasinghe leveraged a Class D topology, one that happens to be less costly to implement than the more common Class A or Class A/B. He stuck with the same technology for the Thors.
For someone like Wettasinghe, who wants to serve the most discerning slice of the audiophile pie, the biggest hurdle to face with a Class D design may be its reputation. Class D, in producing its output, switches from “on” to “off” (and back again) blindingly fast. This strategy is in contrast to Class A amps which are always “on.”
One of the more noticeable differences with Class D amps is that they run much cooler than their Class A counterparts. The switching keeps the amp from sucking light-dimming amounts of electricity from the wall like Class A components, which themselves usually also generate enough heat to warm a small room.
Class D devices, because of their small size, efficiency, high power output and low cost, began to see wide use in the 1980s, primarily in home-theater applications, where three to five channels of power often were crammed into one amp or even a receiver. As you can imagine, with mass-market manufacturers looking to hit big-box retail price points, the circuits were simple and the number one determining factor for the parts list was “cheap.” Perhaps as a result, these early Class D amps didn’t sound very good.
Fast-forward 20 years and Class D amps began showing up in boutique shops. Many were used to power subwoofers, where high power and control were coveted over resolution. Then, a few brave designers began trying Class D for serious high-end amps. But when audiophiles listened to many of those early models, they came away unimpressed. As a result, Class D’s second-rate status continued to cling to subsequent models like dust on an electrostatic panel.
Moving to head of the class
Like any newer technology, it takes awhile for designers to learn what works and what doesn’t. (Remember the shrill sound of early compact disc players?) In the same way, there has been a learning curve with Class D. Only public perception doesn’t seem to have caught up quite yet.
Case in point: I was sitting on the front row in Merrill Audio’s darkened room at the 2014 AXPONA show in Chicago. As Sonny Boy Williamson’s recording of “The Sky Is Crying” was cued up on a reel-to-reel tape deck, I heard a gentleman’s voice behind me say to a friend, “What are those monoblocks?” To which the friend replied, “Veritas … I think they are … Class D.” The words came out in the same tone of whispered, barely contained horror that my parents used when discussing someone who had a terminal disease.
The Veritas amps were hooked up to some stunning speakers, Sadurni Acoustics Staccato horns ($40,000 a pair), finished in high-gloss red. This is interesting, I thought, as the tape’s lead-in started to roll; solid-state monoblocks — Class D — driving some of the most sensitive and discerning transducers on the planet. I grabbed the ends of my chair and braced myself for this train to fly completely off the rails.
Instead, though, what came out was almost sci-fi in nature, as if Scotty had beamed a time-traveling Williamson directly into the room. The sound had a purity and, indeed, near-holographic quality that was amazing. I spun around in my chair and saw the man behind me and his friend both checking their jaws for rug burn.
“Merrill Audio,” I wrote in my notebook, adding a star which meant, “I’ve got to check these guys out more later.”
So, you can imagine my delight when the Esteemed Editor emailed me. “Merrill has some new monoblocks, the Thors. Want to review them?”
Hammer of the Gods
Outwardly, the Thors are less pumped-up Chris Hemsworth than lean-and-sinewy Tom Cruise. Done up in black gloss, each is just 9 inches by 9 inches by 2.5 inches (without feet) and only 15 pounds apiece, not much bigger than my Musical Fidelity M1 CD transport.
The Thors may be small, but they are constructed and finished to a level that can compete with nearly any monoblock out there. The casing is machined from a solid block of aircraft-grade aluminum, and includes ribs to limit vibration. Connections also are first-rate, with Cardas XLRs (only balanced connections are offered) that feature silver support pins with rhodium plating and gold plating on the body. A Furutech IEC provided the power connection.
According to Merrill, the engine of each Thor is based on what he learned in designing the Veritas. The Thors use UcD modules that are claimed to approach the sound of their bigger brother’s Hypex NCORE technology, but at a lower cost. (The Thor’s modules share 75 percent of the same parts as the Veritas, with additional custom work on the circuit boards.)
The bottom of each chassis has holes for Stillpoints (which are provided, another nice touch) and also contains a mute switch and red light that glows when the unit is operating. I didn’t pop the top to look inside, as Merrill discouraged that, and it voids the service guarantee. I am told, though, that the interior features the shortest possible signal paths and soldered or screwed-down connections. In addition, Merrill reportedly divides the interior to isolate circuits and limit interference. And, there is a generous three-year warranty. All in all, you get quite a bit of engineering for this price point.
While waiting for the Thors to arrive, I had thoughts of going full-on Art Dudley and building a pair of stands to get the amps off the carpet in my listening room. But when the units arrived, I was so eager to hook them up that I sat the Thors on top of my mid-century teak rack. They were close to the preamp, it was easy to make and break connections, and their Stillpoints feet seemed to be isolating them well on the very heavy piece of Scandinavian furniture, so there they stayed for the length of the review.
I started out by subbing the Thors for my reference Krell FPB-300 stereo amp. Preamp was a Krell KRC-HR and speakers initially were the mighty Revel Studios, followed by some sessions with my Martin Logan Odysseys. Silver discs were spun on the Musical Fidelity transport, decoded through a Mark Levinson No. 30.5, while a vintage, but modified, Thorens TD-125 Mk. II/Ortofon 2M Black combo was on hand for vinyl. Interconnects were a mix of AudioQuest Sky XLR and Lapis XLR. Speaker wire was Transparent Reference XL. Merrill also provided pairs of its own interconnects and speaker wire.
I plugged the Thors into an API Power Wedge using Merrill’s custom-made power cords and left the amps to warm up for a couple of days of playing Doug Raney’s “Guitar Guitar Guitar” (CD, Steeplechase). But I couldn’t help sneaking a listen or two. Right out of the box, there seemed to be something special there, just as with the Veritas.
The laws of attraction
On a crisp Saturday morning in early fall, I sat down to do some serious listening. The first thing I noticed about the Thors was that, without any signal, they were dead quiet. I’ve had some expensive amps that still produced a noticeable hiss even with the volume control only halfway up during this test. I once asked a manufacturer’s rep about his amp doing this, and was told it was “just the unit looking for something to amplify.” When music was supplied, this noise would disappear, he said. I took that with the same box of salt that I use when evaluating diet-pill claims on late-night cable TV ads. But, no such suspension of logic was needed with the Thors. Before I cued up a source, there simply was nothing coming out of the speakers.
Moving on, my initial track was The English Beat’s 12-inch mix of the always-intriguing “Save It for Later” from The Complete Beat (CD box set, Shout Factory). This dance-floor stormer, driven by dueling rhythm guitars and terrific horn work by the aptly named Saxa, emerged from the Revels in all of its frenetic glory. Vocals were solidly in the center and the drums had the weight of a real kit.
It was the bass, though, that really made me sit up and take notice. My Krell amp had hardly been lax in this department, but on the Thors there was something about David Steele’s bass work I had never noticed before. Instead of an insistent thump, there was more there — an additional level of tunefulness and texture that was easy to follow, but not overly prominent.
Although I love this song (apparently I’m in good company — no less than Pete Townshend and Pearl Jam have covered it onstage), it can sound a little aggressive on some systems, my Krell-Revel rig included.
With the Thors, though, I clicked the adjustable gain on my preamp to 6 db, the minimum, and turned the volume up considerably. Not only did the bass character not change, the rest of the presentation displayed a level of resolution I hadn’t heard before. In addition, there was a polish and refinement to the sound, emerging from a black background, that made me want to increase the volume even more. The music retained its ease, drawing me in and compelling me to listen in a way that reminded me of the now-discontinued, but beloved Mark Levinson No. 33H monoblocks. This was startling, since the latter — Stereophile editor John Atkinson’s reference for many years — retailed for about four times the cost of the Thors.
Going to war
I switched to “Under the Pressure,” the leadoff track on Lost in the Dream (CD, Secretly Canadian) by The War on Drugs, one of the best records of 2014. There’s a moment in the middle the song where the drums come to a halt and God-only-knows-how-many overdubbed guitars crackle and snarl like a storm gathering strength on the horizon. The Thors allowed me to hear individual instrumental lines rather than one ominous roar, which contributed significantly to Adam Granduciel’s atmospheric composition.
Seeking to test the Thors with more guitar music, I switched to Dire Straits second album, Communique (CD, Warner Brothers remaster). The Fender Telecaster guitar strumming of David Knopfler, younger brother of virtuoso bandleader Mark Knopfler, is positioned low in the mix and can be almost inaudible on some systems. But with the Thors, his stuttering rhythm line on opener “Once Upon a Time in the West” (a part he lobbied to add to the song) could be followed easily in the right speaker.
On the album’s second track, “News,” the Thors allowed me to hear Mark Knopfler taking a deep breath before starting his vocal about a doomed motorcycle racer. His Fender Strat guitar solo in the middle also showed off the amps’ dynamic range, as Knopfler imitates the kick-starting and revving of an engine.
Then it was on to my favorite audio show test track, Roxy Music’s “Avalon” from the group’s final studio album of the same name (CD, Virgin remaster). The percussion kicking off the tale of hazily remembered post-party romance was clean and more prominent than on many other systems I’ve heard. The entry of Alan Spenner’s bass again showed off the tunefulness of the Thors’ bottom end, while Brian Ferry’s hung-over croon was dead center. This song, as well as many others I played, showed the remarkably good balance the Thors retained throughout the frequency range.
Soundstaging, image height, depth and instrumental decays also were all first-rate. In fact, there were times, such as when I was playing particularly well-recorded albums such as Paul McCartney’s standout Band on the Run, (CD, Universal, Doug Sax tube remaster) or Lindsey Buckingham’s solo work from Words and Music (CD, Reprise special DJ issue), that I almost got up to see if I was listening to my college-era quad system (but in a good way).
The old switcharoo
Now it was time for some changes. I swapped out the Revel Studios for my Martin Logan Odysseys. These electrostatics, which have a nasty impedance dip, can be a challenge for all but the best high-current, high-watt amps. The acquisition of my modded pair, which included upgraded internal wiring and a piano-black finish, was the reason I bought my Krell amp. With anything less than its 300 unmerciful watts, few amps could keep the Martin Logans from sounding rolled-off and somewhat threadbare.
Dropping down to the wattage of the Thors need not have worried me, however. With the Thors advertised to be able to handle even a 1 ohm load, the ‘stats displayed the same excellent bass performance I’d heard through the Studios, but added a bit more magic to the midrange. Highs, checked with the Roxy Music CD, were airy and just as prominent.
The only major difference was the Martin Logans required an increase in gain on my preamp, to 12 decibels, to achieve the kind of weight a rock-n-roll drum kit ought to have. But this increase surprisingly did not impart any tubbiness to the lower midrange, as I’ve heard from some other amps.
The Thors also easily revealed the differences between cables. In fact, when I was breaking in the monoblocks with the Doug Raney disc, I thought the sound had a bit of added warmth — possibly from an emphasis in the upper bass region. I had just installed the Musical Fidelity M1 CD transport, and had used an older digital cable. I switched to a new Kimber reference model and the problem went away.
Next I substituted Merrill’s own balanced interconnects and speaker wire. These proved to be fine cables, and delivered the same level of performance — maybe even better on some material — than my reference wire. I’d suggest that Merrill customers should give the company’s cable a try before laying out the long green for something else.
So, what does Class D amplification sound like? A better question is what does a pair of Merrill Wettasinghe’s new Class D Thor monoblocks sound like? As someone who has listened to a lot of amplifiers, I’d say the relaxed, yet detailed sound makes it a cousin of one of the most highly regarded amps of all time, the Mark Levinson No.33H. The fact that the Thors remind me of the classic Madrigal house sound made even more sense when, after my critical listening was completed, I talked with Wettasinghe and he mentioned he was a big fan of Levinson components in the years before founding Merrill Audio.
To circle back to my opening food analogy, my time with the Merrill Thors convinced me that I really don’t need that gravy. I’m still working on an all-tube system for upstairs. But like cooking a whole turkey and dressing only a few times a year for holidays when I want to splurge, I think most of my day-to-day listening will continue to be downstairs on my current rig.
It seems that most us working types spend a lot of time in this hobby bemoaning how the really good stuff is out of reach. While $4,800 is not chump change, I’d say it’s a bargain for a reference pair of monoblocks that can make you happy with a remarkable range of speakers, all the way from horns and electrostats to conventional cones. And, along without breaking your budget, they won’t break your back, either.
In fact, if you’ve been saving up for a while (or even if you run your own hedge fund) and were ready to spring for some more expensive amps, I’d still urge you listen to the Merrill Thors — they’re that good. Think of how much more you could budget for speakers. And, if you did go crazy on transducers, you wouldn’t have to worry about the Thors not being able to keep up.
I say don’t fear Class D. Forget all that confusing crap about a D grade being just above failing or Class D being the lowest rung on Stereophile’s longtime rating system. As Wettasinghe told me, “It’s just how power is classified, A-B-C-D. It doesn’t mean one is better than the other.” So, get over it.
As for me, I’ve already told Wettasinghe he’s not getting the Thors back. I’ve written the check and made them my new reference. They easily could be yours. Just pass on the gravy.
- Power: 200 Watts at 8 ohms/400 Watts at 4 ohms
- Input impedance: 50 kOhms
- Output impedance: 20 milli Ohms
- Damping factor: 500 4 ohms
- THD: 0.05 percent at 100 watts
- Current: 18 amps typical max
- Frequency response: 10Hz – 30kHz 0/-3db
- Gain: 26db
- S/N: 100dB
- 1 balanced input: Cardas XLR with silver pins, rhodium plate, gold plated body
- 1 remote trigger. 12V for remote turn on/off
- 1 pair of patented Cardas rhodium over billet copper posts
- 1 IEC Furutech gold plated
- 1 custom power cord by Triode Wire Labs, 12awg high stranded copper wire, cyro-treated with red copper receptacles.
- 3 year transferable warranty
- Short circuit protection
- Over-temperature protection
- Auto shut-off in case of fault
- Dimensions: 9” x 9” x 2.5” without footers
- Weight: 15 lbs.
- Approximate number of dealers: 5
- Primary sales method: Internet/factory direct
- Merrill Audio Advanced Technology Labs
- 80 Morristown Road, No. 275
- Bernardsville, N.J. 07924
- Email: Salesfirstname.lastname@example.org
- Website: www.merrillaudio.net
Q&A: A Sidebar with Merrill Wettasinghe
Merrill Wettasinghe was only six years old when he became fascinated with electronics. He built his first crystal radio at age 10 and later constructed other components. An uncle eventually introduced him to the high-end audiophile world, but by then Wettasinghe was performing music as well, as a serious pianist.
In college, Wettasinghe majored in engineering. He went on to practice that trade professionally for several companies, including Hewlett-Packard, where he had a 12-year stint and rose to the executive ranks.
All along the way, though, he never lost his love for tinkering with stereo equipment and wondering if there was a way to make it sound better. He finally gave in to that urge and created New Jersey-based Merrill Audio Advanced Technology Labs in 2010. Since then, he’s slowly and carefully built a line of electronics that have been pleasing ears and turning heads at the major audio shows.
Wettasinghe also, I found, is a very nice, thoughtful and patient man. The latter was obvious and much appreciated as he spent several long phone conversations with me over the course of the six months it took to complete a review of his Thor monoblocks. The following is a Q&A I did with him toward the end of that evaluation period.
Part-Time Audiophile: Your new Thor monoblocks are Class D. Can you explain what that means, in simple terms, and tell us why you chose that strategy for your design?
Wettasinghe: I was testing a lot of devices for what became the Veritas (his $12,000, 400-watt monoblocks), and the Hypex NCORE modules exceeded my expectations. I decided to build a pair of mono amps around them that would offer great sound at a certain price point, Later, the trickle-down of that work became the Thors. They share three of the four modules that make up the NCORE output stage. I modify the rest of the board.
As far as what Class D is, there are a lot of misconceptions. Some people think it means digital, but the Thor is an analog amp. When the IEEE (Institute of Electrical and Electronics Engineers) started naming things, Class A was invented first, so it got the first letter. Class B was invented second, and so on.
The way Class A works is it operates in the middle of two voltages. It is always “on.” With Class A/B, which became common, the amp operates in Class A for the first so many watts and then goes to Class B. In Class B, the signal is split into a top half and bottom half and the point where it crosses over is zero. So, it is a little more efficient. Class C is used in radio transmission. In Class D, the audio signal is converted into a series of pulses at the beginning and at the end you filter or smooth the pulses out. It is much more efficient than Class A or Class A/B.
Part-Time Audiophile: Some veteran audiophiles consider the older Mark Levinson amplifiers to rank among the best ever made. To me, the ease and refinement of the Thors is an awful lot like the much-revered Levinson 33H monoblocks, which if they still were in production today probably would cost at least $25,000 a pair.
Wettasinghe: I was a huge Levinson fan before I started my own company. One thing they did with their amps was use overbuilt power supplies. That gave them plenty of current so they could handle difficult loads. With some other amps that do not have this design, the sound can change with impedance.
Levinson also used very high quality parts throughout, That’s another thing I do with Merrill products. Why put a plastic speaker connector on your high-end amp, even if it has gold-plated pins? That plastic still is making a difference.
I sometimes might go overboard in all the parts I use, like the Stillpoints for the feet. It cuts into the margin. But I feel like they all improve the sound.
Part-Time Audiophile: A lot of us stereo nuts spend most of our time trying to find components that match each other to create a certain synergy. Along this line there are some widely held beliefs, such as horns pairing best with low-watt tube amps and electrostatics needing higher power. But I’ve heard your amps sound great on both of those speaker types, as well as cones. How did you achieve that?
Wettasinghe: Some speakers, such as horns, are so efficient that they will reveal any noise. Low-watt amps tend to have fewer parts and produce less noise, so that’s why people like them better for that application. Many electrostatics can have an impedance that drops from 8 ohms to maybe only 2 ohms as you go up in frequency, so higher-wattage, high-current amps tend to sound better with those.
The Thors offer both low distortion and high current. They not only sound good with horns or electrostatics, but also any conventional speaker which has fairly stiff cones — and that is most speakers these days. You want a stiff cone with the Thors because they can handle very fast transients. If you have softer cones with these monoblocks, you will get some breakup.
Part-Time Audiophile: You started your company during a transitional time for the high-end, with a lot of people listening to MP3s and many brick-and-mortar shops closing. What do you see for the future of the hobby?
Wettasinghe: I think the future is good. There are a lot of high-end shows now where people go to listen, as well more local audio societies that meet regularly. And, there are e-zines like yours that get a tremendous amount of hits. So, the word gets out.
Merrill Audio really focuses on customer satisfaction and service. We have a longer warranty than most (three years on the Thors), a trade-up program and a 30-day trial period on anything you buy. That dedication to the customer is something I learned at Hewlett-Packard.
I set up my business to do a lot of direct sales over the Internet. I have about five dealers, but most of the sales are from customers calling into the office. I have buyers not only in the United States, but Australia, Singapore, Asia and Europe. Sometimes we have to use Google translator to communicate (chuckles), but we make it work.
Part-Time Audiophile: What’s next for Merrill Audio?
Wettasinghe: I have finished a new phono preamp that aims to be state of the art. I’ve been working on it for seven years. It will cost $15,500. I’ve also developed the Taranis stereo amp, which has fewer parts than the Thor and is in one box. It sells for $2,500.
I have two new preamps in the works. One will sell for $3,500, with an optional DAC and phono stage for an extra $1,000. The other will be a higher-end model at about $10,000.
I’m also doing a limited run of Thors in a pearly white finish, instead of the piano black. There’s no upcharge for the first 10 pair. After that, there might be if I decide to offer that permanently as an option.