The Heretic Loudspeaker Company is a relatively new player in the world of high-efficiency monitor-style speakers.

Heretic AD612 Monitor Loudspeaker

Owner and designer, Robert Gaboury, decided that the world needed an exceptionally accurate loudspeaker that didn’t need a lot of power to drive it. His inspiration came from the Altec-Lansing Utility monitor, dubbed the 612, which was widely used in 1960s recording studios for monitoring purposes. Mr. Gaboury took that design and applied modern speaker engineering to build an almost full-range speaker the likes of which are rarely seen today.

Highlights

The Heretic Loudspeakers AD612 Monitor Loudspeaker

  • Designed and built in Quebec, Canada
  • Two-way coaxial design
  • 12-inch high-powered woofer
  • One-inch coaxial compression driver
  • Short exponential horn profile
  • Flexible placement options
  • FSC 12-ply birch plywood construction
  • Point source design
  • Environmentally friendly finishes
  • 10-year warranty
  • Works with a variety of amplifiers
  • Groovy styling
Introduction

From the early 1950s until the early 1980s, Altec-Lansing was known worldwide for making state-of-the-art high-efficiency loudspeakers. In 1979, I purchased one of the last speakers they produced with this mindset, the model 14. Altec designs from that era are still sought out, and it’s not unusual to see speakers from that period being used in some tremendous music systems today.

Robert Gaboury, the founder, owner, and designer of The Heretic Loudspeaker Company in Saint-Laurent Montreal, Quebec, has been an aficionado of some of those designs, including the Altec 612 utility monitor, which was an ancestor to my Model 14s from 40 years ago. This monitor used a 12-inch woofer with a one-inch coaxial compression driver tweeter. One of the advantages of this design is the point source configuration. The tweeter is at the center of the woofer (behind the dust cap), which has the effect of the sound emerging more coherently than one would get from a series of drivers in a vertical or horizontal configuration. To do this right requires an abundance of skill, especially in the design of the crossover.

Mr. Gaboury’s dream was to make monitor speakers that combined modern driver and crossover technology with the ability of a 12-inch woofer to move a lot of air without requiring a lot of power. After several years of research, he introduced two models with the same driver component: the AD612 and AD614. The AD612, which is the larger of the two, is under review here.

The Heretic Loudspeaker AD612 Monitor Specifications
Type:

Two-way coaxial design

Input power:

3 Watts to 300 Watts

Frequency response:

40-20,000Hz

Typical in-room response:

32-20,000Hz

Model:

303 coaxial transducer

TITLESPEC:

DESCRIPTION

Woofer:

12-inch high-power

Tweeter:

One-inch coaxial compression driver

Sensitivity:

97dB @ 2.83 Volt @ one meter

Crossover:

1,700Hz, 2nd order Linkwitz-Riley with air core inductors and Mundorf© Caps

Port:

Single ductless

Impedance:

8 Ohms

Dimensions (in):

30.25 H x 25.5 W x 17.75 D

Weight:

68 pounds each

Price:

$9,290 per pair with your choice of finish. This price is for USA purchasers. Pricing for other countries will vary.

Finish:

Water-based Acrylic Black, Semi-transparent linseed oil/beeswax: clear/white wax

SECRETS Tags:

heretic, ad612, monitor speaker, full range speaker, coaxial driver, loudspeaker review, loudspeaker reviews, loudspeaker review 2022, loudspeakers reviews 2022, reviews 2022

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Design

Heretic AD612 Monitor Loudspeaker Black

The AD612 is not a typical loudspeaker in any way. It represents engineering that follows real science, which dictates that a wide bandwidth speaker capable of reproducing clean sound from below 40Hz to 20,000Hz while needing one-eighth the amplifier power (or less) than do most loudspeakers, requires a lot of interior volume. The AD612 has about seven cubic feet of internal volume, and is not in a cabinet one can hide in one’s room. Everyone who has seen the review pair in my listening room has thought it was a pair of subwoofers.

Heretic AD612 Monitor Loudspeaker White

Everything about the AD612 is centered in physics. The wide cabinet serves as the foundation for the speaker’s wavefront, and it’s a speaker one can put up against a wall without compromising the sound stage. There are no DSPs required, and it presents such a simple load to an amplifier that it can easily be driven with a good five-watt tube amp. The ductless port covers about a full octave in the bass range and is designed to extend the bass below 40Hz without any bloat.

The cabinet is an integral part of the speaker’s design. The 12-ply, void-free birch used in the AD612 is strong and light. Instead of trying to subdue the resonances of the cabinet by using heavier materials, Mr. Gaboury makes his enclosures work with the drivers to ensure that energy is released in a timely manner. This takes a lot of listening tests to go along with the measurements, but, when done right, the results can be first-class.

Heretic AD612 Monitor Loudspeaker Driver

The crossover is a serial network consisting of a symmetrical Linkwitz-Riley Second-Order network with high-quality components throughout. Mundorf capacitors, Air Core Solen inductors, and non-inductive air core resistors lead to a crossover which, in layman’s terms, “gets out of the way while letting the 12-inch woofer woof and the one-inch compression driver tweeter tweet.” Without a crossover of this quality, all the work in creating the cabinet and selecting the drivers would be for naught.

There is nothing subtle about the look of these speakers, either. They are big, brash, and take up serious space. All the décor experts in my life love the look, and so do I. As great as are some of the pictures on the website, one really needs to see these speakers in person.

As mentioned earlier, this is a speaker designed to be highly sensitive, with that 97dB / 2.83 Volts / one-meter specification. Increasing 10dB requires 10 times the power to achieve. Most speakers average about 87dB / 2.83 Volts / one meter. This means the Heretic speaker will deliver, with one watt, what the typical speaker will with 10. This design has the potential to allow one to drive the AD612 loudspeaker with a less powerful, less expensive amplifier. We will be testing this theory in our listening portion of this review.

Setup

The AD-612s arrived via truck freight and were well-packaged for delivery on a pallet. The speakers were double-boxed with one-inch dense foam surrounding the speakers. One of the first things I noticed about the speakers is they seemed larger out of the box than the boxes look themselves. This was an optical illusion that was a first in my 45 years as an audiophile. They do have a subwoofer look to them, with the only visible driver being the 12-inch woofer, the tweeter is invisible as part of the woofer. For their size, the 68-pound weight makes them fairly easy to lift and move about one’s room.

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Let’s set the table for this system test starting with the cables. Speaker cables throughout were Blue Jeans 10 AWG in eight-foot lengths. Interconnects were Better Cable Blue Truth XLR Balanced cables. Because of the claims made for these speakers, a variety of pre-amplifiers, power amplifiers, and integrated amplifiers shared duties, with the Yamaha CD-2100S CD/SACD player being the only source for music tracks.

The amplifiers consisted of the Rotel/Michi P5 pre-amplifier and S5 power amplifier, the Cambridge Audio Edge NQ pre-amplifier and Edge W power amplifier, the recently reviewed Rogers Fidelity KWM-88 Integrated Tube Amplifier, and finally the Akitika GT-102 power amplifier. The Akitika was added as lower powered, budget amplifier to test out the efficiency claims that The Heretic Loudspeaker team makes for its speakers. It’s a class A/B 50-watt per channel power amplifier that can be purchased for about $350 as a kit and $550 as a complete unit.

It has been in one of our systems here for over two years and is a quiet, competent amp. Pairing a $550 amp with a $9,270 pair of loudspeakers is one of those ideas that make audio fun. Keep reading for the results of this portion of the test.

The manufacturer suggests 100 hours of break-in before serious listening begins, and 300 hours to complete the process. To ensure no bias entered into the equation while also satisfying my own curiosity regarding possible break-in, I did a 15-minute quick listening test at zero, 100, 200, and 300 hours with sine wave sweeps from 5 to 20,000Hz driving the speakers between the listening tests. Bass definitely improved through 200 hours, and the sound seemed more natural at the 100- and 200-hour mark, with no noticeable difference at 300 hours.

The reason I don’t do significant listening while the break-in period is in process is to make sure it isn’t my ears that are breaking in. I spent my listening time with the fantastic Sonus faber Maxima Amators while the Heretics were breaking in.

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Once I was satisfied that the speakers were ready for prime time, adjustments were made in terms of placement. Robert Gaboury, the owner of The Heretic Loudspeaker Company and designer of the AD-612s, engineered these speakers to be quite versatile in terms of placement. They can be put against a wall to augment bass extension with little to no degradation in the soundstage (a benefit of a wide baffle design with a concentric tweeter/woofer alignment). They can be pulled out from the wall and toed in a bit to make for an even larger soundstage. I ultimately ended with the speakers three feet from the back wall, toed in at about a 10-degree angle. They were 10 feet apart and 13 feet from the primary listening position.

In Use

Let’s Muscle Up with Michi P5/S5

Here we have a speaker with a sensitivity rating of 97dB with a 2.83 Volt input. As the AD-612s are also rated at 8 ohms, this means one watt will deliver 97dB at a one-meter distance. Why use a 500-watt amplifier, right? There is no rule that we need to use ALL 500 watts, and the Michi is a fantastic amplifier, even when delivering a fraction of a watt.

Audiophile Recordings

Audiophile Recordings “Chasing The Dragon II”

Only one disc was needed with the Michi pair driving the Heretics: Chasing the Dragon II, a compilation of 17 different well-recorded tracks covering a variety of music. Two of those tracks are from the bygone era of the Syd Lawrence Orchestra. “Hawaiian War Chant” and “Too Darn Hot” are musical wonders. We have female vocals from Clare Teal as a tribute to Ella Fitzgerald, well presented Bass Cello that sounds live, a huge brass section, and percussion galore. Most speakers, even those that are universally thought of as “good sounding,” lack the natural feeling that one gets from a large orchestra cutting loose and having fun. The AD-612s thrived with these tracks, especially in delivering Clare’s voice and the “bite” of the brass section.

“Drum Kit” is one of the most realistic drum solos ever put on disc, and the AD-612s are nothing short of stellar on this track. The kick drum emerged as one would hear in the studio, from the sound of the head hitting the skin through the decay of the note. The snap of the snare on the rim is accurate, and the Heretics have no problem delivering the exceptional dynamic range of this masterful drum recording.

“Church Organ” is one tremendous test of any loudspeaker, with bass that should be intimidating when presented properly by the loudspeaker. The Heretics were so adept and powerful that I had to call my professional musician son in to hear it. There wasn’t a hint of boom, just deep, mesmerizing bass to go along with an inspiring overall piece.

The Heretic AD-612s, if being graded, would get an “A” on all 17 tracks from this torture test of a CD. If you are wondering whether the Heretic AD-612s can handle a large amp, the answer is yes!

Cambridge Audio Edge NQ and Edge W

Let’s start this with a spoiler: the Cambridge Audio Edge NQ and Edge W were indistinguishable in comparison to the Michi S5/P5 when driving the AD-612s. This started the confirmation process that the Heretics are a very easy speaker to drive. The first disc auditioned was one of my all-time favorite bands performing live in Tangiers. The artist is The Michael Stanley Band, and even if you never heard of them, this collection is something special. The Michael Stanley Band was an Ohio-based rock band that had a fair amount of success in the ’70s and ’80s. What makes this disc so special is they took most of their hits and did an “unplugged” concert.

Michael Stanley

Michael Stanley “Live in Tangiers”

We are treated to acoustic guitar, violin, Michael Stanley’s vocals, and an incredibly talented Jennifer Lee on female vocals. Hearing a lot of what was originally rock anthem songs played in this style is mesmerizing. From the opening track, “Midwest Midnight,” a song about the hard life that rock bands have, one is treated to 30 songs about life, love, loss, and all things between. The Heretics reproduced this performance with a “you are there” feel that was palpable. There is excellent weight on the acoustic guitar, and one can even hear that Michael’s voice has aged over the years. Another trend was also emerging while listening to this disc: I started to look for excuses to listen to more music on the Heretic speakers.

Cowboy Junkies

Cowboy Junkies “The Trinity Session”

The next disc up was the venerable “Trinity Session” from The Cowboy Junkies. Recorded at The Church of the Holy Trinity in Toronto, Canada, this is a single microphone treasure of unamplified music that is in some ways an easy disc for good sound but a difficult disc to reproduce accurately. The AD-612 did a stellar job in the two most difficult areas on this disc: Alan Anton’s bass and Margo Timmon’s voice. The bass on the Heretics sounds like a real bass being played, which is rarer in high-end audio than one might think. Anton has a talent for matching Timmon’s tempo on every song, and the speakers presented his talents without a hint of boom. Margo’s voice floats between the speakers, which is exactly where she should be. Her lyrics are as clear as with any speaker I have auditioned, and the whole band comes together through the Heretics as one would want from a well-positioned, single-microphone performance. The sound stage is predictable, which is a good thing in this instance. We now have two amplifier combinations down, and two to go. Can the Heretics rock with a tube amp? Let’s find out.

Rogers High Fidelity KWM-88 Tube Integrated Amplifier

The KWM-88 was on hand after my recently finished review of this well-engineered amplifier. It’s a tube design, and matching it to the Heretics is something both Rogers and Heretic appreciate. High-sensitivity speakers and tube amps have been an audiophile-preferred combination for as long as there have been audiophiles. After a few discs that one would possibly call polite, it was time to rock n roll. In September of 1979, I purchased a pair of Altec Lansing 14 speakers. They used a 12-inch woofer and a compression tweeter with similar sensitivity ratings to the Heretic AD-612s. A year later, I purchased AC/DC’s “Back in Black” LP, and it was a revelation. It was true hard rock with excellent sound quality, a rarity in those days.

AC/DC

AC/DC “Back in Black”

Pairing the first AC/DC album (in this test, a CD) that featured Brian Johnson on vocals with the band and The Heretics was too tempting to resist. It starts off with “Hell’s Bells,” and one immediately hears a kick drum reproduced with far more accuracy than most speakers. The linearity promised by a proper ductless vent was paying off in a big way. The AD-612s smiled throughout the entire disc. Johnson’s vocals were gritty and powerful. Angus’s guitar work was presented with an abundance of authenticity. Occasional finger slides, no matter how subtle, were audible and the speakers proved again just how agile they are, while still being capable of astonishing amounts of SPL. These large, efficient monitors are, indeed, “Back in Black.”

My only concern with the KWM-88 is that it can drive almost any speaker. What would happen if we decided to use a “small” amplifier with the AD-612s?

The Akitika GT-102 Power Amplifier

As mentioned earlier, the Akitika GT-102 amplifier is a high-value, old-fashioned class A/B amplifier. It is available for $550 assembled (you can save $200 if you are handy and want to assemble a kit) and delivers 50 watts per channel.

I decided to really challenge this combination of a $550 amp and $9,290 speakers with Roger Water’s “In the Flesh” SACD. If you have ever experienced Pink Floyd (or Roger Waters) live, you know it is a completely different sound than a studio recording. Guitar work is a lot rougher; vocals are louder and there is the feeling of raw, all-out performance. The sound guys managed to put all of this into this SACD, and it’s a challenge for any system.

Roger Waters

Roger Waters “In The Flesh”

The combination did a solid job bringing this performance home, even with the 19 to 1 cost ratio between speakers and amp. The helicopter track from “The Wall” is even known by people who think Pink Floyd is a person, and here we got individual blade thwacks as it flies by. The opening guitar work on “Mother” is as warm as the song is chilling. When the band is really jamming, as it does during “Money,” the deliberate distortion that is common in a Pink Floyd concert is front and center. If I could pick one track that really let the Heretic AD-612s and the Akitika amp shine, it would be “Shine on You Crazy Diamond.” The opening guitar work sends the audience into a frenzy, and it is goose-bump material, a remarkable achievement with this modest amplifier.

Let’s Look at Some Measurements

The listening room at our place is one that took a lot of work in setting it to the standards I wanted. With each review, going back 20-plus years, I always wanted to measure a response curve at my listening position without any room correction applied. In the case of the Heretic AD-612s, a measurement was taken at four meters from the speakers at 83dB (which translates into 95dB at one meter).

Heretic AD612 Monitor Loudspeaker Response

The response curve was +4dB from 29Hz to about 7,000Hz, with the expected 6dB per octave downward slope from there. This is the type of response one wants in a real listening room, which will attenuate frequencies above 5,000 to 8,000Hz in most quality rooms.

Heretic AD612 Monitor Loudspeaker THD

The THD (Total Harmonic Distortion) curve was equally impressive. The black line is the frequency sweep, and the blue line is the THD+N. Any point with a 40 dB or greater spread between the lines is 1% THD or less.

At the same SPL, THD is 1.83 percent at 30Hz and drops below one percent from 32Hz and up. This is an excellent THD result, and these measurements confirm the hearing tests that these are accurate, distortion-free loudspeakers that can deliver music as it was recorded at any SPL one could want, with the only caveat being one stays in its bandwidth.

Do They Miss Anything?

There is a certain irony built into the Heretic AD-612 loudspeakers: they look more like a subwoofer than any speaker I can think of, but they actually can benefit from a quality subwoofer. At volume, the AD-612s are an awe-inspiring performer from 40Hz and up. For kicks, I added a single Sonus faber Gravis VI (USD 7,500) using the supplied Speakon cable connected directly to the speaker output on the Michi S-5 power amplifier. This is the single finest subwoofer I have heard, and its twin 12-inch woofers, setting the low pass filter on the subwoofer panel to 40Hz, took the AD-612s to an even higher level of performance. There will be a full review of this subwoofer here soon, but a single and as a pair, in the future. Any store that carries Heretic can help in adding a subwoofer if you want to explore infrasonic bass.

Conclusions

Heretic AD612 Monitor Loudspeaker At a Glance

THE HERETIC LOUDSPEAKER COMPANY AD-612 is an amplifier-friendly loudspeaker that brings a close-to-live performance into one’s listening room and can be driven by nearly any amplifier.

Likes
  • Can be driven with a good 10-watt tube amp
  • Detailed presentation of all types of music
  • Neutral without a hint of harshness
  • Excellent sound stage, even when placed against a wall
  • 300-watt power handling to drive large rooms
  • Nostalgia built in for no extra charge
Would Like To See
  • A matching subwoofer for 10-40Hz reproduction

The Heretic Speaker Company has made something special with the AD-612 (and its slightly smaller brother, the AD-614). It is a speaker that can be placed flush against a wall while delivering excellent performance. It can also be brought out into one’s listening space and toed in, giving a HUGE sound stage. This is ultimately where they ended up in our listening room.

Having musicians in the family, we hear a lot of live music and value a system that doesn’t color the sound. The AD-612s bring accurate sound reproduction into the house for a reasonable price, especially considering that they don’t need an expensive amplifier to perform well. They could easily be a cornerstone to one’s audio system with future upward mobility. If one has, for example, an older integrated amp, a pair of Heretic Loudspeakers can breathe new life into that amp while allowing future upgrades such as an amplifier or a premium subwoofer. For most music, a subwoofer will not be needed, and many listeners will stop with nothing more than just these excellent speakers. They are well worth a visit to your Heretic Loudspeaker Company dealer to check them out for yourself. Highly Recommended.