Review: Fritz Heiler’s Carbon 7 SE Mk 2 bookshelf speakers

Review: Fritz Heiler’s Carbon 7 SE Mk 2 bookshelf speakers

5/14/20 by hilde45

I’m happy to post a review of John “Fritz” Heiler’s wonderful Carbon 7 SE Mk 2 bookshelf speaker. After we corresponded a bit over email, Fritz suggested I try out his speakers and, if I felt inclined, to write something up about them. I do not own them and will be sending them back to Fritz whenever he calls for them. I am not in the audio industry in any way, shape, or form. I’m a college professor and a relative newcomer to high quality audio, though I have been interested and have owned some decent mid-fi gear since the 1980’s.

After spending over a month with them doing a lot of listening, I’m happy to convey my impressions of these speakers. I offer them with apologies in advance: I’m a careful listener and love music; what follows represents my best effort to capture what I heard.

This review ran a bit long, so here are the sections covered.


Burn-in and Equipment
Music Sources
Setup/Listening position


Complex Passages



As relayed on his website, the Carbons are a 2-way vented stand mounted monitor; they have a frequency response of 38Hz - 35Khz +/- 3 db, an impedance of 8 Ohms nominal @ 1000 kHz, and a sensitivity of 88 db. Drivers include, first, a 7" Carbon Graphite Fiber/Paper Pulp composite cone with non-resonant low loss butyl rubber surround & Kapton voice coil former & die cast frame with massive magnet, bass reflex loaded rear port. Second, they use a 1" ScanSpeak Textile Diaphragm wide surround Dome tweeter. There are Acoustic Reality Series Crossovers without any capacitors or resistors in the circuit with the tweeter. 

The speakers are hefty but not unwieldy. Their dimensions/weight are 16H x 9W x 12D, 32 lbs (each). The recommended power is 30 - 150 Watts RMS, without clipping. More details, including very attractive choices of wood grains, can be found on Fritz’s website.

Burn-in and Equipment

Burn in: Fritz told me the speakers had some hours on them but hadn’t been used in a while. I played them for about 50 hours before doing critical listening. My associated equipment had 50-100 hours of burn in.

Equipment used was as follows. Amplification came from a Quicksilver Line Stage (non-remote version) and a Quicksilver Mono 60’s (60 wpc) amplifier. Tubes were stock (12AT7 in preamp; 12AX7B input, 12BH7A driver, JJ KT 88 output). Source components were the Cambridge CXC transport and a Bluesound Node 2i streamer both fed into an MHDT Orchid DAC. Cables included a Toslink for CD, Analysis Plus Crystal Solo coaxial for streamer; RCA interconnects were Analysis Plus Copper Oval; power cords were Pangea AC 14SE MkII for everything but the CD transport and the QS mono blocks, which used Pangea AC 9SE MkII. Speaker Wire was Analysis Plus Oval 12 speaker cables. Power conditioning was by a Panamax 1500. 

Music was served up in CD quality and high resolution files from the CD player, Amazon Music HD, and Qobuz. 

Setup/Listening position

The room is a basement rectangle with a small hallway lead in. It has concrete floors with thin wall-to-wall carpeting and a Turkish rug in front of a couch. Main listening area dimensions are 27’ x 14’ and the ceilings are 6’5” high. Total listening area is about 400 square feet. As far as I can measure, there are no first reflection points close enough to interfere with the initial sound from the speakers.

After some experiments with placement, I set the speakers 3’ 3” from the long wall (made of brick), about 11 feet apart from one another, slightly toed in, and about 9 feet to my listening position on a couch (tweeter to ear). The speakers sat upon sturdy MDF stands about 25” high. Behind the listening position and lining the entire opposite long wall are bookshelves, floor to ceiling, filled with an irregular array of books. 


Complex Passages

Handling complex passages means presenting complex and intertwining melodies and sonorities without muddling them into the sonic equivalent of tangled cords. In Ives’ “Overture & March 1776” the soundstage was spacious enough to present a jarring cacophony in a way that was still musical; the space was big — a snare drum tapped far in the distance while various horns and other percussion were more immediate, albeit spread across the field. Steely Dan’s lusher pieces (e.g. “Black Cow”) contain many more instruments and singers than I realized because the Carbons gave them sufficient separation. 


One of the reasons I ventured into an all-tube system was to experience what people kept referring to as “holographic” sound stages. And while I’ve never owned electrostatic or panel speakers, I had the expectation that a good pair of speakers should be able to recreate wide, deep, and tall arrangements of live music. Placement experiments with the Carbons paid off, and I was treated to a variety of engaging and effective sound stage experiences.

As I mentioned above, Ives’ “Overture” spread a rowdy orchestra before me, presenting a serendipitous and dissonant geography; Brian Eno’s Apollo (“Under Stars,” “Matta,” “Secret Place”) depicted vast textured spaces occasioning tiny events. David Chesky’s “General Image And Resolution Test” from The Best Of Chesky Jazz And More Audiophile Tests Volume 2 provided an opportunity to hear the Carbons produce sounds both to the side and behind my listening seat.

The soundstage produced also expresses smaller performance venues and places individual performers precisely. In Nordic Sound’s Vivaldi recording, “Recitative And Aria,” the string section was clearly localized, as was the soprano, her singing emerging from an atmospheric halo. Jazz duo Towner/Peacock’s bass and guitar strummed right before me; Towner’s fretting was just the right distance from his strums, plucks, and hits. Helen Merrill’s live disc You and the Night and the Music (“You and the Night and the Music,” and “I want to be Happy”) put me in a small jazz club. Keith Jarrett’s trio (Whisper Not, “Poinciana”) opened up into a much larger space; piano, bass, and drums were spread naturally across the listening field, and DeJohnette’s various drums appeared as distinct shapes in space. On that cut, the audience’s applause is dimensioned and articulate — I heard many individuals clapping rather than just a crowd.


Because I’ve spent so much of my life listening to compressed music, it’s been a great experience to listen to high resolution and audiophile recordings. The Carbons were up to the task of tracking big dynamic shifts; among the biggest, Ives’ “Overture” swelled from a whisper to a thunderclap so quickly that I nearly jumped off the couch. Carlos Kleiber’s crisp, dramatic opening to Beethoven’s 7th Symphony moved between sudden and subtle. On Lou Reed’s “Take a Walk on the Wild Side,” the creepy approach of the background vocalists reminded me of the first time that song messed with my head, 40 years ago.


Because I grew up listening to Acoustic Research three-way AR 48s, which have 10” woofers, I was used to mains that could reproduce bass really well. The Carbon’s woofers are not that large, but their bass response is excellent — deep and accurate. Some recordings — such as Donald Fagen’s “Morph the Cat,” or the Towner/Peacock duo’s “Opalesque,” — surprised me with their bass extension. On “Morph,” bass was quick, effortless, controlled; drums had kick and power. On Jennifer Warnes’ “The Ballad of the Runaway Horse,” Rob Wasserman’s bass provided a detailed, rich, woody, heartbeat that propelled the folk tale forward. The Carbon’s conveyed Eno’s Apollo bass impressionistically by creating a fathomless, spatial arena. On all these tunes, the Carbons did all I could have asked for, and it was only when I turned on my REL 328 subwoofer did I realize that there was a bottom end which could be filled a bit further. Still, it was easy to listen without the sub, and I often forgot that I had it.


I’m not alone in wanting instruments to sound like themselves, and one strength to the Carbons is their honesty. Across the variety of music I played, I never wondered what I was listening to (with the exception, perhaps, of Brian Eno!). For example, Ives’ “Overture & March 1776” parades a huge variety of instruments at different distances, both clashing and in unison. I never mixed up a piccolo with a flute or a bass clarinet with a contrabassoon; various percussion instruments (snare drum, tam-tam, triangle, celesta) all played unique role in Ives’ patriotic pileup.

Male vocals were also good tests for the Carbon’s lower midrange. Jazz vocalist Gregory Porter’s sumptuous baritone materialized before me with confidence in “No Love Dying” . His “Lonesome Lover” used a very gentle reverb on his voice which came through nicely; horns were crisp and separated, as were different elements of the drum kit. Fagen’s lead vocal on “H Gang” is double tracked, and the speakers clearly articulated the clever mix which leaves just a bit of space between their not-quite-identical sonorities. Nordic Sound’s recording of “Gregorian Chant” by Crux Fidelis & Consortium Vocale filled the room with a consortiumcohort of individual voices.

Female vocals were especially well drawn; I was already a Jennifer Warnes fan and only later realized that she’s on most audiophile playlists. The Carbons capture her expressive and wide-ranging style in “Lights of Louisiana” and “The Ballad of the Runaway Horse”; her breathy sibilance was lush, but not overdone.

One final word about piano and the Carbons. Second only to guitar, piano is a favorite of mine. The ability of the Carbons to handle it across jazz and classical were crucial to me, and the Carbons did extremely well. Jarrett’s lines (“Poinciana”) were delightfully liquid, Gould’s stereo re-do of the Goldberg Variations (much more dynamic and percussive than his 1955 mono version) was startling and the piano had a personality.


Sticking with piano as a speaker’s crucial test, it’s also worth watching in that instrument’s upper range. The Carbons acquitted themselves well in this regard; again,as a test of a speaker’s treble response, I listened carefully to passages played in the upper octaves. The Carbons performed nimbly; Jarrett’s “Poinciana” had upper notes which trickled and sparkled but with body — never brittle. (This was true both with an all-tube setup and, on an earlier occasion, via my solid state Adcom gear playing through an older non-tube Peachtree DAC-IT.)

Cymbals tested well for treble, also. In “Poinciana” and Steely Dan’s “Babylon Sisters,” ride and splash cymbals had a friendly, musical, metallic ring that didn’t decay too quickly. Snares had a healthy kick. Towner’s picking and percussive scratching on his nylon string guitar (“Creeper,” “Postcard to Salta, “Amber Captive”) were all expressed by the Carbons.


Because I’ve been shopping intensively for bookshelf speakers in the last few months, the Carbons came at a time when I had a lot of other speakers on my mind. I don’t want to drag out what is already a long review, but there are a few things to say immediately in comparison. 

First of all, the Carbons are better (based on what I heard — caveat: outside my home) in tonal balance and imaging than Focal Aria 906, B&W 707, and the GoldenEar Aon 3. None of these speakers are in Fritz’s price class (they’re about $1000 lower) but all have gotten a lot of good press, so it’s worth mentioning that the Carbons blow these away — better bass, more natural and full vocals, and treble that is equally detailed but not too fatiguing. In character, to my ear, Carbons are more akin to the Dynaudio Evoke (especially the Evoke 20) line and a couple of the Totem models (e.g. the Sky and Skylight). I enjoyed all of these speakers, but liked the Carbons more. I also would put the Carbons above of Spendor’s floor standers, including the A4 (about $1000 above the Carbons).

The other speaker I own, purchased to bide some time in quarantine, is the new Klipsch RP-600M. This speaker is 1/4th the price of the Carbons (and weigh half as much). When I first listened to these speakers (after some burn in), they seemed quite different in character but equal in quality to the Carbons. The Klipsches  separate instruments very well and the upper mids and highs are super crisp. Their sound stage is quite wide.

Five weeks later, I realized that there is absolutely no comparison. The Klipsch are completely outmatched by the Carbons — in comparison, they are a bit etched in upper mids and highs, their soundstage is wide but less articulate, their bass is quite present but less woody and organic. They have the potential to fatigue me to the point of reaching for the off button. Also, voices are somewhat less warm, human. With the Carbons, I never wanted to shut them off. While Klipsch’s sound ok, the Carbons helped me distinguish between, let’s say, the “Mercedes level” of a speaker vs. the “Toyota Corolla level” of the Klipsch. (With all due respect to the YouTube reviewers who fall over themselves for the Klipsch.)


As this review hopefully demonstrated, these speakers are outstanding performers, beautifully built, and made with care and quality. They’re the product of Fritz’s long-earned expertise and attunement to what the music wants. Because Fritz sells directly, they represent an exceptional value. I heartily and unreservedly recommend these speakers to anyone looking for a bookshelf monitor. 



Please find below a list of the recordings mentioned in the review.


Gregory Porter, Liquid Spirit (high res): “No Love Dying,” “Lonesome Lover.”

Keith Jarrett Trio, Whisper Not (live): “Poinciana” (CD)

Helen Merrill, You and the Night and the Music, “You and the Night and the Music,” and “I Want to be Happy”

Ralph Towner and Gary Peacock, A Closer View (CD): “Opalesque,” “Creeper,” “Postcard to Salta, “Amber Captive.”


Lou Reed, Transformer (remastered, high res) “Walk on the Wild Side”

Steely Dan, Gaucho (remastered, high res), “Babylon Sisters”

Donald Fagen — Morph the Cat (high res.); “Morph the Cat, “H Gang”

Jennifer Warnes, Famous Blue Raincoat: 20th Anniversary Edition (Digitally Remastered; high res.): “Ballad of the Runaway Horse.” 

Jennifer Warnes, The Hunter: “Lights of Louisianne.”


Brian Eno, Apollo (remastered; CD): "Under Stars,” "The Secret Place,“ “Matta”

David Chesky, Stereo Review & Chesky Records: Gold Stereo And Surround Sound Set-Up Disc, “General Image And Resolution Test From The Best Of Chesky Jazz And More Audiophile Tests Volume 2.”


The Nordic Sound 2L Audiophile Reference Recordings (high resolution)

* Gregorian Chant - Crux Fidelis & Consortium Vocale

* Ives: “Overture & March 1776” by Kristiansand Blåseensemble 

* Vivaldi: Recitative And Aria From Cantata Rv 679, Che Giova Il Sospirar, Povero Core by Tone Wik & Barokkanerne

Beethoven: Symphonies Nos. 5 & 7 Reissued, Carlos Kleiber (Conductor), Wiener Philharmoniker (Orchestra) Deutsche Grammophon, 1996.

Glenn Gould, The Goldberg Variations, Sony, 1981

First of all, the Carbons are better (based on what I heard — caveat: outside my home) in tonal balance and imaging than Focal Aria 906, B&W 707, and the GoldenEar Aon 3.

The tweet Fritz uses though, completely wroth the difference in price to any of them, and by this I mean the performance of the end result, not the component costs.  It's a stellar performer.
Thank you for the very detailed and informative review. It's nice to read the words of a writer who can spell and punctuate too!
You seem more than satisfied with these speakers; so why are you returning them?
@roxy54 Thanks for reading it!
Why I'm not (yet) buying these speakers — fair question. Since January, I have had a deposit on some Salk speakers and his production is shut down at the moment. I consider myself committed to trying them (they'll have a 30 day trial), and I don't know when I'll get them. So, I cannot buy a different speaker until I hear them. If I hear the Salks and they don't impress, I am very open to Fritz. (They have a track record with me, now.) I'd approach that as a purchase (thinking about finishes, other models such as the Carrera BE). In other words, it's the wrong time to buy something else now, i.e., before I try out the Salks. More info than you probably wanted, but all true!
Great review!  Very well written and very informative.  I have not found a single bad review on any speaker that Fritz builds; if someone is aware of one, let me know.

I have however seen review after review about how great his speakers sound with a general consensus about their sound quality.

I should be getting his new model, the Carbon 6 in for review on Monday.  I’m already preparing myself to buy them if I like them as much as I think I will.  
@b_limo Thank you! I'm very interested in how they contrast with the Carreras.
Thank you for the thorough and thoughtful review.

I have most of the recordings you used and I am intrigued by these small speakers!
Really nice review,thank you!I'll be interested in reading about the Carbon6 also.I'm fighting upgradeitis now.I promised myself I was done.Dang!
Thanks @gregm and @jtcf -- Fritz is easy to talk to and not pushy at all. He'd likely let you know if anything was on special, etc.
You had mentioned to me that this is your first high end system... I’m curious to know if you have heard a set-up and or a set of speakers that outperformed what you are currently hearing from your rig.  You’ve made a few small upgrades to your set-up while you’ve had the Carbon 7’s; are the Carbon7’s letting you hear those changes?
Also, you have spent some more time with the Carbon 7’s now; has the honeymoon period started to wear off or are you still enjoying them as much as day 1?  The Carreras had the opposite effect on me.  The more time I spent with them, the more I liked them...

It's hard to say. I listened to some very nice Dynaudios which performed as well as the Fritz but I suspect they were the Special 40's and they were probably powered by a very expensive amp in a very well treated listening room. I'd want a rematch before I'd choose them. Also, I heard a Dynaudio Confidence speaker which was amazing, too. Other than that, I have a friend with an elaborate set of Maggies on VTL monoblocks with an elaborate digital audio server which astounded me. But the Fritz are quite up there — and I won't list all the speakers which didn't measure up. But...have I hear the Joseph Pulsar? Or the Von Schweikert? No. Some of the pricier Totems or Vandersteens or Omegas or Salks ...etc. No. I cannot claim to have that wide an experience. But these speakers are $2500-ish. I mean, really! Hard to beat.

Here are the following changes/upgrades that the Carbon 7s allowed me to hear — which I did not hear before using other speakers:
  • from midfi solid state to tube gear from Quicksilver
  • from ordinary interconnects to Analysis plus
  • from ordinary speaker wire to Analysis plus speaker wire
  • from a Peachtree DAC-IT to an Orchid MHDT DAC
  • from 320bps on Spotify to CD and/or high resolution files
Honeymoon worn off? No. Actually, I did some A/B comparisons *again* with my Klipsch RP-600M. It is an easy to drive and engaging speaker, with a lot of sparkle and airiness. But I did a fun experiment yesterday with two different tracks — I played a very well recorded first movement of Mahler's 9th on the Klipsch and then on the Fritz. I am not kidding when I say that *only* the Fritz could handle the very complex and dynamically motile passages in the Mahler. It's as if the Klipsch just produced noise at that moment, whereas the Fritz sorted it out. The other was comparing Meghan Andrews cut "99" on the Blue Coast Record high resolution recording. The presence of a full flesh and blood person was only in the room with the Fritz; that earthy, palpable midrange. With the Klipsch, it was pretty but not substantial. Thinner. Good soundstage with both, but the Klipsch was just tonally paler.

Thanks for the reply! I was just curious because you have compiled a nice, well rounded system and it wouldn’t be surprising if it was the best you have heard. I forget, do you play any musical instruments or attend live performances?  Those are a good reference point!  The way you spoke about the Carbon 7’s In your review would lead me to believe you Are a musician or that you attend live performances.

It’s interesting that sometimes you are able to tell more of a difference between two products once you have removed it from your system. Upgraded powercords are a great example of this. Once installed, you may hear a slight difference but once you’ve gotten used to them, when you take them out and go back to the original ones, you are able to hear a bigger difference.  

Any word on the Salks you ordered? A comparison between the Salks and Fritz would be interesting, even though the Salks are $800 more and would be more in line with the Carrera BE’s...
Thanks. It seems like I have a system capable of doing justice to the speakers. I was suprised to see a call above for a more advanced system; while I'm sure that would bring out more, I wasn't playing the speakers on a mid-fi system.

I go to symphony and other classical concerts — in good concert halls and churches; I also go to live jazz concerts and occasionally folk concerts. I've gone to concerts all my life.

I used to want to be a jazz guitarist and studied for about a year with jazz guitarist Pat Martino. That was in the late 1980s.

I think I heard the powercords, too. Forgot to mention that.

I want to remove a bunch of stuff and see if I hear a difference. I really have done a lot of blind faith buying of cords, but I found reasonably good stuff at about 50% off, so I've not broken the bank in that area.

FYI: Salk production has resumed. And the Salks are about $1100 more.

I was surprised by Riaa’s comments as well but I wouldn’t take it to heart. There are people  here that consider a $50,000 system to be entry level, lol.  Oh well!

Thanks for the feedback and enjoy your set-up! Its pretty awesome if you ask me and you did a really good job picking out your cabling and components, especially for a first high end system!

Enjoy the music!
Oh, and good to know about the Salks!  Hopefully you get them soon and can report back!
Thanks, much. Didn't take it to heart, just curious to hear that there'd be that much of a jump up in sound quality from my system up. I guess I'll learn!
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