Audio: Listen to this article.
Electrostatic Headphone Amplifiers Review:
Mjölnir Audio Carbon CC
HeadAmp Blue Hawaii Special Edition
Rajiv Arora
When I reviewed the Stax SR-X9000 and Audeze CRBN electrostatic headphones a year ago, I didn’t get to spend as much time with them as I would have liked, due to the demand for review samples. Luckily, later in the Fall, I was able to reprise both of them in my system for a longer loan spell to enjoy them more fully. This time, I wanted to explore a different dimension: electrostatic headphone amplifiers.
I focused my attention on the two most acclaimed electrostatic amps out there: the Mjölnir Audio Carbon CC, and the HeadAmp Blue Hawaii Special Edition. During my time at CanJam SoCal in September, I walked around and sampled as many electrostatic amps as I could, and sure enough, the two that stood out were the aforementioned duo.
While there are even pricier boutique designs like the T2, these are builds that have to be commissioned, and not easily available for review. Some day, I hope to try these, but for now, I was more than pleased to have the Carbon CC and the BHSE in-house for some extensive listening!
My Listening Setup
Baseline Reference System
My baseline reference system for this review is shown in the picture above. It consists of a chain of audiophile switches, feeding my music server, the Taiko SGM Extreme, equipped with the Taiko USB card upgrade. Audio data is output over USB to a Vinnie Rossi L2 DAC module in an L2i SE integrated amplifier. The switches are powered by independent DC rails supplied by a Paul Hynes SR7MR3DRXLFC10 power supply. AC power is delivered via a 6AWG dedicated circuit to a Sound Application TT-7 Reference power conditioner, to which the amps, the Extreme, and the Paul Hynes PSU are directly connected. Additional details are available in the System Details section below.
For this evaluation, I used the L2i SE as a preamp, while driving the electrostatic amps under review via balanced XLR interconnects.
Review Playlist
To enable you to listen to the same tracks that I did, I have created a public playlist on Qobuz USA. This playlist includes the tracks mentioned in this review, as well as some of the others I listened to in the course of this evaluation. Please note that in some cases, the Qobuz track will not match the mastering I listened to, especially since all my listening was with PGGB-256 upsampled files, stored locally on my Extreme server. Still, this gives you a sense for the music I listened to for evaluation.
Mjölnir Audio Carbon CC
Mjölnir Audio sells a line of electrostatic amps built by Icelandic DIY builder Birgir Guðjónsson, based on Dr. Kevin Gilmore’s designs. The Carbon CC (MSRP: $6900, or $7800 with an Alps RK50 volume control) is said to be his current flagship, using the highest grade parts. From the website: “...Higher spec power supply, 99.99% pure silver signal wiring, upgraded TKD volume pot, higher grade resistors for the amplifier channels and finally, new custom made PEEK output sockets…”
Stylistically, the Carbon CC, despite being a no-nonsense black rectangular chassis, is an attractive piece of gear. The glossy black finish and white lettering convey an understated elegance, which is reinforced by the quality of the finish.
HeadAmp Blue Hawaii Special Edition
The Blue Hawaii Special Edition (BHSE) also uses a Kevin Gilmore design, licensed and built by HeadAmp. This design uses a hybrid approach with solid state gain stages, and a tube output stage. The BHSE is intended to be a state-of-the art design, as is reinforced by the use of a separate power supply unit. Justin Wilson, the president of HeadAmp, who demoed the amp to me at CanJam, as well as facilitating my review unit, also stressed that the tubes have been carefully selected for excellent sound quality, so the user doesn't have to roll tubes unless they want to. The BHSE uses matched Mullard EL34 tubes. The BHSE is available in two volume control configurations: a DACT 24-step (MSRP: $6995), and a stepless ALPS RK50 (MSRP: $7995).
Visually, the BHSE is just stunning. The fit and finish of the case and faceplate are top-notch. The unit can be ordered with faceplates and trim in several attractive colors. My review unit was satin blue, and it caught the eye of, and received universal praise for its looks from, everyone who stepped into my listening room. The BHSE’s looks absolutely befit its claim to flagship status. But looks aren’t everything in high-end audio. It was time for some listening!
Listening Test Methodology
Since I was using my Vinnie Rossi L2 DAC/L2i SE (abbreviated as VR) as a DAC/preamp, and since only the BHSE review unit had the upgraded ALPS potentiometer, I eliminated the volume control differences by setting both amplifiers at maximum gain, and using the VR’s volume control.
Listening Impressions
Mjölnir Audio Carbon CC
Since I had previously used the Carbon CC amp for my SR-X9000 and CRBN review, I won’t repeat my detailed impressions of the Carbon CC here, and instead refer readers to that review. There, I had compared it to a baseline of the Stax SRM-T8000 driving SR-009S headphones:
As good as the SRM-T8000 sounded, the Carbon CC took things to a different level. The bass got deeper, tighter, and more impactful. Instruments took on a solidity that made them sound all the more real. There was an increase in dynamics as well. The Carbon CC also seemed to dial down the SR-009S’s inherent brightness, which was very welcome. Finally, there was an added bit of richness and refinement in the Carbon CC.
Reacquainting myself with the Carbon CC driving the SR-X9000 and the CRBN, my impressions were only reinforced. The Carbon CC works wonders on electrostatics, a genre of transducers known to be susceptible to a brighter tonality and weak bass. Through the Carbon CC, that is definitely not the case. The sound signature is spacious, dynamic, full-bodied and refined.
Head Amp Blue Hawaii SE
Before receiving my review unit, I had listened to the BHSE at CanJam SoCal in September, driving the SR-X9000. Even under show conditions, this amp had made me sit up and take notice. What got my attention was the density and bass I was hearing, which was not what I expected from a tube output stage amp. This piqued my interest enough to request a review unit, and Jason graciously obliged.
Once the unit was in house, I let it run in with continuous music before doing any critical listening. When I did, I felt vindicated, as the sound quality flowing through the unit was just addictive! Everything I had heard in SoCal was evident in abundance, but in my system, I could now hear the resolution and nuance that was hard to do at the show. I knew I had a tasty comparison on my hands!
Comparison of Carbon CC and BHSE
Chicago’s second studio album, Chicago II (Rhino DVD-Audio, 24/96), is early Chicago, gloriously rambunctious and brash. On Movin’ On, the BHSE conveyed plenty of low-end grunt with refined tonality, particularly evident in the blare of the brass. Perhaps too refined? On the Carbon CC, the trumpets were abrasive, with more bite. The BHSE was easier to listen to, while the Carbon CC seemed to convey the grittiness of the music more. Both placed the ensemble in a large soundstage, with the Carbon CC being just that extra bit punchier.
There is no dearth of great recordings of Haydn’s “London” symphonies, but I’m partial to this 1993 recording by Roger Norrington’s London Classical Players of Haydn Symphonies 99-104 (Erato, 16/44.1). The Carbon CC was again punchier and more dynamic, with crisper transients, and slightly more microdetails, especially on the timpani. But theBHSE countered with more seductive massed violins, sweeter woodwinds, and more refined horns. These differences between the two amps were small, and I was hard pressed to pick a clear favorite.
On another favorite album, Sibelius: Symphonies 2 & 5, Osmo Vänskä, Minnesota Orchestra (BIS, 24/96), the findings were similar. The soaring french horn in the opening theme of the first movement of the 5th symphony benefits from the SR-X9000’s huge soundstage and both amps portray this very capably. This is mesmerizing music, and the BHSE pulls you in more emotionally. Yet when you listen to the tapestry of sound in the crescendos, the Carbon CC allows you to hear deeper and differentiate individual instruments just that extra bit better.
Wow, talk about yin and yang! On track after track, these amps showcased their respective strengths. The Carbon CC had more authoritative and articulate bass, crisper transients, a big, dense soundstage, excellent dynamics, without a hint of solid-state brightness or harshness. In many ways this is an SS amp with some tubelike strengths.
The BHSE brings its own game. It projects an equally big soundstage, with a more precise placement of instruments. Tonal richness is another BHSE strength, but this is not gooey, syrupy tube sound. Instead, it’s seductive and draws you deeply into the music. This same holistic consideration applies when it comes to bass. Yes, in direct comparison, the Carbon CC is stronger, but yet when listening to BHSE, from my initial audition at CanJam to the months at my house, I never once considered the BHSE’s bass lacking. In many ways, this is a tube amp with solid-state strengths.
Concluding thoughts
I expected this to be a close contest, as both the BHSE and Carbon CC are very well-regarded and popular electrostatic amps. This is exactly what I got. To call one of these better than the other is foolish, because they each have complementary strengths. Which one is right for you depends on the attributes you value more.
Are transient response, dynamics, density, and deep articulate bass of primary importance to you? You might find the Carbon CC more to your liking. The BHSE has these attributes too, if not at quite the same scale, but if you also value a piece that sounds a bit more refined, organic, and more emotionally involving, then the BHSE may just be the ticket.
I personally place a huge value on transparency and transient response, along dynamics, density, and bass, so were I making this purchase, I’d pick the Carbon CC.
Ultimately, if you’re in the market for an electrostatic amp at this price point, don’t go by my preferences. Both the Carbon CC and the BHSE deserve a careful audition.
System Details
Music Computer: Taiko Audio SGM Extreme Music Server, Taiko USB upgrade
DAC: Vinnie Rossi L2 DAC module
Electrostatic Amps: Mjölnir Audio Carbon CC, HeadAmp Blue Hawaii SE
Reference Headphones: Stax SR-X9000, Audeze CRBN
Ethernet Switches: SOtM sNH-10G, Uptone EtherREGEN, Buffalo BS-GS2016 (modded for LPS)
Power supplies: Paul Hynes SR7MR3DRXL (dual regulation, 3-rail)
Power Details: Dedicated 30A 6AWG AC circuit Sound Application TT-7 Reference Power Conditioner
Power Cables: Sablon King (wall to TT-7), Sablon Prince (Extreme),
Cardas Clear Beyond (L2i SE, SR-7),
Cardas Clear for all other components
USB cable: Sablon Evo 2022 USB
Ethernet cables: Sablon 2020, Supra Cat 8
DC cables: Paul Hynes fine silver (SR-7)
Headphone cables: Transparent Ultra cable system
Accessories: Synergistic Research Tranquility Base XL UEF. Galileo MPC, Synergistic Research MiG 2.0 footers, Taiko Audio Daiza Isolation Platforms, High Fidelity Cables Trinity Helix Headphone Module.
Acknowledgments
Many thanks to the following companies for supplying components, cables and accessories to aid in this evaluation:
* Stax Japan, for the SR-X9000 headphones,
* Audeze, for the CRBN headphones,
* Cardas Audio, for a full loom of Cardas Clear cables.
* Transparent Audio, for the Transparent Ultra headphone cable with a full complement of headphones leads and source terminators.
About the Author
Rajiv Arora — a.k.a. @austinpop — is both a computer geek and a lifelong audiophile. He doesn’t work much, but when he does, it’s as a consultant in the computer industry. Having retired from a corporate career as a researcher, technologist and executive, he now combines his passion for music and audio gear with his computer skills and his love of writing to author reviews and articles about high-end audio.
He has "a special set of skills" that help him bring technical perspective to the audio hobby. No, they do not involve kicking criminal ass in exotic foreign locales! Starting with his Ph.D. research on computer networks, and extending over his professional career, his area of expertise is the performance and scalability of distributed computing systems. Tuning and optimization are in his blood. He is guided by the scientific method and robust experimental design. That said, he trusts his ears, and how a system or component sounds is always the final determinant in his findings. He does not need every audio effect to be measurable, as long as it is consistently audible.
Finally, he believes in integrity, honesty, civility and community, and this is what he strives to bring to every interaction, both as an author and as a forum contributor.
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