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Equipment Review

March 2002

deHavilland Aries 845 Mono Amplifiers

by Bill Cowen

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Review Summary
Sound "The thing that will grab you first and foremost with the Aries 845 is the midrange; there is a level of natural detail and immediacy that [Bill] found captivating"; soundstage "depth and width were first-class," but "there was a definite loss of [treble] shimmer and extension"; ultimate output levels and "bass slammin’" just aren't the strengths of the Aries 845.
Features SET circuitry using the 845 output tube; precision stepped attenuators are a $600 option and turn the amps into a single-input integrated amp.
Use Bill "discovered some noticeable gains with reasonable attention paid to isolation and support" of the amps as well as the need for at least 30 minutes of warm-up, with one hour being better still; adjustment of bias voltage requires the use of a milliamp-capable voltmeter.
Value "Not for the headbanger, but more for the audiophile who looks for contemplation into the art and intonation of music."

I first heard of deHavilland amplifiers via a tag line on tubewizard.com, a website that is an oasis for true tube junkies who wish to have antique Hickok tube testers repaired and/or calibrated. My natural curiosity resulted in a quick click to the link for deHavilland’s site, and I was intrigued by their offerings of SET tube amplifiers based on 845 output tubes. For those well-versed in SET offerings, the 845 tube topology typically offers more power than the more usual 300B tube found in so many SET designs. So when offered the chance to review the Aries 845, I gladly accepted. I wanted to hear what the minds at deHavilland had created.


The Aries 845s are a $6000 USD pair of monoblock amps that claim a healthy 22 watts of output power per amplifier from the aforementioned 845 output tube. While rather industrial-looking, an aluminum faceplate adorns the front with the deHavilland logo engraved and then hand-painted across the width, and a pair of nicely finished wooden side rails add some pleasantries to the otherwise all-black chassis. A toggle power switch is located on the front panel, along with a pair of indicator lights that signify main power and the application of B+ voltage to the tubes. The review amps were fitted with precision stepped attenuators on the front panel (a $600 option) that enables the use of a direct-feed from a CD player or other line-level output source. The IEC receptacle for mains power is located on top of the chassis, as are the single pair of Edison-Price binding posts for the speaker taps. This may prove problematic for extremely stiff and/or bulky power cords and speaker cables. The input RCAs are mounted more conventionally on the back panel and have ample room for even large-diameter cables.

The tube complement (per amplifier) is a China-sourced 845 output tube, a NOS RCA 6SN7GTB, and a Westinghouse-branded 6AV5GA. Each Aries 845 measures 12"W x 18"D x 10"H and weighs 57 pounds. Note that the amplifier inverts phase, so if the rest of your system is phase correct, you will need to reverse your speaker cables in order to maintain proper system phase.

Setup and use

The Aries 845s, which I used both as power amps and with a source directly in, are relatively straightforward to set up, and they come with sparse, yet fully adequate instructions. The tubes are shipped uninstalled, and after placing them in the proper sockets and connecting signal and power cables, the amps are ready for initial fire-up. deHavilland makes careful note that the amps should not be powered up without a load connected to the outputs (i.e., don’t turn the amps on until your speakers are connected). Flipping the main switch illuminates one of the front-panel lights to indicate power, and after approximately 30 seconds, the second light is illuminated to indicate the application of B+ voltage to the tubes. Next to the output tube, two sockets are provided for inserting the leads from a standard milliamp-capable voltmeter for setting the bias voltage. A small knob located next to these sockets adjusts this voltage. One cautionary note: Small movement of this knob produces major changes in the bias current, so go easy with it. deHavilland recommends a setting between 60 and 70 milliamps, with a maximum of 70. After some experimentation in this area, I found that 65 milliamps produced the best sound. A higher bias current gave the bass a touch more control, but also seemed to add some stridency to the treble. A lower setting resulted in a warmer, more "tubey" sound, but also imparted some looseness and loss of definition in the bass. I preferred 65 milliamps in the context of my system.

During the several months I used the amplifiers, I had no serious operational problems. The input and output transformers on both amps vibrated more than I’d like, exhibiting both an audible buzz and tactile vibration from the amplifier itself as well as a low-level buzz through the speakers. This was not distracting or bothersome, just an observation. After hours of operation, the transformers and chassis got quite warm, but not too hot to touch.

I also discovered some noticeable gains with reasonable attention paid to isolation and support. I’m a big fan of the Greater Ranges Neuance isolation shelves (very light and rigid), and felt that with the Aries 845s placed on the Neuance, there was a marked increase in the sense of air and dynamic alacrity as compared to putting the amps directly on the floor. There are so many different isolation/tuning schemes, tools, and methods available these days that it would be impossible to try everything. The combination I tried produced some very pleasing results, as Neuance shelves have with other amps I’ve used, so I stuck with them throughout the review period.

Finally, I was a bit perplexed when I first fired up the amps. The sound was strident, razory, and somewhat fatiguing. After checking connections, playing with a few different isolation schemes, and playing around with the bias setting, I finally achieved a sound that I considered worth pursuing. However, the next night, I was met with the same razory, etched sound, and then it dawned on me that warm-up was the issue. Further listening on different nights confirmed this finding: these amps need quite a bit of warm-up time before they morph into their best behavior. Anything less than 30 minutes warm-up was not too enjoyable. After 30 minutes and approaching one full hour put the amps into their best light. Now, no self-respecting tube-head expects any tube amp to sound its best when cold, but it seemed that the Aries 845s were especially demanding in this regard.


The thing that will grab you first and foremost with the Aries 845 is the midrange. Although the mids are somewhat more highlighted (more present?) than those of many other SET amps I’ve spent time with, there is a level of natural detail and immediacy that I found captivating. Take "These Things" from Robert Cray’s Midnight Stroll CD [Mercury D-173659]. Cray’s voice comes through with depth and harmonic richness that I’ve heard from very few amplifiers, even some costing much more. Guitar notes were perhaps a bit forward in the mix, but not in an unnatural fashion, just a little different than I’m used to. Tonality was most excellent, with an ample amount of low-level detail, resolution, and where appropriate, well, a certain amount of wail. Plopping Enya in the CD player was a real delight. Enya’s voice from "A Day Without Rain" from the CD of the same title [Reprise 9362-47426-2] simply melted amidst an expansive, airy soundstage. Depth and width were first-class, as were perceived physical proportions of both voice and instrument.

Associated Equipment

Loudspeakers – Coincident Speaker Technology Total Eclipse.

Amplifiers – Cary Audio Design CAD-805C monoblocks, Cary Audio Design 280SE "V-12."

Preamplifier – Cary Audio Design SLP-98.

Phono stages – Art Audio Vinyl One, Audio Electronic Supply PH-1.

Digital – Electrocompaniet EMC-1 CD player.

Analog – Eurokit Premiere turntable, Graham 2.2 tonearm, Benz-Micro MC-SCHEU and Dynavector Te Kaitora cartridges.

Interconnects and speaker cables – Coincident Speaker Technology interconnects and speaker cables, Omega Micro A-7 interconnects, Coincident and Cardas Golden Cross phono cables.

Power conditioners and power cords – Shunyata Research Hydra power-distribution center, Shunyata Research PowerSnakes King Cobra and Black Mamba power cords.

Accessories – Black Diamond Racing cones and Round Things, Michael Green Designs Pressure Zone Controllers, SolidSteel rack, home-brew sandboxes, Greater Ranges Neuance isolation shelves, ASC Half Rounds and Tower Traps, Marigo Audio Labs VTS tuning dots, Walker Audio Ultimate and Standard Valid Points.

Bass wise, the Aries gave up a bit of ground to several other SET amps I’ve heard. What presented itself in my system was a somewhat curtailed, somewhat diminished lower-frequency spectrum. Bass slammin’ just isn’t the forte of the Aries 845. Although there is adequate weight and foundation in the bass frequencies, there isn’t a tremendous amount of power or jump factor. With smaller-scale works, I found this to not be a pervasive liability, but with more hard-driving rock pieces, for example, the "whomp" and stomp were softened and rolled off. For hard rockers (like me, from time to time), careful auditioning in your system is required to determine if the Aries 845 can deliver the low-end crunch that appeals to you.

Dynamically, the Aries 845 was most competent, as long as volume levels were kept within the limits of the power capability (more on this below). There was a good sense of rhythmic vitality, evidenced by the fluid and continuous timing of both micro- and macrodynamic elements. Chris Isaak’s "Baby Did a Bad, Bad Thing," from Forever Blue [Reprise 9362-45845-2] gave a good example, with the echo-fade guitar notes blending nicely with the drums and bass guitar notes. The timing of dynamic elements is one of those things that lends itself to foot-tap when it exists, and lends to shortened listening sessions and watching re-runs of The Simpsons when it doesn’t.

Moving up the frequency scale into the treble, I found less to be enthusiastic about. Treble notes were somewhat reticent, and while they were not quite to the point of sounding closed-in, there was a definite loss of shimmer and extension, lending to a portrayal that was a bit dull-sounding overall. While such a trait might be a blessing with an overly bright and/or analytical system, it moved things in the wrong direction with my all-tube system, and with my speakers that are revealing and extended, yet never bright or harsh. Further, it was difficult to achieve any moderate SPLs in my (admittedly) large room, as when the amps were pushed to even moderate levels, audible distortion became immediately apparent.

And this distortion was not benign and/or mildly noticeable; it raised its head in an ugly fashion much like that of a solid-state amp driven into hard clipping. I don’t know exactly why this occurred, as based on past experience with similarly (and even lower-) powered amplifiers, the specified 22-watt power rating should have produced fairly loud listening levels before stressing the amps past their available output capability. I’ve been able to achieve much louder SPLs from both the 15Wpc Audio Electronics Super Amp and the 10Wpc Wavac MD-300B amp, both into the Coincident Total Eclipse speakers. Perhaps some impedance mismatch between the Total Eclipses and the Aries 845s was at fault here, but maximum SPL levels, as measured at the listening seat with a Radio Shack SPL meter, peaked at around 80dBs before obvious distortion resulted. Changing the position of the stepped attenuators, and/or changing the bias current had little, if any effect on the maximum volume capabilities.


Amplifiers on hand for comparison were the $9000-per-pair Cary Audio 805C monoblock SET amps (50 watts each), and the $4000 Cary Audio 280SE "V-12" tubed push-pull stereo amp (50Wpc in triode). At nearly double the rated power output, both Cary amps were capable of significantly louder levels. No surprises there.

The more expensive 805Cs produced a larger, more textured and delineated soundstage, as well as a firmer grasp on bass and upper-bass notes. While both amps exhibited a marvelous midrange, the Aries was a little more pronounced in this area -- a little more highlighted if you will. Details that the Cary glossed over were more apparent with the Aries 845, yet not to the point of being distracting or hyped. The Cary amps trumped the Aries 845s in both bass and treble extension, offering more information at the very top and bottom of the frequency spectrum, as well as more weight and authority in the lower registers. Neither of these amps should be mistaken for tight’n’dry bass machines, however. Further, the Cary amps produced clarity and ease through the upper-midrange and lower-treble regions that, in comparison, sounded somewhat coarse and grainy through the Aries 845s.

The less expensive 280SE was a horse of a different color altogether. It offered much better control, speed, and dynamics in the bass, which is not totally surprising given its push-pull topology. The midrange was not as textured, nor were harmonic overtones as detailed and palpable as presented through the Aries 845. The Aries 845 also had a somewhat softer, more polite sense to treble notes, and did not scale quite the heights of extension mustered by the 280SE. If I had to pick an amp for the musical genre being played, the 280SE would be my first pick for rock and pop. The Aries 845 would get the nod for small-scale vocal ensembles, simple jazz, and light classical, so long as the limited volume capabilities didn’t prove a liability.


The deHavilland Aries 845 mono amplifiers are not for the headbanger, but more for the audiophile who looks for contemplation into the art and intonation of music. The Aries 845s reminded me most of a classic tube design from years gone by, or of an old Quad loudspeaker that did the midrange so very, very well but faltered somewhat on the frequencies above and below. Many folks enjoy and eagerly seek such sound, and if you’re one of them, put the Aries 845 high on your audition list. If you want to infuriate the neighbors with wall-bulging bass whomp and police-notifying SPLs, look elsewhere.

In any event, extreme care must be taken in selecting the proper speaker to use with these amps. A high-sensitivity speaker (95dB or higher, I suspect) is likely mandated unless you listen in a very small room at low volumes. Proper care with isolation pays big dividends, and sufficient warm-up time prior to the listening session is highly recommended.

...Bill Cowen

deHavilland Aries 845 Mono Amplifiers
$6000 USD per pair; stepped attenuators add $600.
Warranty: Two years parts and labor, 90 days for the tubes.

deHavilland Electric Amplifier Company
332 Alamo Square
Alamo, CA 94507
Phone: (925) 837-7201

E-mail: 6SN7@abac.com
Website: www.dehavillandhifi.com

deHavilland responds:

Thank you for the review and the opportunity to make manufacturer's comments. Our records show that the test amplifiers sent to Bascom King for measurements and the amplifiers sent to Bill Cowen were configured for 4-ohm service. The Electra-Print output transformer does not have separate 4, 8, and 16 ohm taps. All the secondary windings have to be hardwired together for the desired output impedance. This has the design advantage of having all of the secondary windings engaged at all times, but it means that the impedance has to be wired by us in advance of shipment, in anticipation of the loudspeaker to be used.

Using our amplifier set up for 4 ohms would not be optimal on an 8-ohm speaker, and a high potential for mismatch on the Coincident Eclipse with its 14-ohm impedance. Zero-feedback single-ended amplifiers are load sensitive, and I am not surprised that Bill had problems with the bass and ultimate output levels. We apologize for this error and need to be more cognizant of what speakers a reviewer will be using in terms of impedance.

We hope these observations help to clarify the review.

Kara Chaffee
Chief Engineer
deHavilland Electric Amplifier Company

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