You are reading the older HTML site

Positive Feedback ISSUE 28
november/december 2006



Ios 845 amplifier - a review

as reviewed by Max Dudious





Well, hi again. The other night I was in a late night telephone conversation with my nearly life-long (well, 50 year) audio buddy, Cornu di Bassetto, after hearing a concert where a seventeen year old Julian Bliss played a very touching reading of Mozart's Clarinet Concerto on the Basset Clarinet. We spoke of how hard it was to keep up one's enthusiasm for new performances, or new audio gear. Think of it: you can say how a certain piece of gear was (or wasn't) well-made, sounded (or didn't sound) very good, and was (or wasn't) good value for money. Once you've said that, and you could do a pretty good job in three sentences, you're done. Well, then, what else can you do? You can try to be learned, by being technologically up to the minute on the latest developments in the audio arts. Or you can try to be entertaining, by being witty and clever in your delivery of the same old same old. Both of these point back to the reviewer instead of pointing to the piece of gear under consideration. And if you blow your own horn too much, you risk becoming a horse's ass and losing your reader. Plus, there are so many me-too products, it is increasingly hard to hide your disinterest and to avoid becoming a bore.

So here I am again, your eccentric old Uncle Max, trying to find a hook for a real goodie this time: a Class A, single ended (directly heated) triode, 25 watts RMS per channel (into 8 Ohms), very solidly designed (five separate transformers for various circuits), no expense spared on premium parts, zero negative feedback, stereo amplifier that sounds pretty neutral to me; yet is able to deliver all the things we questers for the grail of dynamite sound value highly (sweetness and authority), whose name rightly translates from the Greek (I'm told) to "Island Paradise." This is an excellent-sounding piece, the kind you might wish you had with you if forced to survive on a desert (if electrified) island paradise. So David Robinson said to me months ago, but I had to hear for myself. I think deHavilland has an outstanding amplifier here. And a bargain at the price of $6K (I'm serious!), especially when compared with the $20K and $30K amps out there. O.K. That's it. I'm done ...Just kidding.

Background of the Firm

George Kielczynski met Kara Chaffee in 1986 (How's this for a cute Hollywood boy meets girl scenario?) at a Northern California Tube Enthusiasts Association meet in San Francisco. Kara had built an SET amplifier that delivered 15-watt/ch, and brought it over to George's place for a listen the following week. He was blown away. They built an amplifier together for George, and pretty soon they started building them for friends. Then, as so often it happens in the audio business, by 1997 they were partners making deHavilland amps for the general public, a Svetlana 572 push-pull model that delivered 75 watts being first of their issue.

George describes this serendipitous event as two "tube nuts" finding each other, two individuals who were "passionately involved with vacuum tubes," who had been living and breathing vacuum tubes, and that passion had been the root of their tube-love as "amo" (Latin for "I love,") had been the root word of "amateur." I applaud them for going pro with their passion. I'm jealous that George found a woman with whom he can discuss circuitry and the sounds they generate. My wife, La Dudeen, also known as Grammy Dudious, can hear a faint buzzing when the tungsten wire in an incandescent light bulb is about to give out (so she has "big ears"), but she doesn't enjoy the fussy aspect of the audio hobby. Whenever I ask her to evaluate some tweak I'm very taken with, she says, "It sounds great. Your big system always sounds great, Max: Oh venerated Old Dude." I can never catch a break.

George says he thinks his gear is "over-designed," because each deHavilland amplifier is built to last a lifetime. That explains why the Ios has five power transformers, "where most designers would combine at least several of them into a single unit—we have a separate transformer for plate (845 v.) voltage, another for the filament of the 845 tube, another for the bias supply, another for the timer/l.e.d. circuit, and another filament transformer for the 6AU5 (tube). In that sense, we just don't cut corners," says Kara. "Our gear may look a little plain-Jane, because we put the money into the design." I haven't been to their factory, but I assume the entire line benefits from this philosophy. I expect that many plain-looking deHavilland amps and preamps will be in operation for a long time.

So what you need to know about this firm is this: Two amateur tube-heads found each other and began building SET amps for themselves, then their friends, and finally for the public. They tend to over-design the circuits to minimize down-time, and this leads them to spend on expensive parts like custom-wound transformers instead of fancy face-plates, bells and whistles. The result is very sexy performance from very utilitarian-looking gear. If you are up to hearing someone rave about just how good an all-'round amplifier the Ios is, stick with me.

The Sound

Nearly six or seven years ago, now, audiophile Dr. Ijaz Khan took me and his pair of heavily Pooged Marantz 8Bs to a very high-toned dealer somewhere near the D.C. beltway. The tube amplifier in favor then was the Carey, renown for its gloriously plummy mid-range; I've forgotten the model number, but I remember a pair were pretty expensive for amps in 1999, say $10K. We A/B tested them on a pair of Quad electrostatic speakers, and before much time passed the owner asked us if we were going to market a new amplifier based on the Marantz, because if we did he wanted the first pair. We then repeated this test, using dynamic speakers for the second run. We got the same results: the Marantz delivered less wooly bass, and less splashy highs than the SET Carey. The Carey delivered a more romantic mid-range, without doubt, but not without more obvious colorations; the human voice sounded more chesty than neutral, celli sounded a bit too warm, both more gorgeous than real. The winner was a pair of forty-year old, tried and true, Marantz 8Bs; a Williamson-type amplifier, each run in triode (push-pull), and strapped to mono (delivering about 40 watts per channel) with up to date substitutions for pre-computer parts in critical spots of the circuit by modern parts (metal-oxide 1% resistors everywhere, polypropylene and polystyrene capacitors in the signal path, quadrupled rail capacitance reservoir, and improved hookup wire). I made a snap judgment at the time, that the world of Single Ended Triode amps would likely be a dead end in the evolutionary tree of audio.

Of course, I was wrong. My snap judgments have a way of being wrong ...often. I couldn't foresee that computer industry circuit modeling allowed engineers to work out the problems of the single-ended triode design. Today there are many different manufacturers of SET amps, preamps, even headphone amps, and in my listening tests they are doing just fine. Nearly all of them have eliminated, or minimized, the anomalies noted above. The results are truly fine sound, more fine than the "Golden Age" of tubes ever achieved, though some of the "golden oldies" did a damn good job for what they were. The current generation of SET amps are leaner, more transparent all the way across the frequency range, more dynamic than all but the best solid-state gear, able to bring out the best from medium to high efficiency loudspeakers, a perfect match for any real high-efficiency speakers, and more than OK for bi-amplified, moderately efficient systems that use a subwoofer. With the deHavilland Ios amplifier driving all-but-the-woofer, and a solid state amplifier driving the sub, the result is often the best of both worlds. This means: big and textured bass; retrieval of down-in-the-mix micro-details, convincing sound-staging with a good facsimile of the original recording venue, plenty of dynamic contrast; plus the pretty flat-frequency-response with extended performance in the highest and lowest octaves. The deHavilland Ios is a first-class amplifier worthy of being the centerpiece of almost any first-class system (except when mated to some power hungry Werewolf loudspeakers).


When the deHavilland Ios came in, I was fiddling with a David Dicks' single-driver' wide-band design, a high output Audio Nirvana 8" co-ax (based on some of the design elements of the 8" Lowther series), in a ported "monitor" sized box. It was pretty good value for money at the entry level, as I wrote in my review. I played it with a range of amplifiers, and some matched up well, and some didn't. With it, the deHavilland seemed rolled off at the top. Despite what I knew about matching drivers and amplifiers, I mistakenly thought this was a feature of the amplifier. It turned out to be a feature of the interconnects and the speaker cables I was using. But it took me a while to stumble through the exercise of figuring that out. The lesson learned, once again, is "Everything Matters!" The best, most pricey cables can sound like doggy-doo if mismatched to the wrong loudspeakers. The deHavilland proved to be among the most cable-sensitive amplifiers I've had around. Together with the monitor, it was touchy, but finally I heard what the designers had in mind when they built the speaker system. With the right cables the speakers performed quite well, within their design limitations, which made it a pretty good surprise.

Some cables, when you plug them into a familiar rig, might immediately give the rig a subtle (almost un-noticed) click up or down in the presence range (2k-4kHz). Others might bring up the bass a nearly un-noticeable notch, or give you some more air in the highs. The original combination of amplifier-cables-speakers was a bit dull, with the highs rolled off. After I fiddled around a bit, I found some cables that gave the speakers a better audible combination. It was as if someone had punched an imaginary "Loudness" or contour switch. So some care must be taken in cable selection to optimize the performance of the Ios. And this can only be accomplished with some educated guesses and some trial and error. You'll need a good setup man to optimize this amplifier, but the juice is worth the squeeze. When you find the sweet spot of the Ios, everything will open up, and the result can be transcendent. You will have to learn to trust your ears, your judgment, and your taste. That's how the big boys do it.


The deHavilland Ios can range in sound pallette from a little soft to very bright. This was brought home to me with a tube rolling exercise I did under the tutelage of George Kielczynski. I listened to the amplifier with a stock pair of 845 output tubes that came with the amplifier. After I'd had the amplifier to listen to for a while, George sent me a pair of "more detailed" 845Bs, made by the Chinese firm of Shuguang. These tubes cost more (twice as much, natch), and George told me Shuguang made a "Super 845" that cost twice again as much, or more, and assured me the "Super 845" was to the more detailed 845B, as the 845B was to the "stock" 845. Not to labor the point, you can coax more and more performance out of this basic amplifier design by rolling up to more detailed and much more pricey tube sets. And from what I've heard, the differences are real, not subtle. More detail in the bass, mid-range, and trebles. Everything gets clearer and cleaner, as though a velvet curtain, not a filmy veil, between the speakers and the listener had been removed. It becomes a question of how much more detailed you want to hear; or how "sweet" are your main speakers? or listening room? or aging ears? If you fall in love with this amplifier in its stock form, you might anticipate stepping up in tube class. I mean, if you don't mind a $6,000 price tag for the amplifier, how could you balk at an additional $500 for a pair of super-premium output tubes.

Associated Gear

During the direct comparison with my rebuilt Marantz 8Bs I used the Marantz 7C pre-amplifier, also much rebuilt as above. The combination of Marantz preamp and deHavilland Ios amplifier was like a marriage made in heaven. The two pieces loved each other so much I feared we would have a meltdown. In many ways (smooth frequency response, dynamic bloom) the two amps sounded a lot alike, but I'd have to concede the plummy midrange was a tad sweeter, and the imaging was a tad more precise on the Ios than on the Marantzes; though the wooly bass and splashy highs I assumed were inherent in SET designs were gone from both. Then, for fun, I substituted the SinglePower SLAM headphone amplifier for the Marantz 7C preamp. This was another fortuitous match-up. The SET SLAM also managed to produce a gorgeous mid-range with both amps. But sadly, as it was designed to play with headphones, it didn't love producing big crescendos. That difficulty drifted away when I substituted a pair of 98dB efficient Lowther 5A systems for my larger 89dB 5-way speaker (my updated variation on the Dynaudio flagship, their 5-way Consequence 70 model).

The combination I liked best was my 18" Hartley-Klipsch woofers from 100Hz down, through my Shadow electronic crossover and a souped-up and dedicated Adcom 555 bass amplifier; and my Lowther 5A speakers, from 100Hz up, through the Shadow and the Ios amplifier. Not that there was anything wrong with the bass on the deHavilland, but it is widely accepted that Lowther bass has some difficulties. So the biamping was to overcome the Lowther bass, which (without help) is non-existent from 25Hz - 50Hz and peaky from 50Hz - 100Hz, not the deHavilland which was admirable down to 40Hz when played full range through my top 4-way speaker (the 100Hz and up portion of my 89dB efficient Big Dude speaker) by itself: no electronic cross-over, no bass amplifier.

I also used my much re-worked Levinson JC-2, featuring the classic John Curl design, with modern Curl-recommended parts replacements, and a dedicated laboratory power supply, set for 16.5 v. (DC), instead of the factory wall-wart set at 15 v. This piece (ignoring the phono section that had some problems with imaging), will run with the big dogs as a line stage once it has been up-dated. A resourceful scrounger can usually find one at the right price pretty quickly. The front-end was either a Marantz 8260 CD/SACD player, or a twenty year old VPI HW 19 also rebuilt with modern VPI parts, a Souther Tri-Quartz tone arm (with a Clearaudio wiring harness) with a Grado Statement cartridge, through a spiffed with soft rubber feet Lehmann Black Cube that was designated "Improved" due to its tripled (to 600 ma) power supply.

Interconnects and speaker cables in use were some by Ecosse, Goertz, Harmonic Technology, QED "Profile" Silver 12 (a Nordost clone), and some others I had around the little beach shack. Different speakers liked different cables with different amps, and since this is so subjective (varying with age, sex, cables, tube types, room size and treatment) I won't go into my preferences here for the Ios with my gear, in my room, through my ears. I will give you this much to go on: the Ecosse were very polite, the Goertz coppers were on the warm side of neutral, the Harmonic Technology fiber optic cables were the most neutral, the Harmonic Technology metal cables were on the sparkly side of neutral, and the QED Profiles (stranded silver in Teflon, flat configuration) were most sparkly.


Suffice to say, the deHavilland Ios acquitted itself admirably, make that extremely well, in all circumstances. It was gorgeous, silky in the mid-ranges, boom-and-fuzz-free on the bass, tizz-free on the trebles. It presented the sound stage as just slightly smaller than a French cathedral, when that was the recording engineer's idea of what was called for, and it also could do a small ensemble in a small room convincingly. Some people find 25 watts per channel too low a power rating. I have a little trouble with that idea. Remember, the difference between 25 watts and 50 watts is only 3dB. That is to say, if you have a medium sized room, and fairly efficient speakers, you might get a nosebleed or an ear ache at 50 watts for any lengthy period. If you have a very efficient set of speakers, like Lowthers, you might get such symptoms from 25 watts, and maybe from 10!! So all that is relative. If you have loudspeakers that have an insatiable craving for current, like Count Dracula's for blood, the Ios is not for you. If you have relatively efficient speakers, the line forms on the right. This amplifier is so sensitive that different AC cords, interconnect cables, speaker cables, and tubes can each affect the sound. The stock complement is OK, being fairly neutral. If you start tweaking the amplifier it can be expensive, but that's how one "voices" a system.

If your system falls half-way between highly efficient and pretty inefficient, you probably ought to consider one of the other, higher output amps in the deHavilland line; their Aries GM-70 comes to mind. I'm relatively certain they will all feature the same design philosophy: quality parts over flashy cosmetics. And I've come to respect George and Kara's ears: what they've said about various things, like tubes, I agreed with. That is to say, so far what they've written has matched my experience regarding "sound," so I'd tend to believe their promotional material, and I'd expect a consistent "house sound."

I'm not trying to equivocate, but even my quibbles have a plus and a minus side. Yeah, the power-rating is low, but what a gorgeous sound they make. Yeah, they are cable and interconnect sensitive, AC cord and tube sensitive, but that signifies they have the ability to bring up the subtlest changes in the music as well, allowing you to voice your system to taste. They are expensive, sure, but they are a bargain when compared to some of the pricier SET amps, and they do offer expensive parts rather than expensive-looking face-plates. Overall, this may sound like a pretty mixed bag, but there are far more goodies than clunkers in the mix. Handled intelligently, or with some loudspeakers (like the Quad Electrostatics, or Lowthers, or other horn-loaded high-efficiency types) with which they would be a no-brainer, you can get some truly wonderful sound, as good as it gets, without taking a second mortgage on your home. Can you read my lips? An excellent amplifier. Subtle and delicate when that is in order: powerfully authoritative when that is the order of the music. The Ios is an excellent all around performer.

Strategy and Tactics

Dropping six K into your sound system is something that has to be handled with finesse. You might have to redesign your kitchen or master bath first. Then when your partner sees how you are eager to please, you might get away with a new amplifier, stress-free. If you see that as a possible strategy, let me remind you that such home improvements are good in the present, but have the long term benefit of increasing the net-worth of your home upon re-sale. So, if your kids are about to leave for college, or get married, you might want to take on a smaller home when the moment is right. If you see your family about to enter that stage of life, you could rationalize a new kitchen or bath with the real increased selling price you might ask down the road. This might make it easier to spend six Large on an amplifier. Hell, if you are going for a status kitchen, you might be able to go for a new preamplifier as well. Maybe. The King knows what works best in his castle.

More Information

If you want to read more about various deHavilland gear, go to and surf around. There are links to other reviews, articles on various tubes and tube rolling, and specification sheets. I find the spec sheets very impressive, with long lists of high-quality parts that go into each and every one of their products. If you decide you want to purchase one or another of their amplifiers or preamplifiers, I'm sure you can receive good counsel from either George or Kara over the telephone, or through email. And when you place an order, just do a Ländler up to the phone, and be sure to tell 'em, "Maxie Waxie sent ya."

Ciao, bambini.

A slightly different version of this article appears in the current issue of Audiophile Audition.