| April 15, 2009
deHavilland Fisher Model 50A Mono Amplifiers
Progress, by definition, is forward motion, even in
audio. Glances back to accomplishments of the past are fine for enthusiasts of vintage
gear and do-it-yourselfers, but established commercial outfits such as deHavilland
Electric Amplifier Company aren’t supposed to take us back to yesteryear.
They’re supposed to gallop us into a better-engineered future. At least, that’s
what most high-enders would assume. But Kara E. Chaffee, chief engineer of deHavilland and
for ten years known for the manufacture of superb, low-powered, single-ended-triode (SET)
tube amplifiers, recently had an epiphany about a vintage, push-pull set of class-A
monoblocks.
About 18 months ago, a reviewer friend (not I) asked
Chaffee to restore to operating condition a pair of original Fisher 50A mono amplifiers, a
model developed in 1954. She took them apart and, after getting completely familiar with
their schematics and design, put them back together, this time with a bit more capacitance
in the power supply. She came to see that the design was not precisely vintage, if vintage
meant an overripe midrange, high coloration, and woolly bass. The 50A’s stock
features -- dual tube rectification, choke-input power supply, interstage transformer
drive, tube-regulated bias supply, and 1614 pentode tubes operating in triode output mode
-- all shouted quality and translated into excellent sound by today’s standards.
"The Fisher 50As were transparent yet full sounding," Chaffee told me recently
in a phone conversation -- not thin, they produced excellent detail without being forward.
But after shipping the 50As off to her friend, Chaffee
couldn’t get the sound of them out of her head. She sat down at her drafting board
(she still uses a physical drafting board and mechanical pencils), began to draw parts,
schematics, and values, and soon got the idea that she could manufacture this amp herself
-- upgrade its parts, clean up its looks, and recapture its sound for the contemporary
audiophile. To do this, she uses better grades of materials -- a milled aluminum chassis,
a machined top plate and transformer endcaps -- and has beefed up the circuit with more
current (four times as much in some places) and made some modifications. For sonic
reasons, she replaced the original 12AU7 tube in the second gain stage with a 6CG7. She
used a Lundahl interstage transformer to produce better bandwidth than the original, and
put new old stock (NOS) Russian and Jensen paper-and-oil capacitors in the signal path
instead of the paper-only caps Fisher had used. She eliminated one gain stage and an
input-gain potentiometer, thus simplifying the amp’s front end and further increasing
its transparency. Finally, she replaced the original 1614 output tubes ("which no one
loved," she said) with reissue Genelex Gold Lion KT88s, which would operate in
class-A and in triode mode -- just like the originals.
The result was one pair of deHavilland Fisher 50A
prototypes, rated minimally at 40Wpc in push-pull. They successfully debuted at the 2008
Vacuum Tube State of the Art Conference in Vancouver, Washington. Chaffee also showed them
at the 2008 Rocky Mountain Audio Fest, to acclaim from attendees and the audio press
alike.
Description and operation
The deHavilland Fisher 50A monoblock ($7250 USD per pair)
is smallish (9.25"H x 9"W x 16"D) and weighs about 42 pounds. A pair fit
comfortably side by side in a conventional audio rack with usable space of about 20"
wide or so. Each can also go next to the speaker it drives, in a more conventional
monoblock placement. Very handsome, the 50A is available in natural aluminum, or with
anodized black sides and a natural silver top plate. Each amp’s two transformer
covers are black, with oblong ventilation slots on the rear surface, near the top. Though
fairly retro in appearance, the 50A’s lines are clean, with little touches -- the
Model 50A badge on the long side panel, the deHavilland logo in red on the narrow front
panel -- that lend an air of contemporary suavity.
Each 50A has nine tubes: two KT88 output tubes (6550, KT90,
and 6L6 tubes are drop-in replacements), one 12AU7 for the first gain stage, two 6CG7s
(one for the second gain stage, one for voltage regulation), two 6CL6s for the interstage
current drive, and two 6CK3 rectification tubes. Aside from the aforementioned Genelex
KT88s, which are of new manufacture, Chaffee gets her results by using a mixture of NOS
signal and rectifier tubes -- Sylvania, Amperex, RCA. The Fisher 50A operates in class-A,
push-pull, triode mode. How much in class A? Chaffee says for more than 50% of its
stated output -- to about 25W.
One retro feature that Chaffee retains as stock is the
barrier strip on the rear panel, with its 4- and 8-ohm taps, but she also offers the
option of Cardas binding posts with either the 4- or 8-ohm tap hooked up, depending on
customer preference. With the Cardas posts, the ohm values of the taps can easily be
converted, if any change is needed, with a simple solder job of one wire at the back of
the chassis interior. My review pair had the Cardas binding posts set for the 8-ohm taps.
Also on the rear are the input for a 15A IEC power cord, a
screw-in holder for a 5A fuse, and a ground-float switch. This switch, a feature on all
deHavilland amps, is used mainly to shunt the ground so that it flows only through the RCA
interconnects, eliminating potential ground-loop problems. It can be used or not,
depending on individual circumstances, but there can be an audible advantage in floating
the power-line grounds. I did so, using my interconnects for both my signal and
ground-path return. Finally, as the amp’s input is exclusively single-ended, it has
only an RCA input jack.
On the top of the 50A, near the front, is a simple on-off
switch. Sitting between the two transformer covers, about midway and to the left side, is
an onboard meter and switch for setting the bias of the output tubes. The top plate is
perforated with two separate fields of air holes for ventilation -- one, measuring
3"x 3", near the 6CK3 rectifier tubes at the front end, and another, measuring
2" x 3", to the right of the bias meter. There is also a line of small holes
between the transformer covers along the top left side of the amp. It all adds up to a
look of functionality dressed with taste.
To bias the 50A, you simply fire it up and, after letting
the rectifier tubes warm up for 20 seconds, flip and hold the bias-meter switch. This
activates the meter, which reads the output current passing through the KT88s. Chaffee
sets the bias at 140mA, which is marked by a bold red line on the scrolled meter face. The
bias can be adjusted perfectly with a black knob next to the meter.
During the review period, most of which fell during the
Oregon winter, I appreciated the moderate doses of heat with which the 50As cheerily
warmed my study. But as winter turned to spring and outside temperatures rose above the
low 70s, these class-A amps raised the temperature enough that I had to open a couple of
windows to cool the room.
The deHavilland Fisher 50As sounded best after about 30
minutes of warmup.
System
The Fisher 50A amplifiers went into my reference system:
Cary 303/300 CD player; Nottingham Spacedeck turntable with Heavy Kit, Nottingham 9"
Spacearm tonearm, Zyx Airy 3 moving-coil cartridge (0.24mV), and Herron VTPH-2 phono
stage; Thor TA-1000 Mk.II and deHavilland Mercury 3 preamplifiers; Air Tight ATM-2 stereo
power amplifier; Von Schweikert Audio VR5 HSE loudspeakers (91dB/6 ohm); Cardas Golden
Reference and Verbatim interconnects (RCA); and Verbatim speaker cables with jumpers.
Mainly, I listened to the Fishers using the deHavilland
Mercury 3 preamp, and to the Air Tight ATM-2 with the Thor TA-1000 Mk.II or Mercury
preamp. I use a Balanced Power Technology Clean Power Center passive line conditioner for
the phono stage and preamp. The Cary player goes straight into the wall with a Harmonix
XDC Studio Master power cord. The Fishers were each plugged into a Cryo-Parts power strip
with Cardas Golden Reference power cables, and the strip itself was plugged into the wall
with another Golden Reference. Other power cords were Thor Red, Fusion Audio Impulse, and
Fusion Audio Predator. I have two 15A dedicated lines, both with Oyaide R1 duplexes. I
used PS Audio Critical Link fuses in the Cary player and deHavilland preamp.
My equipment rack is a Finite Elemente Signature Pagode
with Cerapucs under the Cary player. The room is treated with sound panels from Acoustic
Sciences Corporation; bookshelves line the right wall, shelves of LPs the left. The
listening room, which is also my study, is fairly small (12’ x 15’ x 8.5’);
I listen both in the nearfield, and on a couch about 8’ away from the plane described
by the front baffles of my speakers. The Von Schweikert VR5s are toed in about 3", so
that the tweeter axes fire slightly to the outside of my ears in my standard listening
position.
Vintage design, contemporary sound
Transparency wasn’t the first thing I thought of when
I heard the Fisher 50As. Instead, I thought of tonal density and weight. The 50As created
an audio tapestry -- an overall lavishness and permeable luxuriance open at times to
stunning accents and sparkle, anchored by the gorgeous weight of its own fabric. Yet
nothing seemed out of balance or over-the-top -- no artificial "detail"
bordering on brashness, no thickened and overemphasized midrange masking a missing top end
or bass, no too-forward treble or bass heaviness at all. These characteristics were akin
to the signature deHavilland sound I’d come to know from the Aries 845 and GM-70
monoblocks. Their designer describes the 50As as "easy-goin’ and relaxed,"
but to me they sounded more refined and distinctive than that -- like a clear incoming
tide that rushes over a reef, flooding the shallows with swirls and eddies of sound,
surging and withdrawing seductively, then returning with an onrush of surf that curls
through the clarity of the lagoon. I’d call their sound "romantic" except
for their precision, the wealth of detail they provided, their fulsome sonic palette. The
Fisher 50As could capture the weight of symphonic music, as well as all the snap and
sizzle of a salsa band.
I began my listening simply, testing tone with a solo
instrument that’s a particular favorite -- the cello, the baritone of the orchestral
strings. János Starker’s recording of J.S. Bach’s Suites for Solo Cello
(SACD/CD, Mercury Living Presence 470 644-2) sounded flat glorious. Starker’s cello
could sound nimble and sprightly in the Courante from Suite 4, for example, a
dance-like movement spiced with luscious octaves and rich in overtones. Or, in the Allemande
from Suite 2, it could be dark, mordant, and brooding, with a sinuous and aching melodic
line. Whatever the case, the character, pitch, resonance, and speed of vibration of each
string was movingly evident and palpable through the Fisher 50As. As Starker’s quick
intakes of breath punctuated these performances, the sublime illusion was presented of a
single musician playing a single cello in my study, sonorously and tragically alive.
Next, I listened to a violin soloist with orchestra -- a
recording of Henryk Szeryng performing Mozart’s Violin Concertos No.3 in G,
K.216, and No.5 in A, K.219, with Alexander Gibson conducting the New Philharmonia
Orchestra (LP, Philips Festivo 6570 024). Szeryng’s tone was just slightly dry,
eschewing the silvery sound of Jascha Heifetz, but his expressive range seemed the greater
for it, luxuriating in a darker, more somber mood in the Adagio of Concerto 3,
before breaking through to an utter sweetness in the middle passages of his cadenza. In my
experience, the sound of the violin is one of the hardest to reproduce -- many audio
systems render it as all too glossy, impenetrable in its silkiness, creating spurious
homogeneities of tone that belie the wide palette of timbres and musical emotions the
instrument can convey. The Fisher 50As, though, made Szeryng’s violin even more
expressive than I was used to, ranging through Concerto 3’s festive opening Allegro,
the alternately dark and mellow Adagio, and finally to the sprightliness of the Rondeau
(Allegro), revealing richer and more nuanced timbres, more complex harmonics, and a
more saturated tone when called for. The orchestra piped, plucked, and bowed through a
decorous, dancelike accompaniment that also demonstrated the vibrancy and grace of the
Fisher amps.
On Ellington Indigos, Duke Ellington and his
Orchestra play like a jazz chamber orchestra (LP, Columbia CS 8053). The first number,
"In My Solitude," has a resonant and liquid piano intro by Ellington that gives
way to comping as the horn section swings into the tune. Via the Fishers, the tune was
sweet and warbling, with fabulous tonal weight and authority throughout.
And so it was throughout the entire LP: full, saturated
saxophones; a brilliant and brassy trumpet; fabulously rich and weighty horn choruses; and
bass thump and drive. Each solo instrument -- Russell Procope’s clarinet, Johnny
Hodges’ alto sax, Paul Gonsalves’s tenor, Clark Terry’s trumpet -- had a
gorgeous specificity, a tonal signature and boundaries that seemed like anchors of sound
in the floating choruses of brass and woodwinds. Each cut was its own magical reverie --
sashaying saxes and brushes lapping a snare drum, metallic clouds of brass fanfares, a
tinkle or stride from Ellington’s keys, and airy flights of solos floating in from
anywhere in the orchestra. Listening rapturously, I couldn’t have been more happy
than if I were sitting in a club as these gargantuan ghosts of jazz preached the silly out
of me. The Fisher 50As and Ellington’s music were a perfect match -- both were rich
in mood and complex in scope, harboring deep sonic momentum, then releasing it in the
choicest drifts of airy nothing and such sweet thunder.
Talk about tonal weight and density -- Joe Cocker’s
1969 debut album, With a Little Help from My Friends (LP, A&M SP 4182), with
its cast of superstar British sidemen, rocked me all over again. Tony Visconti’s ace
engineering produced a dense, saturated tone, and the system captured it with terrific
torque and resolution. Cocker’s smoky baritone, nowadays whittled down to a wheeze
and a rasp, in 1969 had drive like a freight train, and his gospel skills were unmatched
until Teddy Pendergrass came along. Hoots, swoops, sustained shouts, warbles -- Cocker had
them all. "Sandpaper Cadillac," a little rock ditty probably thrown together in
the studio by Cocker and keyboardist Chris Stainton, is a small showcase of these skills,
along with the virtuoso accompaniment on electric guitar of Jimmy Page, formerly of the
Yardbirds and on his way to Led Zeppelin. Stainton fills in on bass, piano, and organ as
the other two sidemen lay down a funky blues walk of a start, piano and bass on the beat,
while Cocker croons a bit before the shouts and hollers come, interrupted only by the tiny
canticle of a solo-piano bridge. The Fisher 50As had no trouble controlling the VR5
HSEs’ dual 7" woofers; the tune’s bass foundation was always solid, without
lagging or bloat. Page’s fuzz-box guitar obbligatos sounded punchy and crunchy, his
tube-amp distortions (a Marshall with 5881s and GZ34 rectifier?) in time with the flow of
the tune. And Cocker’s vocal snuck and snaked up to the climax of his signature
sustained wail. There was that unmistakable grain to his voice, like a wisp of peat at the
bottom of a glass of Scotch, the system capturing all its various shades of tone and
shifts of vocal timbre all through the workingman’s waltz and whorehouse cha-cha of
the song. What the Fishers did was render the tiny, blues-based accelerations and
decelerations of the music’s momentum, and capture all the Cockney nuance of this
Britband performance. In each passage, the sounds came through with shoulder-shaking
immediacy, the music calling out to make my poor, beer-chugging, fiftysomething,
Friday-night body move.
For contrast to this vintage rock, I put on some acoustic
piano music. This was something the Fisher 50As excelled at, producing a vibrant, deeply
resonant, harmonically rich sound no matter the format. From "Red Book" CDs, for
example, I enjoyed pianist Ivan Moravec performing Chopin nocturnes, Alfred Brendel in
Beethoven’s concertos, Emil Gilels playing Brahms’s Concertos 1 and 2, and
Mitsuko Uchida in Mozart sonatas -- quite a range. But Rudolf Serkin’s performance of
Mozart’s Piano Concerto 25, with Claudio Abbado and the London Symphony Orchestra
(Deutsche Grammophon 410 989-2), provided a particularly fine illustration. Serkin’s
supple arpeggios, somewhat damped trills, and the accompaniment of the flutes and
violins, made for decorously merry listening. When the full orchestra joined in the first tutti,
a Jovian thrum and weightiness came through, evoking a sweet gravitas that only Mozart
can. The Fisher 50As did especially well with the bass viols in the first movement, Allegro
maestoso, their lightly bowed notes sonorous and fulsome, filling the woofers of the
right speaker with a warm vibrance that seeped away into the books of poetry and
philosophy that line the shelves along that wall. But, again, it was Serkin’s arpeggios
and trills in the long expository passages of this music that stirred me, his
interpretation so elegant, genial, and accomplished. The Fishers rendered all of these,
and each of the orchestral tuttis as well, with a fine and formidable ease, never
once losing resolution, force, or grace.
So far, so good -- tone, tone, tone. What about
imagery, soundstaging, and that modern thing called PRAT (pace, rhythm, and timing)? For
these I went south, to Cuban son montuno, and East, to Russian Modernism.
"Yiri Yiri Bon," from Eliades Ochoa’s Tribute
to Cuarteto Patria (CD, Higher Octave World 49640), is a feast of Cuban son music,
with what seems a small orchestra of rhythm instruments. The lead guitar and vocals, tres,
claves, maracas, güiro, bongos, and stand-up bass come through with terrific
clarity and sparkle. First comes the intro, on lead guitar; then, after the startling rap-rap
of a ringed finger on the wooden side of a güiro held up to the mike,
the son kicks in with the full group -- guitars and tres strummed and
plucked, bass thumped, claves tapped, maracas rattled, and a gorgeously intricate jarabe
on the bongos. Then, over the ample tide of this Cubano sound, Ochoa cries out a
tremulous, warbling "¡Yimboró, yimboró!" My entire room
completely coupled to the speakers, the sound at times seeming like full surround rather
than directional -- and yet, when I wanted to, I could identify the position of each
instrument in space, and the male chorus spread out across the rear of the soundstage. The
Fisher 50As presented what could have been a welter of percussion instruments and all
their various timbres with fine imaging, a good lateral soundstage, tremendous PRAT and
sparkle, and complete alacrity and precision, along with their characteristically
saturated tone.
The famed Russian conductor Valery Gergiev conducts
the Kirov Orchestra in one of the most stirring recent recordings of Stravinsky’s Le
Sacre du Printemps (CD, Philips 289 468 035-2). It’s a fine disc with which to
test the sonic palette of a system, and particularly of amplifiers. In Part One’s Introduction
and The Augurs of Spring, Stravinsky’s modernist ballet seems at first a
series of exquisite miniatures, as the bassoon, flute, and oboe take their brief solos.
Then the dance begins with a series of sharp, pulsing, bowed strokes from the strings that
are full of eccentric, thrilling accents and stirring fortes. After the first
fanfare and initial blast of bass-drum strokes, a spinning drama builds among the horns,
strings, and woodwinds, which share and alternate in taking the theme. The Mock
Abduction culminates in assaultive, elephantine crescendos -- the horn, woodwind,
string, and brass sections swell to the edge of shrieking cacophony, this rapidly followed
by a series of thunderous strokes on the bass drum that could be the death of an ordinary
amplifier -- if not in tonal accuracy, then in the congestion of timbres; if not in a
shallow, shrunken soundstage, then in the faintness of bass slam and speed.
I’ve heard solid-state amps achieve such slam, but not
without sacrificing tonal color and treble clarity. And I’ve heard tube amps deliver
the sparkle, but without the slam. The Fisher 50As reproduced all of
Stravinsky’s compositional complexity as manifested in this magisterial performance
without shying away, with no diminishment of orchestral flavors, and with thundering
blasts of bass drum and timpani. When I listened at moderate levels, my handheld
RadioShack SPL meter measured the peak output as topping out at 95dB on the bass-drum
strokes, confirming what, at that first stroke the first time through, my gaping mouth was
already saying: Wow!
A question remained about voices. I brought out recordings
by sopranos Renata Tebaldi, Maria Callas, and Victoria de los Angeles. I ended up
gravitating to "O mio babbino caro," from Puccini’s Gianni Schicchi,
sung by de los Angeles, with the Orchestra of the Rome Opera House conducted by Gabriele
Santini (LP, Angel/EMI AV-34048). This is one of the great soprano arias, and de los
Angeles sings it with moderate vibrato and long, full, expressive notes. It’s a
touching interpretation, and the Fishers rendered it with purity and smoothness. So often
with recordings of sopranos, one hears only the voice, not the singer’s body -- the
diaphragm and midsection, which provide the foundation for the voice. With the Fisher
50As, I felt as if I was hearing the full creature -- all of the loveliness of de los
Angeles, with no plaintive tinniness or shriek. Her top notes were full of dynamism,
whether in attack or diminuendo.
Comparison and conclusion
The Air Tight ATM-2 stereo amplifier, itself an audio
classic, albeit a more recent one, has been my reference for over two years. An 80Wpc,
high-current, push-pull design that operates in ultralinear class-A/B, it generally has
served me wonderfully, especially in combination with Sonus Faber’s Grand Piano Home
speakers. However, the Von Schweikert VR5 HSE speakers have revealed characteristics of
the Air Tight that the warmish Sonus Fabers had left hidden.
Frequently, and especially with orchestral music, I heard
brightness and a kind of "mail-slot" effect in the Air Tight’s sound -- as
if the top and bottom of the full range of frequencies had been chopped off. The Air Tight
didn’t produce anywhere near the bass and slam of the 150Wpc, solid-state PBN
Mini-Olympia amp I’d reviewed last year or the 40W deHavilland Fisher 50As. There was
also a slight overdriven quality to the treble: a decided lack of silkiness and a somewhat
grainy top end. I would have liked more body and midrange warmth, too. My notes on
listening to some of the same orchestral recordings and piano concertos mentioned above
tell me that, through the Air Tight, the violins were slightly glossy (though not
bleached), timpani strokes were soft, and timpani rolls were muted, more midrangey than
deep bass. I wrote that crescendos tended to lose refinement and articulation through the
Air Tight ATM-2, confusing the VR5 HSE speakers. To say that I was dissatisfied is an
understatement. I felt frustrated -- I’d upgraded my speakers, and now my reference
amp no longer seemed to be the performer I’d thought it was.
But with operatic and choral voices, particularly tenors
and sopranos, the Air Tight was superb -- clear, clean, extended highs, pretty on top, and
very liquid. Always lovely with singers, the ATM-2 worked exceptionally well with the Thor
TA-1000 Mk.II or deHavilland Mercury 3 preamplifiers and the Von Schweikert VR5 HSE
speakers.
Yet, overall, this was a no-brainer -- whatever the Air
Tight ATM-2 could do, particularly with voices, the Fisher 50A monos could do at least as
well. And what the Air Tight could not deliver -- tonal weight, midrange warmth and
body, bass slam and definition, a full sonic palette -- the Fisher 50As delivered in
spades. The Fishers and my Von Schweikert VR5 HSEs seemed a perfect match.
If your speakers can get by with relatively moderate power
(40W nominal, perhaps 45W at clipping), you should strongly consider auditioning the
deHavilland Fisher 50A monoblocks. Their combination of top-to-bottom balance, clean and
resolving highs, magnificent bass and slam, articulate speed and PRAT, and gorgeous
brocade of sound, seems to me very hard to beat. In fact, I couldn’t beat
them. I gave in to the music, sold the Air Tight ATM-2, and bought the review pair of
Fisher 50A monoblocks. They took me back to the future, and I’ve never been happier
with my system’s sound.
. . . Garrett Hongo
garretth@ultraaudio.com
deHavilland Fisher Model 50A Mono Amplifiers
Price: $7250 USD per pair.
Warranty: Three years parts and labor.
deHavilland Electric Amplifier Co.
2401 NE 148th Court
Vancouver, WA 98684
Phone: (360) 891-6570
E-mail: 6sn7@abac.com
Website: www.dehavillandhifi.com
|
