Biasing the Power Tubes
As with all power amplifiers that are not self-biasing, hand biasing the
twelve power tubes is essential for optimal performance. Jadis recommends
that you bias the power tubes anywhere between 4 and 5 volts. Pierre has
even experimented with biasing to 6 and higher.
Choosing the right bias for your musical taste is essential to getting the
best from the DA-7. In my experience, the higher the bias, the richer the
sound. But higher bias also means that tubes run hotter and burn out faster.
It can also produce sound overly rich and full, to they extent that the amp
begins to sound too sweet, warm, thick, or even syrupy (depending upon your
choice of tubes).
It would be very nice if Jadis had made biasing the DA-7ís twelve power
tubes as simple as adjusting twelve individual settings on the top of the
amp and reading the results via a built-in gauge. No such luck. Instead,
Jadisí diminutive bias adjustment screws are located inside the amp. You
must turn off the amp, remove the protective tube cage on top, turn the amp
on its side, remove the 9 screws that hold the bottom plate in place and get
the plate out of the way before the bias adjustments become visible.
Once you turn the amp over, expose the adjustment screws, and turn the amp
back on until it stabilizes, you must work with four adjustment screws, one
for each row of three tubes, rather than twelve screws, one for each tube.
Jadis forces you to bias an entire row of three tubes at a time. And while
the screws are easy to turn, the tiniest movement can make a big difference
Given that no two power tubes measure exactly alike, and that bias requires
readjustment as tubes age (differently), you must bias the three tubes in a
given row to an average level, and recalibrate them every three or four
months. To facilitate the process, you will find yourself mapping out the
twelve tubes on a sheet of paper, writing down initial bias levels, and
adjusting from there.
If you encounter a marked disparity in bias levels in a particular row of
three tubes, you must then begin to swap tubes from row to row until the
bias range in a particular row is as close as your particular assortment of
twelve tubes allows. Assuming you donít burn a hand or drop a tube in the
process, getting it right can be fun. Itís a bit like a treasure hunt, and
ideal for compulsive-obsessive personalities.
Itís an especial joy when you discover that the bias of an individual tube
is to some extent dependent upon the bias of the other two tubes in its row.
When you move a tube that measures 5.3 volt to another row, it may suddenly
measure 4.6. Hence what initially looks like a good move may not prove
Moving power tubes between sockets and rows is not as intellectually
challenging as playing chess, but it does require attention and patience.
Much experimentation is required to get your twelve tubes positioned
optimally. You may even have to purchase new tubes after you discover that
eight tubes are easily adjustable while the four others variously measure
much higher or much lower than the others. This becomes more of an issue as
Operating a voltmeter (I use a Radio Shack) to measure the bias is easy. You
put one lead on the chassis, another on the end of one of the twelve fuses
(one for each power tube) easily accessible inside the amp.
Warning. Turning the bias screws is fraught with danger. Brush against the
wrong bit of metal with a metal screwdriver and you may be shocked blue by
500 Volts. This may help cure your schizophrenia, but at the cost of the
hair on your head or, if you donít have any . . . letís not go there.
The trick is to use a plastic screwdriver to adjust bias. Touch the wrong
thing, and no harm is done.
Not so fast. Finding a plastic screwdriver in this day and age may require
another little treasure hunt. It seems Radio Shack no longer stocks plastic
screwdrivers. Nor do major automotive tool distributors (at least in N.
I spent an entire afternoon searching for a plastic screwdriver. I went to
carpet stores, auto parts stores, a locksmith, hardware stores, you name it.
I tried everything short of driving 45 minutes each way to a computer chain
outlet that couldnít tell you what they stocked when you called them on the
Finally, a local locksmith suggested I check out ďthe old guy in the TV
repair shop across the street who keeps irregular hours.Ē Inside a virtual
museum of television history, open for 60 years and stocked with more
antiquated TV consoles than I wish to recount, stood a man well into his 80s
who boasts that he still works 12 hours a day. Behind him, on his tool
display, hung six long Zenith TV adjustment screwdrivers in their original
packaging. One had a zip code for the Zenith address; one other was
manufactured before zip codes came on the scene. I bought one of each size
available. One fit the Jadis. I am still alive to tell the tale.
Models and Distribution
I briefly discussed the Jadis amplifier line with Pierre Gabriel. In his
estimation, the next model up in quality from the DA-7 Luxe is the JA-30 30W
Class A monoblocks. These also cost $10,500/pair. 30W pure class A usually sounds
more powerful than 30W A/B, but itís still 30W.
Then come the JA-80 80W Class A monoblocks, which are very different animals; rather than
using a board, they are exclusively hard-wired and employ Jadisí proprietary
triple charge technology for even better sound. Thanks to dollar
devaluation, they cost $18,500/pair US. I didnít even ask the price of the
200W monoblocks that many favor.
Pierre also extolled the virtues of the Jadis DA-60 INOX-LUXE, a 60W per
channel, Class A, auto bias, triple charge technology integrated amp that
costs $10,500. I quote: ďFor an integrated, this is our Ďkiller product.Ē
Iíve put in my request for a future review.
As of this writing, Brooks Burdan Ltd. in Southern California has become the
first in-state distributor of Jadis products. Four more U.S. dealers should
be in place by the summer.
Authorized repairs and upgrades for older Jadis units in the United States
are available from Ron Cox in Colorado (970-882-2530). Like Brooks Burdan,
who carried Jadis for many years, Ron knows Jadis backwards and forwards and
makes all repairs with Jadis parts. People on the East Coast can work with
Jadisí other knowledgeable authorized repair/upgrade person, Avis Brand
When I received my used Defy 7 Mk. II, Scot Markwell informed me that the
wire to the speaker outputs, which runs much of the width of the chassis,
had been upgraded to a Siltech silver harness. Scot explained that while
Jadis stock wire was good, it has a soft, overtly romantic presentation that
lacked tight focus and detail. The Siltech silver harness, in his opinion,
made the presentation far more accurate and realistic.
Even though Pierre Gabriel states that Jadisí present choice of internal
wire is quite good, he offers a similar upgrade to the DA-7 using his own
proprietary cabling. The upgrade can be performed on both the speaker
outputs and the preamp (source) inputs. This is a Jadis-sanctioned upgrade.
If anyone contacts Jadis in France requesting an internal wire upgrade, they
are directed to Pierre who performs the service and installs his own cable.
Pierre explains that manufacturing his cable is far more complicated than
simply removing silver wire from a roll and putting a shield around it.
There are a large number of time-consuming steps involved.
My DA-7 came equipped with Pierreís cable mod to the speaker outputs. While
I have never heard the amp without the upgrade, I have every reason to
accept what Scot and Pierre claim that the speaker output cable upgrade
accomplishes. I do know for certain, after much experimentation with hook-up
wire in my former Bruce Moore Companion III preamp and Michael Green
Chameleon III speakers, that choice of hook-up wire makes a major
difference in sound quality and resolution. Ask Mike Farnsworth of Talon
Audio, who not only changed the hook-up wire in the Khorus X, but also its
braiding configuration. I therefore have every reason to recommend the
I look forward to the day when Pierre has enough extra hook-up cable
available to send me his upgrade cable for the inputs. He claims this will
result in a considerably more detailed presentation. This will be all for
the better. While the DA-7ís resolution tops what I heard through the Defy 7
Mk. II, I have heard more throatiness on Terry Evansí voice when listening
through good solid-state amplification. My hunch is that the change of wire
to the DA-7 inputs will greatly increase resolution.
The Jadis DA-7 Luxe is among the best sounding amps I have yet auditioned in
my home. I would not have devoted close to 3400 words (so far) to discussing
how to get the ultimate sound from this amplifier if I did not find the
effort worth it.
Last night I sat in rapt silence listening to the entire ECM disc of Chants,
Hymns and Dances. The disc features improvisations on music by Gurdjieff and
Tsabropoulos performed by Anja Lechner on cello and Vassilis Tsabropoulos on
piano. The team is beautifully recorded, flattered by an extremely spacious,
resonant acoustic of the kind heard on so many ECM recordings produced by
With many of the amplifiers, speakers, and cabling Iíve auditioned, a lack of
ultimate transparency encapsulates voices and instruments recorded in a
resonant acoustic in a somewhat gray, whooish halo. No such issue listening
to Chants, Hymns and Dances with the Jadis DA-7 equipped with Pierre
Gabrielís preferred tube complement. Thereís a great deal of clarity and
detail on top, accompanied by an extremely realistic sense of listening to
two musicians situated in a large resonant space. The effect, given the
trance-like nature of the music, is mesmerizing.
Listening to these artistsí improvisations on Gurdjieffís music through the
DA-7 gave me as direct a connection to the soul of music as Iíve experienced
in my years of sonic exploration. Itís as though all those metal boxes and
wires finally got out of the way, leaving me and the musicians alone in the
I of course auditioned two of my stand-bys, the opening of Rachmaninoffís
Symphonic Dances (Reference Recordings) and Canteloubeís Songs of the
Auvergne as performed by Karina Gauvin and a chamber ensemble (CBC Records).
With the GE 5751 JANs in the transmission stage, the sound is very crisp,
full, and transparent. Bass is extremely tight, piccolos sing, the triangle
In my extremely live space, minimally treated due to the spousal acceptance
factor, the GE 5751 JANs give highs a bright, slightly silvery quality
(similar to what I heard in far greater abundance from the Parasound Halo JC
1 monoblocks) that some may find objectionable. Thereís a similar brightness
to Davidís tenor voice when he practices his Church music in our dining
room. For such listeners, the GE 5-Star 5571/7025 combo in the transmission
stage, or even a GE 5-Star 5751/GE 5751 JAN combo, may prove more enjoyable.
At first I thought that bass sounded less full using four GE 5751 JANs
rather than either tube combo mentioned above. This, I believe, is due in
part to the speed of the GE 5751 JANs. The more romantic presentation of the
5-Star tubes adds a modicum of extra resonance to drums, double basses, and
even cellos that is not always heard in live performance. The 5-Stars also
soften the top a bit, so that the initial attack is not as fierce, and
bathes the presentation in a most wonderful, romantic glow. It may not be
exactly lifelike, but it sounds positively delicious.
While all three tube choices suggested above conveyed the complexity of
Gauvinís voice, the GE JANs made the sharp leading edge of the tone more
apparent. The 5-Star combo put more emphasis on the sound beneath the edge.
Some might say that the 5-Star combo is less detailed, softer, and more
forgiving. But itís also less crisp and transparent.
When it comes to truthfulness of presentation, we can only speak with
certainty if we are intimately familiar with the acoustic environment in which
a performance is recorded. All the tube choices offered so far are extremely
satisfying musically. Choice will ultimately depend upon associated
equipment, cabling, room configuration, and acoustics.
Listening to excerpts from the recent Telarc hybrid SACD release of
Beethovenís Symphony No. 9 with Donald Runnicles conducting the Atlanta
Symphony proved another rewarding experience. (I played the recording in
two-channel mode using the Theta Gen. VIII). Using the 5-Star combo in the
DA-7, I played the final "Ode to Joy" to nine attendees at our recent potluck.
It was so gratifying to watch everyone sitting with rapt attention.
Although a number of listeners commented on muddiness in the upper bass - a
situation somewhat room dependent and far less noticeable with all GE 5751 JANs in place - I was most struck by the clarity and focus of voices and
instruments. Even at loud volume, with instruments, soloists, and chorus
going full blast, the DA-7 transmits information with enviable clarity,
offering promise of energy to spare. And it sounds so beautiful!
As I reread this report, I wonder if some readers will
somehow equate "beauty" with softness. Please don't. The slam on drums in
Terry Evans' great Blues No More (Audioquest/JVC-XRCD), the sharpness
of attack on the drums edge, the sizzle of the cymbals - all are as fast and
realistic as it gets. If I were to distinguish between the Jadis DA-7 Luxe's
speed of attack and that of the killer Parasound Halo JC-1 monoblocks, I
would say, to use an analogy, the Jadis might leave you or your partner
wanting more, while the Parasound's aggressiveness might be best described
as "Slam, bam, thank you ma'am." A chacun son gout.
I have just revisited a marvelous, transportive recording of Himalayan
singing bowls, Deuter's Tibet - Nada Himalaya 2 on New Earth
Records. I first auditioned this disc on the excellent Red Planet Labs
STR201 stereo amp. With the Jadis, the edge of attack on the high-pitched
bells is extraordinarily clear. Overtones go on for days, blending into a
mesmerizing sonic tapestry. Underneath those high sounds, lower gongs
judiciously struck in the background extend way beyond and
above the speakers. Yes, it may be a sonically compromised Redbook CD,
lacking the resolution of DVD-A and SACD. But the special qualities of these
bells, which have been used for meditation and spiritual practice in India,
Nepal, and Tibet for thousands of years, comes through virtually
undiminished with Jadis amplification.
Diana Krallís by now Verve classic When I Look in Your Eyes presented a
wonderful smoky sultriness with the GE 5-Star 5751/7025 combo. Using all GE
5751 JANs revealed more of the artificially miked sound around Krallís
voice, and rendered accompaniment far more crisp and present. Both
presentations were delicious in their own way. The combo of GE 5-Star 5751
and GE 5751 JAN, which Iím still experimenting with, may ultimately prove
the most satisfying of the lot.
I guess Iím not finished with tube rolling after all.
The Jadis DA-7 Luxe is a wonderful-sounding amp. Its wealth of sonic beauty,
openness, air, and power are matched by a frequency extension and sense of
control often absent from tube gear. Offering the dual advantages of cooler,
less power-consuming Class A/B operation, the Jadis DA-7 Luxe is a must-audition for anyone desiring hour after hour of gratifying listening.
- Jason Victor Serinus -
Digital Front End
Sony 707ES transport modified by Alexander Peychev of APL Hi-Fi
Theta Gen VIII DAC/Preamp
Theta Carmen II transport (on loan from Theta)
Jadis DA-7 Luxe
Talon Khorus X speakers MK. II (with latest modifications and Bybee filters
on woofers and tweeters)
Nordost Valhalla single-ended and balanced interconnects and balanced
Nordost Valhalla bi-wired speaker cable
Nordost Silver Shadow digital interconnect for DVD-V
Nordost Valhalla Power Cables
Elrod EPS-2 Signature
Also on hand and sometimes used:
Interconnects: WireWorld Gold Eclipse 5 and Gold Starlight 5 digital,
Harmonic Tech Magic One, Acoustic Zen Silver Reference II balanced, and
Nirvana BNC-terminated digital.
Power cables: Elrod EPS Signature 2 and 3 plus EPS 1, 2, and 3; WireWorld
Silver Electra 5, PS Audio X-treme Statement, Harmonic Tech, and AudioPrism
PS Audio P600 Power Plant power synthesizer with MultiWave II
PS Audio Ultimate Outlet; PS Audio Power Ports
Ganymede supports in main digital chain and under speakers
Michael Green Deluxe Ultrarack, Basic Racks and Corner Tunes
Michael Green Audiopoints, and Black Diamond Racing Cones elsewhere
Shakti stones on amp, Theta, and transport
Stillpoints ERS EMI/RFI sheets on most components
Bedini Dual Beam Ultraclarifier, Audioprism CD Stoplight,
Marigo Signature Mat for use atop CDs, Ayre demagnetizing CD and the
original Sheffield/XLO demagnetizing and break-in CD.
25.5í deep, 37í wide opposite the speakers, 21.5í wide in the listening
area. Ceilings are 9í2Ē high with heavy wooden cross-beams. Floors hardwood
and carpet. Speakers are totally decoupled from the floor, resting on
Ganymede supports and maple.