See the complete review in TONE AUDIO
Magazine No.71
- 40 watt dual mono amplifier.
- Optional transformer b alanced XLR
Inputs & RCA.
- Input level control makes it
possible to use with no preamp.
- Ultra cool bias adjustment - no
tools required.
- Large Meters - let you maintain
PERFECT tube matching without effort.
- Exotic parts - cost no object
design.
- Compatible with a wide range of
speakers
- KT66 Ultra-linear output stage is
also compatible with other tubes.
- Dual Mono design
- Lifetime warranty
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One
of the things that makes the Zen
Mystery Amp unique is it's insane
power supplies.
A typical tube amplifier this size
uses power supply capacitors
totaling about 80
micro-farad. |
 |
The Mystery Amp has 45 00
micro-farads. Yes, that's
about 50 times more than
normal but we did mention that
this was a cost no object design
and th e massive capacitors come
with some huge sonic benefits.
Each amplifier's power supply has
enough stored energy to start your
car and melt all four tires to the
garage floor!
In fact, these capacitors are so
large that the amplifier sounds as
if it's being run on batteries.
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Steve Deckert - owner DECWARE High
Fidelity Engineering
ZEN MYSTERY AMP
The
Zen Mystery Amp's bias system makes
sure you know if your matched tubes
really match, let you force them to
match when they don't and keep your
tubes from failing prematurely not to
mention sounding their best throughout
their entire life cycle.
THE ZMA ADJUSTABLE BIAS SYSTEM
The Zen Mystery Amp features
4 independent bias supplies and 4
precision current meters, one for each
output tube, so that adjusting one has
zero affect on the others!
The meters give you a
real time view of how each tube is
doing and how well they match each
other.
A simple balance control
between each pair of meters lets you match
the tubes at any time while the amplifier
is on.
The meters also show
you if a tube is going bad and which one -
at any power level.
A visual power indicator,
the meters begin to dance when the amp
reaches maximum output.
True Analog movements in
each meter make it possible to predict
tube performance by simply watching the
meters behavior during warm up.
The
Mystery Amp came directly from our
signature Zen TORII mono-blocks.
We wanted something with similar
performance, but in a single chassis and
at a reduced cost. By building two
mono amps in a single chassis,
eliminating the fancy transformer
covers, reducing the power a bit, using
smaller meters and finally by making
balanced XLR inputs optional ~ it was
possible to maintain the same cost no
object design and internal parts used in
our $12000 mono-blocks.
The Mono-blocks are unique in that they
have a massive power supply with caps so
large it is possible to eliminate the
choke and any dropping resistors feeding
the output stage. Unless you see
an amp with similar size caps, you can
be certain that it has at least one if
not both of these current limiting
necessities. This is why the
Mono's sound better than almost
everything. Well, on that note,
the Mystery Amp explores this zen
approach a little further by doubling
the capacitor size and eliminating the
dropping resistor that feeds the input
stage. Instead a vacuum regulator
tube was used to drop the voltage with
no heat and 20 times the ripple
rejection of the resistor it
replaces. This was a personal goal
of mine because it makes this the first
tube amp power supply in the world that
doesn't use a choke or any
current robbing resistors to supply both
the input and output stages of the
amp. Consequently there is no heat
or parts to fail. The real
impressive part however is the liquidity
and speed that results from eliminating
these parts.
This is about as close to pure DC power
as you'll ever get in a 500 volt
amplifier. As a result, the
Mystery Amp will have about 50 times the
immunity to dirty power from your wall
outlet.
In the Mystery Amp, I created
independent bias supplies for each
output tube so that when you adjust one
tube, it does not affect the other
tubes. That way you only ever have
to adjust it once, instead of ten times
until you happen to hit it just
right. Also a lot of time was
spent defining windows of adjustment
that worked with all the recommended
output tubes without allowing the user
to get into too much trouble should
he/she miss adjust it. In fact,
most of the time it will impossible to
get into trouble ensuring long happy
tube life.
The biggest thing is output tube
matching in push pull amplifiers for
linear output and max power, so to that
effect rather than have a bias
adjustment for each tube, we have one
for the pair and one as a balance
control located between the meters so
that the user can perfectly match the
meters at any time in less than a
second. Each channel is set up this way.
You'll find this handy since tubes drift
with temperature and this allows you to
counter it on the fly as you listen
without tools. It takes all the
pain in the ass out of owning a fixed
bias amplifier. Of course the
meters make great tube testers and
clipping indicators allowing you to see
if any one tube is prematurely clipping
relative to the others despite being
perfectly matched at idle.
The voicing on this
amplifier is more particular than
anything I've done, short of the TORII
Mono's. I say that because I have
a very strong preference for the 6N23P
input stage as that is the only tube I
like in this amp. Cryo-treated
with silver leads, and flat stacked
beeswax film caps are used for all
internal coupling, and 2 watt carbon
composition resistors throughout the
signal path. Factory Tube
compliment is the Tungsol KT66, and OA3
and for the driver stage a pair of
Russian 6N23P-EV.
Another delightful thing about this
amplifier is that is has zero negative
feedback so the imaging and sound stage
depth are unrestricted and capable of
rending whatever is on the recording.
In the end, it is every bit the fidelity
and performance of the Zen TORII Mono's
with a bit sweeter top end. On
most speakers greater than 86dB there
was no noticeable difference in power
between the Mystery Amp and the Mono's.
The OA3 feeding the input stage combined
with double the capacitance of the
Mono's gives the Mystery Amp
unparalleled accuracy and liquidity.
NOTE: There is also a forum
thread on the Mystery Amp that I
started early in the design process.
-Steve Deckert
World Voltage
compatibility 50/60Hz
INPUT TUBE
Compatibility: 6N23P, 6922, 6N1P, 6DJ8,
7DJ8
OUTPUT TUBE
Compatibility: EL34, 6CA7, KT77, KT66,
7027, 5881, 6L6G
INPUTS: OPTIONAL
TRANSFORMER BALANCED XLR INPUTS
INPUTS: SINGLE-ENDED RCA
INPUT
OUTPUTS: 4 & 8, or 8
& 16 OHM SPEAKERS
IDLE CURRENT: 40~70 MILS
PER OUTPUT TUBE - ADJUSTABLE
HIGH B+ VOLTAGE: 410 VDC
WITH LOAD
INPUT IMPEDANCE: 100 K
OHMS
INPUT SENSITIVITY: FULL
POWER @ 2.0 VOLTS ON RCA INPUT
POWER INTO 4 , 8 or 16
OHMS: 38 WATTS PER CHANNEL
NOISE: -90dB
PRECISION CURRENT METERS
0 to 100 MA
WINDOWED BIAS CONTROL to
ADJ OUTPUT TUBES
DYNAMIC BIAS BALANCE
CONTROL FOR PERFECT MATCHING of EVEN
UNMATCHED TUBES
600V CRYO TREATED COPPER
FOIL BEES WAX - SIGNAL CAPACITORS
OPTIONAL 20 POS STEPPED
ATTENUATOR w/ GOLD CONTACTS for INPUT
LEVEL (GAIN) CONTROL
4400 UF 500V LABORATORY
GRADE POWER SUPPLY CAPS
GOLD TEFLON INPUT JACKS
RECTIFICATION: ULTRA
FAST RECOVERY 3 AMP 1000V
MACHINED STEEL CHASSIS
with POWDER COAT FINISH
HI-GRADE FUSED IEC
CONNECTOR for REMOVABLE POWER CORD
SOFT START- NO STANDBY
NEEDED
SHIPS WITH:
PREMIUM GRADE KT66
OUTPUT TUBES
PREMIUM GRADE 6N1P-EV
INPUT TUBES
OA3/VR75 REGULATOR TUBES
SIZE: 19-1/8" WIDE
x 13-3/4" DEEP x
8-3/4" HIGH
NET WEIGHT: 43 lbs.
WARRANTY: LIFETIME TO
ORIGINAL OWNER / 90 DAYS ON TUBES
We carefully hand select and match the
tubes for these amplifiers. The
amplifiers are tested and burned-in
with the tubes you get.
These include four Russian Military
Grade 10,000 hour 6N23P-EV's with gold
grids, four KT66's and two OA3's per
amplifier. (Note the amplifier
is also compatible with 6N1P / 6922 /
6DJ8 / 7DJ8 as well as KT77, EL34,
7027, 5881, 6L6)
The
ZMA comes with some options.
All of these
can be configured from within the
shopping cart.
OPTION 1
- VOLTAGES
You will be able to select between
110/120 volts 50/60Hz or 220/230/240
volts 50/60 Hz. We will
investigate your countries actual
voltage and plug type and wire the amp
accordingly.
OPTION 2
- WOODS
You can select from a black figured
base OR contemporary styles like the
ones shown below. Along with the
option to have one made in custom
woods. When custom woods is
selected, a phone call about what wood
and what finish you want will happen.
Base options from top to bottom:
Maple, Cherry, Black, Walnut, Black
Figured.
OPTION 3
- VOLUME CONTROL
You may select from a normal
smooth-action volume control OR a
stepped attenuator if you prefer
those. Our attenuator has 20
steps.
OPTION 4
- KNOBS
There are also some knob
choices. From left to right
are Ebony, Gold, Black, Cream,
Walnut.
OPTION 5 -
OUTPUT TRANSFORMERS
Your amplifier can be configured to
use 4 and 8 ohm loudspeakers, OR it
can be configured to use 8 and 16 ohm
loudspeakers.
OPTION 6
- INPUTS
The amplifier comes standard with RCA
inputs (aka Single-Ended inputs) but
can also be configured with
transformer-balanced XLR inputs.
When the amp is configured for XLR
inputs, you will still have RCA inputs
and either can be used, but not both
at the same time.
ZEN MYSTERY AMP OWNER'S MANUAL
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