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pa21 User manual
Serialnumber: .....................................................
Mystère
FUSE
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INSIDE
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The pa21 maximizes all our efforts with more power, more
dynamics and greater flexibility. The full-sized chassis allows us to use
larger transformers and bigger caps and resistors, delivering greater
control and detail.
The result is 55 watts of pure pentode output per channel, and
im proved stability throughout the amplifier. We do implement a very
modest amount of global negative feedback to make the amp rock
solid.
With more room at their disposal, our engineers continued to
search for improvements, such optimal efficiency, the lowest signal
degradation and the greatest immunity from noise and hum. They
accomplished just that, with carefully separated and laid-out signal
ground, power supply ground and chassis ground schematics.
We’ve also advanced our proprietary Adaptive AutoBias board with
a special circuit that re-calibrates it for EL34s or KT88s. One flick of a
switch allows you to run either tube at its optimal level. And as always,
the board continuously monitors each tube, tweaking it to its sweet
spot. There’s no biasing, no need for matched tubes, no worries.
Combine the pa21 with its matching full-size ca21 preamplfier,
and experience a truly reference-quality system, without a typical
reference-quality price tag.
Specifications
Power output 55+55W @ 8 Ohm 1%thd
Bandwidth 4Hz-80kHz +/- 0,3dB @ 1W
9Hz-52kHz +/- 1dB @ 40W
Noise <-90dB wtd-a
Gain 26dB (20x)
Distortion 0,09% @ 1W
0,2% @ 10W
1% @ full power 55W
Consumption 230W max
Net weight 27 kg
Dimensions 430x420x200 mm (l
xwxh)
Websites
ww w.mystere-eu.com
ww w.mystere-usa.com
pa21 Description
Mystère
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pa21 Thank you
We would like to thank you for choosing our Mystère pa21 stereo power amplifier as an important part of your music system.
Working with components across the spectrum day in and day out for more
than 30 years led us to adopt an unassailable philosophy: the only acceptable
level of quality for the products we produce is the highest quality, regardless
of price point.
We have staked our reputation on this and are certain that the products we’ve
already brought to market reflect this principle. We feel comfortable in stating
that our standing in the audio community is of the highest order and we’re
certain that Mystère will only serve to enhance that standing.
We hope that the Mystère pa21 stereo power amplifier will make you want to
follow our next steps in expanding this new range of products. If you have any
questions or comments, don’t hesitate to contact us. You can also share your
thoughts with others at www.audioreview.com or other review sites. On the
www.mystere-eu.com website you will find links to these and other websites.
Our prices are kept low by using word-of-mouth and customer feedback, and
we would appreciate hearing what you have to say about our product. If you
need service during or after the warranty period, please contact us.
Thanks again for your support!
Herman van den Dungen - DUROB AUDIO BV
Table of Contents
Description
................................................................................................ 2
Specifications
..................................................................................... 2
Thank you
..................................................................................................... 3
Warning - Setup - Contents
..................... 4
Inputs - Controls
........................................................................ 5
Protection
..................................................................................................... 5
Tube Basics
................................................................................................ 6
Troubleshooting
........................................................................ 7
Warranty Info
....................................................................................... 8
Story - Contact
................................................................................ 9
Copyright - Durob Audio B.V. 2009
Mystère
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pa21 Warning - Initial setup
To prevent serious injury, electrical shock or fire:
• Do not operate with bottom plate removed.
• Keep away from rain and moisture.
• Disconnect all cable connections before changing fuses and/or tubes.
• Do not replace tubes without reading instructions.
• Do not replace fuses or tubes if you have any doubt about your ability to
do so. We accept no responsibility for any personal or material damage
due to incompetent use or users.
• Remove the Mystère pa21 from its packaging. Use the white gloves.
• Remove the tube cage by pulling it up and away from the amplier.
• Remove the protective foam surrounding the pre-installed tubes.
• Check that each tube is rmly seated in its socket. Use gloves.
• Replace cage back in its place if desired.
• Check to see the power switch is o (down).
• Connect each source to the corresponding plugs.
• Connect output of preamp with input of poweramp.
• Connect your speaker wires, positive to positive, negative to negative.
• Plug the powercords into the preamplier and amplier, then into the
wall sockets.
• Switch the preamplier on and wait for 30-60 seconds while to warm up.
• Switch the poweramplier on after the preamplier has been on for 30-
60 seconds.
• The tubes will be warmed up and ready to use in about 30 seconds.
Mystère
Contents
1x Mystère pa21
Stereo power amplifier
1x Power Cord
1x Owner’s Manual
1x White Gloves
Tubes 4x 6SN7
4x KT88
Fuses
Littelfuse Series 218 or 219
1 x 3,15AT (100-120VAC)
1 x 1,6AT (200-240VAC)
Warning
Do not replace fuses with any
fuse other than the same type
and rating as used by the factory.
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pa21 Front panel - Rear panel
The front panel of the Mystère
models is like the rest of the
chassis, finished in high gloss
piano lacquer finish. The power
switch is located on the right
side of the amp, just behind the
front plate. On the leftside, just
behind the front plate, you will
find the EL34/KT88 switch.
Looking at the rear panel, you
will note one pair of stereo inputs and the pair of speaker terminals. Attach the positive (+)
from your loudspeaker to the
4 or 8 ohm terminal that most
closely matches the average
impedance of your loudspeakers according to their manufacturer’s specifications. The negative (-) from your loudspeaker
attaches to the 0 Ohm terminal.
Tip: Experiment using the 4 or 8 Ohm positive (+) terminal to find the best match
for your speakers. Do not make any assumptions. Trust your ears.
Mystère
Fuse Protection
A note on fuses: Fuses are safety
valves. They should always be
replaced with the exact same
value and type.
Warning: Never attempt to
check or replace a fuse while the
amplifier is plugged in. Turn off
the amplifier. Unplug all speakers,
components and AC cords. Wait
10 minutes to let tubes cool
down and the circuit to fully
discharge.
Mains Fuse:
The mains fuse is located on the
rear of the amplifier, at the top
of the power cord socket. The
fuse holder can be snapped out
using a small slotted flat blade
screwdriver.
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v1 v2
pa21 Tube basics
The 6SN7 tubes will have a life of about 10,000 hours. However, the life span of
power tubes is more difficult to predict. It greatly depends on how “gently” or
“roughly” you use your amplifier. In general, under normal conditions, you can
figure between 2,000 and 3,000 hours.
Here are some tips on using tubes:
• Do not use treatments on tube pins or in sockets.
• If you decide to experiment with other tube types, it’s best not to swap
tubes in and out repeatedly, as you never want to cycle (pre)amplifiers
on and off rapidly. They should be left off for at least five minutes. Further,
every time you insert a tube, you stand a chance of loosening the tube
sockets. It’s okay to have fun, and we support that, but don’t go crazy and
swap tubes in and out twenty times in a day.
• Some tubes and tube socketshave a “center key” which must correspond!
If you use“brute” force and misalign, you will damage important and expensive parts of your amplifier!!
• The Mystère pa21 has a warm-up time of just a few minutes. Do not leave
the amplifier on 24 hours a day.
• Break-in yields improvements. Every tube, when new, needs to be left
alone for a little while. So, when your amplifier is new, or when you retube it, it may take a little time to settle in. There is however no fixed “time
rule” for break-in.
• Please note that tubes can vary electrically, and by plugging in the wrong
type of tube you can damage the amplifier, and void your warranty.
Mystère
Tube Tip
Some 6sn7 tubes are more
microphonic than others. In
your pa21 the 6sn7 positions
most sensitive to this are the
input tubes V1 and V2.
Experiment if you want
with different 6SN7 tubes in
the market to get your optimal sound. You also may experiment with the different
tube-dampers available in
the market to fine-tune your
amplifier.
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pa21 Troubleshooting
Some tips:
• No output. Power is on, but power LED is o and tubes do not light up.
AC cable makes bad connection in IEC connector. Please check.
• No output. Power is on, but power LED is o and tubes do not light up.
Mains fuse is out. Replace fuse as per instructions on page 5.
• No output. Power is on, but power LED is o and tubes do not light up.
Mains fuse is not out. Thermal protection may have switched off power transformer. If so, the power ampli-
fier will switch on again after internal temperature of power transformer returns to normal. Overheating
might be caused by higher environment temperature than normal or heavy use.
• No output. Power LED is on and tubes do light up normally.
Check preamp, input and output wiring; if all seems to be OK check power amplifier.
• Hum or noise coming from one channel.
Noisy tube. First swap the 6SN7 tubes left to right. If noise follows tube swap, then you have found the
problem tubeset. Now swap one by one from left to right. If noise follows, you have found the problematic
tube.
• Hum coming from one channel.
Possible bad output tube. Swap the output tubes in pairs from right to left. If hum follows the swap, swap
the far left and far right tubes. If the hum returns to the original problem channel, you have found the
problem tube. If not, swap the inside output tubes left to right.
• Noise/distortion coming from both channels.
Tubes may be in need of replacement. Read page 6 for tube basics and replacement options.
If you try these possible solutions and problems persist, contact us or your local distributor for further
investigation.
Mystère
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pa21 Warranty Information - Terms & Conditions
Two-year limited warranty.
Six-month warranty on stock vacuum tubes
1. Limited to original purchaser. This warranty is for the sole benefit of the original purchaser of the covered product, and
may not be transferred to a subsequent owner.
2. Conditions & Limitations. This warranty is subject to conditions and limitations, as follows. This warrantly is void and
inapplicable if the product has not been used in accordance with the instructions found elsewhere in this manual, or
if it has been misused, abused, damaged by accident or neglect, or in transport once in possession of purchaser. The
warranty is also void if the product has been tampered with or has been repaired or modified by anyone other than
Durob Audio BV or its specifically authorized representatives.
3. Remedy. If this product contains material, manufacturing, or workmanship defects, it must be packed in orginal packaging and returned to Durob Audio BV or its authorized representative via insured freight, at the owner’s expense.
Returned products must be accompanied by written description of the defect, and a return authorization number
(available from Durob Audio BV or the authorized representative via e-mail). Upon receipt of the defective product,
Durob Audio BV or the authorized representative agrees to repair the product without charge for parts (except vacuum
tubes if the unit is more than 6 months old), or labor. The product will then returned via prepaid, insured freight, with
carrier at the sole determination of Durob Audio BV or the authorized representative. This constitutes the purchaser’s
sole remedy.
4. Design change. Durob Audio BV and its partners reserve the right to modify their products or change specifications at
any time without obligation or liability to previous purchasers.
5. Miscellaneous. Any implied warranties relating to the above product shall be limited to duration of this warranty. This
warranty does not extend to any indentical or consequential costs or damages to purchaser or third-parties. Our liability
will be no more than the amount you paid for the product that is the subject of a claim. This is the maximum amount
for which we are responsible. This warranty gives you specific legal rights. You may also have other rights which vary
from country to country and state to state.
Mystère
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The Mystère Story
It’s midnight and the year is 1,500 BC. An eerie wind is blowing across the Salisbury Plain in southern England and the flat, green ground is bathed in the
moon’s ghostly light. A faint orange glow can be seen in the distance, seemingly coming from a huge circle of majestic stones that stand out in solitary
grandeur against the barren landscape. As one draws closer, dark figures dancing around the wooden fire that smoulders at the centre of the great circle of
stones become visible. Strangely, not a sound can be heard. The whole place is shrouded in mystery.
I am, of course, referring to the world-famous Stonehenge, which stands to this day as a powerful tribute to the people of the late Stone and Bronze Ages
and consists of a ring of extremely large stones and while modern techniques in archaeology have helped shape new theories about these stones, their
ultimate purpose nevertheless remains a fascinating and enduring mystery.
Whatever their exact purpose was, recent research has revealed that the stones at Stonehenge are able to contain and amplify sounds. Furthermore, most
sounds made in the centre are not clearly transmitted beyond the rings of stone.
Almost all of the stones at Stonehenge were shaped, with the inner surfaces of many stones being dressed to be either flat or concave and their outer
surfaces irregular or convex. The contrasting acoustic experiences between the inside and outside of the stone circle that result from the shaping and
placement of these stones may have been utilised by the ancient builders to isolate people on the outside from the activities at the centre. An audience
occupying the inner circle of Stonehenge would have heard amplified sounds. In contrast, no-one outside the monument could have clearly seen or heard
events within, thus creating a sense of mystery!
Recent research suggests that the original Stonehenge probably had an almost concert-like acoustic that our ancestors developed and perfected over
many generations. While undertaking a series of tests, one researcher commented, “A simple drum beat sounded incredibly dramatic. It felt special.”
Similarly, we want to invite you to join our select inner circle of audiophiles to sample the delights of the Mystère series. Be enticed towards the faint orange
glow of the tubes that peer out from between the vertical slots of the sleek cover. Marvel at the realism and joy of music that has been perfected over many
generations of equipment design, resulting in the Mystère range of audio products. Now your search for the ultimate experience is over!
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Sales & Support
Mystère - Durob Audio BV
P.O. Box 109
5250 AC Vlijmen
The Netherlands
+
31 73 511 2555
www.mystere-eu.com
info@mystere-eu.com
Email us for your local distributor
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