This is the amplifier that I started DECWARE
with in 1993. It's been 25 years since that first amp and now there are
thousands in service around the world. I've taken everything I've
learned in this 25 year period and applied it to
this Anniversary Edition. This amplifier is like my
Steve Deckert - owner DECWARE / High
Fidelity Engineering Co.
Zen Triode 25th Anniversary Amplifier
- 6P15P-EV output tubes driven by a 7DJ8 dual-triode
- 2 watts RMS per channel or 6 watts in mono
- 3 independent tube-regulated power supplies
- Vacuum-tube rectification
- Pure Class-A single-ended triode operation
- Zero negative feedback
- Decware UFO wide-bandwidth output transformers
- Runs speakers between 2 ~ 16 ohms
- 24K Gold-plated components
- No circuit boards
- Analogue incandescent back-lit amp meters
- High-mass steel chassis for low micro-phonics
- African Padauk hardwood with Janka hardness of 1,970 lbf
- Lifetime warranty
Zen Triode 25th Anniversary Amplifier
SE84UFO25 uses voltage-regulation tubes in series with the high-voltage
supply for each audio tube including the output tubes!
cleans the high voltage power beyond what is possible with external
power re-generators. In fact it's like listening to batteries with
This approach is not possible in other
amplifiers because VR tubes are rated at around 30mA and most output
tubes draw well over that! Luckily the Zen Triode amplifier uses an
output tube that draws only 25mA making this unique opportunity
All of this makes the power supply a little more
complicated than our other models... In fact there are only 2 resistors
and 1 capacitor in the entire signal path of this amplifier.
Everything else you see (pictured right) is the power supply.
are additional benefits as well. The are three values of
voltage-regulator tubes. Each one has its own voltage drop and
corresponding number. So by changing the voltage regulator tube you
change the voltage feeding the input tube which changes how it sounds.
this means is that if you buy an expensive input tube you will now be
able to hear it with three different plate voltages instead of one. The
sound goes from dreamy and euphoric to tightly focused and highly
accurate. This ability to hear three different sounds from the same
input tube when combined with use of the input-tube bias switch doubles
it to six different sounds.
This unique voicing tool is legendary
because every special input tube a person might buy is going to have
some equipment it sounds better in than others. The reason for this is
the differences in voltage and current from one piece of equipment to
the next. The Anniversary Zen Triode lets you find that magic operating
point for any input tube by ear so you know it's perfect.
This amplifier has a singular goal
and that is to push what serious audiophiles think is good resolution
to a higher benchmark. A benchmark well beyond what we feel is possible
in a mass-produced hi-end retail market.
SE84UFO25 close-up view of input tube socket
design maintains a purist and minimalist approach which is why it only
has one pair of input jacks and why those jacks are located less than
one inch away from the input tube.
If you plan to run the
amp without a preamp and need more sources we have a silver-contact
switch box available. Also if you plan to run balanced signals to the
amplifier we have a balanced input transformer. These two compatible
items are our models ZSB and ZBIT, both available on this site.
with a fully-floating output stage the amplifier can be run in mono by
series connecting the output jacks. This approach avoids the
dreaded parallel bridging smear common with most stereo amps when
strapped into mono. Transparency is protected with no audible
trade-offs and 3 times the power. So if you get one of these amplifiers,
fall in love with it but wish it had more power, get a second one.
SE84UFO25 rear view
The SE84UFO25 is using the best grade of audio parts
available as standard fare but there are still a few options that can be
selected when you're in the shopping cart:
1) No Volume Controls (we will set the input sensitivity for you)
2) Infinitely-Adjustable Smooth Action Volume Controls
3) 20-position stepped attenuators
If you choose option 2 or 3, you can also choose the knobs to go with it. Knob choices
We recommend the black or cream chicken-head knobs for best performance.
The SE84UFO25 also comes with a fantastic cryo-treated
copper foil beeswax signal-capacitor. If you want you can have your amp
custom built with VCAP brand copper foil caps. The option is presented
in the shopping cart when you purchase the amp.
1) poly film cap 2) aluminum foil beeswax 3) copper foil beeswax 4) VCAP.
If you have no idea which option would be
better, get the default cryo-treated copper-foil beeswax caps as they
sound as good as the VCAPs but do not require the long burn-in period
before they start sounding great. The beeswax may eventually wear out in
20 or 30 years and may need to be replaced. The VCAP will last
forever. I would not say one cap has more resolution than the other so
we demo the amps with either cap.
The SE84UFO25 also comes with a
beautiful exotic solid-hardwood base. It is made from African Padauk,
Vermilion. This wood was chosen because because it has a high hardness
and a modulus of elasticity (1,700,000 lbf/in2)
that works in a complementary fashion with the high-mass steel chassis
to drain vibration from the chassis to the plinth or audio rack it sits
You can however opt to have your amp shipped in a
custom non-refundable base made from any hardwood if a
different appearance is preferred. Shown below is a base done in natural
Zen Triode 25th Anniversary Amplifier
you choose to purchase this amplifier with our special tube compliment
you will be pleased to learn that we
carefully hand select and match the tubes for this
amplifier. But it goes way beyond that... tube matching is followed by
an in-depth distortion analysis and channel matching in the actual
amplifier. By this method we can be sure the factory tube complement is
perfect in every way. Not only is the gain and trans-conductance matched
for each channel but so are the harmonics. When this process is
complete, the three audio tubes are red-tipped as part of the reference
grade factory tube complement.
Tube complement for the SE84UFO25 comes in this custom case.
The included output tubes are a matched pair of Russian
military-grade 10,000 hour
6N15P-EV's with gold grids. These have proven unbeatable
for 25 years in Decware amplifiers and were chosen over directly-heated
triodes like the 2A3 and 300B because they are more neutral, faster and
have better extension in the frequency extremes. These long-life tubes
were used in radar display units. Being designed for video these tubes
have a wider bandwidth than most audio tubes. These are N.O.S. tubes.
These tubes will be red-tipped.
The included rectifier is a
current production 5U4 that we've found to have respectable sonics when
compared to the N.O.S. tubes from the 1940's ~ 1970's.
included voltage-regulator tubes are a pair of N.O.S. OA3/VR75s which
glow orange and OD3/VR150 that glows purple. The orange OA3 tubes
located at the rear of the amplifier can be seen from anywhere in the
room and become visual clipping indicators exactly like the meters. That
means that when the amp is nearing its power limit, both the meters and
the OA3 tubes will begin to flinch. This allows you to see when
the amp is near clipping before any distortion is ever heard. A very
handy tool to help you use all of its power effectively.
OD3/VR150 glows purple however due to the smaller shape of the tube it
is hard to see the glow. Other OD3/VR150 tubes are the same size as the
OA3 so if you prefer the light show, you can buy some of them. That
said, the OD3 can be replaced with an OC3/VR105 or an OA3/VR75 to
intentionally change the sound of the input tube. Both of these variants
for the OD3 are included so that you have all three on hand to try.
included input tube is a special hand-selected N.O.S. 7DJ8 that was
chosen for its sonics and matching. This tube will be red-tipped.
ALL of the options described above can be selected and priced in the shopping cart.
|| 17 lbs. ea.
|| 9.0" H x 7.125"
W x 14.0" D
| Circuit type
| Power output
|| 2.3 watts RMS x 2 or 6 watts RMS x 1
| Input voltage
|| 1.5 volts for
| Noise / Hum
|| -79 db U / -58 db U@120HZ
|| 20 Hz ~ 80 kHz
|| 5U4G or 5AR4 or TYPE80 with adapter
| Output tubes
|| SV83/6P15P-EV or
| Signal tube
|| 7DJ8 but compatible with 6N1P, 6N5P, 6N11, 6922 or
|| Decware UFO
|| Precision WW & MF
by DALE, VISHAY, RHODERSTEIN
| Signal Cap
|| Cryo-Treated Copper Beeswax Film and Foil OR Copper Foil VCAP
| AC cord
|| Removable power
|| 65 watts
| Input jacks
|| RCA type
Gold / Teflon
dB or higher is
WORLD VOLTAGE COMPATIBILITY
All model SE84UFO25 amplifiers come
standard with a 50/60 cycle world-voltage-compatible transformer and
will be hard-wired for your country's voltage and supplied with the
correct type of power cord.
SE84UFO25 shown in the test rack
ZEN TRIODE 25th Anniversary AMPLIFIER
The development of this amplifier has
been documented in real time on our excellent audio forum! It is
recommended reading as this amazing thread will take you on a
start-to-finish journey about the best sounding amplifier Decware has
Here is the link to the thread:
SE84UFO25 Owner's Manual
Please download the above .pdf manual and read!