Products: Opera Audio Consonance 8.8R
- J500 Plus - integrated tube amps
Manufacturer: Opera Audio Co., Ltd - Beijing, CHINA
Approx price (in Italy!): J500 Plus: 2600 €/$, 8.8
Ref: 2800 €/$
Reviewer: Lucio Cadeddu - TNT Italy
Reviewed: February, 2004 Among tube nuts there are different
opinions on how a good amplifier with vacuum tubes should
be designed and made: PCB'ed against hard wired, high
power vs low power, solid state PSUs against tube rectifiers
but...most of all...push-pull VS single-ended. Roughly
speaking, pairs of push-pull vacuum tubes allow to build
high power amplifiers but the complexity of the circuit
trades off some transparency. Single-ended designs, being
much more "straightforward" (almost a wire with gain)
are said to be much more "musical", transparent and natural
sounding...on the other hand they deliver only few watts
of output power. I don't want to support one or the other
brigade, just put two similarly priced designs one against
the other to discover if is there some truth in these
audiophile myths. Finding similarly priced push-pull and
single-ended designs isn't an easy task, finding two such
amps from the very same manufacturer seemed even harder....until
I came across Opera Audio, a Chinese HiFi Company, and
its vast catalogue of amplifiers, either solid state or "tubed" ones (even hybrids!). Enter the
Opera
Audio Consonance 8.8R and the
J 500
Plus : the first is a quite traditional push-pull
of 6550's (a KT88 option is available) which delivers
50 watts per channel, the other is a minimalist single-ended
design using the famous 300B triodes delivering a mere
9 Class A watts into each channel. Both amplifiers make
use of chinese or Russian ElectroHarmonix vacuum tubes. The
Consonance 8.8R is claimed to be a "class A" push-pull amplifier. Now,
50 watts under pure Class A mode from a quartet of 6550's
is something hard to believe, especially if you consider
this amp never runs as hot as such a design is expected
to do ;-) Opera Audio claims a "biased voltage" of -35
V and a current (Ip) of 40 mA (Class AB, perhaps, seems
more reasonable). The input stage uses 2 dual triodes
12AT7 while the driver stage uses 2 x 12BH7's. The 4 x
6550 tubes are claimed to be selected pairs. These are the mostly relevant (claimed)
tech specs: Output power: 50 watts, RMS @ 1kHz
THD: < 1% (50 watt, 1kHz)
Frequency response: (-3dB @ 10 watt) 6Hz-60kHz
Input sensitivity: 180mV
Input impedance: 50k ohms
Output impedance: 4-8 ohms (user switchable)
S/N ratio: 90dB
Power consumption: 90watt
Tubes: 6550 x 4, 12AT7 x 2, 12BH7 x 2
Size: 470 (L) x 400 (P) x 200 (A) mm
Weight: 30kg
Facilities: Volume, Select, Power On/Off The model
J500 Plus is a minimalist single-ended Class A design with zero
total feedback. The input stage uses 2 x 12 AX7 tubes.
These are the mostly relevant (claimed) tech specs: Output power: 9 watts, RMS 1kHz
THD: < 1% (5 watt, 1kHz)
Frequency response: (-3dB @ 5 watt) 10Hz-47kHz
Input sensitivity: 180mV
Input impedance: 100k ohms
Output impedance: 4-8 ohms. (user switchable)
S/N ratio: 82dB
Power consumption: 90watt
Tubes: 300B x 2, 12AX7 x 2, 6SN7 x 2, 5AR4 x 1
Size: 435 (L) x 390 (P) x 215 (A) mm
Weight: 25kg
Facilities: Volume (via remote), Select, Power On/Off These two amplifiers have been delivering
their watts into different sets of speakers for several
months (thanks to CometAudio, the Italian distributor).
I've tried to match them with different "partners", including
tough loads (Thiels) and easy stuff such as full-range
crossover-less loudspeakers. Push pull VS Single Ended First of all, it is CLEAR that these
amps aim at different audiophile niches. The push-pull
8.8R should be the right amp for anyone willing to "taste"
vacuum tubes without sacrifying high power and SPL. The
single-ended J500 Plus should be the right choice for
the seasoned tube nut ready to sacrify power in order
to get better transparency. We will see if this still
holds true after the listening tests :-) This comparison
test shouldn't appear as comparing apples to oranges.
Instead, it makes much sense to me. Choosing a HiFi component
is ALWAYS a compromise, a "give and take" game. In this
article I'll try to describe you what to expect from these
different designs. Let me remark that my findings will
be related to this very pair of integrated amps and by
NO MEANS they can be "extended" to different and more
general situations. Enough of this blurb, here we go. The
8.8 R makes use
of a quite unusual "magic-eye" as power output indicator.
More or less, it is the same device you can find on old
tube radios, where the magic-eye (a vacuum tube) was used
to station fine tuning. The claimed 50 watts, as far I
can guess, are realistic so this amplifier is perfectly
comparable to a mid-powered solid-state integrate amp,
in terms of raw output power. Let me note that it does
sound exactly like a 50 watter, despite the urban legend
that claims 50 "tubed" watts equal 100 "solid state" watts.
In my opinion, this is just a legend, nothing else than
that. Its tonal balance is rather on the warm
side, with a recessed mid range and a pronounced, overblown
mid-bass. If this is what you'd expect from a traditional
tube amplifier...well, this amp won't delude you. Anyway,
there's something fascinating and charming in the sound
of this unit, something that lets you listen to your favourite
Music for hours and hours, forgetting the meaning of "listening
fatigue". It does
nothing to stay "neutral" or tonally balanced. Instead, it seems it finds amusing
to impose its tonal balance and interpretation to the
Music it plays. Despite the different pairs of speakers
I've used to test it, the amplifier sounded more or less
the same, obvious differences aside.
The overall distortion is very low, even at high listening
levels tough the tonal balance seems to vary with the
position of the volume control. It sounds softer and euphonic
at low levels, then becomes more aggressive when playin'
it loud. This is a problem which is common to many amplifiers
but with the
8.8 R the phenomenon is
very noticeable .
Human voices are reproduced with grace and the expected
velvet touch. Too much velvet may be unwelcomed by some
singers, tough :-) As a result, even aggressive voices
(think of hard-rock singers) are transformed in gentle
smoke-filled jazz-club performers. Not good, if your name
is David Lee Roth or Brian Johnson ;-)
This phenomenon is certainly due to the aforementioned "recessed" midrange that helps to tame harsh recordings
but subtracts "life" when needed, as well.
The same happens to guitars and string instruments in
general. All goes well when they get played softly...but
when the going gets rough the amp adds too much (velvet)
of its own and loses the plot.
Not different its behaviour with drums and percussions.
Let me put this straight, before going any further: this
amplifier sounds
dead slow . It imposes its own
(slow) pace to every kind of Music it plays. Though this
may seem bearable with no-rythmic Music, it becomes BORING
with the musical genres that LIVE thanks to the rythm.
So, while this amp may sound charming with some Music,
with rock it may become boring as hell (or is it Paradise
to be boring? :-)).
Just play something like Prodigy, Chemical Bros, Maxim
etc and you'll live an almost mystical experience. This
amp is able to subtract almost every bit of energy from
those tracks. Of course, in the long run, you can even
get used to this kind of "performance" but - to my ears
- it is excessive.
I've tried to find a reason for this behaviour but somehow
failed to get an answer. It doesn't matter the speaker
you plug into it, it doesn't matter if you use the 4 ohm
or the 8 ohm outputs ...it always sound like...sleeping.
Incidentally, during my search for answers, I've found
the 4 ohm output to be better sounding than the 8 ohm
one (regardless of the speakers' impedance). As you can
expect, considering what I've just written, the
Opera
8.8R isn't a master in the dynamics department.
It always reacts slowly to the inputs it receives from
the source. In terms of pure sound pressure levels it
gets the job done even with tough-to-drive Thiel loudspeakers
(low sensitivity + low impedance). It does exatcly what
a 50 watter is expected to do, nothing less and
nothing
more . For example, I've been able to exploit
its full power output (the magic-eye power indicator dancing
at full scale) even with quite efficient speakers like
the
Embryo
by The Sound of the Valve , 93 dB/W/m full-range loudspeakers. Finally, let me spend two words on the "soundstaging" ability of this amp. Let me debunk another
myth, here. Many tube nuts, not familiar with good solid
state stuff I assume, claims that only with tubes one
can get a wide and deep virtual soundstage. Some claim
the image created by their amps is so wide and deep that
they need to go out in the backyard to fully enjoy it
:-)
In my opinion, there are good and bad amps. Good amps
are able to create a realistic soundstage, bad amps can't
(unless the designer ignores the importance of this parameter,
e.g. in Flat Earth territory).
The
Opera 8.8R does its job nicely,
building a stage which is wide, deep (no, not THAT deep)
and quite "stable" and focused. Nothing that will make
you ring your neighbourhoods to warn them about instruments
playing unexpectedly into their living room ;-) ...and now for something completely
different :-) Switching to the
J500 Plus
it is immediately evident that few things stay the same
and that many others change. Before explaining these in
detail let me say that the differences between these two
amps are NOT subtle.
Let's see: first of all the tonal balance changes dramatically,
becoming much more neutral with no trace of overblown
mid-bass or recessed mids (like with the
8.8 R
). That charming touch is still there, as is
the low distortion that makes the listening experience
100% fatigue-free. Of course, you should NEVER forget
this is a 9 watts amp! Don''t ask for more or, boy, you'll
be in trouble.
Human voices appear to be much more natural and...ehm...human
than with the push-pull amp. The heavy "interpretation" imposed by the
8.8 R has gone and voices
can really "sing", each one with its own imprinting: harsh
when harsh, velvety when velvety and so on.
Hence, I can say that the recessed mids are gone and so
the "warm" balance of the previous amp. After continuous
listenings with the push-pull amp, switching to the single-ended
may be a shock. Ears get used to a certain tonal balance
quite easily since our brain tends to automatically "equalize".
Hence, in a quick A-B comparison, the single-ended seems
colder and "clinical". Not so! After few minutes you realize
it is much more natural and tonally balanced.
For example, guitars and strings in general appear to
be much more realistic, less "reproduced", if I may. They
sound harsh and metallic when strummed hard, gentle and
harmonically rich when played gently. Troubles arise as soon as you have to
face with the low power output and the dynamic performance.
Let's put it straight once again: 9 watts (NINE), even
if produced by amplifiers which are built by Celtic virgins
under half-moon, are N I N E watts . It doesn't matter
how much you have paid for them. They are NOT ENOUGH to
produce significative sound pressure levels with mid-sensitivity
(91-93 dB/w/m) loudspeakers into a decently sized listening
room (30 sqm?). You need either a smaller room or far
more efficient loudspeakers (95 dB, at least).
No matter how carefully you play with that volume knob...you'll
end up experiencing raw
clipping when
playing highly dynamic musical programs. Who said tube
amplifiers clipping is gentle? You should listen to this
poor boy screaming "Lower! Lower!" each time the going
gets rough! Hey, I'm not referring to continuous clipping...this
is easy to get once you run the amp at full steam. No,
I'm referring to
wild dynamic clipping!!!
Let me elaborate this a little bit further.
Imagine yourself enjoying your favourite orchestral movement,
waiting for the deeply emotional crescendo and
fortissimo
. ...then suddenly...shreeeeeek.....and the poor
300Bs grasp for breath! Not different if you're listening
to a rock song...all goes well until the...chorus! Then
BAM! distortion figures go ballistic!
Strange? No way!! This is OF COURSE
100% normal. The way it should be, there are laws of physics
that can't be forgotten, even by vacuum tubes! This is
just to
warn you on what to expect.
If you end up buying a few watts power amplifier because
convinced by efficient marketing hype...be ready to keep
that volume down if you want to avoid distortion. So,
be a conscious buyer and know yourself and your needs.
If your room is very small, your speakers are extremely
efficient or you are used to very low listening levels
then these 9 watts could be sufficient. Otherwise (big
room, < 93 dB/w/m speakers, high SPL listening) forget
it. The worst thing you can do to this otherwise delicious
amp is pushing it over its natural limits. In order to
deliver its (good) sound it requires to be put in a logical
and convenient environment (room and speakers). Dynamic limitations aside, this
J500
Plus beats the
8.8 R in terms
of speed, pace and rythm. Within its limits, it is fast
and lively, more...much more than the push-pull one. OK,
the latter sounds louder...but that's all, dudes. Unfortunately
I haven't been able to partner the
J500 Plus with 100+ dB/w/m loudspeakers. I assume the result would
have been simply amazing. From the point of view of soundstaging,
this amp is on a par with the push-pull one, even slightly
better: more air surrounding the instruments, more transparency
and perhaps a couple of inches ;-) of extra width and
depth. Complaints Chinese made HiFi gear is quickly reaching
high standard of craftsmanship and finish. These two amps
look nice and solid, being built with care and good quality
materials. They are BIG and, even worse, TALL. This means
they will force you to use the top shelf of your rack,
if you don't happen to own (shame on you) an analogue
record player. Heat build up is NOT negligible especially
with the
J500 Plus . The covering grid
protects the hot 300Bs but after a few hours it becomes
hot itself as well. Moreover, the grid has two lateral
holes that leave enough room for an adult's hand (imagine
that of a child). Not good. Even worse, the
8.8R
comes without tubes protection so you have to
store it far from children's and pets' reach.
The remote, available only for the
J500 Plus ,
is weird looking and not 100% intuitive. Even worse, it
adjusts volume only (no input selector, no mute, no stand-by).
The number of source inputs is sufficient for most uses
and both amps use good quality RCAs. The binding posts
for speakers are easy to use and nicely built (see pic).
The power cord is of the detachable kind while the transformers
are sufficiently protected.
During use, the single-ended makes a
slight high-frequency "buzz" , nothing that can be heard
while Music is playing. The push-pull is dead quiet, instead.
The owner's manual is very informative and complete as
it also included some basic theory on tube circuits. The
quality of the shipping boxes is of paramount importance
with tube gear and these amps come with excellent "packaging".
Also supplied is a pair of white cotton gloves, to be
used to install or remove tubes. The two pairs I tried
were too small for my hands, though (and my hands aren't
big). Finally, two words on price. My comments
are referred to the current "Italian" price. It is not
a mystery to anyone that these amps can be bought directly
from China at a fraction of the cost (more or less 800
$ each!). It takes a lot of efforts to understand how
this can become almost 3000$. Anyway, there are taxes,
custom fees, shipping costs, customer care, advertising
costs etc etc. I don't know which is the situation outside
of Italy so you may find these amps for much less then
the cited price. Ask your local distributor and adjust
the quality/price ratio accordingly. Of course, at 800
$, these amps are unbelievable bargains. From the point of view of pure sound
quality I think I've written everything needed to understand
what to expect from them. The push-pull is warm, slow
and "good 'ol days" sounding. It has plenty of power but
fails to get the fundamentals done right (rythm, for example).
The single-ended one, on the contrary, is quicker, more
transparent and overall more natural but fails to deliver
sufficient power when needed (if partnered with less than
95 dB/w/m loudspeakers). I'd love to get a mix of the
two amps (power, pace and balance) but, hey, this is the
real world.
Summarizing, and considering the
J500 Plus
is even slightly cheaper, I'd rate the
8.8R a bit overpriced and definitely worse than its single-ended
brother. Conclusions Push-pull or single-ended? With respect
to the comparison test I've made I have no doubt: the
single-ended is a far better amplifier. Only, it needs
high sensitivity loudspeakers, small rooms or low listening
level habits. On the other hand, the push-pull amp sound
powerful and charming, definitely
tubey . If
is this what you're looking for, a listening test might
be enlightening. Copyright
2004 Lucio Cadeddu - www.tnt-audio.com