M400S are mono blocks featuring complete hand crafted chassis. It has a simple design, is easy to use, and offers outstanding headroom performanceControl Functions:
specs...

Power On/Off
Inputs: Left, Right

OUTPUT IMPEDANCE: 4,8 ohms. (User selectable.)
Output Power at 1 kHz for less than 1%THD:- pentode/triode switchable
40W x2 -pentode mode & 22 wpc triode mode
Triode vs. Ultralinear
There is one other toggle switch on each monoblock towards the front. It is labeled Ultralinear toward the front and Triode towards the rear. Triode mode reduces the output to about 22 watts instead of 40 but tightens the bass end somewhat and gives sweeter, more "tubelike" midrange reproduction. The Ultralinear mode was an invention of David Hafler and Herbert Keroes in l951. It uses tetrodes or pentodes and special taps on the output transformer. These tapes are connected to the screen grids of the tubes, causing them to be driven with part of the output signal. This lowers distortion, and is seen on amps using only certain power tubes, of which the EL34 is one.

Bandwidth at - 3dB: 6Hz to 60kHz
Signal/noise: 90dB
Input interfaces: 1 group (RCA)
Input Impedance: 100k
Consumption: 90wx2
Tubes: EL34x 4, 6922x2, 6189x2
Dimension: 355(L) x 200 (H) x 150(W) mm x 2
Weight: 10.5kg x 2(Net); 21.5kg (Shipping)
Opera Audio Consonance
M400S Monoblock Tube Power Amplifiers 9/2001

David Wurtz - Editor,
Australia

Specifications
Power Output: 40 Watts RMS (Class AB)
Frequency Response: 6Hz - 60kHz (-3dB @10 Watts)
Total Harmonic Distortion: Less than 1% @ 10 Watts @ 1 kHz
Input Impedance: 100kOhms
Input Sensitivity: 600mV
Signal to Noise ratio: 90 dB
Output Impedance: 4 or 8 Ohms (User Selectable)
Power Consumption: 90 Watts
Dimensions: (H x W x D): 150mm x 200mm x 355mm

Weight: 12 Kg each

Distributed BY
QUEST FOR SOUND
2307-R BRISTOL PIKE
BENSALEM PA 19020
215-953-9099

Introduction

Dearly underpaid, we are gathered here today to discuss the age-old problem of hi-end audio, partners and your bank balances. OK, so it's a terrible beginning, but isn't it always the way..."Gee this is a great sounding unit, how much is it again? Ohh...Ummm...O.K...I will have to save up for that, and I will be back another time...Thanks anyway..."

Sound familiar??? It has for me in the past! The lifestyle decision of good food on the table, nice clothes on my back, or a great sounding sound system, is a very interesting one. We all (well most of us anyway) make several sacrifices when trying to budget a new piece of equipment. I know I would be lying if I said my taste/hunger for hi-fi had not left me a little short for other necessities on a few occasions. I must admit that a very sad side of me really finds funny and also appreciates the saying, "If you have to ask how much this is, you probably can't afford it". That's me buy the way! "How much was it again?" Hoping the next price I'm given is less than the last one the salesman gave me!

Fortunately, today's market supplies a plethora of high quality electronics at more than realistic prices, even for tube driven gear that can tend to be more expensive compared to similar performing transistor types. You just have to look around (which could take you years) or read the literature supplied by your favorite, hard working, audio/visual website...Secrets!

Herein is introduced the Chinese designed and completely hand made Opera Audio"Consonance"range of pre and power tube amplifiers. Opera Audio, founded in Beijing China in 1994 by a youthful pair (both in their early 30's) of audiophiles, are turning lots of heads for the quality verses price stakes in a cutthroat industry. I must also admit when I first heard that there was a completely hand built Chinese made tube amp manufacturer, who is trying to compete for a small slice of the valve amplifier sales'pie, I was a little bemused, and...well...a little skeptical. This was mainly due to the fact that America and Europe seem to dominate the manufacture of such products. Let's see how the Consonance M400S performed when I put it though its paces.

Let's Get Physical
Opera Audio's owners and designers, Lui Zhao Hui and Ma Wei, have based the design of their amplifiers using the classic 1930's tube design made famous by Western Electric.

The M400S pair sport a very classic, and yet modern look, having a timber fascia with"burnt in"brand labels and green power LED. The body of the unit is stainless steel with two large transformers (one for power and the other for the output), each within its own canister, and four valves (tubes) mounted on top. These valves consist of a 6922 dual triode input, a ECC82 dual triode driver, and two EL34 output valves used in a push-pull, class AB configuration. The measurement point and screw adjustment terminals for adjusting the bias are also on the top of the unit in front of and behind the EL34s respectively. The back of the unit has an IEC power socket, a small toggle power switch, three binding posts (Common, 4, and 8 Ohms) and a single input RCA socket. The speaker binding posts and RCA input socket are of a high quality. The power switch lacks a little in comparison to the other high quality hardware the unit posses. I think I would have also like to have seen this switch on the front, as it is a little awkward to turn on and off from the rear. When the units were sitting up on my equipment rack, I managed to burn my forearm reaching over the back to switch them off (it's probably a case of my being foolish for putting them up there in the first place :-)). The bottom has four large, silver"dome shaped"feet. The units weigh in at 12 kilos each, most of that weight being from the transformers, and they feel quite solid in construction.

The Sound
Using a Toshiba transport, Perpetual Technologies DAC, and the Osborn Titan References for loudspeakers, I connected the M400S in. The manual states that the units require only 5 minutes to warm-up. I like to allow up to an hour to make sure everything is warm, but you don't get that luxury all of the time.

To sum up the sound of the unit in one word...ummm...sorry, just can't do that, I must say straight-out though that this pair of monoblocks do not sound like your typical valve driven unit. The M400S has tubs full of speed and weight, which is more a characteristic of transistor designs and yes, they sound more like transistor driven units. The soundstage is more than adequate, wide and deep, and the three-dimensional characteristics did not change with the different styles of music I played. I kept thinking to myself that this sort of performance should cost more, and I think that once China is in full swing some day, they probably will cost much more.

Through the spectrum, I noted that the bass response was deep and weighty, while still maintaining its overall integrity. As I said before, this is not really typical of small valve units, but definitely a welcome surprise. Lower mids were well represented with naturalness in voices and excellent speed, along with good transient response, whether a piano key was striking its destinations or Stone Temple Pilots' grungy guitars were powering though their rhythm structures. Midrange performance was dynamic and very neutral in its reproduction and the best example (if only small) of the Opera's tube style sound. The high frequency detail was crisp, but not too forward. If anything, it just missed the subtle sweetness that you find in most tube designs. Remember the price though!

Complicated sequences of rock were handled very well. The bass response is probably the best feature of the Consonance, and even at high levels the bass was rock solid and deep. This is where I feel a lot of valve driven units I have auditioned can tend to suffer. The M400S monoblocks are rated at 40 Watts rms each, and as many others and myself have mentioned before, amplifier power is all directly relative to the sensitivity of the speakers. A 40 Watt amp into a loudspeaker with a sensitivity of 90 dB for 1 Watt @ 1 meter (which is about average) will produce a maximum of around 106 dB of sound pressure. This is more than enough for any home hi-fi application that I could think of. Most popular music has a dynamic range of about 10 dB, and classical music is around 25 dB (affected by the amount of compression used in the CD production).

Think of it this way: If I am playing a piece of music with the lowest (not average) sound level being around 80 dB (which is not exactly quiet), the M400S amplifier would easily handle the transients (26 dB available) required to correctly reproduce almost any piece of music. Oh, I almost forgot to mention that these figures are for one loudspeaker only, so using a pair (as we all do) adds another 3 dB to the maximum output.

Vocal oriented tracks from Australian artist/performer Wendy Mathews had a lovely deep richness not often found in an amplifier in this price bracket. Telarc's version of the 1812 Overture was reproduced very well, not lacking in any department. Trumpets were sharp, violins detailed and well rounded. The M400S has good separation between all instruments - and the cannons at the end of the piece-"Played hard-done well"! Remember, we are talking about dynamic range here, not absolute loudness. If you want those cannons at 110 dB, an amplifier of much more power is in order.

Conclusion
I really enjoyed the company of the Opera M400S pair for the period of time I had them. They are by far the best value for money tube monoblocks I have come across. They really do a more than admirable job of delivering good sound. That's what it's all about, and if you can save a few bucks in the process, all the better!

Copyright 2001 Secrets of Home Theater & High Fidelity.

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