Test Report Of Four Tube Amplifiers Including Consonance R1.1, PM-1 & M500
In IMAGE HIFI 6/2000








Reference 1.1, PM-1 & M500





Pear Audio




Test Report Of Four Tube Amplifiers Incloud Consonance
Reference 1.1, PM-1 & M500

Translated from Image HiFi 6/2000

Valve Amplifiers by E.A.R., Opera Audio and Pear Audio

Words: Roland Kraft (translation T. Loesch), Photos: Rolf Winter

The designers of this Valve Features participants are Tim de Paravicini, Bojan Hajdinjak and Liu Zhao Hui. This means made "made in England", "made in Slowenia" and "made in China" - can it be any more international?

The key info right at the start: Editor in Chief Dirk Sommer feels that in this publication topics other than "only" Valve Amplifiers should be covered. A view not shared by the Author of these lines, given that Valve Amplifiers are the second or third nicest thing in the world. Still reality pressures dictate that that in itself unnecessary Equipment like transistors (yuck), 86-decibel loudspeakers (aaaargh), 5000 deutschmark LP pickups (gulp), record players without magnetic field bearings (bahhh), CD-Players (PlayStation) and naturally Cables (okay...), Features (7-Series without typeplate, oh god), Show Reports (C.B. with O∩hEocha Design) and X-Files (post nationalist meta vibes -- cool) must be published. Which at the bottomline means that place for Valves is lacking.

Longwinded, extremely difficult negotiations finally resulted in the following: The Valve Feature appears in instalments, planned are at the moment two parts, the first you are reading now. We continue in the next issue, though the ordered glassware could easily last for another instalment. Also planned is a small valve Journal and naturally a Internet report.

Test Valve Amplifiers Opera Audio Consonance PM-1/Reference 1.0/M500

Price 15000 Mark

These units, phonostage, preamplifier, poweramplifier -- hail from China, more precisely from Beijing. They comply with the concept held by real Valve enthusiasts, not unsurprisingly perhaps, given the large number of High End activities in China. Starting with the brief, but well written operating manuals we can further note the clear electrical construction, the high quality components and attractive casework. The latter, accented with real wood helps specially the preamplifer Reference 1.0 to a noble appearance. For this unit we noted a surprising fighting weight of 15 kilogram, caused first by the massive aluminium front panels and secondly by a substantially overdimensioned transformer ensemble. Contrary to the monoblock poweramplifier's 每 more on this in a moment 每 the preamplifier is build on a printed circuit board; two ECC82 double triodes grace the valve sockets. Sporting only three inputs the Reference 1.0 is hardly a connection marvel; purists however will not need any more and will rather point towards the high karat ingredients of the Preamplifier.

These show themselves after lifting the wood clad lid, where we must note with a wink that in Beijing different views regarding the precise fit of screwholes are held than over here. Yet we bear the fiddling with composure and rather look at the Transformers in their screening case and consider the fact that the powersupply employs choke filtering. No less surprising is the Volume control, consisting of a multistep switch combined with noble resistors and the fat Solen polypropylene powersupply capacitors are used. The principle is becomes quickly clear: extremely simple, feedback free circuit 每 only two triode systems in standard circuits are in the signalpath -- high quality components, excellent powersupply. Sonically this way can result hardly in anything wrong, specially with the critical coupling capacitors coming from a well-known audiophile component maker.

Structurally the 300B Monoblock poweramplifier's follow suit; simplicity is the motto, bringing us to the -- with single-ended amplifiers essential -- choke filtered power supply. This naturally uses a Valve rectifier; here we find a 5Z3 from Chinese production in the socket; however internally this unit reminds me strongly of the common 5U4. Used as voltage amplifier/driver is the well-known 6SL7, here in form of a JAN 6188 from American manufacture. The only highlight for the circuit design is the use of one triode as anode load for the other; in America this is called "series amplifier" or "SRPP" ("shunt regulated push-pull"). This circuit offers both adequate gain and low output impedance, as it is well know that a large power triode is not easy to get "into gear". Via the coupling capacitor 每 a polypropylene unit from Wima 每 we connect to the grid of the dc heated 300B. The Chinese manufacturer uses Valves from domestic manufacture, whose cathode is connected symmetrically via two 20 Ohm resistors. The correct operating point is achieved by the voltage drop across a 1kOhm high power cathode resistor; giving us the standard connection for most 300B single-ended amplifiers.

Power Transformer and filter choke are located below a shielding cover -- this is technically more relevant than a thick-walled case

By the way, "official" 300B's, oriented on the original Western Electric Amplifier WE 91A use a difficult to obtain 880 Ohm cathode resistor. In direct contrast to the preamplifier, the two monoblocks have not been constructed with audiophile components; instead we find quite common components 每 except for some (Chinese) resistors of a very antique looking construction, known only to the historically interested radio amateur. Not that it effects the function in any negative way. The sonically critical heater voltage for the directly heated 300B (heater = cathode) is produced by a simple rectifier-capacitor circuit; one often sees the well-loved 5V Regulator in this position.

The abandoning of the integrated regulator and the thus less stable heater voltage complies with the views of some valve enthusiasts, who steadfast

The old motto of the "short signalpath" is taken literally by this 300B Amplifier, more is not needed for nine watt

maintain that a triode with unregulated and thus passive heater supply sounds better.

A negative feedback loop between output transformer and input stage is not diagnosed; the 300B fan's see this with pleasure. No less of a pleasurable view is presented by the pure ceramic valve sockets and the absolute "high-end" binding posts for 4 Ohm and 8 Ohm loads. The placement of the power switch directly on the back of the amplifier gives however reason for criticism 每 it is simply inconvenient having to bend and reach over the chassis every time. All transformers have black covers, three in number, if desired a further cover for the valve ensemble can be used. Despite the only twisted -- not shielded -- pair of input wires between input connector and voltage amplifier the noise levels of this amplifier are really fine. Lowther equipped loudspeakers are offered from the same German distributor, which are with more than 100 Decibel efficiency very sensitive to any hum or hiss (we will soon report on these highly interesting loudspeakers). Both the preamplifier and the poweramplifier's from Opera Audio show themselves as exemplary quiet -- compliment.

Finally, available optionally is a two part phonostage, named PM-1, as a matter of course with wooden front panels. One of the two enclosures' houses only the powersupply, the voltages are connected via a special connector. With a weight of nine kilograms for the ensemble one not only notes the very strong enclosures but also a hefty torroidal main's transformer with powersupply regulation. The 1800 Mark phono-stage, with reference to amplification and the 47kOhm input impedance, is tailored to use of Moving Magnet Cartridges, Moving Coil systems require a further stepup transformer. The circuit is based on one ECC83 Triode per channel, the two systems forming a two stage amplifier. The RIAA Equalisation works as active, frequency dependent negative feedback between amplifier output and the cathode of the first valve; the removal of DC from the feedback however requiring an extra coupling capacitor on the output. A further (positive) feedback loop connects the two triodes' cathodes, whose cathode resistors are not capacitively decoupled. The manual simply states "deep negative feedback" and quotes a surprising 86db signal to noise ratio.

The Volume control is manufactured by hand and with much effort from individual resistors - the steps are o.k.

This then makes itself very positively known in practical use, even if some radio frequency pickup somewhat spoils the picture. However, in all fairness, this illness is extremely dependent upon location and is usually easily cured with a few picofarad additional capacitance on the phono input.

When used as chain - phono-stage, preamplifier, power-amplifier - the resulting overall gain is notably on the high side. This manifests itself thus that with a 96db sensitive speaker appropriate for 300B's the 9-o'clock position of the volume control leads to already high levels. Of very little help here was the minus ten decibel gain switch, this actually operates as muting switch and almost completely kills the output. Should one use a MC stepup transformer, a low stepup ratio should be chosen. Yet, in the mentioned 9 o'clock volume control setting no objectionable background noise could be heard, illustrating the usability of this Chinese system with high sensitivity speakers very successfully. By the way, for the volume control: the fat, chrome plated knobs on the preamplifier tend after a while to get loose and turn on their axis - a small aesthetic blemish easily solved by tightening the small screws in the knows with a suitable Allen key.

Contrary to the small mechanical problems, these Chinese units show that when it comes to making music they can measure up without problems to the big names in Valve Audio. Here the power amplifier leaves some room for ones own experiments - instead of the chinese300B any other version of the famous triode can grace the socket. Appropriate pricewise seemed a pair of Sovtek 300B's that worked well with the power amplifier and offered more subtlety. This means that the tow monoblocks using the standard 300B's played very powerful, big and quick footed, offering through the bank an energy charged impression. Feisty, and sometimes hairshirted the M500 offers the warm fundament and the almost sleepwalker like rhythmical surety known from other 300B concepts. With that the Bass reaches comparatively low, which says something about the quality of the output transformer. With regard to detail and resolution in the treble it is marvellously possible to live with the mono's the way they come out of the box; if -- by the way -- the basic condition - namely a lot of sensitivity behind the amp - is fulfilled. With the Sovtek in the socket the somewhat hairshirted tonal leaning is exchanged for a trace of more charm and refinement - a matter of taste, not the least determined by the character of the Speaker used. The Sum then as far as the power amplifier is concerned: a perfect 300B starter drug.

Accounting for the almost classical recipe for success, namely a simple valve circuit combined with an extensive powersupply and high quality component, it is not surprising that Reference 1.0 linestage preamplifier delivers the goods. The preamplifier is exemplary transparent, but clearly shows the use of valves, thus sounds liquid, full of temperament, is never aggressive, retains tonal colours and space, knows neither hum or hiss and if one wants to find any reason for complaint, one might find small issues of microphony, but such an old topic for valve preamplifiers. Short and sharp, a big recommendation, especially in teamwork with CD Players. Okay, more is certainly possible. This Chinese preamplifier stops on the one before last (pressure) step in the Bass Basement, but on the way down there neither contour nor control is lacking. A little above this, the knife-edge walk between fullness and precision succeeds greatly and in the midrange others manage the famous tic more liquidity, more expressiveness, more dynamic. But, and that is the most important most important question, at what (extra) cost? The fact is, in this case the price/sound relation is incredibly good and whoever wants more has look much further up, among the super expensive monsters. A small drop in tension, sorry in sound must be accepted by those who extend their system with the PM-1

A small drop in tension, sorry in sound must be accepted by those who extend their system with the PM-1 Phonostage. Compared to the other players this duo reveals itself as too pedantic, sometimes stoic. Okay, all comes clearly etched, almost officially fastidious, however also, yes, somehow totally unerotic. Maybe some of the liquidity is missing, that the charm of Valves was lost. As swinging and elastic as the Pre/Power combo steps, as stiff, as braked down is the presentation of this Phonostage. That is despite the for Valves almost reverence inspiring freedom from noise; despite clear plus points for the rendition of space, which is stable, deep and thus convincing. Both the impulsiveness and the excellent timing abilities as well as the tension build-up that the pre- and power-amplifier manage so well are subdued; furthermore the rendering of the low frequencies is less palpable and visceral. This is not the least the result that now grey dominates over deep black, that the low frequencies seem not as far extended downwards. Non of this should be seen as devastating criticism, but only as a note that the phonostage plays below the level of other components from the same house.

Image x-tract

For the money, that is dead sure, a fine combination; if one listens very closely and can overlook minor problems - all of mechanical nature -- that is. Nothing for the soldiers of battles of mass and overbuild among the Audiophiles. Yet sonically a safe bet for valve novices, who may not have the equivalent of a nice family saloon car to dispose off, but also would like something better than the average. My personal sonical extra tip are the 300B monoblock amplifiers, which even equipped with china triodes produce great fun - instead of expensive valves better buy records!
image infos
Opera Audio Consonance Reference 1.0
Inputs............................... 3 X Line
Outputs............................. 1 X Line
Features...............................screte .......stepped attenuator, mute-switch
.no negative feedback, choke filtering
Size (W/H/D)...............................3/32/10cm
Warranty...............................12 Month
Opera Audio Consonance M500
Power...........9 Watt (Manufacturers rating)
Output...........4/8 Ohm Bin
ding Post Inputs...............................4X Line
Features........300B singleended ......Monoblock with choke filtering ........and valve rectification
Size (W/H/D)............22/17/41cm
Warranty...................12 Month
image contact
Opera Audio - Boldyreff+Mende GdBR,
Beierheimer Allee 30, Karlsruhe;
Tel.: 0721/9665402;


Copyright©2004 The Opera audio Co.,Ltd
  powerby hifi-china.com