AVALON Mono Power

Audio Valve Avalon Mono Power Amp
As in the other PPP units PPP30 , PPP45 and so on the power tube EL 84 or 6BQ4 is installed. Some changes had to be done to get more power reserves out of the basic concept. The driver stage is amplified by an ECC 83 and ECC 82. This leads to two more tubes-finally eight power tubes which deliver the necessary current to the output transformer. Also the current had to be higher chosen to adjust to the changed conditions. In this new development the power transformer has nearly 200W. Why this new AVALON ? It is to reduce the wide distance between PPP45 and Challenger amplifier series. A combination with electrostatic loudspeakers requires sometimes more than 45W as the PPP45 has but the Challengers with up to 150W could be too strong. 
So there has to be a new unit which has between 60W and 80W and this power level is realized in the mono power amplifier named AVALON. The whole concept is lodged on only one double sided pc-board. Four anode electrolyt condenser with nearly 1000 uf provide for the needed currents at a high dynamic. There are two trimmers for the bandwide and the input sensitivity on the pc-board which has ceramic sockets. In this way the adjustment to the different hifi products is easy. The bandwide can be reduced by a trimmer capazitor and takes the scarf of the high frequences. The input sesitivity is adjustable between 0 dBm and zero. 
All power tubes operate in class-A - the bias-current in the tubes is controlled by cathode resistors. We chose qualitativ high tubes (SOVTEK) so the full automatic bias regulator (ABR) is not necessary in this concept. As on the other mono amplifiers there are the main switch on the right and the stand-by switch on the left side of the front pannel. Both functions are shown by LED-s. On the rear side there are high current speaker terminals for 4 and 8 ohm load, the RCA jacket for the input signal, also the main plug. 
The size is identic with the case of the ASSISTENT 20. All parts of case are in 3mm and 5mm steel and laser-cut.
The AVALON is AudioValves latest and more powerful addition to its fine line of mono bloc amplifiers in the PPP 30 and PPP 45 series. It produces 75 wpc with a hefty damping factor of 60. It continues our time-tested and perfected proprietary parallel push-pull design. With the AVALON, the listener is immediately struck by the brilliance and authority of the sound coming from such a compact set of monoblocs. 
They are truly meant for the music lover who will be captivated by the sonic surprises waiting to be found through these wonderful tube amplifiers.
techn. - specs:
Concept: parallel push pull circut 
bias regl. for all power tubes 
Output Level: 25 V max. - at 8 ohm load
Power Output: 60 - 80 Watt 
Power Bandwide: 4 - 34.000 Hz 
Distortion: 0,3% - 40 Watt - 1 Khz 
Noise: 0,8 mV
RCA Input: 47 Kohm (0,775 mV) 
Output Impedance: 4 - 8 ohm 
Power Consumption: 200 Watt 
Line Voltage: 115 - up to 250 VAC 
Valve Line - Up: 1*ECC 83, 1*ECC 82, 8*EL 84 
Dimensions: (w-d-h) 210 * 32 * 220 mm 
Weight Net: 14 kg 
You can, almost undoubtedly, identify the devices under review here. The Company’s aesthetics are so distinct that it’s almost impossible for their products to escape one’s attention. Audio Valve was founded by Helmut Becker, both a musician and a sworn tube-circuit lover. Their product range solely comprises amplifiers, i.e. six power amps, two preamps, two integrated amps, a phono stage and two headphone amps. On just a glance, their common characteristics bespeak a specific philosophy that proves to be most interesting, to begin with. Mr. Becker is fond of serious wattage designs that are able to provide adequate -to say the least- drive to potentially any load. In addition, they are solidly built and carefully engineered -employing selected premium components-, but also fully loaded with features to maximally favor ease of use. Apparently, the German maker doesn’t care to go cheap on switches and terminals under the pretence of minimalism nor does he feel intimidated to show the interior of his creations, that’s why all of them are covered by a distinct transparent acrylic cap. To back that policy, it should not be neglected mentioning that Audio Valve is apparently not very keen on launching new models. The Eklipse/Avalon ensemble has been on the market for several years, having undergone no serious modifications, a testimony of diachronism that’s most desirable, nowadays. Shall we proceed to the details?
Overview, technical aspects
As far as aesthetics are concerned, there is not much more to mention. The Eklipse as well as the Avalon have a particular design, which -to my impression- will either acquire devoted fans or sworn enemies. The chassis’ of both devices are made of steel plates, a choice favored by Becker over new-era aluminum, as best serving mechanical and electrical isolation purposes. The hood is transparent, allowing for a fully visible interior. Air circulation and adequate cooling are ensured by wide vents above the tube arrays. This approach stands for Audio Valve’s considerable differentiation in aesthetics, a path which does not neglect security, as it solely permits visual access to the glowing glass without exposing kids or animals to burn-high temperatures. The final touch to the combo’s looks is “golden”, courtesy of the terminals and lettering on the power amp and of the preamp’s rotary knobs. As posted on the Company’s own site, the preamp can also come with a standard silver finishing option. 
PHOTO: Audio Valve’s aesthetics are particularly distinctive. The transparent top plate is a standard preserving their particular looks and displaying a mighty orderly implementation.

PHOTO: The Eklipse features seven line inputs, a tape loop, as well as two single-ended and a balanced output; you will probably not be missing anything here.


In terms of connectivity, the Eklipse features seven line inputs and an isolated (according to Audio Valve) tape loop, as well as two single-ended and a balanced output. The desired active single-ended out is user selectable, whilst the balanced out is always live. Input selection is carried out through relays, placed on a separate PCB, next to the good quality gold-plated RCA sockets. An interesting element here -which is also indicative of the manufacturer’s attention to detail- is the provided contact-cleaning feature, a process carried out by an oscillator that triggers each relay a few hundred times.
The Eklipse’s inner world (or so to speak, given its transparent cover) is where conventional methods blend with solutions that follow an out-of-the-ordinary path. The design itself is implemented on the base of two ECC82 twin-triodes (EH) per channel, forming a two-stage circuit. The second stage acts -according to Audio Valve- as an inverting amplifier, which restores the phase slope so that the preamp’s out is on phase with its input, while at the same time allowing for only a small percentage of local negative feedback. As far as this Company is concerned, global negative feedback is not a good idea… The volume pot is a classic motorized Alps, but it is its placement on the second stage that deserves further reference. While it accounts for a most competent solution, ensuring low noise, there is one caveat: the preceding circuit’s overload margin has to be very high, as its gain is constant, non-variable, whilst the input signal level applied on each instance cannot be predetermined by the circuit designer. Audio Valve works around this problem in a way that’s nothing short of impressive. First of all, the Eklipse’s inputs are spec’ed at a different sensitivity each, thus covering the range between 15dB and 26dB, so it is up to the user to choose the appropriate one. Secondly, the preceding circuit’s overload margin is indeed really high, rated at no less than 15Vrms. The preamp’s alimentation starts with a large transformer featuring dual secondary windings (one per channel) and, from this point on, follows a dual-mono architecture, employing separate rectification-filtering and stabilization. Heater voltages are also stabilized, utilizing commonly used 78xx series circuitry. Component quality is top-notch, as in very low tolerance Dale/Vishay resistors and high-temperature rated capacitors. Interestingly enough, the preamp’s circuit board is printed, instead of being implemented the classic/vintage way, i.e. with terminal strips and a “spider” layout. Nevertheless, the PCB breathes very high quality, whilst Audio Valve claims it to be compliant with military specification.
PHOTO: The Avalon follows a monoblock architecture. Notice the elongate ventilation grills right above the output tubes, for adequate cooling. 
PHOTO: The Avalon’s only featured input is a single-ended one, but, as usual, there are two pairs of speaker terminals to choose from, depending on their nominal Ohm load. 
The Avalon stands for what appears to be Becker’s favorite topology. It is therefore a push-pull design, employing many tubes wired in parallel, in order to fetch adequate power provisions that won’t pose restriction as to the type of speaker used. The output component is a classic, the EL84 pentode, featured in quad-arrays per polarity and biased in class-A. The EL84s are preceded by an input stage, which employs a 12AX7 input tube and a 12AU7 driver/phase-splitter tube. Each tube is auto-biased, while a LED visual interface is there to monitor their status and to inform the user, by lighting up, in the case of their mandated replacement. The amp’s PSU is “crouched” beneath the main circuit and consists of a 200VA transformer along with dual rectification (one rectifying bridge per polarity) and filtering. Build quality is on the same level as the Eklipse’s, sporting premium componentry, zero floating cables and a well-designed PCB. The user has a say in both frequency response (as in highs roll-off) and input sensitivity, as they are both adjustable, but only a single-ended input to choose from – no balanced, sorry. There are, however, as previously mentioned, two pairs of speaker terminals, for 4Ω and 8Ω loads. According to the manufacturer, the Avalon is capable of outputting up to 80W on an 8Ω load. Frequency response covers the range from 4Hz to 34kHz, while THD is claimed to be 0,3% at 1kHz and 40W of power.
Lastly, the Eklipse/Avalon package includes a remote, featuring volume control, mute function and input selection, provided that the latter’s remote control-ability is activated on the preamp first. 
PHOTO: Two twin-triode tubes per channel account for two preamp stages. Volume attenuation is implemented at the second stage, to achieve lower noise. On the left can be seen the stabilizer ICs. Component quality is very high.
PHOTO: The output stage is a class-A biased push-pull, utilizing four EL84 pentodes per polarity. You can see the driver stage (12AX7/12AU7) on the right and the two rectifying bridges on the left.
Bench measurements
What’s to be primarily noticed of the Eklipse’s measurements is its high overload margin. On the 17db gain input, we saw levels of more than 15Vrms causing no severe distortion-related problems. Frequency response is very good, with no challenges worth mentioning, while channel differences are kept exemplarily low, well below 0,5dB, and this regardless of the volume knob’s position, denoting the pot’s fine tracking. Harmonic distortion ranged up to just below 0,02%, on the whole frequency spectrum (0,018% at 1kHz & 1Vrms output), whilst SMPTE intermodulation distortion figures were equally good, showing only 0,010% at 1Vrms. The preamp’s noise proved to be vanishingly low, i.e. 89dBA at 1Vrms/1kHz, but a difference was noticed between the two channels. The right channel (probably the one located closer to the transformer, that is) reached as… high as 86dBA. Exceptional low-noise performance can also be observed on the corresponding chart, where the power supply’s interference (at 50 & 100Hz) is at any rate kept below -90dB for a 1 kHz signal. The same chart reveals a successive order of 1 kHz harmonics whose level is very quickly and smoothly dropping. Crosstalk performance was not bad either, at -78dBr (1 kHz @ 1Vrms ref. level).
The power amplifier proved to be powerful enough, outputting 70Wrms on an 8Ω load (while running at a 3% distortion threshold), a figure that remained intact also at 4Ω, using the respective speaker terminal. It therefore scored very close to its theoretical limit, given the 25V (max.) output level posted by the manufacturer. Measuring a 4Ω load on the 8Ω terminals fetched much less power output, namely 45Wrms under a 3% distortion threshold. Maximum output was obtained with 980mVrms at the input. Expectedly, distortion remained stable up to ca 2 kHz and, from there up, it started mildly increasing, to reach 3% at 20kHz for 10W of power at 8Ω. As with the Eklipse, frequency response presented no problems here either, fluctuating within 1dB (at 10kHz and 30 kHz). Distortion charts show low PSU-induced noise (50Hz and 100Hz components are measured below 100dBr with a ref. output level of 10W/8Ω), but also reveal a “cheerful” harmonic behavior, which nevertheless decays smoothly. What’s most intriguing in the Avalon’s case is the relatively increased intermodulation distortion, as “given out” by the lobes that accompany the fundamental frequency as well as its harmonics. This is also confirmed by a no less than 0,64% figure, statically measured per SMPTE (50Hz/7kHz 1:4) at 10Wrms/8Ω. It is, however, highly probable that the issue is solely related to the review sample, which has apparently been of rather high mileage.
all CHARTS: look at the original review:
click here to see all original measure graphs
The Eclipse/Avalon ensemble was put in the place of the reference Melos Plus Series Line & Parasound HCA3500 combo and was asked to drive the ATC SCM50 PSL. The source was a “classic”, namely the P70/D70 duet, communicating in dual AES-3 via Nordost’s Valhalla Digital interconnects. Occasionally, I would switch to high-definition material, running foobar2000 software player through dCs Puccini U-Clock.
The preamplifier features a native soft-start circuit that induces an about 60-second time-delay, to allow stabilization of current flow as well as progressive tube filament heating. The preamp’s output has to be manually activated by the user and the same goes for the power amplifier, which features an “Activator” switch on its front face. During the review process, critical listening would only take place after allowing a ten minute warm-up period, although I don’t think that this would actually be necessary. All components utilized by Audio Valve are of very low tolerance, I therefore vividly doubt that they are influenced by fluctuating temperatures, not to mention the fact that both devices operate in class-A which means that they reach their operating temperature really fast.
The initial impression created upon listening to the Eklipse/Avalon combination is that of a system with high drive and control abilities, resulting in a pleasant character that predisposes for prolonged listening sessions at a high volume level. Of course, the Avalon is by no means a power-beast, it would therefore reach its ceiling much sooner than I’m used to expect of my HCA3500, still producing levels high enough to be considered satisfactory. Concurrently, up to its limit and a tad above it, this amplifier never becomes unpleasant, exhibiting only a progressive loss of perceived transparency as a sign of overloading. If kept within its limits, though, it will reward you with a righteously voluminous and very detailed low-region, which was only observed to have a slight tendency towards over-control, an exceptionally transparent midrange, which is also one of the most tire-free I’ve ever come across, and an extended, very well outlined, if not a bit programme-flattering, treble. 
The latter characteristic may well qualify as the most substantial of Audio Valve’s ensemble, whose nature proved very generous on harsh or shrill productions, thus retaining its stress-free status throughout listening sessions, in a way seldom seen. It even managed to counter-balance the SCM50’s canning -let alone unsettling- ability to reveal everything, but without compromising equilibrium inherent in its own recipe; I would easily rate the outcome as accurate, for there hasn’t been a single moment, during this review, when I would sense something was concealed or, most importantly, missing. 
Another point of interest would be dynamic response. As Audio Valve’s combination proved virtually silent (even for those curious enough to stick their ear to the tweeter), it can effortlessly blast from a pause to a crescendo’s peak, qualifying as a solid bridge between demanding oeuvres and exigent listeners for whom “very good” begins at “sensational”. This is also aided by the combo’s competence at soudstaging. Fed by a very detail-oriented source, such as the P70/D70 pair, and with some highly resolved -if not over engineered- productions, the Eklipse/Avalon system managed to create an airy yet stable sonic scene, animated to its exceptional depth of field, where instruments could easily be located and soloists could almost be seen in the listening room, even at a loud volume. This behavior is fully compatible with our measured results, i.e. minor L-R channel differences (of just a few tenths of a dB) and very low crosstalk. 
Resultant of all the above elements: Audio Valve’s separates turn out to be serious generic-use gear, as they more than cope with a vast programme range, from small ensembles to symphonic music and from there to electronika. Most of all, it seems to feel at home when asked to command high sound pressure -which is rather uncommon among tube designs- courtesy of the Avalon of course.
To conclude… 
…reviewing Audio Valve’s ensemble ended up being a most pleasant surprise. Delicate though it looks, it is nonetheless ready to sustain real-world, casual use, without posing any prerequisites or demanding any kind of compromise. 
Extended dynamic headroom, enhanced drive-abilities and a wisely balanced -even if slightly “personal”- approach of the treble region are the very attributes that result in a mighty interesting option for all those seeking thoroughbred, but not extravagantly priced, tube-gear. Please… listen!
Original review: Dimitris Stamatakos
Rendition in English: Nikos Douris 


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