AAAVT Sonus Mirus 40 integrated amplifier

02.12.2013..

Introduction

The tube integrated amplifier that we are testing today is the first totally "Made in Italy" by AAAVT, a one man company that we all know for the very competitive price/quality ratio of the devices imported from China.

The core is Mauro Scarabotti.

Sound mixer, sound technician, responsible in the past for the designing and installation of low frequency systems in a big firm, Mauro spreads everywhere his ardent passion for the tube amplifications. He founds his small but fierce distributive reality through which he introduce in Italy some Chinese devices that he adapts or amends in order to get good quality and good prices.

 

Design

The AAAVT Sonus Mirus 40 is a tube integrated amplifier entirely designed and realized in Italy for the Hi-Fi and Hi-End market. In these amplifiers, you can find ten years of experience and all Mauro's passion. There are two operational modes: ultra-linear and triode. The circuitry is traditional with the preamplifier tube in SRPP: this stable scheme is perfect to work with and without feedback. All the transformers are "hot-melt" coated in order to minimize the mechanical noises and have laminated iron cores of excellent quality. The amplifiers are equipped with an aluminium remote control.

The Sonus Mirus 40 can mount EL34 tubes, like our exemplar, KT77 or 6CA7. The older brother has 50 watts and uses KT88, KT90 or KT120 tubes upon request.

Mauro told me that the chassis are the only parts realized in China, while the assembly takes place in Italy, where the transformers come from as well.

 

Manufacture

"Traditional" is the best adjective for this amp. Black chassis, tubes and transformers in view, removable grid to cover the tubes. On the frontal are the volume control, the on/off switch, four inputs, and the knobs to select the ultra-linear or the triode mode, with or without feedback.

The adjustment of the bias is very simple thanks to the lateral trimmers. The suggested operational values go from 350 mV to 400 mV.

On the back are the four line inputs, the outputs for the loudspeakers settable on 4 and 8 ohms and the IEC socket of the mains cable.

When you remove the lower panel, you can see the core of the device: it is well-finished, neat, air-wired and with components of extra quality. I cannot judge the technical aspects, but what I see is reassuring and makes appreciate the human, patient and meticulous work made.

Inputs and volume are replicated on the remote, except for the circuital configuration that is selectable only from the front panel.

 

Listening test

Let us open the games. Yes, because with this Mirus you can play. The switch from one circuit to the other, the real game, has to be done at a very low volume, to avoid any shock to the loudspeakers. That being said, I propose my personal sequence of tests which, considered two-plus-two possible combinations, brings to four listening conditions:

 

  • ultra-linear with feedback
  • ultra-linear without feedback
  • triode with feedback
  • triode without feedback

 

We have therefore the following scheme:

 

Ultra-linear with feedback – The scene is right between the loudspeakers. The image is more precise and defined in a scale virtual space in comparison to the dimensions that the instruments will have in the room. Full orchestra and dynamics gain from the maximum offered wattage.

 

Ultra-linear without feedback – A light veil falls down, there is less control, but the impressions I told before are confirmed.

 

Triode with feedback – It seems another amplifier. The scene is inside the room and it is no more defined by the space of the speakers or in the space between them. The sound is more "aggressive", present, material. It is more like a real event.

 

Triode without feedback – Another veil falls down and, also in this case, the previous impressions are confirmed.

 

However, with my loudspeakers, whose efficiency is quite high (96 dB) and have a simple module, the best choice has been the triode without feedback. If in the ultra-linear mode the low range was drier and ready, in the triode mode it was more articulated and involving. If in ultra-linear the scene was very defined and respectful of the instrumental proportions, in the triode mode the instruments were closer, physical and present. The ultra-linear composed a scene, the triode took you into it.

 

Anyway, if you use loudspeakers with a more contorted mode, with a more complex crossover and all below 90 dB of efficiency, the triode is really bad, so the ultra-linear is the best choice.

 

Pros

The Mirus is an amazing laboratory. It gives you all the warmth and the magic of the best tube amplifications. Multiplied by four. Differences are not opinions, but beautiful realities very easy to hear, perceptible, present at the listening.

 

Cons

When you have found your sound, suitable to your taste and - most important, to your loudspeakers - the other modes are meaningless and no more interesting. The device has given to you everything. End of the games.

 

Maybe

The Mirus leaves no doubts. If you want to examine it in depth, go to the final advices.

 

Quick metaphors and final recap

The Sonus Mirus 40 is a true act of love. It is a very well made amp with a very good quality/price ratio. In fact, it is totally hand-made, with point-to-point soldering, wrapped cables, selected top-quality components, etc., etc. It shows competence and DIY skills. It is also fully-developed. With decades of historic knowledge. Mostly if the DIYer or enthusiast is a friend and ask you, - like in this case - a limited hour cost, out of the market or impossible to support for a firm.

 

The AAAVT is made with care and - most of all - respect for the buyer.

 

The weak point of the device is its own strength. With the Sonus Mirus 40 amplifier, you can largely listen to the history of tube circuitries, to their “sound” and have at your disposal several devices at the same time. My experience and wisdom tell me that such kind of realizations does not bring – unavoidably - to "extreme" results. This amp makes everything good, but does not stand out.

I mean, in any case, we are talking of a realization that, for cost, manufacture and performances, actually stands out.

 

Who it is intended for?

The considerations I made, do not diminish the value of the design and device, but bring to good, simple and sound "purchasing advices". You have just to know what you are going to buy.

The Sonus Mirus 40 and – I presume – also its big brother 50, are devices for people that have more than one pair of loudspeakers. For people at first steps that want to make some experience, a great experience. For people looking for a no-compromise device and capable of "introducing to the listening" of the main differences in the world of the tube amplifications. For people who like to change their loudspeakers for test or demonstration. For people that want to get purist results without equalizers, banished by the Audiophile International Convention. For people who look for great performances without using the cables as equalizers, worse audiophile practice.

The Mirus is not suitable to people that have already heard everything, that look for a device that is extreme in its absolute performances, hence very demanding.

In this sense, it is a first amp to have a listening experience with, to let "be astonished by special effects", the sole amp to get involved by the tubes, or... the second amp for who has already a top-level amp.

In conclusion, if you want or need to demonstrate several kind of loudspeakers with a linear mode and a mid/mid-high efficiency, and feeling the "effect" of driving them with many amp gathered in just one device, the Mirus is an irreplaceable tool of work and pleasure.

Practically unique.

 

 

SCHEME SUMMARY

Tone colour| extension in frequency, ability to faithfully reproduce the instrument and its harmonics

The device is well selective, although not extremely. Natural and pleasant are repeated words in my listening notebook.

 

Dynamics | micro (detail) and macro (absolute) transients extension and rise time

Natural, graceful, not very pronounced dynamics, with that "velvet" that is typical of the best tubes, at least in my opinion.

 

Image | ambiance, transparency, scene, sound planes, virtual stage, sense of presence, resolution

As I said, it strongly varies depending on the circuitry. You chose, compatibly with the loudspeakers.

 

Tone | general equipment setting, if present, or characteristic: e.g. warm, cold, changing, amber, glossy, mat ..

It depends a lot on the tubes. I tested the amp with two sets, KT77 and EL34, and I personally prefer the second ones. The sound of the device is lightly warm, but not opaque.

 

Emotion | the capacity of emotional involvement, depending a lot on couplings, an absolutely anarchic and personal parameter

With quick loudspeakers with a complaisant mode, the Mirus performs at best. This parameter, also in this case, depends on the set of the amp, the most suitable for the loudspeakers in use. Generally, it is about a tube amp that stays a step beneath the surprise, maybe also for this, always pleasant.

 

Manufacture and Packaging | In its kind, exemplary the first one. A solid standard of double cardboard and plastic packaging the second.

 

Price/quality ratio | If you like to experiment sounds and hearing the differences, the ratio is very high with no competitors at all.

 

 

Official technical specifications:

Output power into 4 and 8 ohm: 2x40W ultra-linear, 2x21W triode

Frequency response: 20Hz-30 kHz ±0,5dB

Input sensitivity: 220mV ultra-linear, 160mV triode

THD: Max 0,3% 440Hz

Outputs: 4 and 8 ohm

Input impedance: 100Kohm

Tubes complement: EL34, KT77 or 6CA7 x 4, ECC99 x 2, and ECC803S/12AX7 x 2

Power requirements: 230/115VAC, 50/60 Hz

Power supply: 115V 60Hz, 230V 50Hz

Power consumption: <300W

Damping factor: 8-10

Signal to Noise: 80dB linear, -92dB A weighted

Inputs: four, also remote-controlled

Volume: Alps potentiometer with remote-controlled motor

Controls: variable feedback ratio and triode/ultra-linear mode selector

Dimensions: 410x410x240mm (WxHxD)

Weight: 28kg

 

Official Italian dealer: direct selling

Official current price in Italy: 1,950.00 EUR

Associated equipment: to my system

 


by Giuseppe Castelli
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