The M2Tech Crosby expresses from the very beginning the high efficiency and relaxed power typical of the class D, which allows it to drive the majority of the speakers with ease and without apparent failure. Moreover, its driving capacity can be increased by setting it in bridged mono. It is equipped with both single-ended and balanced inputs plus a trigger input/pass-through. Its class D design makes it practically free of malfunctions or damage and all possible overload situations are immediately signaled on the front panel. In everyday use it turned out to be a real "mule": reliable, silent and always on the piece. Imagine what could have happened if you had two available ... ;-)
It does not have the lightness, in my opinion inexpressive, of the Technics SU-G700 or the ambitions of the Specs, legendary creations for sound but still developed around cheap modules in class D. Crosby is rightfully part of the most recent series of M2Tech luminaires: the Rockstars. And this is: Crosby is "rock". Especially when two are used in bridged mono.
We have recently tested how a couple of cheap final class D can do even in bi-amping and in the last Degustazioni Musicali event the demo of Marco Manunta, engineer and responsible M2Tech, has obtained great appreciation just using two bridge Crosby. This significant difference in yield compared to the more traditional amplifications in the AB class struck me. I then deepened the subject with Marco's experience and the live voice: "In relation to your observation on the bridge behavior of amplifiers in class AB and class D, I basically agree with you: the latter behave better than the first ones.
Looking back on the reasons, I can not help noticing that when we connect two channels of a bridge amplifier, each channel "sees" a load equal to half the actual load. So, if I have a nominal 8-ohm speaker, with all that this statement implies at the actual impedance and phase curve level, and I drive it with a bridge amplifier, each branch of the amp will work in all respects on a nominal 4 ohm load. Hence the different behaviors: an amp in class AB is generally equipped with protections that limit the supply of current. It is clear that if I ask the amp to work on smaller loads, and therefore to deliver higher currents, I will more easily lead amp protections to intervene in peaks or at certain frequencies, where the actual load module reaches its minimum or where the phase shifts are more intense.
On the other hand, a class D amplifier does not have intrinsic limitations, since it works practically always in interdiction or saturation, in regimes, that is, where the dissipation is minimal and the operation safer. For this reason, because of the maximum current that can be supplied by the power amplifiers and the current limitations of the power supply, a class D amplifier works quietly on low loads. Moreover, class D projects are generally optimized for low loads, in order to maximize efficiency.
For these reasons, except for special cases of class AB amplifiers designed specifically for bridge operation, class D generally gives the best in bridge mode while the AB class makes more single-ended."
In short, the Crosby is the amplifier, the power unit, tailor-made for its DAC/pre, the Young MkIII, both for external appearance and for sound integration. The synergy between the two devices is deliberately studied and succeeded. What is the big advantage? As you will read later, in the lines of our friend Gennaro Muriano, he can obviously be connected to any pre, to take advantage of the further "swing" offered by an analog amplification stage. But ... he does not need it! The sensitivity and gain of the Crosby do not require the interposition of a preamp, particularly a high output one. The cleaning, the transparency and the overall consistency of the sound message benefit from it, but the further push of a pre can sometimes result in compression and hardening of the listening signal.
Among other things, taking advantage of the M2Tech DAC, the Crosby closes the circle of an ideal audio system of quality friendly for the younger generation, where the ability to listen to their music through the simple Bluetooth connection aptX can make “dad system" a real discovery!
As anticipated, I now leave you to the words of Gennaro's technical analysis and listening impressions. In this first four-handed article experiment, which I hope I can replicate, I have limited myself to my usual "buying advice", since most of our objects of desire are often done well, if not very well , but they must be understood and addressed to their ideal user, who might look for both the relative advantages and the relative relative limits. As the same object of this test, M2Tech Crosby, made for pleasure, to be appreciated and be forgotten in everyday use.
G.C.
Every time I approach listening to an amplifier that I don't know, especially if it is a new model, I always put myself in a condition that I define as "passive observer", in the sense that, not knowing what I have to expect, I prefer to put myself there to hear what the newcomer has to tell me. I do not say to approach the object in a completely neutral way, because it would not be correct. When I am in front of a product that intrigues me, regardless of the commercial sector, I begin to wonder what the designer wanted to get when he worked, what sound he had in mind and what were his musical orientations and his experiences. All things that say a lot about that object and why it was made. And they also outline what would be expected and what not. But above all, what is the appropriate context for that amp expresses its actual potential and performance, without being mortified in settings far from its basic orientation.
I consider the amplification the key element of the audio chain and also the most fascinating. The source determines how - quality - and how much - quantity - will be read from the recorded medium. The speakers have the degree of interpretation that the musical message can have. But the amplifier has the task of acting as a communicator bridge between the two parts, which otherwise could not communicate, and its role of union between two substantially different elements is not so simple. Its behavior depends on the timbre and dynamic imprint that the system will take and the reason is easy to understand: the amplifier takes the low voltage signal from the source, which would be too low in terms of energy/current to move a heavy mechanical element like a speaker. After having elevated it in voltage and in energy, it transfers it to the speaker/speaker which, by its nature - it is one or more mechanical elements moved by electric current but with sizes and weights which are not negligible - can not be linear in moving at all frequencies. This causes a contrast, an effort in the amplifier, due essentially to the fact that the speakers oppose to the movement imposed by the amplifier. The harder the speaker is, the more complex the filter, the lower the efficiency and the more energy will be needed to compensate for the loss of movement. Conversely, a very light speaker and a basic filter will require little energy to move, ie you will have high efficiency. Something similar to what happens when we walk a steep uphill road, perhaps full of curves: gravitational weight is opposed to our progress and tends to bring us down, so we have to work harder to win the opposing force and continue. If we also have a heavy backpack with us, it is very likely that we will not make much progress, if not with extreme slowness. Making a similarity: the lower the efficiency of the speakers and the greater the number of filter elements, the steeper the ascent will be and our backpack will be heavy.
This pair of power amplifiers are the first objects that I find to try and review for ReMusic and when the director Castelli asked me if I wanted to try amplifiers, without even asking what it was, I immediately said: yes! I always love to try an amp. Although my room is a seaport and, for one reason or another, there is a continuous coming and going of amplifiers of various types and ages.
I already knew M2tech quite well, because in the past I had the opportunity to have some of their products, especially for several months, the famous DAC Young, to whom this model of amplifiers is explicitly dedicated.
The Crosby is very compact and fairly light, about 3.5 kg, characteristics that make it very versatile and practical. I imagine it as an ideal complement to a compact, high-quality full-liquid system consisting of one or two Crosby, a DAC, a pair of quality bookshelf loudspeakers and a PC or media player.
I also knew that the newly built class-D amplifiers had come to a good degree of development, to the point that they could be a valid and practical alternative to the classic mid-class AB amplifier, because the electric and sonic performances are the same, they are often even better in D.
When I got the two finals I immediately unpacked and placed on a shelf next to my usual electronics but I did not listen to them: first I wanted to keep them in sight to get in tune with them and in the philosophy of their use.
The test took place in three different phases to test the different operational possibilities:
- as a stereo final connected directly to a source with variable output
- same condition but connected to an active pre
- in a mono bridge configuration
In the meantime I peeked a bit inside one of them and chatted with the manufacturer, in the person of the excellent Ing. Manunta, who told me some about the origins of the project. The amplifier is based on the classic and well-known Ice Power modules to which a M2tech production card is added, which integrates the input circuit and handles selection of the different inputs. Manunta told me that the board also handles the IcePower module's parasitic input capacity, which could create some idiosyncrasies if connected to sources with poor propensity to capacitive loads.
I first tried one of the two amps in standard stereo mode, connected to a pair of Kef Reference One and to the variable output of a mid-high-end Denon CD player, using the RCA unbalanced inputs: half an hour of settling and heating and I switched to listening.
I know the behavior of my Kef well when they do not like an amplifier, but this was not the case and immediately what I felt is a nice performance in terms of pleasantness of sound: the Kef sang limpid, fluid and with a pleasant backbone down. Normally they work with a Pioneer A-858 Reference, a robust, top-of-the-90's, over 100 watts per channel, which provides, in my opinion, the right amount of verve to my far too English ladies.
Switching from the Japanese to the Italian power amp I did not notice a loss of "pulse" in the two British drive, even when I pushed them hard. 60W are not few for a domestic listening in normal setups and in fact I have never found myself short of energy in any condition of the test. The Denon is a reader that I appreciate for the natural transparency of his sound and for the overall balance and here I found to be an excellent partner for ours: hours of listening ranging from jazz, blues and swing in which I was substantially estranged from the context of the test, because I prefer to focus more on music than on the system. If then something inside calls my attention, then it will be the emerging peculiar character, which will say the object in question.
For the second stage of the test I used a Counterpoint SA-3000 valve preamp which passed by my laboratory for assistance, the reader remained the same Denon. With the preamp, things change slightly, I feel that using the amps together with a preamp can maybe slightly change the excellent result that I had instead found in the direct use of the source. The reason, I think, is due to the fact that this power amps already have a fairly high gain, being them purposely designed to be coupled directly to a DAC or to a passive preamp: instead, the contribution of further gain does not benefit at all to the sound. As I have noted, they prefer to be driven by not too low impedances, this not for electrical idiosyncrasies but only for reasons concerning the balance of the timbre. What happens is a hardening of the voice in general, that beautiful feeling of compact and smooth sound that I had perceived at the beginning has now been resized, you can only see between the lines.
Even using other preamps with a little lower gain, the worsening was less evident but always noticeable. Normally the good preamplifiers have enough low output impedances to drive even low-sensitivity amplifiers or low input impedances. This is not a panacea for the small Crosbys, which instead prefer the output from a bit less "muscular" sources.
The third stage saw the two power amps configured in mono bridge to a declared power of 180 watts each. In addition to Kef, this time I also used a pair of IMF stand-alone Compact Monitors, professional near-field loudspeakers with characteristics similar to the Ls3/5a but more incisive and precise. But also rather harsh, with efficiency around 81 dB and impedance of 6 ohms. Well, in this mode I used Denon and the Kef first, to see what they could do in this configuration. Well, I could say that the amps substantially remain same devices, I didn't feel any significant change, neither better nor worse, compared to the standard stereo operation, only the sensation of a discrete greater presence of low range, combined with less damping, feeling which has a real cause, because in bridged mono mode the two channels are added in series, and therefore their output impedance is double, causing a lowering of the damping factor and a consequent greater persistence of the low range. In addition to this, the possibility of achieving quite higher volumes.
Switching to IMFs, I also changed source, which was now a valve 0.6t Lector cdp, connected via pre-passive. In this mode I didn't find the same enjoyment as before, it was all a bit flatter and I had to raise the volume to recover the verve and the beat I had found at the beginning. But this I do not think is due to the hardness of the monitors as to the fact that they are closed speakers, while the Kef are reflex, and have therefore a rather linear response. In addition, the monitor setting highlights the high and medium register, which is fairly indulgent to those on the other side who give voice to them.
In conclusion I have to say that this objects I liked it a lot: small, handy, well sounding if used for uses suited to their nature, silent and performing in every situation. I do not generally like to describe the proof of an electronic with the usual terms of audio review, it gives me the idea of a somewhat aseptic description. Instead I prefer to express my impressions in a simple way, as I would describe them to a friend or someone who asked me about it. These small power amps - only small in size - are good for a high quality liquid music system; very good in an AV system where music occupies an important place; interesting in a traditional chain with physical source like CD or other, where however the great digital performances of its partner Young MkIII can also make use of interfaces with many other types of amplification.
G.M.
Official technical specifications
Inputs: single-ended RCA, balanced XLR, 3.5mm trigger Jack
Outputs: post speakers, trigger pass-through Jack 3.5mm
Sensitivity: 1.25 Vrms, 5V trigger
Input impedance: 47kohm single-ended, 20kohm balanced
Signal to noise ratio: 115dBA stereo, 118dBA to bridge
THD + N: 0.005% at 60Wpc on 8ohm
Output power before clipping: 60Wpc 8ohm stereo, 110Wpc stereo 4ohm, 180W 8ohm bridge
Supply voltage: 100-130Vac or 200-240Vac, 50/60Hz
Power consumption: 615W stereo, 440Wpc on 4ohm mono, 1.5W standby
Dimensions: 200x50x200mm LxAxP
Weight: net 3kg including accessories, gross 3.5kg
M2Tech Crosby quick manual: download here
Complete M2Tech Crosby manual at the date of review: download here
Official Italian dealer: to Marantz Italy / Hi-Fi United website
Official current price in Italy: 1.190,00 EUR
Associated equipment: to Giuseppe Castelli's system
