Musical Fidelity 550Κ: Τί είναι πάλι ετούτο;

[Κώστας Φ.]

H ιδέα πίσω από το 550K Supercharger είναι προφανής και το πρόβλημα που περιγράφει υπαρκτό: Οι ενισχυτές χαμηλής ισχύος δεν μπορούν να δημιουργήσουν πολύ υψηλές στάθμες με τα σύγχρονα ηχεία μέτριας ή και χαμηλής ευαισθησίας.

Ενώ τις περισσότερες φορές σπανίως ακούμε σε στάθμες που -έστω- πλησιάζουν τα 100dB SPL στην θέση ακρόασης, το δυναμικό περιθώριο που απαιτεί η μουσική (δηλαδή οι στιγμιαίες στάθμες κορυφής) μπορεί να είναι πολύ υψηλό. Σε αυτά τα στιγμιότυπα ο μικρός ενισχυτής αποδεικνύεται ανεπαρκής και εισάγει έντοντες παραμορφώσεις.

Ολα καλά μέχρι εδώ. Για πολλούς από τους audiophiles αυτό είναι ένας κανόνας, γι'αυτό άλλωστε υπάρχουν και οι "αξιοπρεπείς" τελικοί των 200-300W. Αλλώστε, αυτή είναι και η φιλοσοφία της Musical Fidelity εδώ και καιρό. Ως εκ τούτου η πρόταση των Αγγλων θα έπρεπε να είναι σαφής: Πετάξτε τον "πενηντάρη" στα σκουπίδια (ή χαρίστε τον -τέλος πάντων) και αγοράστε έναν kW550 ή κάτι πιο ισχυρό.

Πρός έκπληξή μας, το 550K αποτελεί μια εναλλακτική πρόταση: Τοποθετείται μεταξύ του υπάρχοντος ενισχυτή και των ηχείων και αναλαμβάνει να απαλλάξει τον πρώτο από τις δυσκολίες οδήγησης των δεύτερων, πρσθέτωντας καμμιά δεκαριά dB δυναμικού περιθωρίου στο σύστημα. Ετσι, όπως φαίνεται το πράγμα, έχουμε να κάνουμε με έναν τελικό ενισχυτή ο οποίος διαθέτει εισόδους υψηλής στάθμης και ένα αποδεδειγμένα καλό κύκλωμα με δυνατότητα μεγάλων ρευμάτων, κάποιοι κακοπροαίρετοι μάλιστα ίσως θυμηθούν τα πάλαι ποτέ boosters των συστημάτων αυτοκινήτου...

Εδώ βεβαίως, μιλάμε, για ένα "booster" το οποίο χρησιμοποιεί το κύκλωμα ισχύος του ολοκληρωμένου kW550 (ρυθμισμένο για χαμηλό κέρδος τάσης, αφού αυτό το προσφέρει ο ενισχυτής που προηγείται) και έχει δυνατότητα να δώσει μέχρι 250Α κορυφής! Κατά την εταιρία, η παρεμβολή του 550K επιτρέπει στον παλαιό ενισχυτή να λειτουργεί πολύ χαλαρά, σε περιοχές κοντά στο 7% του ρεύματος που θα έπρεπε να αποδίδει σε διαφορετική περίπτωση, επομένως την ηχητική συμπεριφορά του συστήματος την καθορίζει πλέον το Supecharger.

Ολα αυτά, βεβαίως, είναι πιθανόν να ισχύουν αλλά το συνολικό concept εξακολουθούμε να μην το καταλαβαίνουμε, πέραν μιας οικονομικής πλευράς, η οποία θέλει δύο 550K (που χρειάζονται για δύο ηχεία) να στοιχίζουν αρκετά λιγότερο από έναν "ολόκληρο" kW550, με άλλα λόγια, πρόκειται για μια ευκαιρία να αποκτήσεις ήχο Musical Fidelity με χαμηλότερο κόστος...

Πηγή: avmentor.gr

 

[Κώστας Φ.]

Απάντηση: Musical Fidelity 550Κ: Τί είναι πάλι ετούτο;

Περισσότερες λεπτομέρειες και πρώτες ακουστικές εντυπώσεις απο το WhatHiFI.

"'So is it really loud now?' - that's the reaction I keep getting when I mention I'm running a pair of Musical Fidelity Supercharger 550K power amps in my system, writes Andrew Everard. And one of my fellow Gramophone writers wants to try them, but is worried he'll have to wait until the neighbours are out.

That's not the point about the Superchargers - yes, they will make your system go louder if you really want, but at £3000 a pair they might seem quite an expensive way of achieving that. No, what the cylindrical MF amps are all about is improving the dynamics of your system, from the big stuff right down to the way fine detail is conveyed.

Never let it be said that Musical Fidelity's Antony Michaelson isn't a persuasive salesman. When he gets behind a product - and he's very much behind the Superchargers - you tend to know all about it. So far we've had a visit to the listening rooms here in Teddington followed up with a delivery of a stack of samples, and since taking a pair of Superchargers home I've received a number of calls, the main essence of which has been So...?'.

Actually, I didn't need that much convincing - I'm yet to see what the WHFSV review team make of the units they have, but my initial reaction when I heard a demonstration was what I've referred to in the past as 'one of those silly grin moments'. So I was pretty keen to get a pair home and give them a try. Well, a couple of weeks on, and I've used them with a number of amps, including an old Marantz MusicLine combination, Shanling's flea-powered but oh-so-sweet-sounding MC-30 'music centre' and, most of the time, the Onkyo TX-SR875 receiver.

Now what I heard someone refer to the other week as 'the big Onk' is no slouch when it comes to music-making in stereo - and you're hearing that from someone who used to believe AV receivers were akin to the great evil when it came to music systems - but the Superchargers take it into a whole new league.

As I write this I'm listening to some Bach solo string music arranged for the lute and played by Nigel North in a four-disc Linn box-set available for a giveaway £20. The system is Naim DVD5, the Onkyo, PMC OB1s with Tannoy ST50 SuperTweeters, with all the cabling from Chord, and I have to say I have never heard better-sounding music in this room in the five years since we moved here.

Solo lute music may not be the kind of material for which most people would consider massive amp power an essential, but with the chargers in harness the music takes on a fluidity, presence and impact way beyond the already impressive results achievable when the speakers are connected directly to the receiver.

Pull them out and the music is pleasant, enjoyable but a little flat, though still remarkable by AV receiver standards; plug them back in and the whole sound opens up while at the same time snapping into sharp focus. In fact, the effect is even more pronounced when taking the MFs out than it is when plugging them in.

When I set the system up I re-ran the Onkyo's automatic calibration system, and noted the front left and right channels were now set with a few decibels of extra roll-off, which would surely defeat the whole purpose of having the chargers in the system. Far from it: listening to one of the Proms the other night on BBC HD I was struck by the gorgeous timbres being revealed in the period instruments of the joint forces of the Orchestra of the Age of Enlightenment and the Freiburg Baroque Orchestra.

Having recorded the concert, I then tried the Music for the Royal Fireworks both with and without the Superchargers, the difference best summed up as 'very nice' on one hand, and 'wow!' on the other. So why do they work? Well, if you wish you can take with a pinch of salt the slide-rule Musical Fidelity has produced to show you how your system matches up to the demands of your speakers and real music, but the principle seems to be all about taking the pressure off your amplifier.

The theory goes that, driving the benign load the Superchargers present, your amplifier can reveal its true qualities, leaving the chargers to do all the really hard slog. It's a persuasive argument, but one I wasn't sure about - I had bad memories of using booster amps taking speaker-level input in car systems back in my dim and distant, and remembered just how bad they sounded. But using the MF amps dispels any such doubts.

In fact, now I've been living with the Superchargers for getting on for three weeks, I have to close with a note of caution: these are probably not amplifiers you want to audition if you have any weakness in the 'Oh go on, then - do you take credit cards?' department..."

whathifi.com

 

[argi]

νομιζω οτι το ειδα στο hi fi news ακριβο ανευ λογου

 

[Κώστας Φ.]

Απάντηση: Re: Musical Fidelity 550Κ: Τί είναι πάλι ετούτο;

νομιζω οτι το ειδα στο hi fi news ακριβο ανευ λογου

Αργύρη, δες και μία σχετική συζήτηση εδώ. Είναι πάνω-κάτω το ίδιο concept.

 

[Tidal__]

Kαι εγω διαβασα ενα review στο hifi +.....το δοκιμασαν αρκετοι συντακτες και ολοι συμφωνησαν οτι αλλοιωναν τον ηχο του συστηματος παρα τις υποσχεσεις του Michaelson.

 

[Κώστας Φ.]

Απάντηση: Musical Fidelity 550Κ: Τί είναι πάλι ετούτο;

Δεν το έχω διαβάσει το review και δεν μπορώ να ξέρω. Δεν ξέρω και μέχρι ποιο σημείο μπορεί να συγκριθεί με τον F4 του Pass. Ο F4 πάντως, για τον οποίο γνωρίζουμε περισσότερες λεπτομέρειες, δεν αλλοιώνει τον ήχο.

 

[Κώστας Φ.]

Απάντηση: Musical Fidelity 550Κ: Τί είναι πάλι ετούτο;

Έτοιμο το review απο το Stereophile.
Στα $5000 το ζευγάρι στη άλλη όχθη του Ατλαντικού...

"So if you're interested in reproducing musical realism at home, how much power do you really need? More than you might think, says Musical Fidelity's Antony Michaelson, who offers his reasoning in a white paper. Michaelson's bottom line is that with loudspeakers having normal sensitivity, you are going to need at least 500W to reproduce music's transient peaks in your listening room at a realistic level.

...

What is a Supercharger?

Built in Taiwan, it's the same 550W monoblock amplifier circuit used in Musical Fidelity's kW550 integrated amplifier—which, MF claims, is quiet, linear, tonally superb, and produces high powers—550W into 8 ohms or 750W into 4 ohms—with ultra-low levels of distortion. MF claims the 550K delivers about 250 amps of current peak–peak, with a massive voltage swing.

In the 550K, however, this circuit is used in a low-gain configuration: you connect your existing amplifier's output from its speaker terminals to the 550K's input terminals. Then, using a short jumper cable (supplied), you connect the 550K's output terminals to your speakers. Thus, instead of your regular amplifier seeing a typical reactive, low-impedance loudspeaker load and being asked to produce volts, amps, and high peak current beyond its capabilities as it attempts to follow the music's dynamic range, it instead sees the constant resistive load of a high-impedance input circuit. MF claims that an amplifier driving the 550K is called on to deliver only about 7% of the current required to drive a typical loudspeaker. Essentially, your existing amplifier is now acting as a preamplifier for the 550K.

...

Conclusion

There's nothing particularly new about the technology behind Musical Fidelity's 550K Supercharger. Anyone old enough to remember first-generation car-stereo separates can recall that these were strictly "speaker out" devices; adding more power required "speaker-level," input-based amplifiers. The 550K's input circuitry is similar, as is the input circuitry of powered subwoofers that can be driven by amplifier outputs and claim to take on their tonal character. But despite these obvious antecedents, until now no one, to my knowledge, has thought of using the technology in a full-frequency power booster for a high-performance audio system.

Using a variety of very different-sounding amplifiers of various power outputs overwhelmingly demonstrated to me that the 550K Supercharger will retain the sonic attributes of your favorite low- or medium-powered amp (50–200Wpc), whether tubed or solid-state, while increasing its output by 10dB or more. The result will be dynamic realism and, in most cases, better overall performance. You can have your cake and make it rock, too.

If you attend a lot of concerts—whether of classical, rock, jazz, or all three—and are thus attuned to the true dynamic range of live music, listening at home to a limp, dynamically restricted stereo is disappointing. But once you're hooked on real-world dynamics at home, it's hard to give them up. That's why I can't part with my 1000W Musical Fidelity kW monoblocks, and that's why the 440W mbl 9007 monoblocks I reviewed in September 2006 proved so satisfying.

Dynamics aren't everything, of course. But if you feel that your system has everything but full dynamic range, or if you're curious to hear if it's possible to improve your system in that area, there's now a way of getting realistic dynamic performance without sacrificing any aspect of what you already like about your system.

The 550K Supercharger is an innovative but no-brainer, "Why didn't I think of it?" product that offers massive reserves of power at a reasonable price. I have no doubt it will measure well—most Musical Fidelity products do. Dealers should let shoppers take 550K Superchargers home and try them for themselves before buying. Few will be returned." -- Michael Fremer


"Like Musical Fidelity's kW750 monoblock—on which, I understand, its circuit is based—the Supercharger 550K offers a superb set of test results. In fact, its measured performance is actually a little better than that behemoth's. In its intended role of "supercharging" its owner's low-power amplifier, the Supercharger should have no problem performing as promised". -- John Atkinson


Full Review: Stereophile.com

 

[Κώστας Φ.]

Απάντηση: Musical Fidelity 550Κ: Τί είναι πάλι ετούτο;

Kαι το Hi-Fi Choice...

"Summing up is difficult. While the 550K is clearly a high-quality monoblock power amplifier that offers massive power output at a relatively modest price, the results of inserting it into a system Supercharger-style were not entirely predictable."


For

• Offers good sound, and superior dynamic range and headroom across a range of material
• Comes with versatile line- or speaker-level inputs

Against

• Supercharger concept works well with valve amps, but sounds best when used just as power amp, fed from pre-amp
• Could be crisper and tauter

Verdict
This exceptionally powerful and unusually versatile power amp delivers good sound, ultra-wide dynamic range and offers lots of headroom for peaks. The Supercharger concept is particularly well suited for use with high-quality, low-power (valve) amps.

Full Review: tech.co.uk