Going all spinal tap
Without wishing to contradict my oft-stated
aversion to ear-bleeding levels, I must admit that – on occasion – I do go all
Spinal Tap on my system, if both the mood and the music invite it. Oddly
(another admission) I do not necessarily mean music that begs copious levels,
such as ‘I Can’t Explain’ by the Who, or ZZ Top’s ‘Gimme All Your Lovin’’,
songs that simply cannot be played softly. Instead, I base my volume settings
according to the vocalist’s angst.
Krell’s
S-550i will be the potent 2 x 275-watt “big brother” to the firm’s current
S-300i integrated amp.
Why I am currently undergoing a Glen
Campbell obsession has much to do with his acclaimed farewell album of last
year. As one of the most intensely tortured songs I’ve ever savored from the
country milieu is Conway Twitty’s sublime ‘It’s Only Make Believe’: I was
delighted to find it on Campbell’s Collection [EMI Gold 243 5 77507 2 1], and
played it to death while reviewing the MyDAC.
It builds to an intensity that is almost
disturbing, a mass of instruments and voices as grandiose as the J Geils Band’s
‘I Can’t Believe You’ or Dolly Parton’s reading of ‘Put A Little Love In Your
Heart’. Campbell soars, the key changes lifting him up, up, up to a point where
you think his voice just has to crack. It doesn’t.
Neither does the Krell. The form, the
scale, the sheer power were so capably, competently resolved that to ask more
would be to exhibit the selfishness of some cretin on The Only Way Is Essex.
Never
did the Krell miss a beat. And never did I miss separates.
Inevitably, though, one must bang head if
one is to exploit the power of the Krell in a brutal manner, rather than as a
means of preserving dynamic swings or other bombast-free uses of a surfeit of
wattage. With iPod in hand, I played Led Zeppelin’s ‘Good Times Bad Times’ from
the Mother ship collection, an MP3 download.
Aaah, Bonham’s percussion! ‘Massive’ is one
of those words like ‘awesome’ or ‘epic’ that has become robbed it of its true
meaning and impact, but there is no other word to describe the sensation. The
man abused those drums; beat them like a crazed version of a Roman galley’s
pausarius, and the power was palpable. Beneath it was Join Paul Jones’ rich,
mellifluous bass. The Krell offers both a podium.
Never did the Krell miss a beat. And never
did I miss separates.
Krell’s Legacy
Krell’s enduring legacy is that of a
high-end brand with a penchant for power. I’ve lost count of the number of
Krell amplifiers that have served time in my system, but not one can be
recalled for any lack of power.
Krell’s
enduring legacy is that of a high-end brand with a penchant for power.
It must be remembered that Krell first made
its presence known by being able to drive seemingly impossible loads, most
notably the various Apogee full-range ribbon speakers (especially the
Scintilla). Thirty years ago, Krell amps were the default choice for something
unbreakable, unbowed by ‘difficult’ oats. The S-550i continues this tradition,
but with one or two nods to the 21st Century, including its iPod
dock. For those who might wonder how so much can be offered for a relatively
reasonable $7547 – and that is ‘reasonable’ in the context of amplifiers of
this power delivery – one needs to look at the small print at the back. ‘Made
in China’ it says.
Lab report
The amplifiers may be separated by some
four years but the new S-550i bears a striking technical resemblance, extra
power notwithstanding, to Krell’s own S-300i [HFN Feb ‘09]. Both amplifiers
share a distinctive distortion pattern of 3rd, 5th, 7th
and further odd harmonics that are highest at low power (~0.065% at 1W/8ohm)
but then reduce with increasing power to ~0.035% at 10W, ~0.012% at 100W and
0.008% at the rated 275W/8ohm. This trend, incidentally, is also shared by
darTZeel’s extraordinary NHB-458 monoblocks [HFN Jun ‘12] and is consistent
under continuous or dynamic output conditions [see Graph 1, below]. The latter
graph also illustrates the S-550i’s prodigious capacity, its 2x275W/8ohm rating
exceeded to the tune of 2x335W/8ohm and 2x600W/4ohm and lifted still further to
390W, 750W, 1370W and 2400W into 8, 4, 2 and 1ohm loads under dynamic
conditions. This makes the S-550i the most powerful and load-tolerant
integrated that we’ve tested in HFN for many a year (if not ever).
Dynamic
power versus distortion into 8ohm (black trace), 4ohm (red), 2ohm (cyan) and
1ohm (green) speaker loads. THD falls as power increases
The amp’s output impedance is not
vanishingly low at ~0.075ohm but it is very uniform across the audio range, as
is its frequency response almost irrespective of load (-2.05dB/100kHz into 8ohm
to -2.25dB/100kHz into 1ohm). Like the S-300i, however, the S-550i also shows
an ‘engineered’ mid-bass bump of up to +0.05dB from 50Hz-300Hz just as its
overall A-wtd S/N ratio is about 10dB lower than the ‘average’ integrated at
just 73.4dB (re.0dBW). Like the S-300i this is not hum but a broad white noise
that may exert some pleasing subjective influence. Readers may view an in-depth
QC Suite report for Krell’s S-550i integrated amp by navigating to www.hifinews.co.uk and clicking on the red
‘download’ button.
Distortion
versus extended frequency from 5Hz-40 kHz at 10W/8ohm. Trend is fairly uniform
Specifications
·
Power out (<1% THD, 8/4ohm): 335/600W
·
Dynamic power (<1% THD, 8/4/2/1 ohm: 390W/
750W/ 1.37kW/ 2.4kW
·
Output impedance (20Hz – 20kHz): 0.070 –
0.083ohm
·
Frequency response (20Hz – 100kHz): +0.05dB to
-2.0dB
·
Input sensitivity (for odBW/275W): 71mV/ 1200mV
(balanced)
·
A-wtd S/N ratio (re.0dBW/275W): 73.4dB/97.8dB
·
Distortion (20Hz – 20kHz re.10W/8ohm): 0.055 –
0.016%
·
Power consumption (Idle/Rated o/p): 81W/978W (2W
standby)
·
Dimensions (WHD): 438 x 148 x 450mm
Verdict
There have been massive integrated
amplifiers int eh past, such as Perreaux’s Eloquence 250i, which obviate a need
for separates. Without hesitation, I nominate the S-550i as a perfect choice
for those who want unbridled power yet will not or cannot house two components.
It is a beast of an amp, such that I think I’ve found something currently
available to drive even Scintillas. Yes, that kind of beast.
Sound
quality: 87%
