Building on the success of the award
winning S-300i integrated amplifier, the S-550i boasts the sound quality
and power output capable of driving any loudspeaker to its maximum
performance. Delivering 275 watts of stereo output, the S-550i is a
power source for virtually any speaker on the market while occupying a
fraction of the space typically required for a system delivering this
sound quality. The S-550i is outfitted with balanced and single-ended
inputs, iPod dock, and Theater Throughput™ mode. Developed by Krell,
Theater Throughput™ simplifies integration into home theater systems.
For custom integration applications, 12 volt triggers, RS-232
connectivity and rack mount ears are included. Operational parameters
can be customized via the menu system that is accessible from the front
panel or the included brushed Aluminum remote control.
The preamplifier section features circuit
concepts from Krell's flagship Phantom preamplifier. Krell Current Mode
provides unequaled bandwidth for the most revealing playback of today's
high resolution music sources. Direct coupled circuitry eliminates
impact-robbing capacitors from the signal path and an elegant,
custom-machined level control adjusts volume. Discrete circuitry, in a
balanced topology, is afforded its own power supply regulation. All
signal gain is realized using surface mount technology featuring
proprietary current mirrors with nearly 500 times the open loop
linearity of other designs. Negative feedback is not used anywhere in
the preamplifier, nor is it necessary. Open-loop distortion is typically
less than 0.003%. The volume control is realized with a balanced
resistor ladder - bandwidth and transient response of the preamp
circuitry are virtually unaffected by the volume setting.
Power Amplifier Highlights
The S-550i packs a massive 1,750 watt
transformer and 68,000μF of capacitance into an elegant 5' high chassis.
This power supply feeds classic Krell circuitry throughout the topology
using only discrete circuitry. As with all Krell amplifiers, the S-550i
design is an ideal voltage source. That is, the S-550i doubles its power
output when a speaker's impedance is halved. For the S-550i, the results
are 275 watts into 8 Ohms and 550 watts into 4 ohms. This capability is
essential for realistic reproduction of a recording's dynamic content.
Most amplifiers can't deliver this power doubling, leaving music
sounding compressed and lifeless.
1 pr. balanced via XLR connectors
3 pr. single-ended via RCA connectors
1 dedicated iPod input via 30-pin connector
1 pr. preamp outputs via RCA connectors
1 pr. speaker outputs via gold-plated binding posts
1 RS-232 input via 9-pin D-subminiature connector
1 remote IR detector input via 3-conductor 3.5 mm connector
1 12 VDC trigger input via 2-conductor 3.5 mm connector
1 programmable 12 VDC trigger output (30 mA maximum current) via
2-conductor 3.5 mm connector