Integrated Amplifiers




Vanguard
Integrated Stereo Amplifier

The Vanguard incorporates a 200-watt-per channel amplifier and a Class A preamplifier, enclosed in a chassis that borrows its design and construction from the new Krell Foundation preamp/processor, Connect stream player, Illusion preamp and iBias amplifiers. An optional, field-installable digital module with USB, HDMI, coaxial, and optical inputs as well as Ethernet audio and apt-X Bluetooth streaming will also be available.


The Vanguard’s amplifier incorporates a massive power supply with a 750 VA toroidal transformer and 80,000 microfarads of storage capacitance. The tremendous amount of energy on tap provides 200 watts per channel into 8 ohms and 400 watts into 4 ohms. Two quiet, thermostatically controlled fans permit the use of a surprisingly compact chassis.


The preamplifier section of the Vanguard borrows its balanced, fully discrete Class A circuit concepts from Krell’s top-of-the-line Illusion preamplifiers. Krell’s Current Mode technology is employed to assure unequaled signal bandwidth, easily enough to handle the latest high-resolution PCM and DSD audio sources without impacting high-frequency response and detail.


Packed with many of Krell’s most musical-sounding technologies, the elegant chassis is living-room-friendly. Yet it has enough power to achieve incredible, lifelike dynamics with any speaker.


The front-panel menu system provides configuration features such as input naming and input trim. Theater Throughput mode lets the Vanguard serve as the core of a surround-sound system without sacrificing two-channel sound quality. Analog Inputs include three stereo RCA and one stereo balanced XLR. High-quality WBT speaker cable terminals provide a secure, electrically ideal connection.


The Vanguard also offers features that make it perfect for custom installation, such as 3.5mm jacks for IR input and 12-volt trigger input and output, as well as optional rack-mount ears. Additionally, the unit can be controlled with home automation systems through its Ethernet connection.


A key option for the Vanguard is the digital module, which can be added at the factory or by a dealer. The digital module includes USB, HDMI inputs and output, coax and optical digital inputs; Ethernet music streaming controlled through dedicated iOS and Android apps; and apt-X Bluetooth wireless for convenient streaming from phones, tablets and computers.

 

The Vanguard also offers features that make it perfect for custom installation, such as 3.5mm jacks for IR input and 12-volt trigger input and output, as well as optional rack-mount ears. Additionally, the unit can be controlled with home automation systems or the Krell web server through its Ethernet connection.


Vanguard Specifications

Inputs
1 pr. balanced via XLR connectors
3 pr. single-ended via RCA connectors


Outputs
1 pr. speaker outputs via WBT gold-plated binding posts


Control inputs
1 remote IR detector input via 3-conductor 3.5 mm connector
1 12 VDC trigger input via 2-conductor 3.5 mm connector


Control output
1 programmable 12 VDC trigger output (300 mA maximum current) via 2-conductor 3.5 mm connector


Input impedance
Balanced: 95 kΩ
Single-ended: 47.5 kΩ


Frequency response
20 Hz to 20 kHz +0, –0.01 dB
<2 Hz to 150 kHz +0, –3 dB


Signal-to-noise ratio
>90 dB, wideband, unweighted, at maximum gain, referred to full power output
>97 dB, “A”-weighted


Gain
48 dB


Input sensitivity
Single-ended or balanced: 160 mV RMS


Total harmonic distortion
<0.015% at 1 kHz, at 200 W, 8 Ω load
<0.13% at 20 kHz, at 200 W, 8 Ω load


Output power
200 W RMS per channel at 8 Ω
400 W RMS per channel at 4 Ω


Output voltage
113 V peak to peak
40 V RMS


Output current
16 A peak


Slew rate
50 V/μs


Output impedance
<0.066 Ω at 20 Hz
<0.075 Ω, 20 Hz to 20 kHz


Damping factor
>121 at 20 Hz, referred to 8 Ω
>106, 20 Hz to 20 kHz, referred to 8 Ω


Power consumption
Standby: 12 W
Idle: 70 W
Maximum: 1300 W


Heat output
Standby: 41 BTU/hr
Idle: 239 BTU/hr
Maximum: 4436 BTU/hr


Dimensions
17.1 in W x 4.15 in H x 17.5 in D
434 mm W x 105 mm H x 445 mm D


Weight
Unit only: 39 lb [17.7 kg]
As shipped: 47 lb [21.3 kg]


Digital Module Specs
Coaxial and HDMI inputs support PCM up to 24-bit/192kHz. optical input up to 24-bit/96kHz


USB and Network streaming support MP3, AAC, WMA, WAV(PCM), FLAC, ALAC up to 192kHz


Bluetooth streaming supports A2DP, AVRCP, HFP, HSP



Download the "Vanguard Setup Guide"


S-550i
Integrated Stereo Amplifier


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.




The S-550i packs a massive 1,750 watt transformer and 68,000?F 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.




Click here for Reviews, Downloads, & Specifications



S-300i
Integrated Stereo Amplifier


The S-300i is the first Krell integrated amplifier to feature iPod connectivity and extends the award winning tradition of audiophile grade integrated amplifiers.

A low profile chassis fronted by an elegantly finished silver Aluminum front panel hints at the potent circuitry hidden within its walls. Small in stature but big in performance, the S-300i integrated amplifier develops 150 W into 8 Ohms and 300 W into 4 Ohms. Employing a massive 750 VA toroidal transformer and 38,000 microfarads of capacitance guarantees huge power capability for maximum dynamic impact. Both balanced and single-ended inputs are provided, and the Theater Throughput™ mode, developed by Krell, simplifies integration into home theater systems. Robust WBT binding posts provide superior loudspeaker cable termination. New for the S-300i is direct connection for all generations of Apple iPods /iPhones with complete control of the iPod functionality via the included remote control. Unique for the category, the S-300i taps audio from the fully differential output included in the internal DACs of iPods/iPhones and maintains this balanced signal throughout the circuitry.


The S-300i features the latest Krell Class A, direct coupled design, and fully balanced preamplifier circuitry for the lowest noise reproduction possible. 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.


The included solid aluminum remote control replicates all front panel options as well as providing control for a connected iPod/iPhone. RS-232 is also included for inclusion in advanced control systems.





Click here for Reviews, Downloads, & Specifications