KWA 150 Amplifier

The Absolute Sound Review by Dick Olsher, currently online!

KWA 150 TAS review by Dick Olsher

New praise for the KWA 150 from CES 2010 - Bob Levi of Positive Feedback Online:

Continues to Shine!

I love the excellent Modwright 150 Power Amps every time I hear them. Dan Wright just does not miss no matter what he builds. These 84lb. beauties sound like the finest tube amps with power to spare… and there's not a tube to be seen! With 150 watts into 8ohms and 250 watts into 4 ohms, they are up to any task. I have not heard all solid-state amps, but I have heard many costing three and four times what these do and not sounding one whit better. These would be the solid-state amps I'd buy if I were in the market for a tip top amplifier with both delicate nuances with really big balls, too. Made in the USA!!

CES 2010 Show Coverage from Bob Levi

The KWA 150 provides the strengths of both tube and solid state products: 3-D sound-staging, holographic imaging, and a beautiful midrange of tubes, combined with sparkling highs, low distortion, bass resolution, and control of solid state.

The heart of the KWA 150 Amplifier is a single voltage gain stage called the "Solid State Music Stage." The circuit was developed by Alan Kimmel, creator of the exceptional vacuum tube "Mu" stage.

Features include: high-low bias switch, stereo/bridge-mono switch and true balanced floating inputs, accepting balanced and unbalanced inputs. The design incorporates a regulated power supply for the input stage, Cardas' best connectors and oversized heat sinks. The first watts operate in pure Class A.

The KWA 150 uses no global feedback, is direct-coupled, fully differential, dual-mono, bridgeable, and designed and built in the USA.   

Design Specifications of the KWA 150:

Fully dual-mono internal design, including separate power transformers, power supplies and input and output stages for ideal separation and exceptional soundstage.
Chassis design and internal layout optimized for lowest possible noise floor, providing greater micro-detail and micro-dynamics for a natural and organics sonic presentation.
Fully discrete 'Solid State Music Stage' design by Alan Kimmel, offering midrange of tubes as well as muscle and speed of solid state design.
Zero global Negative feedback.
(24) High Current 'Thermatltrak' Bi-Polar output devices for extreme linearity and speed.
Over 180,000uf total power supply capacitance reserves for deep and tuneful bass.
Lundahl Input Transformer coupled floating ground design, preventing ground loops and isolation from ground mains, for exceptionally low noise floor.
RCA and XLR inputs transformer coupled to fully balanced circuitry.
Proprietary protection circuitry operating completely outside of signal path, protecting both amplifier and associated system components with ZERO impact on sonics.
DC input and output protection
Over-current protection.
Output short-circuit protection.
Thermal overload protection.
Proprietary 'RFB' circuit to protect amp in case of single rail fuse failure
Class A-AB operation.
Bias optimized for low distortion, heat and sonics, allowing for lower operating temperatures, and ideal sonic presentation.
Pure copper pcb traces, offering the lowest possible impedance.
Extremely short signal paths and highest quality MWI capacitors and audio grade signal path components for sonic purity.
Technical Specifications:

Dimensions: 17"Wx17"Dx9"H; Weight 84lb packed.

Power: 150W @ 8ohms; 250W @ 4 ohms; 450W @ 8 ohms bridged mono; 650W @ 4 ohms bridged mono. ALL power ratings at .05% THD!

Noise Floor: -100dB (Unweighted)

Bandwidth: 10Hz - 100Khz (+0, -1dB)

KWA150SE:

Upgraded model of Lundahl input transformer for improved speed and dynamics.
Circuit design revisions to input circuits that lower distortion and improve dyanmics and resolution.
Cryo-treated, solid core ultra-pure input wiring and 12GA stranded audio-grade output signal wire to binding posts.
Revised capacitor bank (current storage design) that increases total storage (capacitance) and also lowers power supply impedance, which translates to faster current delivery to the output stage.

This all translates to the following in terms of sonics:

A more open and resolving overall presentation.
Tighter and faster bass and transients.
Improved speed and dynamics, whilst still retaining tube-like midrange qualities.
Improved soundstage and low-level cues due to an even LOWER noise floor.

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