ModWright KWA-100SE Reference Solid State Stereo Power Amplifier

This solid state stereo power amp is the upgraded version of Modwright's KWA-100. It is rated 100/100w into 8 ohms, and has been in the Modwright line for most of the past decade. Retail price in the US today is $5250. I am selling this for a friend. It is a smooth and objective-sounding solid state power amp with both true balanced and single-ended inputs. The "SE" version is substantially-upgraded from the base KWA-100. From Modwright:

"...The KWA 100SE offers exceptional performance in a dedicated stereo power amplifier. Possessing a tube-like midrange of Modwright's flagship KWA 150SE and greater levels of detail and bass slam than the former KWA 100. This is primarily due to 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.

The end result is the KWA 100SE offers the strengths of both tube and solid state designs: 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.

Features

The KWA 100SE provides a strong 100+W into 8 ohms and 200W into 4 ohm loads, capable of driving even the most difficult to drive loudspeakers.

The inputs are true balanced floating inputs, accepting balanced and unbalanced signals from the XLR and RCA inputs respectively.

The KWA 100 SE also incorporates a regulated power supply for the input stage, and oversized heat sinks. The first watts operate in pure Class A.

The KWA 100SE includes the following upgrades over the former KWA 100:

• 20 output devices total, opposed to 12 output devices in the former KWA 100.
• 88,000uf increase in total main power supply capacitance.
• Upgrade of over twenty (20) key signal and power supply capacitors to MWI custom capacitors.
• Upgrade of key signal path resistors to Precision Japanese Takman Carbon Film resistors.

The results include better bass response, speaker control, and improvement in low-level detail and overall resolution.

Design Specifications of the KWA 100SE:

• 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.
• High Current MOSFET output stage 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 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.

KWA 100SE Specifications

Power Ratings: 120W 8 ohms; 210W 4 ohms.
Power Transformer: 500VA.
Bandwidth: 10Hz – 100Khz (+0, -1dB).
Noise Floor: -97dB.
Gain: 26dB.
Input Impedance: Min. 15K 50Khz; 23K 1Khz.
Input Sensitivity: 1.5V
Dimensions: 17.75W x 17.5D x 6.5H
Weight: 40 lbs (47 lbs. shipped)..."

This amp works perfectly and is in excellent condition. I graded it as "Very Good" only because it's a one-owner amplifier originally purchased in 2014 and used lightly by a primary-tube-amp-listener who used it in a smoke-free household. Not much to see -- but it pretty blue LEDs glow through the amply-vented top.