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M5

Monaural Class A Amplifier

M5 Monaural Class A Amplifier

Driven by the success of the BSC-100m amplifier, the M5 Class A monaural power amplifier redefines the standards set by its predecessor and becomes the new reference in class A amplification. The M5 amplifier is a direct manifestation of an accumulation of knowledge spanning over 20 years, representing a powerful, yet nimble and soulful, presentation realized through bold and compact industrial stylings.


The M5 is built around a massive 1,450 VA custom Plitron™ toroidal transformer that is coupled to an aluminum sub-chassis and machined aluminum outer chassis. The M5 has separate power supply sections for the output stage and critical driver circuitry, with over 108,000 microfarads of capacitance delegated to the output stage. All circuitry is complimentary, discrete, and Class A, including the output stage.


The M5 is rated at 150 watts into an 8 ohm load, but can double its output power for each subsequent impedance below that, delivering 300 watts into 4 ohms, 600 watts into 2 ohms and a massive 1,200 watts into 1 ohm and below. The resulting effortless control of the loudspeaker is one of BSC Audio's key sonic attributes.


The M5 amplifier utilizes a bias control switch conveniently located in the front of the faceplate. The signature triangular control switch can turn the fully class A amplifier into a high bias class A/B amplifier, and further into a more economical, class B amplifier. Reducing the bias allows control over the unit’s heat output and energy consumption when critical listening is not the priority. Along with the bias control switch, the massive internal heat sink towers are configured strategically to help centralize and focus the excessive heat energy, further enhancing the cooling capabilities of the unit and minimizing the impact on your listening environment.


The M5 produces an effortless and quick, yet emotional performance, coupled with a rich presentation achieved only through the very best in Class A amplification. When paired with the L5 preamplifier, the M5 completes a playback system capable of meeting the highest standards in music reproduction.

Output Power: 150 W into 8 Ω, 300 W into 4 Ω, 600 W into 2 Ω, 1,200 W into 1 Ω
Total Harmonic Distortion: < 0.04% at 20 Hz to 1 kHz, < 0.60% at 10 K, < 0.75% at 20 K, all referenced to 150 W 8 Ω 2.83 V
Signal-to-Noise: > 110.00 dB unweighted, > 116.00 dB, A-weighted, all referenced to 150 W 8 Ω 2.83 V
Input Impedance: 48 K balanced via XLR connector, 20 K single-ended via RCA connector
Power Consumption: Stand by Mode: < 2 W, Idle: 800 W, Maximum: 1,500 W
Downloads: Quick Start GuideOwner's Manual
Click for full specifications >>

5 Series Overview

BSC makes Class A amplifiers and utilizes Class A circuits. Class A components offer many electrical advantages over low, high, and even sliding bias class A/B designs, such as self-regulation, minimized high order harmonic artifacts, and lower distortion - all of which contribute to better sonic performance.


"Most, if not all, of my very favorite playback systems throughout the 1980's to 2000's contained relatively simple, but powerful class A amplifiers. The magic midrange and air surrounding all of the instruments and voices had to be a prominent characteristic in all of my products." - Bret D'Agostino


BSC products have a 5 year warranty for parts and labor.

Power Supply

Based around a 1,450 VA custom toroidal transformer and over 108,000 microfarads of filter capacitance, the M5 amplifier can deliver thunderous power output. The M5 amplifier doubles its 8 ohms rated output power into 4 ohms at 300 watts, 2 ohms at 600 watts, and 1 ohm, where it produces over 1,200 watts continuously. The M5 has a more than comfortable abundance of power to control even the most difficult of loudspeakers while maintaining its continuous current class A operation.


The M5 has two ultra-quiet Plitron™ toroidal transformers coupled to one high current and two fully regulated power supplies. The second transformer is designed for the soft turn-on and other low level circuits to allow the M5 to be activated either by a 12-volt trigger source or the front panel switch. The M5 draws less than 2 watts in standby mode.

Output Stage

The M5's output stage is comprised of 4 massive, internally mounted heat-sink towers designed to cool all twelve of the 230 volt, 17 amp, 200 watt output devices. All power signal routing traces are curved and constructed of gold plated 3 ounce copper. The towers are optimized to disperse the heat generated by the 150 watts of pure Class A power over a wide cross section, reducing the overall chassis temperature. A unique aspect of the output stage is that it is nestled between the heatsink towers. The output circuit boards are mounted in a way that allows maximum heat transfer, but also field serviceability should it become required.

Bias control switch

The M5 allows the user to quickly reduce the Class A bias on the amplifier to a half-power, approximately 75 watt, high bias class A/B mode, and further to a very low power ECO mode via the front panel rotary switch. Bias flexibility allows control over your power demand and ambient temperature in different listening situations, but does not limit the amplifiers output power potential.

Input Stage

The newly designed driver section of the amplifier is based around a discrete, complimentary, and DC coupled circuit transferred onto a 4-layer circuit board. The signal paths are made of gold plated 2 ounce copper, and are kept short and utilize curves in order to pass critical analog signal through the least amount of circuitry possible. All the components meet or exceed military standards, and are over specified to promote long life expectancy.

Protection and Chassis

The M5 has several layers of protection circuitry outside of the signal path designed to protect your amplifier and surrounding equipment when possible. Protection reacts to short circuit, excessive DC offset, over current, and excessive temperature situations should any of them occur. The M5 external chassis is comprised of ½ inch thick machined 6061 aluminum. Each panel is affixed to the ⅛ inch thick aluminum sub-chassis with stainless steel fasteners. The face plate components are machined and sculpted from solid 2 ½ inch aluminum blocks. Every part is custom machined: from the multi-part bias knob assembly to the solid brass and gold plated output binding posts. A custom automotive finish is applied to the cosmetic metal surfaces to enhance and protect the M5's visual architecture.

Dimensions

16.50 in (W) x 10.90 in (H) x 20.75 in (D)

or 419.10 mm (W) x 276.86 mm (H) x 527.05 mm (D)

Full Specifications


Output Power: 150 W into 8 Ω, 300 W into 4 Ω, 600 W into 2 Ω, 1,200 W into 1 Ω (under ideal power conditions)
Output Impedance: < 0.125 Ω at 10 Hz to 30 kHz
Gain: 25.75 dB
Input Impedance: 48 K balanced via XLR connector, 20 K single-ended via RCA connector
Input Sensitivity: 1.80 V RMS balanced or single-ended
Frequency Response: 10 Hz to 30 kHz +/- 0.25 dB
Total Harmonic Distortion: < 0.04% at 20 Hz to 1 kHz, < 0.60% at 10 K, < 0.75% at 20 K, all referenced to 150 W 8 Ω 2.83 V
Signal-to-Noise: > 107.50 dB unweighted, > 116.50 dB A-weighted, all referenced to 150 W 8 Ω 2.83 V
Power Consumption: Stand by Mode < 2 W, Idle: 800 W, Maximum: 1,500 W
Inputs: 1 single-ended via RCA connector, 1 balanced via XLR connector
Outputs: 1 pair custom designed gold plated binding posts 0.25 in (6.40 mm) spade terminal width
Dimensions: 16.50 in (W) x 10.90 in (H) x 20.75 in (D)
or 419.10 mm (W) x 276.86 mm (H) x 527.05 mm (D)
Weights: unit only weight: 105.00 lbs (47.63 kg)
shipping weight in carton: 122.00 lbs (55.34 kg)