Adcom GFA-5705 5 Channel Amplifier

Adcom GFA-5705 5-Channel Stereo Power Amplifier at Vinyl Sound Buffalo NY

The Adcom GFA-5705 is a high-performance 5-channel stereo power amplifier engineered specifically for home theater systems that demand real power across every channel. Delivering 200 watts per channel into 8 ohms with all five channels driven simultaneously, the GFA-5705 brings the same high-current authority and low-distortion performance Adcom is known for to the full surround sound experience. Available at Vinyl Sound in Buffalo, NY.

Power Output and High-Current Performance

The GFA-5705 is built to drive a very broad range of loudspeakers, including those with very low impedances, at sustained high-power levels even when impedances are highly reactive. Great care was taken to ensure distortion remains extremely low, particularly when driving highly reactive loads in which the phase angles of voltage and current are substantially different. To achieve this, three pairs of specially selected TO3-type metal-cased bipolar output transistors are used per channel — 15 pairs in total — in a triple-Darlington configuration that ensures very efficient power delivery to reactive loads regardless of phase angle. With 200 watts per channel into 8 ohms and 300 watts per channel into 4 ohms across all five channels driven simultaneously, the GFA-5705 maintains full dynamic authority from quiet dialogue to full-range multi-channel peaks.

Massive Toroidal Power Supply

At the core of the GFA-5705 is a substantial power supply built around a high-efficiency toroidal transformer, chosen for superior voltage regulation and minimal radiated noise. The transformer feeds an enormous storage bank of 30,000µF of filter capacitance per channel, totaling 150,000µF across all five channels. This reserve ensures stable, unwavering voltage under any power demand, keeping every channel composed and in control from sustained low-frequency passages to instantaneous transient peaks.

Build Quality and Construction

The GFA-5705 is built to the same standard of physical quality as its electronic performance demands. The front panel is crafted from heavy-gauge anodized aluminum extrusion for durability and a clean, professional appearance. The chassis, top cover, and rear panel are constructed from heavy-gauge steel, both painted and baked for long-term durability. The result is a substantial amplifier that suits both dedicated listening rooms and custom installation environments.

Key Features

• Balanced XLR and unbalanced RCA inputs on all five channels for flexible system integration
• 24K gold-plated 5-way speaker terminals on all channels for secure, low-resistance connections
• Auto ON/OFF and 12V/5V DC trigger input/output for automated system control
• 200W per channel into 8 ohms / 300W per channel into 4 ohms, all five channels driven simultaneously
• 150,000µF total filter capacitance (30,000µF per channel) for massive power reserve and sustained high-current delivery
• High-efficiency toroidal transformer with exceptional voltage regulation, minimal noise, and low leakage inductance
• Drives low-impedance and reactive speaker loads with stability and control at all output levels
• Damping factor greater than 300 from 20Hz to 20kHz for tight, authoritative bass across all channels
• Ultra-wide power bandwidth from 5Hz to 100kHz (-3dB)
• Purpose-built 5-channel design for home theater surround sound systems
• Dual voltage compatible at 120VAC and 230VAC / 50-60Hz for worldwide use
• Heavy-gauge anodized aluminum front panel and baked steel chassis for long-term reliability

Technical Specifications

Frequently Asked Questions

What is the Adcom GFA-5705?

The Adcom GFA-5705 is a 5-channel stereo power amplifier rated at 200 watts per channel into 8 ohms and 300 watts per channel into 4 ohms, with all five channels driven simultaneously. It is built around a high-efficiency toroidal transformer with 150,000µF of total filter capacitance and balanced XLR inputs on all five channels, and is designed for home theater surround sound systems requiring high-current, low-distortion power across every channel. It is available at Vinyl Sound in Buffalo, NY.

Can the GFA-5705 drive all five channels simultaneously at full power?

Yes. The GFA-5705 is rated at 200 watts per channel into 8 ohms and 300 watts per channel into 4 ohms with all five channels driven simultaneously, not just a single channel as is common in many competing multi-channel amplifier specifications. The 150,000µF power supply filter capacitance and toroidal transformer maintain stable output voltage under the full demand of five simultaneous high-power channels.

What type of home theater system is the GFA-5705 designed for?

The GFA-5705 is ideal for 5-channel surround sound systems using front left, center, front right, surround left, and surround right speaker configurations. Its high-current output stage maintains stable performance even when the phase angle between voltage and current diverges significantly, making it particularly suitable for demanding speaker systems, low-sensitivity designs, and dipole or bipole surround speakers that present complex impedance curves.

What is the significance of the toroidal transformer and 150,000µF filter capacitance?

The toroidal transformer in the GFA-5705 provides superior voltage regulation and lower radiated electromagnetic interference compared to conventional EI-core transformer designs, reducing noise pickup in sensitive audio circuits. The 150,000µF of total filter capacitance (30,000µF per channel) acts as an energy reservoir that supplies instantaneous current during transient peaks without waiting for the transformer to respond, ensuring the amplifier maintains stable output voltage and control during demanding multi-channel passages.

Can the Adcom GFA-5705 be installed in an equipment rack?

The GFA-5705 can be placed in a standard equipment rack on a dedicated shelf, but rack mounting brackets are not available for this amplifier. At 81 pounds and with maximum dimensions of 10.75" x 19" x 19.75", it requires a sturdy shelf with full support across its base. Adequate ventilation clearance of at least four inches on all sides must be maintained to prevent thermal shutdown.

Does the GFA-5705 work with low-impedance or reactive speakers?

Yes. The GFA-5705 was specifically designed to drive loudspeakers with very low impedances and highly reactive loads at sustained high-power levels. Its 15 matched pairs of TO3 bipolar output transistors in a triple-Darlington configuration maintain stable performance even when the phase angle between voltage and current diverges significantly, which is characteristic of electrostatic, planar magnetic, and other reactive speaker designs commonly used in high-performance home theater systems.

Is the Adcom GFA-5705 compatible with both 120V and 230V power?

Yes. The GFA-5705 is dual voltage compatible, operating on both 120VAC and 230VAC at 50-60Hz. Confirm the voltage setting matches your local supply before connecting the unit to power for the first time.

Where can I buy the Adcom GFA-5705 in the USA?

The Adcom GFA-5705 is available at Vinyl Sound, an authorized Adcom dealer in Buffalo, NY. Browse the full power amplifier collection at Vinyl Sound or contact our team for home theater system configuration advice and in-store listening appointments.