FB100 Stereo Class-D Amplifier Kit

Get the best sounding stereo amplifier for home audio with the SylphAudio FB100!

The FB100 is designed with a focus on measured performance and predictable real-world behavior. By implementing advanced post-filter feedback (PFFB) without compromising the TPA3251’s output capability, the design achieves class-leading performance for a TPA3251 operating in stereo BTL configuration

The amplifier uses an ATS-TI1OP-519-C1-R3 heatsink (originally designed for the TPA3255), paired with a large PCB area (137 * 100 mm) to ensure adequate heat dissipation and thermally stable operation. An additional heat spreader is applied to the preamp section to further improve long-term reliability.

The preamp section employs a split power supply, eliminating the need for an extra set of input coupling capacitors at the preamp frontend. This allows for only a single series input coupling capacitor in the signal path per channel, reducing potential coloration or haziness that may be introduced by multiple coupling stages. The module consists of four single-ended amplifiers, configured as 2-channel differential inputs and 2-channel BTL outputs.

Dedicated post regulators are used for each preamp rail, along with a separate post regulator for the TPA3251 supply. Regulation for the preamp section is maintained even when the main supply voltage is reduced to 24 V DC, ensuring consistent operating conditions across a wide supply range.

Oversized film capacitors are used in the Class-D output filter, together with flat-wire output inductors selected for low loss and stable performance, contributing to clean and controlled output under real speaker loads.

Elna Silmic II input caps

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Sept. 2025 update: optimized capacitor selection for the power supplies. Improved sound quality: deeper soundstage, finer highs, and tuned for a warmer sound.

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Package Includes
1 pc FB100 module (stereo BTL).
2 pc female 2.54 mm 3 pin connector.
6 pc female faston tab

Specifications
Supply Voltage: 24V DC min to 38V DC max
Unclipped Power (<1% THD+N, 38V): 55W-8Ω, 100W-4Ω
Input sensitivity: 4V RMS
Voltage Gain: 14dB (5V/V)
Input configuration: Fully Differential
Load impedance: 4Ω or 8Ω
Idle dissipation: ~5W at 38V DC
Footprint: 137mm x 100mm x 45mm (L * W * H)
Gross packed weight: 450g

Recommended Power Supply
(NOT INCLUDED)
– 36V to 38V DC Single supply SMPS 200W or higher.
– DO NOT use power supply with split rails.
– Mean Well RPS-500-36-C or LRS-200-36
– Use 35V DC for unregulated “linear” supplies

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Shipping
Shipments are consolidated once a week. Kindly wait for the tracking info to become available. Courier is a European Postal affiliated company with normal shipping ETA of 5 to 8 weeks.

Contact us for combined shipping options and actual rates.

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contact@sylphaudio.com

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Prices are subject to change without prior notice.