SMT-PBTS v4.0

firmware configuration guide v4.0

SMT-PBTS v3.0

• Ultra small and compact design; it’s smaller than a deck of cards.
• Bluetooth v5.0 specification via Qualcomm’s CSR8675 SoC.
• Connect up to 2 devices simultaneously for shared musical playback.
• Up to 800ft theoretical Bluetooth connectivity range using external antenna.
• Studio quality, Hi-Res audio playback with up to 24-bits and 192kHz sample rate support (only using AptX HD codec).
• Incredible, best in class frequency response; 35Hz-22KHz @-3dB (only with associated speakers and enclosure).
• High efficiency eliminates the need for heatsinks.
• Hybrid amplifier design consisting of Class D amplifiers for the bass drivers and linear Class AB amplifiers for the left, right, and center tweeters.
• Ultra low total harmonic distortion, even at maximum power: ~0.05% THD.
• Ultra low signal to noise ratio: > 100dB
• 35W + 35W onboard Class D amplifiers with 3x1W Class AB amplifiers.
• Built in startup pop/thump suppression for the on-board amplifiers.
• Uses the highest audio quality preamplifier op-amps in existence: OPA4134, OPA2134 and OPA134.
• Uses high-end Panasonic acrylic resin film caps for all audio decoupling filters.

SMT-PBTS v1.4.1 RELEASE

• Fixed typos in README.md and added missing info

SMT-PBTS v1.4 RELEASE

Improvements and fixed issues:
• Added missing resistors for surround sound decoder
• Partially fixed crosstalk issue between surround channels
• New optional extension module: XR1075 BBE Bass Booster
• Added new input/output connections on main PCB for XR1075 preamplifier module
• Fixed reversed surround channels
• Removed high pass filters on TPA3128D2 inputs
• Added BoM
• Added schematic
• Fixed SPI female pin headers for reprogramming KRC-86B v4.0

Still known issues:
• Still some crosstalk issues on surround channels
• Static noise on turn off and pop on turn on.
• Occasional Idle popping from interference between KRC-86B v4.0 and TPA3128D2

SMT-PBTS v1.0 RELEASE

Initial Release (Gerber file only)