Sincere audio products include handheld microphones and portable Bluetooth speakers, with rechargeable power and MP3 playback for personal listening and singing.
Sincere products documented here include the Y1 handheld audio microphone and the OPT90 cassette-style Bluetooth speaker, offering rechargeable power and MP3 playback.
Browse model-specific manuals for charging, Bluetooth pairing, playback controls, memory card compatibility and safety instructions. For repairs or warranty questions, check your product documentation and contact the store of purchase.
Selected manuals from manuals+ curated for this brand.
Watch setup, installation, and troubleshooting videos for this brand.
Common questions about manuals, registration, and support for this brand.
The available documentation includes instructions for the Y1 handheld audio microphone and the OPT90 cassette-style speaker. Match the model number on your device to the manual.
Turn on the speaker, enable Bluetooth on your phone or tablet and select OPT90 from the available devices. The manual advises pairing within three minutes of turning on the speaker.
The OPT90 manual specifies microSD cards up to 32GB, formatted as FAT32 and containing MP3 files. Inserting a card switches to SD playback mode.
Use the supplied Type-C cable with a 5V power source. Its charging indicator is red while charging and turns off when fully charged.
Consult your product's warranty documentation and contact the store of purchase. The OPT90 manual states that its warranty is valid only in Japan and requires the warranty certificate.
No. The OPT90 manual uses registration to mean Bluetooth pairing with a phone or other device. No separate online product registration service is identified in the available information.
