Circuit diagram for a two-way active audio crossover, supplied as a 134 KB PDF. The name gives no designer, part numbers or crossover frequency, so expect a generic…

First part of the service manual for the Audio Pro A4-14 speaker, a 6.15 MB PDF identified by the spk and sm1 tokens and paired with a second volume.

Schematic in PDF form, 2.03 MB, for a subwoofer identified in the name as e150p. No manufacturer or board revision is stated, so confirm the model label on the enclosure…

Hi-fi 2.1 amplifier schematic credited to SeahorseDIY, in a 688 KB PDF. It covers a stereo-plus-subwoofer layout, likely with the crossover or filter stage feeding the…

Word document of 497 KB, titled in Indonesian for a subwoofer circuit at 80 Hz. The file likely contains a filter or crossover design with a cutoff around 80 Hz for…

PDF schematic for a 2.1-channel power amplifier, meaning two satellite channels plus a subwoofer channel.

Schematic, per the sch suffix, for the Audio Pro Ace Bass B2-70 subwoofer. The 546 KB PDF covers the built-in amplifier, likely including the ACE-Bass circuitry, Audio…

Second part of the service manual for the Audio Pro A4-14 speaker, going by the spk and sm2 tokens.

Sallen-Key subwoofer filter schematic as a 389 KB PDF, with a source tag in the file name.