Schematic of a 2.1 channel amplifier based on the TDA2030A, from Technical Mriganka, in a 416 KB PDF.

Technical Mriganka 2.1 amplifier design using the TDA7379 and TDA7377 power amplifier ICs, a 206 KB PDF.

2.1 channel hi-fi audio amplifier circuit by Technical Mriganka, a 164 KB PDF. The title does not name the amplifier ICs or output devices, so identify them from the…

2.1 amplifier schematic built around the TDA7294, by Technical Mriganka, in a 219 KB PDF.

2.1 amplifier schematic attributed to Amiru, a compact 98.7 KB PDF. The name gives no details about the ICs or power level, so the diagram itself must be read for…

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…

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

Tone control circuit intended for a 2.1 channel audio system, in a 159 KB PDF. It shows the bass and treble adjustment network that sits between the source or preamp and…

Modified 2.1 channel amplifier schematic, a 90.6 KB PDF; the title does not say which original design was altered or which ICs are used.

Datasheet PDF for the 2SK1058, a 55 KB file. This part number belongs to the 2SK series of N-channel field-effect transistors and is widely known from audio power…

Matrix 1.4 amplifier design in BTL configuration, meaning bridge-tied load where two amplifier halves drive the speaker in opposite phase, as a 1.76 MB PDF.

Large 962 KB PDF for the LM324P, the quad operational amplifier in a plastic DIP package, as the P suffix commonly indicates.

PDF of 6.86 MB titled for an XTi series, with no brand given in the name. Crown sells a power amplifier line called XTi, so the document may relate to it, but contents…

Indexed as a schematic, the 124 KB PDF named 2SJ193 most probably holds the datasheet for that JIS-numbered P-channel FET.

PDF for the KIA324P, a KEC quad operational amplifier compatible with the widely used LM324, in a DIP package as the P suffix suggests.

This 93.0 KB PDF carries the part number 2SJ258 and nothing else. The 2SJ prefix, under Japanese JIS numbering, indicates a P-channel field-effect transistor, so expect…

Here the 2SK1234 N-channel field-effect transistor is described in a 46.1 KB PDF. The 2SK code marks it as an N-channel device under the Japanese JIS scheme, used in…

Schematic document in PDF format, about 1.80 MB, filed under the name TAS6534, which looks like a Texas Instruments part number from the TAS automotive class-D audio…

The 2SK1375 N-channel field-effect transistor is covered by this 150 KB PDF, filed under schematics in the catalogue.

Datasheet-type PDF for the 3SK271, around 32.7 KB, catalogued in the schematic category.

Compact 25.2 KB PDF named for the 3SK301, categorised as a schematic but most likely a part datasheet. Nothing besides the type number appears in the name.

Component PDF for the 3SK285, 22.2 KB, placed in the schematic section of the index. Only the part number is given.

A 111 KB PDF for the 2SK1453, placed among schematics, although the part-number naming points to a component data sheet.

An 80.6 KB PDF named after the 3SK265, filed under schematics but most likely a datasheet for that single device.

PDF documentation, 32.7 KB, for the 3SK269, indexed under schematics. The JIS code 3SK marks an N-channel field-effect transistor with four terminals, generally a…

Datasheet PDF, roughly 82.3 KB, for the 2SK222, catalogued among schematics. The JIS 2SK series denotes N-channel field-effect transistors, and the name supplies no…

Datasheet-style document for the 3SK302, a 26.0 KB PDF indexed as a schematic. The 3SK prefix in Japanese JIS numbering denotes a four-terminal N-channel field-effect…

Compact 65.7 KB PDF for the 2SK2539, listed as a schematic but named after a discrete semiconductor.

Small 33.0 KB PDF for the 3SK144, catalogued as a schematic but named for an individual semiconductor, so it is most likely a datasheet.

Reference sheet in PDF format for the 2SK2549 field-effect transistor, 373 KB in size. In the JIS numbering used by Japanese semiconductor makers, 2SK denotes an…

Component datasheet for the 2SK1057, packaged as a 55 KB PDF. The 2SK prefix marks an N-channel FET in the Japanese numbering system, and this number sits in the same…

Part datasheet for the 2SK2033, provided as a 296 KB PDF and filed under the schematic category. The 2SK prefix follows the JIS standard for N-channel FETs.

Studiomaster M1000 schematic, supplied as a 576 KB PDF. Studiomaster builds professional audio gear such as mixers and amplifiers, and a diagram like this is used to…

Datasheet document for the 2SK1103 transistor, filed as a 29.5 KB PDF. Parts beginning with 2SK are N-channel field-effect transistors registered under the JIS scheme…

Listed as a schematic, this 246 KB PDF carries the name 2SJ201, a JIS part number for a P-channel FET, so it is best treated as a component datasheet.