Designed as a midrange alternative to satellite speakers and floorstanding speakers, bookshelf speakers offer a good compromise between size and power. Bookshelf speakers usually come as a twin set of two large units, which can take up a decent amount of space. The Edifier D12 (pictured) solves this problem by self containing two bookshelf speakers into one single unit.

Being a single unit, the Edifier D12 takes up less space than the R1010BT bookshelf speakers. Not only is the Edifier D12 smaller and more compact, it is also more powerful than the 24W RMS R1010BT bookshelf speakers. The D12 speaker unit is capable of up to 70 Watts RMS of continuous power, which is distributed between two 19mm silk dome tweeters (for the treble) and 4-inch mid bass driver (for bass and vocals). Each tweeter is capable of 15 Watts RMS, while each mid bass driver can handle up to 20 Watts RMS.

The Edifier D12 drivers are housed inside a wooden enclosure, which has a leather like finish on top and bottom and natural wood finish exposed on the sides. On the back of the D12 unit, you find a non-detachable power lead (1.2 meters long), a plastic switch power button and connectivity ports (RCA, line out and aux in).

On the front of the unit, you find the silk dome tweeters, two vent ports and the mid bass drivers, which are basically rubber cone woofers. The mid bass drivers are powerful and can handle sub-60Hz frequencies. The bass is clean, although it starts to muddle down to about 90Hz. If you want ground pounding and cleaner bass at lower frequencies, you need to connect a subwoofer like the T5 subwoofer into the D12 speaker, which you can thanks to the line out connection on the back of the D12 speaker.

The Edifier D12 speaker weighs 4.3 kg and measures 35cm long, 20cm deep and 15cm high; hence it's a very compact audio system, way more compact than traditional bookshelf speakers. Twin set bookshelf speakers do have an advantage though, and that is the stereo separation, which is naturally wider and more defined than with a self-contained speaker unit such as the Edifier D12. 

Another plus for the Edifier D12 speaker system, it's onboard tone control equalizer (EQ), which consists of three knobs: a bass dial, treble dial and volume dial. The bass and treble dB value ranges from -6dB (-1, -2,-3,-4, -5, -6) to +6dB (+1, +2,+3,+4, +5, +6) so, you can make a total of 12 tone adjustments. The bass/treble tone controls effectively let you control the frequency response of the D12 speaker, which is 54Hz (bass) and 20KHz (treble).

The treble, bass and volume knobs are built inside a metal panel that measures 13.5cm long and 5.5cm wide. The knobs are located on the bottom side of the unit and are made of a soft alloy material. The knobs have an inward concave design and measure 1cm high.

As well as controlling the volume, the volume knob is also a push button designed to toggle between wireless and various wired modes. The D12 speaker has an led light on the front of the unit that lights up a different color according to the audio mode. When switching from bluetooth to wired mode, you cannot maintain a bluetooth connection; however, bluetooth re-connects almost instantaneously when turned back on. When switching from wired mode to bluetooth, you don't have to disconnect the audio cable from the speaker in order to activate bluetooth mode, which is convenient. The line out audio port is handy for connecting a pair of headphones or external speakers. If you do connect external speakers into the Edifier D12 they have to be active (powered) speakers such as the R1850DB speakers.

When adjusting volume, the led indicator blinks with each volume step adjustment. The lowest volume step mutes the sound. The volume knob uses a silent rotary encoder type, which spins infinitely just like the scrolling wheel of a mouse. The volume knob has a notched step control, which provides a gradual volume adjustment in small increments. The bass and treble knobs use traditional potentiometers with a silent notched design so, you can set each dB value precisely. In terms of audio dynamics, both bluetooth and wired modes deliver good sound levels, although wired mode produces a noticeably louder volume output. The bluetooth connection is via standard Bluetooth 5.0 (no aptX or AAC support).

The included IR remote weighs 32 grams and comes pre-fitted with a CR2032 coin cell battery. The IR remote is made of plastic and has rubber buttons, which are level against the remote; hence the buttons do not protrude out of the remote. The buttons have a clicky/responsive actuation. The IR remote is no only convenient but also useful because it features two dedicated preset buttons for movie mode and music mode. The remote measures 13.5cm long, 4cm wide and 0.7cm thick. The detachable front cover of the speaker weighs 109 grams and has a plastic construction covered with spandex like fabric material. A hrome trim and plastic Edifier logo are glued on to the front cover.

On the base of the unit, there is four rubber feet, which means the unit is designed to rest horizontally. There aren't any rubber feet on the sides; however, you can rest the D12 speaker vertically on its side just like a book. There are two accessory cables included. An RCA cable (1.3 meters) and a 3.5mm to RCA cable (1.4 meters). Both cables have rubberized plugs and gold-plated jacks. You can buy the Edifier D12 from amazon. Check out the review of the Edifier P12 passive bookshelf speakers and the Edifier M201BT