Systems List › KRK Systems › 12S2
NotesKRK Systems is mostly known for their active studio monitors which theyâ€™ve been producing for many years, but they also have a range of powered subwoofers to extend the bass response of their monitors. The 12S2 is the second most powerful subwoofer in the KRK lineup. It is a vented 12â€ť system powered by a 220w rated plate amplifier with a suggested retail price of $799. Street pricing dips to around $575 at some retailers.
The 12S2 cabinet is constructed from what looks to be MDF and is finished in a black matte vinyl. The edges of the cabinet have a generous round over and the front baffle has a black plastic trim, which the grille and front firing port mount into. The grille is black steel mesh with the KRK logo, which securely pops into the front baffle and can be removed with a paperclip bent to hook onto the grille. The port is a wide, shaped slot port that has a generous area for a subwoofer of this size. The driver cone is bright yellow, with a black surround and dust-cap and has the look of woven fiberglass material. There is also a blue power LED on the front panel. Overall it is a nice looking unit with good finishing.
Once the driver and amplifier were removed from the cabinet it could be seen that the cabinet uses a number of reinforcing strips on the cabinet walls for stiffening but no cross bracing that couples the walls together. There is also no dampening material in the cab.
The plate amplifier has a huge plate that covers the entire back panel of the cabinet. In fact it IS the back panel of the cabinet. Removing it revealed that it is built on an old school â€śironâ€ť transformer instead of a lightweight and efficient class D design. This no doubt accounts for part of the 67lb mass of the 12S2. The amplifier connections include stereo unbalanced RCA inputs, ÂĽâ€ť TRS and also balanced XLR. All three connection types also include the corresponding pair of stereo sends. There is also a footswitch input that is available for bypassing the subwoofer and crossover for A/B listening with and without the subwoofer during mixing. Controls provided include input volume, crossover with settings of 50,60,70 and 80Hz, selectable 120 or 240v operation and toggle switches for controlling normal or high input sensitivity, standby on or off, 0 or 180deg polarity and ground lift.
The driver has a rather good build quality. The front of the driver looks good with the woven fiber, yellow cone and rubber surround. The frame is a good quality stamped steel unit with under spider venting and generous clearances for excursion. The motor itself appears to be based on a double stack of 0.75 x 6 inch ferrite slugs. The back plate has a large diameter pole vent and also 6 under gap vents. The top plate looks to be about 8mm thick. The voice coil itself looked to be a 4 layer wind nominally 2.5 inches in diameter. Physical overhang of the coil is not much. Perhaps 8 mm. The spider is a 6 inch diameter unit. Judging from the measurements of the 12S2 the driver motor does not appear to use any shorting or Faraday rings to combat inductive distortion.
Probably the most interesting feature of the 12S2 is the slot vent. It turns out that it is a complex geometry made from 2 molded pieces of plastic. The vent is moderately larger in the middle than at the ends and is flared on the exit. In the middle the vent narrows but grows larger in height before curving upwards and expanding again and heavily flaring towards the internal inlet. During testing the vent did appear to behave in a linear manner and with very little vent noise due to high speed air movement.
Clearly the 12S2 has a solid build and parts quality but the sum of the parts is less than it could be. The output and distortion is decent for a sub in this price range and of this size, especially from 35-70Hz. but the response shape and behavior could be much better. The driver appears to have a large amount of inductance and also a rather high Qts which when combined with a smaller cabinet and the vent tuning produces a peaking response shape. The biggest issue though is the crossover implementation, which not only exacerbates the peaking frequency response and limits the useful upper bandwidth of the sub, but also dramatically changes the output level to such an extent that it requires readjustment of the subwoofer volume entirely. Additionally the crossover cannot be defeated for use with an AVR or other processing like most modern active subwoofers. Any use with an outboard low pass filter will result in both low pass filters running in series. If the crossover was defeatable, as is usually the case for use with an LFE channel, it would likely help out immensely, but sadly it is not. A bit of DSP EQ would go a long way as well but it does not appear to be a function built into the current amplifier. In summary the KRK 12S2 offers a good looking and well built unit with good output in the critical 35-70Hz octave, but its performance is hampered by the crossover, lack of a crossover bypass and lack of internal DSP to correct the response shape.