the box pro DSP 18 Sub

In terms of sound, this subwoofer does the job it was designed for, but it doesn't offer a linear response on the declared frequencie range. The manufacturer does not provide details in the user manual about the speaker model used or its impedance, about the amplifier module model used and its specifications, about the maximum input signal supported or if the frequency response is measured at -3 dB or -10 dB. Also, no wiring diagram is provided. On the very low frequency range, below 40 Hz, this subwoofer will have difficulty reproducing the sound satisfactorily. The lack of specifications regarding the speaker model and the amplifier model used, as well as the lack of a wiring diagram, create difficulties in identifying the necessary spare parts in case of need. I requested additional information from the brand owner, who responded promptly, stating that the subwoofer speaker supports a power of 600 watts, at an impedance of 4 Ohm, and the amplification module delivers 800 watts. So, if you are wondering why the "Limit" LED lights up sooner than you expect, here is one of the reasons. Also, keep in mind that when you use both XLR input connectors on the subwoofer, the sensitivity of the input signal increases, and on the low frequency output circuit this signal is summed, and therefore the maximum output volume position shifts down, to about 1 o'clock. Also, you must set the input and output gain levels correctly on the mixer, equalizer or active crossover. There's a good reason for the "0 dB" marking on your level meters. The user manual specifies a peak power of 2400 watts, but some models specify the peak power differently, on some, such as the one in the photo published on the website, appears 1800 watts peak, and on others, such as the one I purchased, 3200 watt peak appears, which raises questions about the honesty of the data declared by the manufacturer and the consistency of the components used in the manufacturing process.
The box appears to be well assembled and solid, but you have to be careful during manipulation because the finishing is easyly prone to scoring.