KLH PRO 51 Bookshelf speakers

KLH PRO 51 is a three-way speaker system with a passive radiator located on the faceplate. The diameter of a soft dome tweeter is 25 mm, mid- and low-frequency ones (with a polymer diffuser) of active cone radiators are 130 mm and 300 mm. The diameter of a passive cone radiator is equal to the diameter of woofer. A recommended power of the amplifier is from 5W to 325W - holy Moses! Certainly, this system requires a corresponding space. Can't all these watts go to waste? Moreover, the sizes of these speaker systems - 381x1062x294mm- require space for their placement. On the other hand, the owners of such outstanding systems will be surprised by their relatively small mass: the speaker systems turned out to be much lighter than they look from the outside. The sound of the speaker systems fully justifies significant sizes. An eye, cast on the frequency response, will be pleasantly amazed by the absence of quite typical failure of the sensitivity on the frequencies from 70 to 100 Hz, but this was expected from such sizes of woofer's acoustic design. Due to the fact that the response on the very bottom falls a little faster than desired, we can say that basses are correct in the highest degree here. From 60 Hz up to 18 kHz the frequency response doesn't almost give reasons for voluminous comments, because an average non-linearity is ±2,2dB. But there is an annoying failure of almost 10 dB in the range from 280 to 380 Hz, but this is, apparently, the cost for the desire to decrease the mass of case: the walls of the speaker systems turned out to be too thin and couldn't resist the desire to "dance" on its resonant (blending) frequency. At the upper part of the range the response doesn't attain for a little to 22 kHz, promised by technical description, but somebody in the audience will hardly notice it. Uniformity of the field is quite high and the sensitivity is just record - more than 91 dB. The average meaning of the module of input resistance is 9,6 Ohm, mean square deviation is 4,8 Ohm, nominal resistance - 5 Ohm. The crossover frequency of loudspeakers by the technical description are 900 Hz and 2,8 kHz.