Noiseblocker NB-BlackSilent, XL1, XL2, XLP3 Rev.3.00
Another group representing German fan makers consists of three models in NB-BlackSilent series from the Noiseblocker Company, which name speaks for itself. The fans are packed in clear plastic casing with a cardboard insert at the bottom:
The detailed technical specifications of the fans are provided on the back of the packaging:
The fans are shipped with four long silicone mounting spindles that should absorb vibrations during work and slightly reduce the level of generated noise:
All three models are manufactured in Germany, belong to ultra-quiet series and third revision (2008 models). XL1, XL2 and XLP fans differ by their supported rotation speeds, and the latter model is also equipped with PWM rotation speed regulator.
NB-BlackSilent series fans look very attractive due to crescent-shaped semitransparent blue blades:
The fans measure 120x120x25 mm, weigh 120 g and 125 g for the PWM model. Each fan has seven blades and a 45 mm rotor diameter:
The rods holding the fan blades are very thin and their top part has semicircular cross-section. Both these things help, even though just slightly, to reduce the airflow resistance and to lower the noise.
Unlike all 120 mm fan models we have already discussed above, the inside of the NB-BlackSilent fan frame has no sharp edges, which should also have a positive effect on the acoustics:
XL1 fans rotate at 1000 RPM (±10%), XL2 fans – at 1500 RPM, and XLP fans equipped with a PWM rotation speed controller can work in the interval between 1000 and 2000 RPM. As a result, these fans generate 41, 58 and 75 CFM airflow and produce 13, 21 and 14-21 dBA of noise respectively, which is unusually low for rotation speeds like that. At this point we can only add that Maximum static pressure is claimed at 0.659 mmH2O for XL1, 1.044 mmH2O for XL2 and 2.653 mmH2O for XLP.
NB-BlackSilent fans use sleeve bearings with guaranteed MTBF of 80,000 hours, which is more like the lifespan of solutions using ball bearings than a common sleeve. In terms of power consumption, these fans can’t boast anything special and don’t support low startup voltage (only 6V).
XL1 and XL2 fans should consume no more than 3.24 W at 0.27 A current, while the power consumption of the XLP model varies depending on its rotation speed between 0.6 and 4.8 W with 0.05-0.4 A current. The recommended retail price for these fans is set at $13 for XL1 and XL2 models and $17 for XLP. They come with 3 years of warranty.
In terms of practical performance, NB-BlackSilent fans did very well and were among the leaders of our today’s test session:
I was especially impressed with the level of noise generated by XL1 fan model, namely, with the absence of any noise in the entire rotation speed range! It is a perfectly balanced fan, with an absolutely noiseless bearing and extremely successful combination of the fan blades shape and fan frame with smooth internal surface. The latter two features are also true for the other two models. They do run noisier, of course, but only because of the extremely high airflow they create, which is, actually, one of the highest in the entire test session. NB-BlackSilent fans reach acoustically comfortable performance level at 1020 RPM. They do not consume much power, even less than the specs claim. Their startup voltages are 3.6 V for XL1, 2.1 V for XL2 and 4.2 V for XLP.