Massive Fan Shootout: 25 Products
from Arctic Cooling, Cooler Master, GlacialTech,
Scythe, Titan, and Zalman

Scythe, Titan, and Zalman

Contents:

1. Review: Arctic Cooling, Cooler Master and GlacialTech
2. Review: Scythe, Titan and Zalman
3. Test Results: 80x80x25 mm fans
4. Test Results: 120x120x25 mm fans
5. Annex 1. Noise profiles (1/3 octave analysis), 80x80x25 mm fans
6. Annex 2. Noise profiles (1/3 octave analysis), 120x120x25 mm fans

Scythe Minebea 12cm Mid and Minebea 12cm High

The next objects of our shootout are two High-End fans — Scythe Minebea 12cm Mid (4710KL-04W-B19) and Minebea 12cm High (4710KL-04W-B29) designed by the leader of this industry, NMB-Matsushita corporation, and produced by the famous Japanese brand Scythe.

Scythe Minebea 12cm Mid

Keeping in mind prestige and achievements of NMB-Matsushita (both the conglomerate as a whole and its constituent companies separately), we can safely assume that Minebea fans must demonstrate the optimal combination of quality and functionality, spiced up with well thought-out and neat engineering approach. They come up to our expectations even under scrutiny and completely lend credence to their High-End status.

The 9-blade impeller has a very interesting aerodynamic configuration, which is designed for maximum performance with acceptable noise ergonomics — sweep and lean blades, chord - 20 mm at the hub and 30 mm at the tip, chord-pitch ratio is 1.25 at the hub and 0.79 at the tip, aggressive angles of attack - 50° and 35°, 0.41 hub-tip ratio, 1.5 mm tip clearance. Minebea's impeller also has three aerodynamic benefactors that reduce the noise and raise its efficiency — a screen on the front edge of the blade, dihedral blade, and smoothed rear edge of the blade.

We should pay special attention to Minebea mechanics based on two ball bearings. The focus is on quality here - we get it owing to high-precision NMB bearings. In their turn, they guarantee as small clearance between the hub and the inner ring of the bearing as possible (no backlash), vibration stability, enhanced reliability (resistance to mechanic stresses), and optimized noise characteristics (these bearings do not crackle and practically don't "hiss").

Silent IC

Another feature of Minebea fans is their advanced electric binding of the engine called Silent IC. The integrated controller is based on Sanyo LB1868M (a counterpart of LB1668M). Interestingly, the outputs of inductor's drivers use integrating circuits (a couple of resistors, a key bipolar transistor, and an integrating capacitor between the base and collector) instead of capacitors. Integrators efficiently protract the front-decay of switching impulses in the inductor coil. As a result, this IC stands up to its title — Minebea 4710KL-04W-B19 and 4710KL-04W-B29 are the only fans today without electric popping in their noise.

Minebea fans look great from the practical point of view as well. They achieve excellent results with acceptable noise ergonomics. They demonstrate the highest performance at nominal speed (1900 rpm for the 4710KL-04W-B29 and 1600 rpm for Minebea 4710KL-04W-B19). But the noise level grows rather high in this mode, which makes them less attractive in the standard mode. Their real potential is revealed at moderate speed — they demonstrate good universality of the impeller, spiced up with ergonomic noise characteristics. So they provide the best efficiency/noise ratio.

Minebea 12cm Mid and Minebea 12cm High are very interesting products with excellent technical properties. Our only gripe is their prices: their average retail price is $18, which makes them the most expensive fans in the market. This price is too high in our opinion, even for High-End. But it cannot be helped —  High-End requires sacrifices. :)

Our shootout also includes Scythe Minebea 9cm Mid and Minebea 9cm High (92x92x25 mm) hors concours.

In technical terms, they are similar to Minebea 12cm (two ball bearings, Silent IC) and differ in highly efficient aerodynamics. We'll review these fans in one of our future articles.

Scythe S-Flex SFF21E and SFF21F

The other two High-End fans from Scythe (S-Flex SFF21E and SFF21F) are based on a technically different idea and have different performance roots (manufacturer — ADDA).

Scythe S-Flex SFF21F

The main peculiarity of the SFF21E and SFF21F fans is advanced mechanics, based on the unique hydrodynamic S-FDB bearing (designed by Sony). S-FDB uses three technical tricks — soft porous structure of the inner surface of the sleeve, hydrodynamic profile of the inner surface (V-shaped grooves) and fully hermetic bearing (polymer coating) to ensure active recirculation and grease confinement inside the sleeve. A special ring magnet is a good addition to S-FDB - it's mounted in the upper part of the bearing unit together with a metal ring pressed into a hub. Its purpose is to improve dynamic balance of the impeller.

Stator and impeller of Scythe S-Flex

These models also look well in aerodynamic terms — parameters of their impeller are intended to reduce noise while preserving the good efficiency potential: sweep and lean blades, the chord is 22 mm at the hub and 32 mm at the tip, chord-pitch ratio - 1.1 at the hub and 0.64 at the tip, angles of attack - 40° and 30°, 0.42 hub-tip ratio, 0.8 mm tip clearance.

The SFF21E and SFF21F also have an interesting electric binding of the engine: along with a neat inductor, the fans are equipped with an unusual IC based on Sanyo LA6583. This chip has an interesting feature - the load (inductor) is connected as a bridge between driver outputs (that is it's a single-coil inductor), so coil switching (switching a single coil between drivers) is smoothed a priori. It looks like a magic recipe to eliminate engine popping once and for all. But it's not that simple in practice — the voice of the SFF21E and SFF21F has a noticeable electric noise, which volume compares to usual fans with noise filters based on capacitors.

What concerns their results, these fans perform well in the standard mode (1600 rpm for the SFF21F and 1200 rpm). They demonstrate good performance and an acceptable efficiency/noise ratio. They also fare well at 1000 rpm, actively competing with Minebea models and SilentBlade II fans from GlacialTech. But efficiency of the SFF21E and SFF21F at low speed (700 rpm) slumps — which actually moves them towards outsiders in our today's shootout. The image of our fans suffers from another not-quite-positive issue in the standard mode as well — the noise generated by the SFF21E and SFF21F includes tonal coloring in this mode that subjectively makes it louder. The problem seems to be in the nonoptimal disposition of stator's holders, which results in acoustic mismatch of the impeller and fan case.

Contents:

1. Review: Arctic Cooling, Cooler Master and GlacialTech
2. Review: Scythe, Titan and Zalman
3. Test Results: 80x80x25 mm fans
4. Test Results: 120x120x25 mm fans
5. Annex 1. Noise profiles (1/3 octave analysis), 80x80x25 mm fans
6. Annex 2. Noise profiles (1/3 octave analysis), 120x120x25 mm fans