Nidec Servo Gentle Typhoon D1225C (2150/12) details
Wondering how the Gentle Typhoon D1225C, the originator of the efficiently shaped rotor, is stacking up against much newer fans today? Very well. Outside the band of the most intense vibrations with annoying resonant frequencies, even from today’s perspective this fan has a top performance-to-noise ratio. In some ways it is even still unsurpassed, and the designers of the time built on strong physical foundations.
The geometry of the Gentle Typhoon D1225C can certainly be described as timeless, it has become the inspiration for many modern fans. But at the same time, we don’t like to see new products described as “just another Gentle Typhoon” and hear that fan development has been stagnant for 15 years (since the Gentle Typhoon was released). It’s akin to blaming cars for having circular wheels – after all, those were already on medieval carriages and of all the options, it’s the best one, oval or polygonal wheels would work worse. And it’s similar with fans.
Inventing significantly different geometries from the Gentle Typhoon D1225C would always be a path to a worse result for the needs of PCs. You’ll see this in today’s tests, where the GT clearly beats many fans despite being a significantly older design. That’s why fan manufacturers with new models are resorting to these shapes and trying to perfect the details. Noctua has gone the furthest in this regard with the NF-A12x25 PWM, and by using a very strong material to construct the blades, they have eliminated the Gentle Typhoon’s main shortcoming, high vibration.
The advantage of a larger number of blades with a more pronounced curvature is that it does not push the air stream into the radial axis. And when it does, it does so to a much lesser extent than computer fans which can be described as standard, run-of-the-mill. That means seven wider blades with a smaller angle, with roughly equal sides (although the one at the motor is always a bit shorter) and with a smaller leading edge radius. The sweep and orientation of the airflow in these designs interferes more significantly with the radial axis and the trajectory is thus more conical. There would be nothing wrong with it in principle, but when the fan is seated in a tunnel, there is always more air friction at the level of the fan itself (under the frame arches) and more microturbulence at the sharp edges of the frame. That alone is a pretty significant handicap for the fan to achieve higher airflow at the same noise level.
If both designs were to reach their physical limits (you know that with fans it is not only the shape of the rotor or frame that matters, but also the strength of the blades or the properties of the bearings, the motor), it is often technically impossible for a fan with a rotor shape resembling the Gentle Typhoon to be noisier at the same airflow.
The Gentle Typhoon fan blades do have very similar proportional characteristics, including perhaps the same area per blade and also the same (or at least very similar) spacing, but there are a few differences as well. The GT’s blade tips aren’t as sharp (as the NF-A12x25) and it is also without the “acceleration” channels on the trailing side of each blade. In return, it has, further down near the motor housing, small serrations that reduce microturbulence and improve acoustic response at these points. Remarkably, Noctua used to use them as well, but phased them out of their designs, as did Fractal Design, for example.
The Gentle Typhoon D1225C is completely made from a composite of PBT, ABS and fiberglass (GF30), both rotor and frame. The material’s strength is lower and thermal expansion higher than LCP-based fans (these include the MSI MEG Silent Gale P12, for example, in addition to the NF-A12x25, of the models tested), so there is a larger gap between the blades and the frame in the GT compared to the NF-A12x25. It’s not a big difference though, it’s roughly a third, and again it doesn’t matter that much. The Gentle Typhoon has very high static pressure, and that’s also because of the proper thickness of the blades. Overall, this is a very sturdy fan weighing in at 198 g. Only the cable is more delicate, unbraided. It has the individual wires “loose”, without a mesh.
Since 2008, although the Gentle Typhoon D1225C initially carried the Scythe brand for a long period, its manufacturer was Nidec Servo. So it seems there were no changes in the design after the “separation” from Scythe. Manufacturing practices across time may have been somewhat different though. However, their effect on the fan’s performance will most likely be minimal.
One more important note about the bearings used. They are ball bearings, meaning robust, although compared to liquid (FDB, SSO2, etc.), especially at lower speeds, they contribute more to the overall noise of the fan. The mean time between failures is given by Nidec Servo as a function of temperature load. Desktops in homes should see 100,000 hours. But for more demanding conditions with typically higher ambient temperature, 45,000 hours at 60°C is quoted.
* When reading performance values, a certain amount of tolerance must always be taken into account. For maximum speeds, ±10 % is usually quoted, minimum speeds can vary considerably more from piece to piece, sometimes manufacturers will overlap by as much as ±50 %. This must then also be adequately taken into account for air flow, static pressure and noise levels. If only one value is given in a table entry, this means that it always refers to the situation at maximum speed, which is achieved at 12 V or 100 % PWM intensity. The manufacturer does not disclose the lower limit of the performance specifications in its materials in that case. The price in the last column is always approximate.
- Nidec Servo Gentle Typhoon D1225C (2150/12) details
- The basis of the methodology, the wind tunnel
- Mounting and vibration measurement
- Initial warm-up and speed recording
- Base 6 equal noise levels…
- ... and sound color (frequency characteristic)
- Static pressure measurement…
- … and airflow
- Everything changes with obstacles
- How we measure power draw and motor power
- Measuring the intensity (and power draw) of lighting
- Results: Speed
- Results: Airlow w/o obstacles
- Results: Airflow through a nylon filter
- Results: Airflow through a plastic filter
- Results: Airflow through a hexagonal grille
- Results: Airflow through a thinner radiator
- Results: Airflow through a thicker radiator
- Results: Static pressure w/o obstacles
- Results: Static pressure through a nylon filter
- Results: Static pressure through a plastic filter
- Results: Static pressure through a hexagonal grille
- Results: Static pressure through a thinner radiator
- Results: Static pressure through a thicker radiator
- Results: Static pressure, efficiency by orientation
- Reality vs. specifications
- Results: Frequency response of sound w/o obstacles
- Results: Frequency response of sound with a dust filter
- Results: Frequency response of sound with a hexagonal grille
- Results: Frequency response of sound with a radiator
- Results: Vibration, in total (3D vector length)
- Results: Vibration, X-axis
- Results: Vibration, Y-axis
- Results: Vibration, Z-axis
- Results: Power draw (and motor power)
- Results: Cooling performance per watt, airflow
- Results: Cooling performance per watt, static pressure
- Airflow per euro
- Static pressure per euro
- Results: Lighting – LED luminance and power draw
- Results: LED to motor power draw ratio