Blade length is always the “topic”, but will be more common with 140mm fans than smaller variants. Some bet on long blades for preference of selected features, the other manufacturer on short ones. And such (short) and overall more robust blades are also used by the 140mm Aorus fan. From certain points of view this is quite a big advantage, but for which something had to be sacrificed. It’s a quid pro quo.
Initial warm-up…
Before we even start measuring anything, we let the fans run “idle” for a few minutes after plugging them in. This is because immediately after a cold start the fans reach different parameters than after a certain amount of short-term operation.
Until the operating temperature of the lubricant is stabilized, a typically lower maximum performance is achieved. This is because at lower temperatures the lubricant is denser, which is associated with higher friction. Therefore, the fans do not reach maximum speed immediately, but only after the first few seconds. Before the first measurements, we therefore leave the fans running for at least 300 seconds at 12 V, or 100 % PWM intensity.
…and speed recording
The speed of the fans is monitored using a laser tachometer, which reads the number of revolutions from a reflective sticker on the rotor. For this purpose, we use the UNI-T UT372 device, which also allows real-time averaging of samples. Thus, we do not record the peak value in the graphs, but the average speed value from a 30-second time period.
However, the speed itself is a relatively unimportant parameter that is often given more attention than is appropriate. This is the case even in many fan or cooler tests, where speed is used to normalize the different modes in which other variables are measured.
However, hyper-focusing on a specific speed is a rather unfortunate decision if only because the fans don’t gain any commonality. At the same speed all other variables are different, there is no intersection. It can be noted that a better normalization would have been by any other variable, whether it be static pressure, flow or noise level, which wins in our case. But more on that in the next chapter.
We only measure the speed so that you can associate a particular parameter (such as the amount of static pressure or some noise level) with something according to which you can adjust the fan yourself. Perhaps for that alone, the information about the achieved speed is useful. As part of the fan analysis, we will also indicate what the fans’ starting and minimum speeds are. Start-up speeds tend to be higher than minimum speeds because more force is required to get the rotor moving than once the fan rotor is spinning, and a minimum power intensity is sought at which the fan does not stall.
Nice to see the 140mm fan reviews rolling!
Also, would it be possible to publish noise samples for your fan/cooler reviews? Preferably for all scenarios where you perform frequency analysis?
And they will continue to come, tests of 140 mm fans. But we probably won’t exaggerate it, so that they stay in a relevant ratio (according to the interest in whichever format in general) to 120 mm models.
Which noise samples do you mean? From spectrographs? Do you want that data for your own purposes, for your own analysis? If so, we can send you the noise levels at all frequencies in all tested scenarios almost immediately (e.g. by e-mail). We can certainly post them on the web somewhere, but it will take more time, as we will need to create a section for this somewhere. Making it make sense on the web will be more time-consuming and at the moment we are quite overloaded and it is hard to find space for extra activities. :/
Always looking forward to your fan reviews regardless of size!
For noise samples, I mean audio files so I can listen to them to make a subjective judgement. In reviews you often mention the differences in frequencies between obstacles/fan models etc. With audio files to listen to, it will be much more easy to understand the difference.
Maybe you can consider compiling the audio files for each fan and upload to YouTube as a video, for example, which perhaps take relatively little effort, though I am not sure if the audio quality is satisfactory. Anyway, it is only a suggestion so please decide on whether you think it is worth the effort or not.
I understand now, and I am also sorry that I am now likely to disappoint you.
Sound recordings are something I boycott against and the goal is to get more and more people to learn to read spectrograms. Sure, it’s more complicated, but we plan to publish materials to facilitate reading these charts. We will select a few fans that have the biggest differences in the frequency characteristic of the sound, make a sound recording of them, and put a spectrogram against it. On it we then explain which component of the sound represents what in the spectral analysis.
You know, I’m willing to sacrifice all my time for these things, but I have to see some meaning behind the results. And sound recordings don’t make sense to me because they can be extremely misleading. While the user thinks he’s hearing the fan, the sound system with the speaker on top is laughing at how they have been perfectly fooled. It is certainly not necessary to elaborate that the same recording sounds different on each speaker (it is determined by the frequency characteristics of the sound equipment of the end user), and this also with regard to the volume that the person sets. To judge something on the basis of the sound recording is therefore very inaccurate and misleading. I would probably suffer a lot when making them with my high demands on the relevance of things and at the same time it would reduce the relevance of spectrogram, which everyone sees the same way.
I believe that after this message you will not give up on our tests and sooner or later you will surely find out (also with the help of various auxiliary materials, which we plan to publish on this topic), that you understand everything perfectly also with the help of spectrograms. 🙂
Not disappointed at all, very satisfied with your answer. Looking forward to the articles explaining spectrograms, I’ll admit I never really understood how to interpret them.