Review on 💨 Enhanced Performance Vornado 723 Full-Sized Air Circulator Fan for Optimal Room Ventilation by Brooke Washington

I just received this fan from UPS about 2 hours ago - I paid for it myself, no samples or discounts. This is my first Vornado fan and I am very impressed - it has a beautiful design and the fan speed range is incredible. I work from home and my office gets very hot - it's best to cool down outside with a fan. my door to push cooler air. Most fans are too loud and annoying, but the 723DC is big enough and can run slow enough to move a significant amount of air at whisper volume. Everything was fine until my son, who we say is "on the spectrum" and doesn't have any major sensory issues, came down the stairs and asked what was making "that noise". He described it as a very high-pitched noise, similar to that of a CRT flyback transformer, only louder. I couldn't figure it was a fan so I asked him to go to the next room and do a blind test to see when he heard a noise. This is a fan. I got him to put his ear to the transformer and the fan - and it's a fan. Reading the reviews, another customer mentioned resonance or noise coming from the case - I assumed they received a defective unit, but now I have an alternative theory. As far as I know there are two ways to control the DC speed. Motor - either vary the voltage (more volts = more speed etc.) or send the voltage in intermittent pulses of different lengths - imagine trying to dim the lights in your dining room by turning them on and off quickly - that's basically the latitude - pulse modulation, but of course this happens at very high frequencies - the upside is that PWM circuits are very well known and reliable, but can generate noise depending on the design. Only 1 in 6 people in my house can hear the noise, but it's extremely annoying and I'll probably have to send it back unfortunately. We don't have pets, but dogs and some other animals also have high-frequency hearing and can also hear PWM noise. However, if you are over the age of 25 and have no pets or small children you are very unlikely to hear this noise and I would highly recommend this fan. During a conversation with them, I told a support person to ask the engineers about their PWM controller and see if they could measure ultrasonics. Maybe they will remake the controller, maybe this is such a rare problem that you shouldn't bother, I don't know.