R&S RTB2004 noctua fan questions/feedback - Page 1
Forum section: electronics / testgear

author: alonsojar
author_rank: Contributor
timestamp: July 18, 2023, 04:17:28 pm
content: Hello,My Rtb2004 is reaching its end of warranty and I'm considering to replace the Sunon stock fan by a Noctua NF-A8 FLX.The Sunon is not probably too noisy, but the fan is running at 1.750 1.850 rpm after some minutes working and never goes down no matter what I do, so very close to its maximun 2.000rpm. It looks like voltage control is not designed to get a wide actuation range on this device.On the other hand the replacement seems easy and not very expensive...Anyone did replace the fan and could share the experience?The Noctua on the specs overpasses the Sunon not only in reduced noise (16.1 vs 20.4 dBA at 2000 rpm), but is also offering more airflow and static pressure at the same rpm (I mean without any Low Noise cable installed).There is a small concern about the current consumption that in the Noctua is 0.84 watts while the Sunon is 0.54W (a 50% more). I'm asking myself if it'll be safe to plug it to the motherboard in the long term.Perhaps the Notcua watts figure is the worst case with the Ultra Low noise adapter resistor plugged in ??What do you think?Thanks in advance!!J.Alonso

author: alonsojar
author_rank: Contributor
timestamp: July 18, 2023, 07:06:40 pm
content: Thank you Peter,I've read this thread time ago. The guy said that the noctua nf-a8 was not making any noticeable difference for him and finally installed a bigger fan requiring a mod. This is far away from my intend and I'm probably less ambitious (and lazy) regarding noise.I'm just asking for people who really installed a noctua 80mm or similar and their experience in the long term.CheersJ.Alonso

author: Rydda
author_rank: Contributor
timestamp: July 19, 2023, 02:26:58 pm
content: Well I'm the guy.And I am still running my 'upgraded' RTB. My reasoning for the modification was basically:- the Sunon fan was no better or worse than several Noctua fans I tried.- every replacement still sounded like a small fan running at high speed. Not a sound I enjoy.- the noise could be lowered by lowering the speed of the fan, but every attempt to lower the speed resulted in an increase in the pcb temperature.For me, it was not meaningful to pursue that path.But since this is an extremely subjective topic, it might be different for You.IMO it is almost impossible to draw any conclusion from information online how you yourself will experience the noise from an instrument. One example: I have been considering an upgrade to the MXO4. This has an audible noise level according to R&S of 34dBA and is described as 'whisper quiet' in every review. The RTB2004 had an audible noise level of 28dBA (also according to R&S), so just judging from these figures, the MXO4 would be 6dB louder than the RTB. And I know how I hated the noise from the RTB./Ola

author: alonsojar
author_rank: Contributor
timestamp: July 19, 2023, 03:53:16 pm
content: Hi Rydda,Your considerations are very reasonable and useful for me.In my case I tested the scope noise using a phone app placed 10cm in front of the screen on the bench. Probably not the best instrument nor placement, but with the room silent it measured 28 dB and with the scope on running normal fan speed (say 2.780 rpm reported by scpi command) around to 40 dB. Too much? I don't know....I've ordered the Noctua NF-A8 and will report the results. A small reduction or even a change in tonality could be enough for me.In the worst case I'll use it in other project (like my nge103b power supply that you reported to have a noticeable improvement). It will take some weeks because I'm waiting also for the molex connector used in the mainboard (micro-fit model if I'm not wrong) that I also ordered and will delay due to holidays season.TnxJ. Alonso

author: pdenisowski
author_rank: Super Contributor
timestamp: July 19, 2023, 08:48:10 pm
content: Quote from: Rydda on July 19, 2023, 02:26:58 pmI've used both scopes (RTB and MXO4) in my very quiet office for hundreds of hours. If I have my back turned to my bench, I can't tell from three meters away if either one of them is on. I've worked in test and measurement for over 25 years (15 at R&S and 10 with another major company) and the MXO4 is one of the quietest instruments I've ever used.I'll see if I can do a side-by-side test sometime next week (I only have an MXO4 at the moment), but as you say, the annoyance caused by noise is a very subjective thing.It would be interesting to do an audio frequency analysis of the noise from the two instruments: I'm not sure it's safe to assume that the audible noise from all instruments has the same (Gaussian, White) frequency distribution, so it may be the case that some types of fan noise are more annoying than others simply due to the spectral distribution of that noise. For example, a fan with a lower overall dBA might be more pyschoacoustically annoying because it has higher frequency audio components. Just a thought

author: alonsojar
author_rank: Contributor
timestamp: August 05, 2023, 06:05:20 pm
content: After some testing with the Noctua NF-A8 FLX fan here is my experienceThe Noctua runs faster, more or less 150rpm faster than oem Sunon in the same conditions. Both fans are rated 2.000 rpm +-10% but for any reason the Noctua runs faster.Maybe the fan control is made using a temp reference and setting a predefined voltage. Then fan speed sensor is only used to veriry fan is turning? I'm not an expert in that.In this condition, the noise produced by Noctua is noticeably higher.After some further testing, loading the fan with a 33 Ohm resistor I can see the same speeds the Sunon had. The noise is perhaps a little less disturbing, but in my phone app it is only reduced 2dBA, so it's negligible.I was also monitoring temperature sensor readings for CPU, ADC and FPGA using SCPI interface and I observed some increase when using the Noctua (2 to 4 degrees), so probably Noctua spinning at the same speed is less effective than Sunon.Conclusion... Rydda experience was confirmed. Probably the noise main source is not the fan itself but the air passing though the device propelled by a fast running small fan. The Noctua NF-A8 is not improving noise and shows a different behaviour. At the end I left the Sunon because I don't want to risk my oscilloscope integrity.Thank you all for your contributionsJ. Alonso

author: Rydda
author_rank: Contributor
timestamp: August 06, 2023, 09:39:27 pm
content: @alonsoQuoteI have been trying to find SCPI commands for temperature measurement, but I can find nothing. So maybe I'm misunderstanding you, or I'm looking in the wrong place or I'm missing some documentation. The only thing I have been able to find is the STAT:QUES:TEMP command to check for temperature errors/warnings. I used this when I did my fan conversion, but imo it was not very useful since no actual temperature values are specified. Neither could I find a SCPI command to check the fan status. The RTB does monitor that the the fan is running and shows a prompt on the screen if the fan fails.

author: alonsojar
author_rank: Contributor
timestamp: August 07, 2023, 07:40:09 am
content: Hi Rydda,I found the scpi commands here in the forum...https://www.eevblog.com/forum/testgear/rs-rtb2004-snooping/50/To check fan speed I use:SERV:MODE WEN;:SYST:FAN:SEN?To check temperatures I've found two ways:1.- SCPI command::SERV:MODE WEN;:SYST:TEMP:ALL?The output for this command has many information, here is a sample"1;CB-ADC0;5323 ms;64562.5 mV;0.000 mA;64.7 'C;93.2 %","2;CB-FPGA;5321 ms;180000.0 mV;0.000 mA;52.0 'C;90.7 %","3;CB-CPU;5323 ms;52687.5 mV;0.000 mA;52.7 'C;94.4 %","4;CB-TMP432;5323 ms;53687.5 mV;0.000 mA;53.7 'C;0.0 %"Current temperatures for every sensor looks to be before the 'C.2.- Another way is to generate a Service Report using the interface menu (Setup-> Device Information-> Service Report)This will generate a serial.zip file in an external usb memory. Inside this file you can find a file named Deviceinfo.txt with information like this:Temperature Sensors1: CB-ADC0: 64.9 °C; Min 51.0; Max 65.4; Warning @ 95.0; Device Off @ 105.02: CB-FPGA: 53.0 °C; Min 47.0; Max 53.0; Warning @ 90.0; Device Off @ 100.03: CB-CPU: 53.7 °C; Min 50.6; Max 53.9; Warning @ 80.0; Device Off @ 90.04: CB-TMP432: 54.4 °C; Min 51.3; Max 54.6Fan Speed = 95.2 %; Min 92.7; Max 95.3 (1823 rpm; Min 1320; Max 1833)Hope this helpsJ.Alonso

author: Rydda
author_rank: Contributor
timestamp: August 08, 2023, 12:24:00 am
content: Quote from: alonsojar on August 07, 2023, 07:40:09 amBeautiful!! Thank you!I had seen the 'device information' menu item of course, but it did not seem interesting, so I just passed it by.I wonder how much else there is about this scope that I don't know .Just as a FYI, here are three excerpts (using my newfound knowledge) from the info utility. After one hour the temperatures are stable.Four channels + sigGen active.The ambient temperature is 26 C.Note the fan speed! Ime fan speed is a very good indication of noise. As far as I can tell, the system never attempts to change the fan speed.Operating time: 3 minTemperature Sensors1: CB-ADC0: 63.5 °C; Min 29.4; Max 63.5; Warning @ 95.0; Device Off @ 105.02: CB-FPGA: 55.0 °C; Min 22.0; Max 55.0; Warning @ 90.0; Device Off @ 100.03: CB-CPU: 42.5 °C; Min 24.1; Max 42.5; Warning @ 80.0; Device Off @ 90.04: CB-TMP432: 47.3 °C; Min 25.1; Max 47.3Fan Speed = 91.8 %; Min 81.5; Max 91.8 (588 rpm; Min 452; Max 593)Operating time: 1 h 1 minTemperature Sensors1: CB-ADC0: 69.2 °C; Min 29.4; Max 70.1; Warning @ 95.0; Device Off @ 105.02: CB-FPGA: 57.0 °C; Min 22.0; Max 63.0; Warning @ 90.0; Device Off @ 100.03: CB-CPU: 50.0 °C; Min 24.1; Max 50.9; Warning @ 80.0; Device Off @ 90.04: CB-TMP432: 52.9 °C; Min 25.1; Max 54.9Fan Speed = 94.7 %; Min 81.5; Max 94.9 (598 rpm; Min 452; Max 609)Operating time: 4 h 1 minTemperature Sensors1: CB-ADC0: 69.2 °C; Min 29.4; Max 70.1; Warning @ 95.0; Device Off @ 105.02: CB-FPGA: 59.0 °C; Min 22.0; Max 63.0; Warning @ 90.0; Device Off @ 100.03: CB-CPU: 50.6 °C; Min 24.1; Max 51.1; Warning @ 80.0; Device Off @ 90.04: CB-TMP432: 53.4 °C; Min 25.1; Max 54.9Fan Speed = 94.7 %; Min 81.5; Max 94.9 (599 rpm; Min 452; Max 610)

author: alonsojar
author_rank: Contributor
timestamp: August 08, 2023, 12:10:57 pm
content: Mine after 1 hour. Room temperature 27 C (and rising)Same conditions, all analog channels and SG on. Of course stock fan.Temperature Sensors1: CB-ADC0: 64.5 °C; Min 28.6; Max 64.6; Warning @ 95.0; Device Off @ 105.02: CB-FPGA: 52.0 °C; Min 21.0; Max 52.0; Warning @ 90.0; Device Off @ 100.03: CB-CPU: 53.2 °C; Min 24.6; Max 53.2; Warning @ 80.0; Device Off @ 90.04: CB-TMP432: 53.8 °C; Min 25.9; Max 53.8Fan Speed = 94.7 %; Min 81.2; Max 94.7 (1795 rpm; Min 1362; Max 1818)J. Alonso