Author Topic: Some lab instruments sound level measurements  (Read 130 times)

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Offline DIPLover

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Some lab instruments sound level measurements
« on: June 02, 2020, 08:55:45 am »
I thought I would share with you some sound level measurements I have taken in my quiet basement lab over the years.

Please note the levels have not been obtained with a calibrated instrument, so the absolute levels are rather worthless. But I have been careful to always use the same device (an old iPhone 4 I keep only for this purpose), running the same software (SPLnFFT), while positioned in the exact same spot and orientation, so RELATIVE levels should be meaningful.

All measurements are db(A).

Room background with everything turned off : 28.0
mac mini 2018 running at low load : 29.7
HP Z820 workstation idling with fans set to lowest speed : 36-39

Logic Analyzers :
HP 1663C : 39.5
HP 1670G : 48.2
HP 16700A : 52.2
HP 16700A refitted with Noctua high static pressure fans :42.5 peak, 40.0 idle

Oscilloscopes :
Tektronix 2213: high pitched whine, otherwise silent
Tektronix 2265 (original model with auto fan speed) : 37.5
Tektronix TDS744A : 43.2
Rigol DS2072A : 38.0
Rohde & Schwarz RTC1002 : 29.8

Others :
HP 5345A counter : 56.0 (a real monster this one!)
Siglent SDG 2042X ARB : 31.4

Obviously the fanless instruments are normaly silent. It's why I prefer my old brown Keithley DMMs to newer models.

The siglent 2042X dominates the soundscape when just the mac is running while the RTC1002 I cannot detect, so a difference of 1.5 db is clearly audible.

What are your experiences soundwise with your gear? Is your lab quiet or noisy?
« Last Edit: June 02, 2020, 09:14:17 am by DIPLover »

Offline Berni

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Re: Some lab instruments sound level measurements
« Reply #1 on: June 02, 2020, 09:24:08 am »
Sound level dB are not really a complete picture of how noticeable a sound is.

Gear that produces a more white noise like sound is much less noticeable than something that makes a high pitched whiny fan noise.

But yeah a lot of big boat anchor test gear has loud fans in it, so i have replaced quite a few fans in it. Sometimes the bearings are shot in a fan, other times the fan is way overspecced for the job because the thing is designed to run  stuffed into a full tight hot rack with poor ventilation. So sometimes just slowing the fan down helps a lot with the noise. I even had a case where flipping the fan around made a big difference to the noise (Objects near the fan blades can make them sing as they pass by). Of course when doing this i would make sure there was still adequate cooling by checking temperatures and running things like PSUs at full load for a long time.

Its possible to make a PC near silent with some nice cooling upgrades, but test gear nope. Just turn up the music louder when working with test gear (I like to have background music when working).

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