Low Noise (Sound) Oscilloscope

[Morgan127]

Hi All,
have anyone found a good oscilloscope that is silent. I really can't understand why all scope is so noisy (at least the one I got).
It should be something like 200Mhz 4 Ch.

TTI has some nice PSUs that is absolute silent.

Cheers

[glarsson]

TTI has some nice PSUs that is absolute silent.

Yes. It is amazing how much power can be had from a stack of two TSX3510P and two TSX1820P. In complete silence. 

[DaJMasta]

I think they just aren't prioritizing it and end up with mediocre fans or an air path that's full of hard edged baffles.  Since it doesn't seem to be well documented and people's opinions of how much is too much vary so much, I'm a fan of just replacing the fan in the scope you have.  It's almost always possible to get a quieter fan for a given unit, though it's sort of a gamble again if you can find a fan rated powerful enough that's quiet enough to suit your taste.

[David Hess]

Tektronix 7904 with two 200MHz 7A26 dual trace vertical plug-ins.

It is a shame that modern test equipment is so noisy.  Even my old oscilloscopes which have fans are practically silent.

[Rich@RohdeScopesUSA]

Our RTB2000 (70MHz to 300MHz) is extremely quiet - so quiet we actually list it in the data sheet:

Maximum of sound pressure level 28.3/30.2 dB (A) at 1.0/0.8 m distance (at +23 °C, 947 mbar (hPa), 20 % rel. humidity), in line with ISO EN 3744.

https://www.rohde-schwarz.com/us/product/rtb2000-productstartpage_63493-266306.html

Our 3000/4000 series are similar (and go up to 1GHz). 

-Rich

[Bob Sava]

I have Siglent SDS1104X-E, that originally sounded like a vacuum cleaner.  If Siglent wanted to, for about the same price, they could have designed it with quiet 120mm fan blowing into the PSU and exhausting through PSU to outside just like ATX PSU, but they did not...

I just modified this scope with with two 60mmx25mm 10dB fans.  It's not silent but it'a what Sharp calls 'library quiet' with their air purifier line, which is about 29dB.  It is probably as quiet as it can be w/o compromising airflow.   For total silence I would have to 3d print a fan shroud as currently the case is amplifying the fan noise.

[Fungus]

Our RTB2000 (70MHz to 300MHz) is extremely quiet - so quiet we actually list it in the data sheet:

You used to make fanless 'scopes. What happened? 

I have Siglent SDS1104X-E, that originally sounded like a vacuum cleaner.

I had a Rigol, same thing.

Now I usually feel the need to double-check the fan is working when I switch it on (it is!). All it took was a $7 fan and 15 minutes with a screwdriver.

[HighVoltage]

The most noisy scope I had was a LECROY.
It was so annoying, I returned it within one week and decided to never buy a Lecroy scope again.

[JPortici]

The most noisy scope I had was a LECROY.

True dat 
my 1989 boat anchor lecroy is among the noisiest pieces of equipment i have used. It's only topped by workshop tools

Newer ones are way quieter though, you should give them another try

[capt bullshot]

A TDS2024 (200MHz, 4ch)  It's rather old, pretty low on memory (yes, I know, this is a major critique point for these scopes), but fanless. An TDS224 (100MHz, 4ch) is even older and worse, but has quicker UI response.
Many of the "new" scopes are really bad in terms of UI responsibility and ease to use in comparison with these old and primitive ones. Especially the TDS224 has an analog scope alike UI and responsiveness, most knobs are single function and simple menus for the basic functions, anyway there are no advanced functions that clutter the menus. That and there noiselessness is the main reason why I still use them as a daily first choice general purpose scope.

If you know about the limitations, it still makes a good everyday usage scope.

[HighVoltage]

The most noisy scope I had was a LECROY.

True dat 
my 1989 boat anchor lecroy is among the noisiest pieces of equipment i have used. It's only topped by workshop tools

Newer ones are way quieter though, you should give them another try

Well, this one was not so old.... it was a Lecroy WaveJet 354A
A modern scope with modern interface and "good looking" too, kind of cute and lightweight.
It sounded all the time more like an airplane jet engine.
I thought the named it WaveJET  for the airplane sound.

[Mr Nutts]

Wasn't this scope just a rebrand of an Iwatsu scope? The GUI doesn't look like it came from Lecroy.

My old Wavepro is pretty loud but the little LT264 I got recently isn't too bad.

And the Agilent and Tektronix scopes at work are about the same when it comes to noise.

[julianhigginson]

I have a dpo2024, it makes a bit of noise, but it's not that bad. I tend to tune it out when it's on for more than a few minutes.

[exe]

I totally agree, it's so annoying. Unfortunately, most people are used to use noisy equipment in noisy environment. This might be okay for work, but I have my lab at home and it's so annoying. Especially high-pitch sounds.

[Fungus]

You know you're in for a good fanning as soon as they start putting Windows operating systems in there.

If R&S have stopped producing the HMO series then then I'm not sure there's any new fanless 'scopes out there. 28dB is very quiet though, if you can afford R&S.

Question: Do USB oscilloscopes have fans? If you have a PC on your desk then that might be an option.

[exe]

BTW, is replacing the fan an option? I'd also check how how components get, may be a fan with less airflow would also do the job.

[nctnico]

BTW, is replacing the fan an option? I'd also check how how components get, may be a fan with less airflow would also do the job.

I won't recommend using a fan with less airflow because that will reduce the expected lifetime of a piece of equipment. What does help is to use a higher quality fan and mounting it using rubber fan mounts. In my experience the rubber fan mounts alone will decrease the noise significantly.

[DaJMasta]

Yeah, generally my approach has been to look for the fan with the higher rated airflow and less noise, a lot of times the parts they're cooling already run warm and prolonged heat will eventually make them fail, so in the interest of having stuff stick around, I try to do at least as good of a job moving air as the OEM fans.  You can run into issues with very obstructed air paths that need a higher static pressure fan to operate, but a lot of the quieter ones don't even specify that, so there are some applications where you just know you don't need too much and there are some where I pick a fan and just test it against the original with a power supply to try to get a feel for whether they push air similarly.

Fan mounts can certainly help, but there is some equipment where the mounting is good and extra mounts do almost nothing.  Sometimes you run into fan grilles or very close heatsinks that just obstruct the airflow, making a fairly quiet stock fan fairly loud... and while they can sometimes be improved with a replacement fan, there's usually a limit to how much of a difference that can make without changing fan positioning or grille cutouts - and especially when EMI sensitivity is an issue with an instrument, I'm hesitant to do much chassis metal work for noise concerns.  Then with older equipment, sometimes the stock fan was actually pretty good at one point, but over time the dust/reduced lubrication/oxidation built up and made it noisy, sometimes just replacing it with an identical one can make a big improvement.

[Fungus]

Yeah, generally my approach has been to look for the fan with the higher rated airflow and less noise, a lot of times the parts they're cooling already run warm and prolonged heat will eventually make them fail, so in the interest of having stuff stick around, I try to do at least as good of a job moving air as the OEM fans. 

I don't know about Siglents, but ... as I pointed out in the "Rigol fan replacement" thread, a Rigol is designed to work in 50 degree Celsius ambient temperatures. I imagine Siglents aren't much different.

That means there's quite a lot of wiggle room if you're using it in a 25 degree office.

[nctnico]

Yeah, generally my approach has been to look for the fan with the higher rated airflow and less noise, a lot of times the parts they're cooling already run warm and prolonged heat will eventually make them fail, so in the interest of having stuff stick around, I try to do at least as good of a job moving air as the OEM fans. 

I don't know about Siglents, but ... as I pointed out in the "Rigol fan replacement" thread, a Rigol is designed to work in 50 degree Celsius ambient temperatures. I imagine Siglents aren't much different.

That means there's quite a lot of wiggle room if you're using it in a 25 degree office.

OMG  Not that nonsense again! Please read up on reliability (MTBF) and how temperature influences that. Every 10 degrees more means half the expected lifetime. The maximum operating temperature means the internal components won't overheat but the lifetime will become a lot shorter. And knowing Rigol costs have already been cut so better have more airflow than less.

[Bob Sava]

Capacitor lifetime is hardly linear and seem long enough up to 60degC:



@nctnico which components are you referring to?

[Rich@RohdeScopesUSA]

Our RTB2000 (70MHz to 300MHz) is extremely quiet - so quiet we actually list it in the data sheet:

You used to make fanless 'scopes. What happened? 

Thanks for the reminder - we actually still do!  The RTH1000 is fanless and goes to 500MHz    But our benchtop scopes all have fans now (unlike the older HMO1002 you are probably referencing). 

-Rich

[nctnico]

Capacitor lifetime is hardly linear and seem long enough up to 60degC:

@nctnico which components are you referring to?

All components! It is a hard rule which is well known for reliability calculations.
Look closely at the graph you posted and you'll see that between 50 and 60 degrees you loose half the lifetime and between 60 and 70 the life time halfs again. It is not a linear relation but exponential (square)!

[Fungus]

That means there's quite a lot of wiggle room if you're using it in a 25 degree office.

OMG  Not that nonsense again! Please read up on reliability (MTBF) and how temperature influences that. Every 10 degrees more means half the expected lifetime

Of course it will reduce the lifetime on paper but will it make a noticeable difference in real life if there's only 10% less airflow? I eagerly await your full analysis/explanation.

Nobody's talking about using fans which have vastly different specs from the originals (assuming the originals are optimal, which they may not be - they're more likely to be over-specified if they have to give you a two year garantee in 50 degree heat).

[nctnico]

Of course it will reduce the lifetime on paper but will it make a noticeable difference in real life if there's only 10% less airflow?

First explain from which dark hole the number '10% less' is coming from.