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Rigol DHO804 Test and Compare Thread

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Martin72:
Hi,

At the moment I have SDS1104X-E, DS1054Z, DHO804, SDS2504X HD and SDS2104Xplus here... ;)
Maybe tonight or tomorrow in the early morning I´ll make some measurings.

Martin72:
Not tonight, half an hour ago...
It's hardly going to be any quieter in the room, I might look for a quieter place - but that wouldn't be practical and that's really the point.
In addition to the actual measurement distance (0.5m away, 1.2m high (ear height when sitting)), I also made recordings in the immediate vicinity of the fan.
This not only blocks out the ambient noise, but also allows you to see the character of the fan in question.
I also took measurements on the SDS2504X HD - somewhat unfair, because unlike the other four scopes, my HD no longer has the original fan - but it wasn't any louder.
An integrated fan controller is quite nice.

Performa01:

--- Quote from: Martin72 on December 16, 2023, 09:49:25 pm ---I also took measurements on the SDS2504X HD - somewhat unfair, because unlike the other four scopes, my HD no longer has the original fan - but it wasn't any louder.

--- End quote ---
These measurements also show how meaningless the dB figures of the "far-field" measurements are, as they indicate only 2.21 dB difference between the SDS2504X HD and the DHO804. Since I know from experience that the SDS2504X HD is barely audible even with the original fan, while on the other hand some people have complained about the fan noise of the DHO804, it's quite obvious that the actual difference must be much more than that.

Looking at the spectra confirms this very clearly: two dominant tones, ~35 dB @ 64 Hz + 34 dB @ 590 Hz for the DHO804 and only one dominant tone 32 dB @ 49 Hz for the SDS2504X HD. Since the human ear is much more sensisitive at medium frequencies like 590 Hz than at low frequencies like 49 Hz, it is clear that there must be a difference like day and night.

And the near-field measurement confirms this very nicely: 20 dB quieter and no dominant frequency for the SDS2504X HD is exactly as expected.

Even the comparison of the "veterans" is quite interesting - I never would have guessed that the DS1054Z is such a hell-machine and manages to be another 6.73 dB louder than the already loud SDS1104X-E...

ebastler:
I think that the noise spectra are hard to interpret and compare in general. Predicting from the spectra how annoying a particular fan sound will be perceived will only be possible with a lot of experience, at best.

My preference would be short audio recordings, to allow for a comparison of the "subjective" effect of each scope's fan noise. If a set of recordings can be made with the same microphone gain setting for a range of instruments, any user who has one of those instruments as their local reference could easily compare and get a good impression what noise to expect from the other devices.

Martin72:

--- Quote ---These measurements also show how meaningless the dB figures of the "far-field" measurements are, as they incicate only 2.21 dB difference between the SDS2504X HD and the DHO804
--- End quote ---

That's why I recorded the spectrum and not just the numerical SPL value.
Whereby +3dB more already means a doubling of the volume and in some frequency ranges of the spectrum this is easily exceeded.

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