Will cabinet and or baffle vibration

3db

3db

Audioholic Slumlord
If these side efects are bad, will these unwanted side effects show up in frequency response plots or can its affects only be measured in the time domain, aka waterfall plots?
 
Swerd

Swerd

Audioholic Warlord
Waterfall plots (cumulative spectral-decay plots in 3 dimensions of SPL vs. frequency vs. time) can be used to show cabinet noise or resonances, or speaker responses. For cabinet noise, the responses of an accelerometer are shown as in the first graph below. The second graph shows a waterfall plot of the speaker's response. In this case the response is speaker output as measured by microphone, instead of cabinet vibrations as measured by accelerometer.

I chose as examples, plots from a recent Stereophile review of JBL Stage A170 speakers. The differences are not immediately obvious. I'm not sure if that long response ridge at about 250 Hz in the first graph can be heard or not. But it's existence suggests a potential source of noise that might be remedied by cabinet damping efforts.

The cabinet noise doesn't seem to appear in the second graph, but it's worth noting that the second graph goes no lower than 400 Hz. Is there a reason why the second graph omits those frequencies? Was it done to hide the effect of cabinet resonance, or is a lower limit of 400 Hz routinely used to avoid the much larger peaks and ridges often seen in the bass and lower mid-range? I don't know.

While we're comparing these two graphs, note the differences in the ranges of time and SPL between them. The plot of cabinet noise (first graph) goes on for as long as 75 msec, where the speaker response plot (second graph) stops at less than 4 msec, a much shorter time span.
1579454153407.png


1579454663072.png
 
Last edited:
3db

3db

Audioholic Slumlord
Thanks for explaing the graphs Swerd. I appeciate your effort. :) I either missed your point in the answer or I didnt ask the question properly. If cabinet vibration is audible, can you see its results in the frequency response curves on and off axes like those published by Soundstage as an example?
 
Swerd

Swerd

Audioholic Warlord
Thanks for explaing the graphs Swerd. I appeciate your effort. :) I either missed your point in the answer or I didnt ask the question properly.
I just re-read my earlier response, and I see I left something out. I should have first said that waterfall plots can be different. It depends on whether cabinet vibrations or speaker responses are measured. And these different waterfall plots can be as different as apples and oranges. I implied that, but didn't directly say it.
If cabinet vibration is audible, can you see its results in the frequency response curves on and off axes like those published by Soundstage as an example?
I don't think so, but I can't put my hands on anything that directly supports that. If a driver has an unusual peak at the same frequency as cabinet resonance, I'd guess the the driver's response would mask the cabinet's response. If a cabinet had severe enough vibration or resonance, it might show up in some kind of frequency response curve. But that's only a guess.

If Dennis Murphy is reading this, I'd like to hear what he thinks.
 
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