Ok, I did the same test again but adjusting for the same amplitude. The result is exactly the same, open (top) has noticeable delay while stuffed (bottom) has less.
Did you equalize the bass between stuffed port and unstuffed port to get the same frequency response? By your post you adjusted the amplitude, not matched the frequency response...
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I think he's more bothered by room modes and placing speakers on a table.
Different woofer/cabinet/room combinations will react differently. Nonetheless, with my system plugging the speaker ports improved my bass response when using a subwoofer. The improvements were smoother frequency response in the crossover region and tighter bass. The result was the same regardless of whether I manually equalized or used Dirac Live. The caveat is that plugging the ports puts a greater limit on how low in frequency I can set the crossover frequency, which is as expected. For my subwoofer placement and the crossover slopes I am using that is not problamatic.
Amplitude and frequency response are two different things. I’m confused by your use of the ‘matching amplitude’. May just be a language barrier! No worries. Can you show the eq you used to match bass response?
Where is the delay you’re seeing in the pic?
I don't know if you get what's happening here. With a single 40Hz tone, equalizing the amplitude and frequency response don't just result in the same thing, they are in fact one and equal. Because the FT of the 40Hz tone is just a single point, it doesn't matter how the sub responds to any other frequency because there is no other frequency.
Check the gaps
Right but these are single frequency tones, so matching amplitude or EQing back to the same frequency response is the same thing, for any given frequency tone, right?
Those aren't 40 Hz, they are 40 Hz plus all of the Fourier components associated with chirping that 40Hz note. And why people keep asking since post 8 about EQ to same FR in order to make any sense of time domain behavior, and any sense of these snapshots of the tone bursts. Also, the global timing appears to be different in some of the plots, although that may be due to not being careful to keep the same setup between runs. I actually really don't know what is going on, which is why some of us are asking for some basic data.
Not really. Virtually every loudspeaker—ported or sealed (or passive radiator, etc)—has an LF alignment that is at least slightly underdamped. Why? Because the goal is usually something in the neighborhood of a maximally flat (Butterworth) response, which is by definition underdamped. Critically damped or overdamped alignments roll off earlier and are likely to sound inferior unless the corner frequency is very low or the early rolloff happens to mitigate problems related to the room.
Who cares ?
Really we need the electrical signal as well.
Did I miss the post showing what the ideal is?
^Thanks mate! ^
The issue you have was discussed ad nauseam in the 70s of the last century. There’s nothing into it. First, what do you mean with ‚underdamped‘? You see a graph, well, but that‘s not what you hear, naturally. I could throw so much at you, all from real science, your ears would ring. The discussion of frequency, phase, time etc needs at least a confident knowledge of basic math, calculus and such. I‘ve not seen any of that, sigh, in this thread.
I‘m not an engineer, but heard about science. The fuss is about the connection between what we see in the graphs, and what we sense when listening. And what „a frequency“ might be when we use it in equations, weighing in the „amount of x“, e/g „delay of y milliseconds“.
Well, no.
