What I really liked in that article is the link to the first part of the series https://audioxpress.com/article/loudspeaker-bass-reflex-alignments
The history is fascinating, along with a broad overview of the alternatives.
The history is fascinating, along with a broad overview of the alternatives.
What bothers me about most discussions of bass reflex alignments is that they only tell half the story -- the frequency domain half. The time domain half (transient response) may be just as important: https://community.klipsch.com/index.php?/topic/172686-ht-2-12-subs-vs-1-15-sub/#comment-2555558
And then the room mucks up even the finest of alignments..
Yes and no. The fact that we can still hear the differences between closed-box and vented-box woofers (using terms like "fast bass"), even in-room, means that even though the room "mucks up" the alignments, it doesn't do so completely.
For more I always thought closed box sounds 'tighter' would be the word I'd use but I can understand 'fast bass' as well, only the cost is less efficient bass I think.
I am curious to learn what makes you so certain "we can still hear etc"?
Overly ringing alignments yes, but for the rest I am a bit more skeptic. Bob Cordell designed filter assisted vented alignments that have near CB characteristics, so it is all a bit less black and white i.mo.
Overly ringing alignments yes, but for the rest I am a bit more skeptic. Bob Cordell designed filter assisted vented alignments that have near CB characteristics, so it is all a bit less black and white i.mo.
It's all anecdotal.
They can only approximate closed-box frequency responses over a limited bandwidth. Vented-box alignments roll-off at 24dB/octave while closed-box alignments roll-off at 12dB/octave, with their attendant phase shift and group delay, and nothing can change that.
EDIT: Well, a 12dB/octave closed box response can be converted to a 24dB/octave response with an extra highpass filter, but not the other way around.
Speaking of history Claus Futtrup researched and wrote these series of articles which describe passing times in the loudspeaker industry.
Of course below Fb of a vented alignment, even with electronical assist it's very hard or impossible to get 12dB/oct rolloff but the question was: can we hear the ringing of the steeper rollof or not. However, this also strongly depends on how low in frequency this rolloff is, not to mention anything else.
Anyway, if one wants a vented alignment with less low-frequency ringing, just tune the Fb lower. This typically results in a higher F3 (I see a low F3 is always had a main priority of the classic alignments) but often a lower F6 and/or F10, F12 which even can be desirable compared to the lower F3, depending on the room acoustics and speaker/listener positioning or EQ using. Another positve effect of this is the vented system unloading goes lower in the spectrum. On the downside, longer or lesser diameter vents can be problematic in more ways.
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Like @Boden mentioned earlier…..below 80hz, it’s all a modal response as the room itself becomes the enclosure/resonator. Those descriptions of fast, tight or articulate bass have little to do with the lowest octaves and everything to do with midbass where percussive impact and dynamics dominate….80-200hz where a listener can experience the direct sound from the transducer in the mid to far field. THIS is where OB/Cardioid excels for the obvious reason……directivity.
It pains me that the hifi/ 2 channel aficionados hold on the same flat earth nonsense…..Harmon proved them wrong decades ago.
It pains me that the hifi/ 2 channel aficionados hold on the same flat earth nonsense…..Harmon proved them wrong decades ago.
I would ease your pain. 😉
Todd Welti at Harman certainly demonstrated that 4 subwoofers are one of the optimum ways to go for LF reproduction, with 2 getting relatively close with sympathetic setup & more than that rarely needed except in specific circumstances. The 'flat earth 2 channel aficionados' you describe however may not be in the happy position of
a/ Being able to afford 4 subwoofers
b/ Being able to use 4 subwoofers even if they have the funds (since not all people have dedicated rooms with freedom to do what they might or might not want. I don't myself, since I live in an ordinary house with other people who need to use it). Or
c/ Caring very much
None of those makes them 'wrong' or 'aficionados [of] flat earth nonsense'. Some may be. I suspect in the vast majority of cases though, it actually means they haven't the funds, haven't the space, or haven't the inclination. Same goes for cardioids or dipoles. Not everybody can use them, or wants to even if they could.
It's nice to see some of the vented alignment derivations collected together -even if they aren't used directly, they have historic interest, & still provide useful examples / waypoints. 🙂
Todd Welti at Harman certainly demonstrated that 4 subwoofers are one of the optimum ways to go for LF reproduction, with 2 getting relatively close with sympathetic setup & more than that rarely needed except in specific circumstances. The 'flat earth 2 channel aficionados' you describe however may not be in the happy position of
a/ Being able to afford 4 subwoofers
b/ Being able to use 4 subwoofers even if they have the funds (since not all people have dedicated rooms with freedom to do what they might or might not want. I don't myself, since I live in an ordinary house with other people who need to use it). Or
c/ Caring very much
None of those makes them 'wrong' or 'aficionados [of] flat earth nonsense'. Some may be. I suspect in the vast majority of cases though, it actually means they haven't the funds, haven't the space, or haven't the inclination. Same goes for cardioids or dipoles. Not everybody can use them, or wants to even if they could.
It's nice to see some of the vented alignment derivations collected together -even if they aren't used directly, they have historic interest, & still provide useful examples / waypoints. 🙂
Richard Small's original articles had quite a variety of alignments. Interesting reading.
From Neville Thiele, http://www.hornlautsprecher.net/Dokumente/Grundlagen/Tiele-Smal-LSPRMTRS604.htm:
"The transfer function of the loudspeaker in the vented box is, in the operational form,
<equation omitted>
where QL is the 'leakage Q', considered as a parameter of the driver. In the 1961 paper, Thiele calculated a similar parameter QB, the 'box Q', as a parameter of the box. When Small showed later that such leakage losses were much greater in the driver than those in the box, so much so that they could be virtually ignored, he still called the changed parameter QB initially, but later called it QL. Thus in the expression above, QL is the loss parameter for the driver, as calculated below."
The Aficionados being the folks with $50k mains and the same in front end gear........the audiophile folks.....that don't have the inclination to spend their $$$ wisely.
It’s an interesting topic.
I would blame the driver before blaming the loading.
I’ve been told by a rep for Beyma that the lPAL drivers produce much tighter bass that a conventional driver. These are low impedance woofers with very low Qts of 0.14.
The new dual gap dual voice coil pro woofers are also much improved in terms of THD, linearity and power compression.
I agree with everything said and would add that a bass reflex enclosure can sound boomy if allowances for room placement are not taken into account. Electrical EQ can fix this of course.
In the land of entertainment (hifi) people will say anything and insist they are right. Sometimes they are but often they are not. It’s a first world problem.
I would blame the driver before blaming the loading.
I’ve been told by a rep for Beyma that the lPAL drivers produce much tighter bass that a conventional driver. These are low impedance woofers with very low Qts of 0.14.
The new dual gap dual voice coil pro woofers are also much improved in terms of THD, linearity and power compression.
I agree with everything said and would add that a bass reflex enclosure can sound boomy if allowances for room placement are not taken into account. Electrical EQ can fix this of course.
In the land of entertainment (hifi) people will say anything and insist they are right. Sometimes they are but often they are not. It’s a first world problem.
I like "simple", low tuned QB3 alignments. They still have that sealed box clean upper bass with better extention and output down low, depending on other factors of course. Assisted alignments can fight the woofer's natural behavior at resonance which often makes the sub sound sloppy and lagging behind the rest of the music. Whether that's a result of group delay or a poorly aligned box, that's a bit debatable, but there's definitely something lacking in the SQ department with assisted alignments in smaller boxes, especially using higher Fs, Qts woofers. I have yet to hear a decent sounding sub using typical high mass, high excursion, wide surround drivers. Those are more for watching movies with lots of explosions, but not good for music.