I think I may have found a topic that is fresh...then again nothing is new under the sun...so here goes.
Vented woofer boxes, to me, is just another horn style. The proper way to use a horn is to have the tuning note, which governs cutoff, a specific distance away from the lowest intended note played.....if I tune my 18" woofer to ~15hz, Decay and Group Delay are significantly improved even before adding damping material into the design, so much so, that it begs to question...are people purposely sacrificing SQ for spl? If I tune to fs 24hz, performance in the 30hz area is bad with group delay and decay, though much louder.
A separate issue; lets put a huge resonance on top of the woofers resonance...who thought that was a good idea! Decay is exacerbated by the lack of control the woofer has at fs! let alone tuning too close to the passband.
I am focusing on 30hz, but as we move the register decay/group delay is improved as well.
Vented woofer boxes, to me, is just another horn style. The proper way to use a horn is to have the tuning note, which governs cutoff, a specific distance away from the lowest intended note played.....if I tune my 18" woofer to ~15hz, Decay and Group Delay are significantly improved even before adding damping material into the design, so much so, that it begs to question...are people purposely sacrificing SQ for spl? If I tune to fs 24hz, performance in the 30hz area is bad with group delay and decay, though much louder.
A separate issue; lets put a huge resonance on top of the woofers resonance...who thought that was a good idea! Decay is exacerbated by the lack of control the woofer has at fs! let alone tuning too close to the passband.
I am focusing on 30hz, but as we move the register decay/group delay is improved as well.
Last edited:
I'm sorry my friend, but you start out with an explicit premise:
You also make an implicit premise I'm unwilling to accept:
In my own modest 2-way setup I'm quite happy to remain ported. If I went with a sub for music though I'd probably seal them for easier crossover matching.
Best,
E
Which I believe is belied by the fact that horns improve coupling of the driver to the air which is demonstrated via higher voltage efficiency, along with other benefits. The voltage efficiency of the ported driver is the same as sealed, but with a varying -3 dB point. Perhaps I am being too rigid.
You also make an implicit premise I'm unwilling to accept:
It is my belief after measurement and experimentation that the audible issuea are rarely the port (but is sometimes) but rather poor integration with the room as a result of lowering the -3 dB point. I've yet to read of any acoustician or speaker designer show the issues with group delay in the bass are all that audible.
In my own modest 2-way setup I'm quite happy to remain ported. If I went with a sub for music though I'd probably seal them for easier crossover matching.
Best,
E
Last edited:
yeah don't read into that too much, its just a way for me to remove the "borders" between the different enclosures.
Look some more...
I have recently surveyed a group of Master Engineers and they show a tendency to favor sealed. I also see a trend to believe that vented design can potentially have "slow bass"....they say slow bass because they do not know the words group delay. I also claim to be able to discern group delay. Sealed sounds "faster" because of very low group delay. People show a trend to feel that a particular design of PMC had "late" bass... of course thats just group delay. Group Delay matters, especially to a mastering engineer. Sealed is the trend, that I perceive. The wisest answer was that it all depends on the execution of the designer not vented vs sealed...Which brings my point...Whos out there tuning to fs instead of tuning to half the lowest intended note? pretty much everyone....my claim is that it can be done better. If you build a subwoofer horn....its fc should be 15hz if you want to play clean down to 30hz....I see the same characteristics apply when I model a Bass Reflex or Quarter wave line....yet this is not the standard or even on the radar...that I know of.
Let this apply to mastering engineers and the people with a need for a more critical listening experience.
I never said that vented is inherently flawed, where'd you copy that from?
This isn't about vented vs sealed. This is about Tuning choices for Vented Design.
Last edited:
I'm well aware of the argument "Sealed better than ported." And not just for subs. In the modern era of nearly unlimited wattage available, my question is: "Why would anyone want to do anything besides sealed?" Is there any claimed benefit other than improved sensitivity?
Group delay: I only have a hazy idea, but doesn't this relate to the goal to minimize phase differences, especially so that the harmonics (overtones) of a note will not vary with frequency? Does that explain what some call "slow" (or "fast") bass? While our hearing is not too sensitive at bass frequencies, just go up an octave or two and we are suddenly in the max. sensitivity range...
And finally, there's no point in building a true "subwoofer horn" unless it's as big as a walk-in closet or, better yet, your garage
Group delay: I only have a hazy idea, but doesn't this relate to the goal to minimize phase differences, especially so that the harmonics (overtones) of a note will not vary with frequency? Does that explain what some call "slow" (or "fast") bass? While our hearing is not too sensitive at bass frequencies, just go up an octave or two and we are suddenly in the max. sensitivity range...
And finally, there's no point in building a true "subwoofer horn" unless it's as big as a walk-in closet or, better yet, your garage
Last edited:
" The proper way" - there is no 'proper' way, only good or bad choices of alignment
'just another horn style' - barking up the wrong tree, that won't help in any practical situation
'performance in the 30hz area is bad' - only if you've used a bad alignment
'who thought that was a good idea' - Thiele & Small among many others
"Group Delay matters, especially to a mastering engineer' - most of us aren't Mastering Engineers
'.Whos out there tuning to fs ... pretty much everyone" .... I doubt it, probably only those who follow one pre-determined alignment
'tuning to half the lowest intended note' I doubt that's practical for most drivers & box sizes
I'd like to see a practical alignment that supports your case, of course it probably comes down to personal preference as to whether the result is acceptable, and whether you're chasing realistic solutions or Theoretical Chimeras
'just another horn style' - barking up the wrong tree, that won't help in any practical situation
'performance in the 30hz area is bad' - only if you've used a bad alignment
'who thought that was a good idea' - Thiele & Small among many others
"Group Delay matters, especially to a mastering engineer' - most of us aren't Mastering Engineers
'.Whos out there tuning to fs ... pretty much everyone" .... I doubt it, probably only those who follow one pre-determined alignment
'tuning to half the lowest intended note' I doubt that's practical for most drivers & box sizes
I'd like to see a practical alignment that supports your case, of course it probably comes down to personal preference as to whether the result is acceptable, and whether you're chasing realistic solutions or Theoretical Chimeras
You are probably right, but I would like to make it clearer as to what people are doing and why I suppose.
You know I'm on a war path when it comes to it lol. Choosing sealed makes it a non issue. A dampened TL or one tuned the "horns way" or both...curiosity may get the best of me.
I'm just curious why people aren't tuning their TL/BR half below intended cutoff, I feel like this option isn't entertained enough and its the better option for SQ.
I'm just curious why people aren't tuning their TL/BR half below intended cutoff, I feel like this option isn't entertained enough and its the better option for SQ.
"Who actually follows the practice of tuning a vented design to half the lowest note then?" _ I would guess virtually no-one, for most woofers this would not produce a useful result, probably something close to a closed box (Aperiodic alignments with high Q drivers are the closest thing I can think of). In practise most boxes are tuned somewhere near Fs, because that produces the most useful results.
Thiele & Small may have led many astray in coming up with their lists of alignments, which are often assumed to be fixed, when in fact they are a continuum.
Thiele & Small may have led many astray in coming up with their lists of alignments, which are often assumed to be fixed, when in fact they are a continuum.
Last edited:
Allen just open up Horn Resp and try tuning a familiar woofer to fs and then to half the intended cutoff...view the 1-2000hz range in the spectrogragh to see decay results and view group delay. Its not hidden. It works identical to how a traditional horn is used. For some reason it is ok for some to slack in the area of group delay and decay, that is what it really is. A trade, gain spl loose sq...The room decay time is significantly longer than the speaker so a well behaved vented design should be just as acceptable as a sealed you'd think. So that would make for a lot of bad vented designs on the market....
Last edited:
FWIW, from a useful gain BW POV, 0.641x Fs is the practical limit and the technically correct limit puts Fs at the mean of its upper/lower mass corner, i.e. a vented alignment's ~equivalent of a reactance annulled BLH:
Flc = Fs*Qts'/2
Qts' = Qts + any added series resistance [Rs]: HiFi Loudspeaker Design
Since this can put woofer tuning down near Dc, impractical except for knowing the theoretical limit.
If the desired Fb doesn't drop below [Flc] and yields the desired peak performance at the desired excursion distortion level and fits in the allotted space, then I see no reason not to tune in this region other than being hugely inefficient.
GM
Flc = Fs*Qts'/2
Qts' = Qts + any added series resistance [Rs]: HiFi Loudspeaker Design
Since this can put woofer tuning down near Dc, impractical except for knowing the theoretical limit.
If the desired Fb doesn't drop below [Flc] and yields the desired peak performance at the desired excursion distortion level and fits in the allotted space, then I see no reason not to tune in this region other than being hugely inefficient.
GM
Last edited:
Wasn't it the whole point to develop br? I mean gain in efficiency in more or less the same volume occupied by a closed box.
About tuning why not choose an alignement favouring complementing your room behavior and which won't affect transcient response too much? Something like a bessel alignement.
This is obvious it is impossible for commercial product, so they choose an alignement favouring a ratio of efficiency/volume of box occupied, or whatever suit them.