Bessel vs Critically Damped Enclosure

Interesting - I agree - every time I mention this fact I am shot down in flames by folks telling me this is swamped by room effects. Very fast Metallica-style bass drumming always sounds like blurry mush to me on such systems, rather than the staccato machine-gun like sound it should be.
I know the type, without all the extraneous speaker induced noise, it's way too 'dry'/'dull', etc..

Raised in a live music environment, if a speaker couldn't replicate a drum kit, then no hope of going 'live' much beyond a 'girl and a guitar'. That said, came close, but never quite got there simply because at the time I didn't have enough cubic $$$ to replicate even one of this system's channels.
 
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I know the type, without all the extraneous speaker induced noise, it's way too 'dry'/'dull', etc..

Raised in a live music environment, if a speaker couldn't replicate a drum kit, then no hope of going 'live' much beyond a 'girl and a guitar'. That said, came close, but never quite got there simply because at the time I didn't have enough cubic $$$ to replicate even one of this system's channels.
Agreed, the first time I played in a band (keyboards) I actually recoiled slightly at the impact and volume of the snare hits. A system needs a huge amount of excess power/dynamic headroom to reproduce this kind of sound accurately.
 
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every time I mention this fact [Head_Unit said "The sub can certainly "ring" on low notes depending on the design."] I am shot down in flames by folks telling me this is swamped by room effects
In the steady state sure. Is that so for the initial transient burst? I don't know if there's been any research in that area. Ah...if it's swamped by room effects why does something like a Bazooka subwoofer sound like what comes out the back of a horse? OK that car cabin "room" is smaller but same principle.

It's also quite possible that like other phenomena, up to perfect timing and perfect pitch, some people are more sensitive and thus picky compared to others. I also believe there may be a significant frequency dependence. Bookshelf boomy at 70 Hz? Ugh. Huge ported monstrosity at 10 Hz? Maybe you can't tell so much. The lower the frequency the longer the wave the more the room has "immediate" influence, don't it?!?
 
In the steady state sure. Is that so for the initial transient burst? I don't know if there's been any research in that area. Ah...if it's swamped by room effects why does something like a Bazooka subwoofer sound like what comes out the back of a horse? OK that car cabin "room" is smaller but same principle.

It's also quite possible that like other phenomena, up to perfect timing and perfect pitch, some people are more sensitive and thus picky compared to others. I also believe there may be a significant frequency dependence. Bookshelf boomy at 70 Hz? Ugh. Huge ported monstrosity at 10 Hz? Maybe you can't tell so much. The lower the frequency the longer the wave the more the room has "immediate" influence, don't it?!?
I am thinking more of energy storage, which is considerable in many designs, that has to be dissipated after the signal has ceased, ie. the 'ringing' seen in step response decay trails most notable in large horn-based subs and which can be in the order of a quarter of a second. Many argue that this is 'lost' in the room reverberation time which is a very fair point, but this long decay is still adding energy to the room when it should not be and increasing RT. Nothing has swayed me from the standpoint that fast decay is equally as important as fast attack time (which is controlled by the HF drivers anyway and simple to achieve). We are shown endless waterfall plots of HF drivers but this analysis seems to be all but absent for subs, where I believ that it is critical to fidelity.
I would never claim to have golden ears - especially at age 61! - but I cut my teeth in professional electroacoustics and have been around live music and system building since my early teens. Personal taste is always a factor, but I do have a professionally critical ear, even if limited by age to 15kHz...
 
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Hello MrKlinky,

I think you can count yourself very lucky to still be able to hear upto 15kHz at age 61, please protect what you have left, no more live music without ear protection would be my advice, FWIW. :)

Cheers
Thank you, I do and I very, very rarely ever subjected my ears to high spl - despite being laughed at for wearing ear plugs at gigs; AC/DC, Status Quo, Metallica etc. - that's why I can still hear 15kHz. It was drummed into me by my first employer in electroacoustics so much so that I even cobbled together some old Koss headphone drivers into double-shell ear defenders for protection when DJing!
I can just picture all the car audio '130dB bass doesn't damage my hearing' idiots looking so cool having to wear bilateral hearing aids in their '30s and '40s...
 
...a tone burst of 6 cycles if 31 Hz has frequency content on either side of 31 Hz. Unless your speaker is flat D.C. to daylight there will be distortion of the amplitude and relative phase between the cycles. Yes, that means there is content below 31 Hz. And above, obviously. Much of that content will get fed to the mains not the sub.
Below is the frequency spectrum of a 6-cycle 31-Hz tone burst. The peak at 24 Hz is –12dB relative to the peak at 31 Hz. As can be seen, there is even some low-frequency content in the 2–3 Hz range. The content at 80 Hz or so is -34.5dB relative to the peak at 31 Hz.
1661684581138.png
 
Going back to BR alignement: what about EBS vs Bessel ? Much larger Vb but nearer sealed behavior above Fb ?
Interesting question. I myself like "under-tuned" designs, slower rolloff, port resonance further down away from the midbass. But I don't like EBS alignments where the response flattens out-I like them to continue dropping albeit slowly. On the basis of zero evidence whatsoever I feel the flattened shelf is unnatural, it's like too resonant or something. I'm not sure how to investigate that. Maybe it's back to what @MrKlinky says about energy storage. I am perpetually wanting to find some simulator that will simulate response to tone bursts at different frequencies.

Someone once posted that while low Qs are thought of as "tighter" their response to tone bursts can actually be too slow. Unfortunately I don't recall how the decay part was.
 
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I am lost as some even input that vroup delay does not matter below Schroeder frequency of the room. Just try to put your chair in a high pression room mode in spite of a low one some others say.

EBS seem to have an edge but at the end one should tune its port in the Fb window allowed by the driver enclosure combo. Can be very few, for instance after reading about the Faital 12PR320 the port tunning tunning seems to be between 36 hz and 42 hz... Vb 70 l to 110 l. F3 and f6 quite differ. F10 close the same...choose in your room...not easy those BR to dexign...
 
Does anyone have experience listening to the difference between critically damped (Qtc 0.5) and Bessel (Qtc 0.577) sealed enclosures?

The 'tightness' and 'speed' are noticeably better with lower Qtc enclosures, with systems over Qtc 1.0 not that uncommon, but sound like mud to me.

Will a Qtc 0.577 sound just as tight as Qtc 0.5? If Group Delay is the reason for the muddiness, 0.577 might even sound better.

With a high qts subwoofer, this makes a huge difference in enclosure size. e.g. with the Wavecor SW312WA03, speakerboxlite calculates 236 liters for Critically Damped and 85 liters for Bessel. This is using the 'unbroken in' manufacture numbers, I'd expect qts to drop, and even if VAS goes up, box size comes down. But this is just an example of how big a difference there can be between them for enclosure size.

Obviously extension is also an issue, but I don't want to go into that in this thread.

What you are talking about is only the small-signal design target and you are really splitting hairs. Who knows what the driver does when you apply 10-100W? It very likely has a different sort of response curve due to driver non-linearities that get worse as cone excursion increases. The typical source for that sort of info is a Klippel measurement.

I am not sure if you considered this, but in modestly sized domestic rooms a Q of around 0.5 (and 0.577 is about the same really) often better mates with the low frequency room gain that is generated by the room. If the response is designed for free-space, with higher Qts and deeper F3 extension than about 35 Hz, the sub WILL sound boomy, overly rich to muddy, because the bass can be significantly boosted by the room gain below 60-80Hz. Similarly the room could have a huge resonance peak that makes subs sound muddy. Have you ever measured the bass in-room?

Also, "speed" is not an audio term. Please stop using it.


EDIT: CRAP!!!! It's another NECRO THREAD raised from the dead. I am so glad I wasted 10 minutes writing a response to it. The OP "bvbellomo" has a deactivated profile, which means he has not logged on since the merge and will probalby never read this.
 
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Oh, that is very strange... I thought this was a necro thread when I posted... because the second post above the text entry box was from 2018 and then there was only one recent one from diyiggy. I noticed a small label that said "other posts not shown" or something like that. Now that diyiggy made another post I came back to see it and noticed that there had actually been a bunch of recent posts in this thread. Strange...
 
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Guys, you see that is not so well known by everyone. Thanks for chimming in. It surely something not new for you but for me it is as I lived till now with sealed bass design but a Proac D15 that is a nice vented for a simple 2 ways with a 17cm.
My first diy was a sealed but voilà I have to understand a liittle more BR as I have a 12" PA driver with its high 42 Fs.
I found this thread after few reading about BR and Bessel that drove me here to necromance it.
Again thank you for you feedbacks as it is not that easy to make an opinion from just theory. Frigthened to make my first BR boomy. Although I should follow some proven design around the 12PR320...around 100L... measuring with accurate T&S seems sensible anyway to first sim.
 
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Interesting - I agree - every time I mention this fact I am shot down in flames by folks telling me this is swamped by room effects. I continue to hear systems having lots of stored energy (folded/tapped horns, ported etc.) as very poor compared with those which do not. Very fast Metallica-style bass drumming always sounds like blurry mush to me on such systems, rather than the staccato machine-gun like sound it should be. (This genre is but a tiny subset of my listening used as a pertinent example, not representative of it!). Step response seems to be so often ignored or overlooked...
‘ride the lightning’ turns to mushy funk ! you are so spot onhere(hear 🙈)!! :) poor Lars…
 
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What you are talking about is only the small-signal design target and you are really splitting hairs. Who knows what the driver does when you apply 10-100W? It very likely has a different sort of response curve due to driver non-linearities that get worse as cone excursion increases. The typical source for that sort of info is a Klippel measurement.

I am not sure if you considered this, but in modestly sized domestic rooms a Q of around 0.5 (and 0.577 is about the same really) often better mates with the low frequency room gain that is generated by the room. If the response is designed for free-space, with higher Qts and deeper F3 extension than about 35 Hz, the sub WILL sound boomy, overly rich to muddy, because the bass can be significantly boosted by the room gain below 60-80Hz. Similarly the room could have a huge resonance peak that makes subs sound muddy. Have you ever measured the bass in-room?

Also, "speed" is not an audio term. Please stop using it.


EDIT: CRAP!!!! It's another NECRO THREAD raised from the dead. I am so glad I wasted 10 minutes writing a response to it. The OP "bvbellomo" has a deactivated profile, which means he has not logged on since the merge and will probalby never read this.
still a good discussion Charlie 👍🏻
 
I assume you agree about the time domain performance of the loudspeaker being irrelevant once you put it in a room.
This is a commonly held belief... It is wrong... Totally wrong and is in fact one of the major falsehoods in loudspeaker and loudspeaker transducer design which has held back acoustic design for decades!

Take any room with good, bad or average acoustic properties, place a piano or cello or any bass (actually any instrument at all) instrument in it.
Have the instrument played at different locations in the room whilst you remain seated in the "listening position" ... The sound will change in tonality as room gain (wall/corner/floor/ceiling) and reflections vary. Similar (but not identical) changes will occur as you move the listening position and or instrument location. BUT..... The fundamental construction of the musical notes does not change at all.

Most important of all is the fact that the TIME DOMAIN structure of the notes remain identical ie the rise time and decay time of the compression and rarefaction of the air pressure (the detection / decoding of which governs 99.9% (ignoring bone conduction) of our hearing mechanism).
So, in a real room with a real instrument if blind folded, the vast majority of healthy humans could easily detect that the instrument is being moved as tonality/reverb would vary with location. Tiny changes in position hard to detect, large changes easy to detect, so far so good.

Important, these changes are subtle... Now compare that with replacing the piano with a loudspeaker, ANY loudspeaker would be easily delectable by the vast majority of listeners... Not a subtle tonal change but a fundamental gross error in the time domain source reproduction ie heavy cones bouncing on rubber suspensions with settling times (as revealed by CSD and time domain plots) in the hundreds of millisecond (typical subwoofer at 100 dB / SPL) Vs the microsecond decay times of the thousands of compression / rarefactions which make up each INDIVIDUAL note.

Now IF TBTL (and also the majority of DIY speaker guys!) are correct it would make no difference at all if the real musical instrument is replaced by a loudspeaker REGARDLESS of its TIME DOMAIN accuracy due to the room acoustics/reverb time being "more important".... Clearly this is wrong.
CRUCIALLY this relates to the loudspeaker transducers (drivers) as well as the cabinet loading.

So the assumption that the quality/accuracy of the loudspeaker is not important due to room acoustics/reverb time being "more important" is wrong.

If one accepts (and some still dont!) that the the human ear brain / hearing mechanism is designed to detect and decode ALL sounds using the time domain then one MUST accept that number one goal in sound reproduction is to perfect the time domain performance of the source ie the loudspeaker transducer and the cabinet / loading of the finished design.
 
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