I don´t care what we call it, but the underlying functionally that is important is how the air column behaves at high amplitudes. A Helmholtz has a constriction that will increase the air particle velocity to some extent. This will modify the transfer curve shape differently at different spl in a highly nonlinear manner with a pronounced hysteresis effect.
In a "classical" Helmholtz bassreflex were the port is some 15 to 30 percent of the driver Sd, the air particle velocity will increase very fast with increased spl. It will quickly start compressing and becoming turbulent, and soon start acting as a very nonlinear loss when the air plug inside the port becomes totally turbulent.
A straight non expanding QW will keep on working as a QW up to very high air particle velocities with some wave steepening within the pipe and some turbulent losses at the exit. Hornresp will not show all the effects of high air particle velocities at high spl. At and above 120 dB peak spl inside of the QW a series of nonlinear acoustic effects start being more dominant in shaping the transfer curve in a useful manner. I guess you need to use something like Comsol to reasonably accurately model and simulate this kind of behaviour.
Simulating Nonlinear Sound Propagation in an Acoustic Horn | COMSOL Blog
Part 2: Modeling the Harmonic Excitations of Nonlinear Systems | COMSOL Blog
A fourth order system serves up four "orders" of 90 degree phase shift. In the bass reflex "phase inversion" system, the 360 degrees of phase shift (at Fb) from the port output lagging by one wave period reinforces the front wave.
Better late than never 😉 .
It's well known that a BR with a small vent will suffer from audible non-linear effects.
It's also well known that, use a large enough vent to keep particle velocity low, and those non-linear effects will be no longer audible. They will basically be a non-issue.
Who cares about "classical" with today's higher excursion drivers.
You just use bigger ports. My last bass-reflex uses 42% of Sd.
Horneresp works for BR's particle velocity too, ya know 😉
I would hope it was obvious the ‘port’ is both starting and finishing in a brand new high pressure area in particular by design. Start of two pipes and or the input from the driver. Anyway you look at it has a distinct advantage on ’turbulence’ and its function regardless of what it ‘technically’ has for a name is holding up the potential that the design is better or worse than the hypothetical idea its founding fathers asked from the start? What to do beyond the BR idea.
Poor guys the only one brave enough to even try to reoresent an idea. The rest dont care anymore or moved on from arguing and haven't exactly failed to deliver on ideas. The ROAR is a champion. period. yep, car audio, but anyone can massage a ROAR into a hifi or no fi application, and PA is EVErything, and arguable the source of the source of what races on sunday, sells on monday. thats missing from the ‘sport’ of speakers and the trickle down affect other ‘sports’ have... NASA is not a sport. They suck, they are tied to an issue. ELON MUSK made space a sport, now look at the results?
heres the sport:
the iron law is the government. figure out how to allow BIG to be accepted and not a misdemeanor or felony. and all while functional and while transportable. Otherwise its just a new era of electromechanical and not much acoustical needs are left in todays box were talking about. The box is outside with us.l with the electromechanical manipulator controls.
What can we do?
A tier of qw paths x4. which bust into 2 functional pairs otherwise
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We should by now know how to design basic BR without problems like 'port noise'. It's not challenging at all, I recently build a simple 'SB28 like' design based on RCF drivers and some Horn Response basics. The only cool thing are the drivers getting better and better and can handle more and more power, which come from cheaper and cheaper amplifiers.
IMHO its more fun for us DIY to explore 'new things' like the Paraflex and Roar, which are, like we did here in the subwoofer form for over 10 years on TH designs, just as exiting.
Anyway... we are going way offtopic (not that i mind)
Basically the BR is a done deal. It's easy to design and cheap and fast to build and can sell for a lot. It also doesn't need much 'Intelligence' because they all look the same and do the same and sound the same and have a basic truck-size format for transportation. Boring yes...
IMHO its more fun for us DIY to explore 'new things' like the Paraflex and Roar, which are, like we did here in the subwoofer form for over 10 years on TH designs, just as exiting.
Anyway... we are going way offtopic (not that i mind)
Basically the BR is a done deal. It's easy to design and cheap and fast to build and can sell for a lot. It also doesn't need much 'Intelligence' because they all look the same and do the same and sound the same and have a basic truck-size format for transportation. Boring yes...
Just to illustrate how the bass reflex has taken over the scene:
Real World Gear: Subwoofers - ProSoundWeb
I would like to keep this friendly and relaxed, this is difficult as we are passionate people (well nerds really) and we will inevitably slide into an opinion war at some point, usually followed buy a solid theory bashing, but you know what, that's OK, just keep it nice 🙂
I started this thread as an attempt to understand why my own experiences both as a critical listener and DIY'er does not match with the current state of the industry and to some regard the theory that supports this.
My background is old school compared to most of yours I'm sure, and my gripe (until proven otherwise) is twofold, one - the conformity in the professional sound industry and therefore the obvious lack of competition/progress, two - my experiences of the this conformity or "modern solution" if you will.
Therefore I wanted to try to understand why, why is there now a staggering conformity, and why am I continuously let down experience wise by this conformity.
Let me describe a bit regarding the theory, I will not argue with the theory since I simply do not have the credit to do so, therefore I will hold the theory as true, but I ask myself what the frames and prerequisites are for those theories, and how do they relate to the experience of the extraordinarily illogical and emotional human being.
Put in a more simple form, we are not microphones, yet I believe that the quality metrics we have set to describe speaker performance has served us fairly well, but we need to be open to the fact that there may still be things left to explore in the theory-experience domain, denying that possibility is not in the best interest of science in any discipline.
A bit about my gripe with the experience, coming from he now ancient world of the late eighteens and mid nineties, a world of blue boxes and horn loaded point sources (back when lasers where cool) culminating in an almost religious live sound experience at the Pink Floyd pulse tour back in -94.
How much better are we today?
I would argue not that much, and so far in this thread there has been very few arguments put forward that addresses this part, namely the experience, the wast majority of comments and explanations (all good and most likely true by the way) has concerned almost exclusively things that are unrelated to the experience of the listener.
Just to recap, here is the "BR is king because"-list again:
Flexible. (multipurpose -> economics)
Scalable. (no need for application specific designs -> economics)
Familiar. (you know what to expect -> convenience/economics)
Compact. (for it's output and range, logistics -> economics)
Light. (for it's output and tuning, logistics -> economics)
Popular. (nothing succeeds like success -> convenience/economics)
Simple. (easy to get right, cheap to build -> economics)
Real World Gear: Subwoofers - ProSoundWeb
I would like to keep this friendly and relaxed, this is difficult as we are passionate people (well nerds really) and we will inevitably slide into an opinion war at some point, usually followed buy a solid theory bashing, but you know what, that's OK, just keep it nice 🙂
I started this thread as an attempt to understand why my own experiences both as a critical listener and DIY'er does not match with the current state of the industry and to some regard the theory that supports this.
My background is old school compared to most of yours I'm sure, and my gripe (until proven otherwise) is twofold, one - the conformity in the professional sound industry and therefore the obvious lack of competition/progress, two - my experiences of the this conformity or "modern solution" if you will.
Therefore I wanted to try to understand why, why is there now a staggering conformity, and why am I continuously let down experience wise by this conformity.
Let me describe a bit regarding the theory, I will not argue with the theory since I simply do not have the credit to do so, therefore I will hold the theory as true, but I ask myself what the frames and prerequisites are for those theories, and how do they relate to the experience of the extraordinarily illogical and emotional human being.
Put in a more simple form, we are not microphones, yet I believe that the quality metrics we have set to describe speaker performance has served us fairly well, but we need to be open to the fact that there may still be things left to explore in the theory-experience domain, denying that possibility is not in the best interest of science in any discipline.
A bit about my gripe with the experience, coming from he now ancient world of the late eighteens and mid nineties, a world of blue boxes and horn loaded point sources (back when lasers where cool) culminating in an almost religious live sound experience at the Pink Floyd pulse tour back in -94.
How much better are we today?
I would argue not that much, and so far in this thread there has been very few arguments put forward that addresses this part, namely the experience, the wast majority of comments and explanations (all good and most likely true by the way) has concerned almost exclusively things that are unrelated to the experience of the listener.
Just to recap, here is the "BR is king because"-list again:
Flexible. (multipurpose -> economics)
Scalable. (no need for application specific designs -> economics)
Familiar. (you know what to expect -> convenience/economics)
Compact. (for it's output and range, logistics -> economics)
Light. (for it's output and tuning, logistics -> economics)
Popular. (nothing succeeds like success -> convenience/economics)
Simple. (easy to get right, cheap to build -> economics)
Here's the thing...as a critical listener, do you find anything better than sealed?
Or, if to gain gain efficiency, a FLH...non-folded if wanting super critical SQ, folded if needed to gain ergonomics?
If yes, I'm listening.
If no, Do you really think all the TH, paraflex, bandpass designs, etc,...
are doing anything other than optimizing to a particular (non SQ) goal ??????
If no, it's just about meeting non SQ objectives....and what's the advantage?
What do your ears need from both sides of the driver the signal coming to you for no other reason than it must because its useful be used, however it cant be a standard 180 flip in the narrow area of whats known as ‘BR/Direct radiator, or TL, 90 degrees for the same idea? What can be done thats ‘forward’ in time ( pun intended🙂
Can we start in the middle and work our way to 45 or even 0 with an no or totally ‘offset’ and play polarity and angles instead of give them away? its not an issue, its just not normal or its? Theres a compound rear vented bass reflex/ TL (no name?)on my computer screen Its great, its simple!! Its ready. Actially, It might not be great , but its ready to be? It needs MOAR or less? Im not sure
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Just please answer my simple question, have you heard anything better than sealed, or FLH (sealed) ?
I dont think Im judge of ‘better’ but a few very ‘different’. Agrueably best yet or better -might- be the long heavily stuffed pvc pipe with 4” rs100s. Or sealed and stuffed hivi m4ns . But thats not bass. That's MtM DIY. And they all have tapped pipe style subwoofers with peerless or tangband
Drivers.
And other things are no different, all subwoofer pipes, TLs and isomaric MLTL is my only ‘reflex’ and that's because its easy to get low and cheap with it., but its a long long port at 2/3 SD for what it is? . So, except for a pair of narrow 10” subs that are high Q in the sides of skinny ‘towers’ and sealed, i think i just put things into whatever might suit them and help whatever a tuned vent duct might from either or both sides. And for sure try and make that ‘better’ if the opportunity arises or ideas, like this thread, leans towards. Eyes and ears usually open, but Mind always open.
Drivers.
And other things are no different, all subwoofer pipes, TLs and isomaric MLTL is my only ‘reflex’ and that's because its easy to get low and cheap with it., but its a long long port at 2/3 SD for what it is? . So, except for a pair of narrow 10” subs that are high Q in the sides of skinny ‘towers’ and sealed, i think i just put things into whatever might suit them and help whatever a tuned vent duct might from either or both sides. And for sure try and make that ‘better’ if the opportunity arises or ideas, like this thread, leans towards. Eyes and ears usually open, but Mind always open.
if i plugged up current vented speakers what do you think? no, unless its over 0.6 Qts or its a tweeter/ upper mid i probably get rid of it or i intentionally bought it to fit in a sealed need. There is no ‘point’ to saying ‘better’ unless youre ignorant of other options that need no introduction the idea that ‘better’ is a label to just throw into anythng is not even possible. Its really quite rediculous to even think someone in a speaker forum would think (other than ‘prefer’) that idea is plausible.
Yes.
Sealed often sound bland and boring. The compress the soundwave the wrong way as to act as a dynamic compressor due to the nonlinear compressive effect of the closed air volume inside the box. Once you get above 2 x Vas or more with really powerful high Bl, Low Qes drivers then they start to sound ok.
I would guess that a 18IPAL in a 500 liter very sturdy build closed box would be quite nice. 2 X 18IPAL in a 2 X 500 liter closed PPSL even nicer. Remember that the box has to absorb just as much energy as is radiating into the room. And it should be able to do this very fast and efficient without standing waves or resonances inside the box or in the box walls.
Most tapped horns and front loaded horns I have heard has sounded much nicer and more correct then any sealed box I have heard to date.
This is not a thing of 'which type is better' rather which gives the most bang for the money for your sound rental company economically, which goes way beyond a 'subwoofer'.
- Warehouse storage space (how much room it takes, every m3 more is money wasted)
- Ease of use (quick to setup on location, time saving)
- Reliability
- Performance
- Rent more yourself of 'brand X' because you don't have enough to supply (this is real world example)
- Requirements of organizer/county/province (real world example)
It's a win for the frontloaded cabinets on most.
But still... we as sound and light rental company where putting out non frontloaded cabs in the field the last six years and gain respect not only by the organizations but also by environment and noise pollution check crew from the provinces were we operate, why? Because you obey strictly to their set of rules.
- The people dancing in front don't give a **** what it is, as long as makes loud noise.
- The noise pollution measuring guys want you to stay in the limit.
- The organizer want to have it sound good without any other problems like warning from noise measuring guys of the province or sound dropouts ,or complains from people that say its painful on their ears.
- Warehouse storage space (how much room it takes, every m3 more is money wasted)
- Ease of use (quick to setup on location, time saving)
- Reliability
- Performance
- Rent more yourself of 'brand X' because you don't have enough to supply (this is real world example)
- Requirements of organizer/county/province (real world example)
It's a win for the frontloaded cabinets on most.
But still... we as sound and light rental company where putting out non frontloaded cabs in the field the last six years and gain respect not only by the organizations but also by environment and noise pollution check crew from the provinces were we operate, why? Because you obey strictly to their set of rules.
- The people dancing in front don't give a **** what it is, as long as makes loud noise.
- The noise pollution measuring guys want you to stay in the limit.
- The organizer want to have it sound good without any other problems like warning from noise measuring guys of the province or sound dropouts ,or complains from people that say its painful on their ears.
I have a real answer and its only aimed at reality, not favorites. It is close to arriving at ‘sealed’ as ‘better’. but its got nothing to do with ‘sealed’, in fact it does a much better job at what you are likely referring to as ‘sealed’. long pipes for the area above sub bass but below the dedicated mid/full area with offset stubs at the start and after the vent gobble higher frequencies and stuffed heavily in those areas create a reflection less rear wave either vented to use or left to fade away as the equivalent of heat in a leaky lossy box? Its likely cleaner than a conventional sealed box thats driver might be pummeled by the panel behind it working against it or even distorting (especially down low where the vented will have less excursion and thus the word ‘better’ as less distortion is the main idea but any of these higher order subs already potentially win that as cone control at the bottom of BW is also less distorted bass...
mark100 - judging by my best expiriences at concerts, FLH, hands down.
USRFobiwan - I'm sorry to hear that, all of it, economics and legislation are two things you ignore only once, and if people do not care either way then why would you bother taking risks.
I realize now that this thread has given me the answers I was looking for, thank you all who has contributed, if I was in the business and making a living from it I would be there to, I would not go rouge or have fancy ideals that may jeopardize my ability to provide for myself, my emplyees and my family, never, I would be pragmatic and get the job done, using BR/linearray combos just like everyone else because that would keep me raider compliant, and trying my best to get it right, no doubt (being an office rat I would not succeed but that's another matter).
Not being in the business makes it possible for me to be more idealistic in my approach because it does not cost me anything, except for running the obvious risk of coming across like an arrogant fool for not acknowledging and respecting the answers as they are provided to me by people in that industry, but trust me, I do, I may not like it, and that is not likley to change, so I will keep dreaming of the days when hornloaded pointsource systems rained supreme and stay a happy DIY'er.
Please keep going though, it is an interesting discussion for sure, I just wanted to let you know I got what I set out to get with this thread.
USRFobiwan - I'm sorry to hear that, all of it, economics and legislation are two things you ignore only once, and if people do not care either way then why would you bother taking risks.
I realize now that this thread has given me the answers I was looking for, thank you all who has contributed, if I was in the business and making a living from it I would be there to, I would not go rouge or have fancy ideals that may jeopardize my ability to provide for myself, my emplyees and my family, never, I would be pragmatic and get the job done, using BR/linearray combos just like everyone else because that would keep me raider compliant, and trying my best to get it right, no doubt (being an office rat I would not succeed but that's another matter).
Not being in the business makes it possible for me to be more idealistic in my approach because it does not cost me anything, except for running the obvious risk of coming across like an arrogant fool for not acknowledging and respecting the answers as they are provided to me by people in that industry, but trust me, I do, I may not like it, and that is not likley to change, so I will keep dreaming of the days when hornloaded pointsource systems rained supreme and stay a happy DIY'er.
Please keep going though, it is an interesting discussion for sure, I just wanted to let you know I got what I set out to get with this thread.
martinsson, i'd also say FLH is the best sound i've heard.
I think because it's essentially a sealed sub, and when i hear a FLH it's almost always outdoors without room modes etc.
I built 4 of Tom Danley's Labhorns almost 20 years ago, and continue to enjoy them greatly.
To all, .....when I've been asking if anyone has heard better than sealed / FLH, I don't mean solely from a subjective point of view.
I'm very much into measurements, and particularly try to achieve very clean impulse responses.
There is no question sealed produces the cleanest impulse response....i think everyone will agree to that.
And in my limited experience (compared to many of you here), bass-reflex makes the next cleanest impulse.
Every time i copy hornresp input fields from sub threads to check out a tapped horn or complicated sub variant, hornresp gives a considerably more mucked up impulse.
And the few tapped horns I've heard just don't seem as tight sounding as either my sealed, FLH, .......or even my BR builds.
martinsson, i pulled the inputs for your Roar 15 from your super blog, to look at the impulse....
For contrast here's one of my BR build's impulse
I wanted to also look at masked from both, but for some reason can't get HR to generate masked for the Roar ??
So here's BR alone..
I know some folks might be saying, what has this to do with why prosound is so heavy into bass-reflex.
Well, my point here is if sound quality isn't really an issue with well-designed BR, the alternative designs really needs to accomplish something extra in terms of ergonomics, efficiency, density, or lower frequency extension, something ! ...just my 2c
I think because it's essentially a sealed sub, and when i hear a FLH it's almost always outdoors without room modes etc.
I built 4 of Tom Danley's Labhorns almost 20 years ago, and continue to enjoy them greatly.
To all, .....when I've been asking if anyone has heard better than sealed / FLH, I don't mean solely from a subjective point of view.
I'm very much into measurements, and particularly try to achieve very clean impulse responses.
There is no question sealed produces the cleanest impulse response....i think everyone will agree to that.
And in my limited experience (compared to many of you here), bass-reflex makes the next cleanest impulse.
Every time i copy hornresp input fields from sub threads to check out a tapped horn or complicated sub variant, hornresp gives a considerably more mucked up impulse.
And the few tapped horns I've heard just don't seem as tight sounding as either my sealed, FLH, .......or even my BR builds.
martinsson, i pulled the inputs for your Roar 15 from your super blog, to look at the impulse....
For contrast here's one of my BR build's impulse
I wanted to also look at masked from both, but for some reason can't get HR to generate masked for the Roar ??
So here's BR alone..
I know some folks might be saying, what has this to do with why prosound is so heavy into bass-reflex.
Well, my point here is if sound quality isn't really an issue with well-designed BR, the alternative designs really needs to accomplish something extra in terms of ergonomics, efficiency, density, or lower frequency extension, something ! ...just my 2c
Add an 80 Hz 12 or 24 dB octave filter to each of those alignments and check the impulse response again 🙂.
FLHs are basically 4th order bandpass boxes taken to their logical limit
THs are basically 6th order bandpass boxes taken to their logical limit
Good integration with the stuff carrying the rest of the frequency range is probably IMO the biggest challenge to get right.
FLHs are basically 4th order bandpass boxes taken to their logical limit
THs are basically 6th order bandpass boxes taken to their logical limit
Good integration with the stuff carrying the rest of the frequency range is probably IMO the biggest challenge to get right.
Agreed Brian, i started to do that and post the impulses with low-pass in place.
But the dang low-pass filter's electrical impulse shape begins to dominate the impulse.
I wish HR has a linear-phase low pass option...
Anyway, since i've got them open..
Here's the Roar 15 low-passed at 80Hz 4th order BW
And the same for bass-reflex
But the dang low-pass filter's electrical impulse shape begins to dominate the impulse.
I wish HR has a linear-phase low pass option...
Anyway, since i've got them open..
Here's the Roar 15 low-passed at 80Hz 4th order BW
And the same for bass-reflex