Designing a 6th order series bandpass using hornresp for an 18" Car sub
rear chamber is tuned to 25hz
when you design for heavy cone subs hoiw much group delay do you tolerate? peak delay is at 25 hz.
Prioritizing output over SQ.
rear chamber is tuned to 25hz
when you design for heavy cone subs hoiw much group delay do you tolerate? peak delay is at 25 hz.
Prioritizing output over SQ.
Equing it, it correct group delay.
Double clic on time scale on hornresp let appear guiline curves.
Moreover in the example below, the ~3ms delay at 100hz can be substracted while analysing the group delay chart when crossed around this frequency.
And crossover, on it own, add it own group delay deviation. It need all to be considered.
Personnally, with good bandpass enclosure filtering well, i somewhat don't here anything bellow 30hz, if induced environnement vibration. Easy to verify with sinwave generator.
Still, harmonic induced by low content is somewhat recognized by our brain and is a know effect yet in records. I wouldn't want to add it from enclosure.
Double clic on time scale on hornresp let appear guiline curves.
Moreover in the example below, the ~3ms delay at 100hz can be substracted while analysing the group delay chart when crossed around this frequency.
And crossover, on it own, add it own group delay deviation. It need all to be considered.
Personnally, with good bandpass enclosure filtering well, i somewhat don't here anything bellow 30hz, if induced environnement vibration. Easy to verify with sinwave generator.
Still, harmonic induced by low content is somewhat recognized by our brain and is a know effect yet in records. I wouldn't want to add it from enclosure.
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If you are worried about boominess around 25 Hz, I bet it sounds tighter than many home audio setups. This assumes that you have equalized the frequency response to your target. For a home audio setup, room acoustics contribute more to boominess than the loudspeaker itself. Room acoustics at bass frequencies are more friendly in a car than in a home, because standing waves do not occur at 25 Hz in a car (the car is too small). At higher frequencies they do occur, but are better damped, because a car is floppy.
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Group delay that low in frequency isn’t much of an issue In my experience, it tends not to be very audible.
Some group delay below 35 Hz can add a "impressive" and "massive" quality to the bass in car audio setups. Quarter wave devices tend to sound better then Helmholtz with high GD, which I believe is due to the lower Q, greater bandwidth and dominant second harmonic distortion character of the quarter wave resonance compared to Helmholtz (which is typical third harmonic distortion dominant with lots of port compression and turbulence on top of that).
You believe a lot of thing, but what is your test protocol ? You seems to keep repeating the same stuffs. As already explained, the Q you talk about can be equed easily, linked to phase, and so to group delay (unless using FIR, but at those frequency, it's actually excluded generally).
Quarter wave have less bandwidth than bass reflex since they inherently acoustically low pass their output. Third harmonic dominant of bass reflex... ?? I don't recall this. Can you explain ?
Port compression and turbulence of small port : can occur with TH too with too small sections at high volume. This is all a matter of tuning and compromise. Nothing magical in one design vs another.
Quarter wave have less bandwidth than bass reflex since they inherently acoustically low pass their output. Third harmonic dominant of bass reflex... ?? I don't recall this. Can you explain ?
Port compression and turbulence of small port : can occur with TH too with too small sections at high volume. This is all a matter of tuning and compromise. Nothing magical in one design vs another.
In other threads here audibility of group delay was discussed.
Greater 400/f(Hz) in ms is considered noticable.
If you hear Bassdrum kick....boom separated, it is a convincing indication.
Greater 400/f(Hz) in ms is considered noticable.
If you hear Bassdrum kick....boom separated, it is a convincing indication.
I can't find anything wrong with repeating simple science from time to time....
From:
I could not link directly to that PDF, but it is not difficult to find.
This is just a simulation, but I am confident enough in Hornresp to show the general behavior correctly of this comparison between Helmholtz and Quarter wave.
Both spl response curves are from a 4th order BP to isolate the port output. Both examples are with a 200 liter closed box enclosing the back side of the driver.
One is with a 100 liter box and a 120 cm2 port 30 long (Helmholtz) front section and the other curve is from a 500 cm2 quarter wave front section without the 100 liter chamber.
Can you guess which is which?
Both the same topology. You just changed geometry. It's semantic. Quarter wave, Helmotz...physics does'nt mind how we name stuffs. You can't generalize on this.
Classic bass-reflex (usual helmotz) is not the same as a BP. I though you where talking about the general reflex cab.
A BP port can be done with whatever port shape, size, number, placement, at some point, you just stop calling it helmotz, and call it quarter wave. Personnaly I don't mind.
Science doesn't mind about our typology. Naming stuff is only a way for us to understand each others.
About your text capture, it explain well that the problem is the shape of the resonnator. In your designs, you use long symetrical (constant surface) segment. When using bandpass with port, i personnally take care doing variable surface port asymetrical output roundovers, as JBL and others do (not always). Glassfiber is my friend.
Still, the more i think about, the more i like ROAR, but not at all for those consideration ^^
Classic bass-reflex (usual helmotz) is not the same as a BP. I though you where talking about the general reflex cab.
A BP port can be done with whatever port shape, size, number, placement, at some point, you just stop calling it helmotz, and call it quarter wave. Personnaly I don't mind.
Science doesn't mind about our typology. Naming stuff is only a way for us to understand each others.
About your text capture, it explain well that the problem is the shape of the resonnator. In your designs, you use long symetrical (constant surface) segment. When using bandpass with port, i personnally take care doing variable surface port asymetrical output roundovers, as JBL and others do (not always). Glassfiber is my friend.
Still, the more i think about, the more i like ROAR, but not at all for those consideration ^^
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Quarter Wavelength Loudspeaker Design
A great site if you would like to learn a little more about quarter wave enclosures.
Well.... By changing geometry you change a lot of stuff. You would not call square tires for "tires" since they clearly does not work as (useful) tires any more (for general road use) - still it is only "changed geometry".
Physics do mind the underlying reason we name different stuff different names. Physics rightly predicts that a burning match will not start a chemical reaction in water but will start a rather violent reaction in mercury fulminate. I prefer water when trying to put out a fire. A bucket of mercury fulminate would scar the living daylight out of me if standing next to an open flame. Hence we as an example use different names for water and mercury fulminate.
Helmholtz and quarter wave might superficially seem similar, but there are rather large differences in real life. Those differences might not be glaring obvious in a simple simulation program. Hornresp does a reasonable job of showing some of those differences. Comsol is even better then Hornresp, but the price tag is as steep and prohibitive as the learning curve for someone like me.
A great site if you would like to learn a little more about quarter wave enclosures.
Well.... By changing geometry you change a lot of stuff. You would not call square tires for "tires" since they clearly does not work as (useful) tires any more (for general road use) - still it is only "changed geometry".
Physics do mind the underlying reason we name different stuff different names. Physics rightly predicts that a burning match will not start a chemical reaction in water but will start a rather violent reaction in mercury fulminate. I prefer water when trying to put out a fire. A bucket of mercury fulminate would scar the living daylight out of me if standing next to an open flame. Hence we as an example use different names for water and mercury fulminate.
Helmholtz and quarter wave might superficially seem similar, but there are rather large differences in real life. Those differences might not be glaring obvious in a simple simulation program. Hornresp does a reasonable job of showing some of those differences. Comsol is even better then Hornresp, but the price tag is as steep and prohibitive as the learning curve for someone like me.
Ok, I so understand better how you think.
I suppose what i just see as good enclosure with long segment(s) fall so in your mind in quarter wave type 🙂
I suppose what i just see as good enclosure with long segment(s) fall so in your mind in quarter wave type 🙂
I didn't recall at first where was the reference about quarterwave i had in mind...writing with passion can make things to seems more complex than they are :
From Pearls from Martin J King Quarter Wave Design
[FONT=Verdana, Helvetica, Arial, san-serif]"The first time you visit [/FONT][FONT=Verdana, Helvetica, Arial, san-serif]http://www.quarter-wave.com/[/FONT][FONT=Verdana, Helvetica, Arial, san-serif], you might get overwhelmed by the tremendous work done by Martin J. King.
I have with great interest studied the information on the site, and Martin has been very patient answering my questions. When I realised quarter wave design was not that mysterious after all, I decided to write this article, which has been reviewed by Martin."[/FONT]
From Pearls from Martin J King Quarter Wave Design
[FONT=Verdana, Helvetica, Arial, san-serif]"The first time you visit [/FONT][FONT=Verdana, Helvetica, Arial, san-serif]http://www.quarter-wave.com/[/FONT][FONT=Verdana, Helvetica, Arial, san-serif], you might get overwhelmed by the tremendous work done by Martin J. King.
I have with great interest studied the information on the site, and Martin has been very patient answering my questions. When I realised quarter wave design was not that mysterious after all, I decided to write this article, which has been reviewed by Martin."[/FONT]
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Thank you for reinforcing my point of better bandwidth and ability to reproduce nonlinear signals (music).
martin is now quick to undo some of his previous narrow focus on .naming. too.
not because he was wrong or because of physics and the earth axis hsihfted😀 i think because he realizes the words mean nothing if he can just express the function and physics even to a non mathematician or acoustical engineer group in todays DIY peers and apprentices to his work and whats taken place while he was busy being a father to now grow daughters.
i think hes back in the game, and fresh from being a successful parent might fuel round 2. a man with nothing to prove, instead a recognized authority. embrace that and he can thrive! he is tolerant of my strange endeavors. they seem confusing because its not the /best/ sound as a speaker design. instead its ways to consistently change using the QW length of a landscape to create change... by coincidence they cross paths as bandwidth in certain momens of drivers, but thats luck or byproduct of most of what i bug him about lately. i can make a perfect textbook TL for anyone or anything if its possible, thanks to paying attention to MJK and asking along the way to learn that. but im asking for imperfect now...its not easy for anyone to explain or understand why,lol... but itw back into using words and the isssues
If you want to avoid using the well established names Helmholtz and Quarter Wave resonator, then what should they be called instead, and why is it important to rename these two different kinds of resonators?
There are some very distinct differences between them, and we need to somehow differentiate between them.
If only used to play steady state sine waves then I can agree that they don't differ that much. Music is another thing altogether.
No, no.. sorry. I agree and have no squabble with that. I’m actually referring to MJKs rants about ‘horn’ vs expanding path TL and the many tapered, restricted, constructed mass loaded pipes that he was quick to help describe and very helpful in doing so. But mentioning ‘taped horn’ is taboo? Or blasphemy because then he Seems to be the one grasping for the eject button. But at the same time has a few curious younger folks trying to see the qw light bulb but instead are confused in a bit of a jab he has all over in his reference at the DIYforums jargon or semantics in this blh entry in the later papers ...
I think he’s changing the ‘atitude’ or whatever. But I’m in no position to speak about or on behalf of the man and mentor except to say positive things ... it reads better and I isnt tainted with the sound of bitter or whatever it was before? And the name game is ironically a bit different than years ago. (In a good way).