Gentlemen, thanks for clearing up my Vtc/Atc confusion. When I would modify existing designs and change those numbers, I wouldn't see much difference and I thought I was doing something wrong.
Just a Guy, do you have a link to that previous discussion about Reynolds Number? I would be interested in reading it to gain more information. I am the kind of person that likes to know the "why" of why things work they way they do, and I love to learn new things.
These online discussion boards can be harsh sometimes, I have had many of my wild ideas heavily criticized - I know the feeling. There are some people that try to strong arm you instead of being respectful of others opinions and ideas.
But I balance that with the fact that the amount of information you can gain is just ridiculous. A couple of days ago I was banging my head on the wall trying to grasp certain concepts of tapped horns and how to use HR. Now a couple of you fine gentleman have been kind enough to share your knowledge and have helped me immensely. When I first took and interest in speaker design years ago, the only choice I had to educate myself were either overly simple texts (that I now realize were primarily nonsense) or more academic texts that were very difficult to understand. There was absolutely no one I could go to to ask a question. Life before the internet could be a very dark place to those who have inquisitive minds and enjoy learning as much as they can about things.
Just a Guy, do you have a link to that previous discussion about Reynolds Number? I would be interested in reading it to gain more information. I am the kind of person that likes to know the "why" of why things work they way they do, and I love to learn new things.
These online discussion boards can be harsh sometimes, I have had many of my wild ideas heavily criticized - I know the feeling. There are some people that try to strong arm you instead of being respectful of others opinions and ideas.
But I balance that with the fact that the amount of information you can gain is just ridiculous. A couple of days ago I was banging my head on the wall trying to grasp certain concepts of tapped horns and how to use HR. Now a couple of you fine gentleman have been kind enough to share your knowledge and have helped me immensely. When I first took and interest in speaker design years ago, the only choice I had to educate myself were either overly simple texts (that I now realize were primarily nonsense) or more academic texts that were very difficult to understand. There was absolutely no one I could go to to ask a question. Life before the internet could be a very dark place to those who have inquisitive minds and enjoy learning as much as they can about things.
I was really really hoping no one would ask for that. But here it is just for you. Welcome to my nightmare.
2 hz tuning - pros and cons
Nothing scientific really happens until the last couple of pages. Everything up to that point is soap opera forum drama.
Just to be really really clear about this link - I'm not proud of how this unfolded. I was excited about an idea, I didn't study it in enough depth before presenting it, and it turned out to be not such a great idea. But it was nowhere near as bad as everyone made it out to be, as proven by the Reynolds number, Moody chart and Harmon paper.
The vast majority of people in this discussion were not qualified in any way to be discussing this. And the couple of people that were kind of qualified were only interested in disproving it in a biased manner.
This is probably my worst forum experience ever and it still makes me physically ill to even think about it. Have fun with it. And if you actually read all of it, give me your opinion.
To be clear about this part, I am probably the harshest critic you will meet, but I prefer to call it blunt, I don't mince words to save feelings.
The problem I have is with people that are not qualified to comment on an issue being the most vocal. I have no interest in winning arguments, I am only interested in eventually coming to the correct answer. What's the point in being wrong and having high self esteem? I'm interested in learning and sharing, not social networking.
Well, as soon as I saw it was on the AVS forum I knew pretty much what to expect and wasn't disappointed. Not my idea of fun though.
I didn't see any point in browsing past the second page since the 'die was cast' early on, so to speak, but I'll give you my opinion anyway.
You created an acoustic high pass filter. As such, there will be virtually no vent output when optimized, same as an aperiodically load TL and since MJK's software has proven to be pretty accurate WRT acoustic resistance loading, I imagine it will perform at least close to its prediction if not spot on.
GM
Hey, Just a Guy - I sped read that link to get a general idea of what happened. It seems to me you were up against what I like to call "flat earth thinkers." GM seems to be pretty authoritative on this stuff, so since he gives you the nod, I will second that.
You should be proud of yourself though - you fought the good fight. I admire a lot of Patrick Bateman's posts here on DIYaudio. He seems to spend a lot of time thinking about the details of speaker design and isn't shy about sharing his thoughts, no matter what they are. People like Patrick and yourself are the one's that may stumble onto something and change the face of speaker design. Think different, I have learned long ago that the status quo is often wrong.
Decades ago I came across a statement and indian chief once made: "It's a good day to either learn, or to die." So that has been my motto ever since - I make it a rule to acquire some form of new knowledge every single day. Heck, I even have my subject already picked out for tomorrow.
You should be proud of yourself though - you fought the good fight. I admire a lot of Patrick Bateman's posts here on DIYaudio. He seems to spend a lot of time thinking about the details of speaker design and isn't shy about sharing his thoughts, no matter what they are. People like Patrick and yourself are the one's that may stumble onto something and change the face of speaker design. Think different, I have learned long ago that the status quo is often wrong.
Decades ago I came across a statement and indian chief once made: "It's a good day to either learn, or to die." So that has been my motto ever since - I make it a rule to acquire some form of new knowledge every single day. Heck, I even have my subject already picked out for tomorrow.
It wasn't a good design. But they were arguing compression (or friction losses) was the problem, and it wasn't. The whole thing was a waste of time, but I did learn something. I could have saved you the time spent reading it and summarized the important points.
1. Moody chart, Reynolds number and friction factor
2. Air flow calculator
3. Maximizing Performance From Loudspeaker Ports paper - http://koti.kapsi.fi/jahonen/Audio/Papers/AES_PortPaper.pdf
It's a good resource. Lots of info in there to answer your questions about your slot port designs.
I took Patrick's name out because I'm only speaking for myself. Make no mistake, I'm not going to change the world. I'm content if I can understand what the real innovators are doing. Acoustical science breakthroughs are hard to come by, and as far as I'm aware Danley is the only person who has made any significant headway in the past several decades. And I doubt I'll live to see anyone else contribute in a similar manner. (And I'm still relatively young.) There have been serious advancements in materials, drivers and simulators but most of the concepts we are playing with were invented 100 years ago.
Anyway, that's entirely too much about me and my train wreck AVS thread, let's see what you are working on.
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It was if the goal was to acoustically protect the driver in a HT app. Normally, it takes a multiple driver array to handle all that is available at THX reference.
GM
GM
Danley's tapped horn is the reasons I am here at DIYaudio. I was completely amazed when I stumbled upon this site and discovered what was going on here. The level of thinking taking place, with people trying to discover how the TH works and how to improve upon the design, is exciting to me. There is a long list of people on this site that I would like to congratulate and encourage for what they are doing. It is an inspiration to me and I am excited to learn as much as I can so I can catch up to the level of thinking they are doing. From what I have read about Tom Danley, if he were younger, this site is where he would be hanging out.
As far as I am concerned, sound reproduction is still in the stone age. There are great inefficiencies that need to be overcome. I think there is a missing link, that once discovered, will completely change the face of sound reproduction. So everyone here at DIYaudio, keep thinking, dare to be different, and don't be shy to share our ideas. And when someone shares a new idea, don't be to hasty to try to shoot it down just because it is new and different. Let it congeal a bit, as it may be a steeping stone to something bigger.
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Question of the Day - Conical / Exponential / Parabolic Horn Types
I have put a fair amount of thought into this, and I can’t seem to make sense of it. In the different tapped horn builds I have examined I have seen all three of these horn types used in the HR simulations, sometimes in combination. I have yet to see any explanation on how and why these horn types are selected though.
Also, although I am familiar with the shapes these horn types refer to, I don’t see a lot of resemblance to them in the actual horn paths of these builds. What am I missing here?
I have put a fair amount of thought into this, and I can’t seem to make sense of it. In the different tapped horn builds I have examined I have seen all three of these horn types used in the HR simulations, sometimes in combination. I have yet to see any explanation on how and why these horn types are selected though.
Also, although I am familiar with the shapes these horn types refer to, I don’t see a lot of resemblance to them in the actual horn paths of these builds. What am I missing here?
Before he started his own business, it was the HE forum, joelist and the late, lamented basslist.
Well, until we figure out how to shrink a WL, AFAIK we're hard up against what TD calls the 'wall of science'.
GM
Hi DHAA,
Just real quickly:
With respect to tapped horns, there are some practical answers to your question in Post #30:
- When you build an enclosure with two sides parallel, and the other two sides are angled to each other the rate of expansion is parabolic. Hornresp will give you a more accurate internal volume that way. But, when you try to export from Hornresp into AkAbak you will see a warning "Must be direct radiator or Con, Exp or Hyp flare." Thus people often just use Con, and export to Akabak to do their real work.
- Sometimes you run out of horn segments in a simulation, and it may be overall closer to the real flare rate to use e.g.: Exp than PAR.
And you are correct, it may not always make any sense, because the designer may just not have cared at that point. By the way, the same holds true for Vtc/Atc, sometimes it matters, sometimes somebody cares, often it is just disregarded, and often it doesn't make any difference. It may be good practice to use it at least as a place holder in your simulations.
Regards,
Just real quickly:
With respect to tapped horns, there are some practical answers to your question in Post #30:
- When you build an enclosure with two sides parallel, and the other two sides are angled to each other the rate of expansion is parabolic. Hornresp will give you a more accurate internal volume that way. But, when you try to export from Hornresp into AkAbak you will see a warning "Must be direct radiator or Con, Exp or Hyp flare." Thus people often just use Con, and export to Akabak to do their real work.
- Sometimes you run out of horn segments in a simulation, and it may be overall closer to the real flare rate to use e.g.: Exp than PAR.
And you are correct, it may not always make any sense, because the designer may just not have cared at that point. By the way, the same holds true for Vtc/Atc, sometimes it matters, sometimes somebody cares, often it is just disregarded, and often it doesn't make any difference. It may be good practice to use it at least as a place holder in your simulations.
Regards,
Using Prof. Leach's compression horn design routine, all 'ideal' [max BW] THs are hyperbolic [around M[T] = 0.5] and most of the rest are hypex [>0.5 <0.6], but these are so little different than a conical and parabolic flare in the LF that parabolic is the norm since it allows straight board dividers in parallel wall boxes to be used to keep construction simple
Using multiple flare factors is for increasing usable HF response in end loaded tapped alignments where little/no compression is used, i.e. in the BW that’s actually horn loaded.
GM
Using multiple flare factors is for increasing usable HF response in end loaded tapped alignments where little/no compression is used, i.e. in the BW that’s actually horn loaded.
GM
He actually does hang out here from time to time. And his posts are very interesting. But when talking about his new(ish) patented devices and sometimes even regular horn theory the bread crumbs he leaves do not necessarily add up to a loaf. You have to really know what he's talking about to gain any substantial info from his posts. You have to know which areas he's glossing over, overly simplifying and completely ignoring.
The science of acoustics has been very well understood for a long time now. Danley has been rearranging the elements a bit to very good effect, but the idea that a 4 inch cube subwoofer will ever play down to 1 hz at 140 db will be accomplished with driver and material advancements (if it's ever accomplished at all) not with acoustic (enclosure) design. There's only so far you can go with moving coil drivers and sheet wood products. One day we might be able to control air in such a fashion to create a pulsating sphere that changes size and shape with frequency and amplitude, but today isn't that day and it won't come from within the ranks of diyaudio. Real advancements are going to require a real bankroll. And realistically they will probably come as a result of spinoffs from advancements in other fields that do have significant cashflow.
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GM and tb46, thanks for taking the time to clear up my confusion on the horn shapes in Hornresp. I have been trying to make sense of that, I am glad to have that answered.
Driver design is actually what I was thinking about - I should have been more specific. To me, the magnet/wire/paper of current drivers (subs in particular) is the equivalent of an incandescent light bulb - hot, energy sucking, and inefficient. There has to be a better way, something analogous to at least a fluorescent light bulb, if not an LED bulb. It will happen, but who knows when?
I was fooling arounds in HR again tonight and have a couple of designs that are near fruition. There is one that I will try to polish up a bit and get posted this weekend. I actually like criticism, so don't hold back. So get your chisels, sledgehammers and chainsaws ready tear my ideas apart!
Driver design is actually what I was thinking about - I should have been more specific. To me, the magnet/wire/paper of current drivers (subs in particular) is the equivalent of an incandescent light bulb - hot, energy sucking, and inefficient. There has to be a better way, something analogous to at least a fluorescent light bulb, if not an LED bulb. It will happen, but who knows when?
I was fooling arounds in HR again tonight and have a couple of designs that are near fruition. There is one that I will try to polish up a bit and get posted this weekend. I actually like criticism, so don't hold back. So get your chisels, sledgehammers and chainsaws ready tear my ideas apart!
Question of the Day - Who's More Senile?
Just when I thought I was understanding the relationship and meaning of each of the HR parameters, I have hit another roadblock.
A while back I had loaded "Old Soundman Welter's" Keystone design into HR and played around with substituting different drivers. I was rereading some of that post again and I noticed another of my helpers, tb46 has made lot's of contributions to that thread. So since I already have those two gentleman's attention, I thought I would take a closer look at that design and see what kind of damage I could do to it.
Well, here is the problem I have run into. In post #1 of the Keystone design, Mr. Welter states that post #96 contains the HR data, and post's #94 and #97 contain the plans (which are all provided by Oliver). I was already using the HR data from post #96, so then I pulled up the plans to see where I could do the most damage to a very fine design. But, ah-ha, I either found a hole in my understanding of what I am doing, or Walter and Oliver are more senile than I am.
It seems to me almost nothing from the plans matches up the the HR data. If I were to look at the plans and calculate the numbers I would be plugging into HR, here is what I would get:
S1 - 7.39cm (depth @ S1) X 63.5cm (interior width of cab.) = 469.37
S2 - 8.06cm (depth @ S2) X 63.5cm (interior width of cab.) = 511.81
S3 - 11.45cm (depth @ S3) X 63.5cm (interior width of cab.) = 727.08
S4 - 25.42cm (depth @ S4) X 63.5cm (interior width of cab.) = 1614.17
S5 - Keystone hole calculation, which seems to be right = 1941.83
Also, L23 and L34 from the plans seem to be vastly different that what is on the HR input parameters of post #96.
So GM and Just a Guy, who is more senile, myself or Walter and Oliver?
Just when I thought I was understanding the relationship and meaning of each of the HR parameters, I have hit another roadblock.
A while back I had loaded "Old Soundman Welter's" Keystone design into HR and played around with substituting different drivers. I was rereading some of that post again and I noticed another of my helpers, tb46 has made lot's of contributions to that thread. So since I already have those two gentleman's attention, I thought I would take a closer look at that design and see what kind of damage I could do to it.
Well, here is the problem I have run into. In post #1 of the Keystone design, Mr. Welter states that post #96 contains the HR data, and post's #94 and #97 contain the plans (which are all provided by Oliver). I was already using the HR data from post #96, so then I pulled up the plans to see where I could do the most damage to a very fine design. But, ah-ha, I either found a hole in my understanding of what I am doing, or Walter and Oliver are more senile than I am.
It seems to me almost nothing from the plans matches up the the HR data. If I were to look at the plans and calculate the numbers I would be plugging into HR, here is what I would get:
S1 - 7.39cm (depth @ S1) X 63.5cm (interior width of cab.) = 469.37
S2 - 8.06cm (depth @ S2) X 63.5cm (interior width of cab.) = 511.81
S3 - 11.45cm (depth @ S3) X 63.5cm (interior width of cab.) = 727.08
S4 - 25.42cm (depth @ S4) X 63.5cm (interior width of cab.) = 1614.17
S5 - Keystone hole calculation, which seems to be right = 1941.83
Also, L23 and L34 from the plans seem to be vastly different that what is on the HR input parameters of post #96.
So GM and Just a Guy, who is more senile, myself or Walter and Oliver?
My name is Art Welter, and I was less senile when I designed the Keystone.
Morphing my name from A.Welter to Walter in the course of a couple paragraphs may or may not be a measure of your senility😉
At any rate, Hornresp won't simulate the Keystone exit, hence the dozens of tests made to determine the optimum exit shape and size.
The overall cabinet size determination was specific to the available trailer space and conforming to truck box integers.
Ah, Art - you got me there sir. I apologize for twisting you actual name and alias - In the past year I have had some growing concerns about my own senility, so there is yet another indication that I am losing it. I have so many thoughts going on in my minds right now sometimes I am not even sure who I am.
But, what am I looking at wrong with the dimensions in the plans versus the HR inputs? I am not concerned with the keystone cut-out right now, just the horn path. Thanks, Art
Hi DHAA,
The Hornresp simulation in Post #96 (see text) refers to the original drawing in Post #48, which was partially based on guessing at the interior. So, good catch, the simulation and the drawing do not match.
I have not been able to model the Keystone TH successfully in Hornresp. I have tried in AkAbak - using a method developed by xrk971 for the Karlson enclosure for the mouth opening, and treating the bottom volume below the mouth (stub) as a duct - and, while closer, I'm not happy with the results of that one either. I was hoping that I would be able to come close to Art's measurements, but that has not yet been the case.
Because of these reasons, I would not recommend the Keystone TH as a learning example for Hornresp, seems to be a good PA TH sub though. Also, all these threads are "works in progress". Good to see someone working his way through this, maybe you have a project of your own that we can take a look at?
Regards,
The Hornresp simulation in Post #96 (see text) refers to the original drawing in Post #48, which was partially based on guessing at the interior. So, good catch, the simulation and the drawing do not match.
I have not been able to model the Keystone TH successfully in Hornresp. I have tried in AkAbak - using a method developed by xrk971 for the Karlson enclosure for the mouth opening, and treating the bottom volume below the mouth (stub) as a duct - and, while closer, I'm not happy with the results of that one either. I was hoping that I would be able to come close to Art's measurements, but that has not yet been the case.
Because of these reasons, I would not recommend the Keystone TH as a learning example for Hornresp, seems to be a good PA TH sub though. Also, all these threads are "works in progress". Good to see someone working his way through this, maybe you have a project of your own that we can take a look at?
Regards,
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