Ported vs Sealed, lets open this can of worms. lol

[audiophyle_247]

I am not trying to pick apart your argument, but this statement is well worth looking at.

The transfer function does not remain constant, unless all environmental variables remain constant. If you switch from a 1cuft sealed box to a 2.5cuft ported one, the change in box volume will affect the cabin volume as a system, unless you built the installation to wall off the enclosure in the trunk for instance. This is actually something I have done in installations. I have build sealed walls with a hole to bolt the box up too, such that different boxes could be constructed without changing the transfer function of the cabin.

But what does all this matter if you roll down the window and everything changes? Or if someone rides with you and everything changes?

To me, that is picking apart, and yes you are right if you really want to get into it.
You can even go so far as to saying climatic shifts can also alter cabin gain because of humidity and barometric pressure changes. Do we really need to get into the depths of the changes?
Along those lines even a nice wet fart could probably alter the vehicles acoustics, should we also include that into our planning?
While the spatial change inside tha cabin may effect its overall transfer function & resonance, it's change will be relevant to the size difference in the box change. (ie small .5cuft to 2cuft size won't be anything compared to a 2cuft to walling off the cabin)

My point is, we can only plan to a certain extent. While these changes will take place, the chances of actually noticing them are slim and the results of planning around them will never be worth the immense time required planning, thus why I don't give them too much consideration.
You will never get the exact same results in a car as modeled, but the more attention you give to the details the closer you can get to what you want. It's a path of diminishing return, and at what point you decide enough is enough is up to you.

I will audition a car with a sealed enclosure, even move it around to test various orientations, then I model that against a new box and let how the small sealed actually sounded help direct the tuning for the new box. I do not need to get very detailed at all to still have great results.

Ajaye, a valid point.
As for the remastered, that would entirely depend on if the artists voice was flat, or if the original recording made his voice sound flat. Which ever recording made the performance as true to live (live in a studio, not at a concert which can have worse acoustics than a car) it would, to me, be the most accurate. There are also many people who believe the original recorded medium makes it sound better, like old record fanatics who must have that hiss & crackle of the needle to make the sound enjoyable, or even those who must have tube amps to get that warmth in the sound. Both have absolutely nothing to do with the original music, but still must be present to enjoy the music.

Also keep in mind that tapes do not contain very low bass, so until the time of CDs sealed boxes provided all the low end you could need/get. CDs changed that, and from then on low bass was readily recorded and sold, and getting that low end to play accurately became important. I can think of a handful of systems from back in the tape days that sounded awesome, and shudder to think what they would sound like by today's standards.

[Eric D]

I can agree with all of that.

I guess the point would then be that your idea of how far to go before you get the diminishing returns is farther than I personally am willing to go.

You choose to model a box, and go from there, I don't go as far as modeling the box, I build it and use test equipment to make adjustments. Either way probably gets to good results, and I will even go as far as to say your method might actually save some time. But, I think saving time is more of a gamble. I have had box modeling get me close on some cases, and get me way off track on others.

[audiophyle_247]

Then we are in accord.

As a profession, I prefer to leave as little to chance as possible and to keep the after-tuning as minor as possible to keep customers from having the ability to really screw shit up. (any more than usual anyway)

In my own car I build many test enclosures, because that is the only way to truly learn what can & can't be heard when enclosure modeling starts to get pretty close to each other.

[Eric D]

Well, it is probably total car audio blasphemy, but if you want to leave little to chance, just go with the manufacturer recommended enclosures.

Sure you won't get 100% performance this way, but I doubt you would get less than 90% performance.

It does all depend on the way a manufacturer comes up with the box design though.

In the case of Rockford Fosgate, they chose to pick a universally accepted volume, and then actually design the subwoofers around that volume.

If I remember right RF subs called for a 1.25cuft box sealed. I remember putting prototype subs in this sized box, and adding weight to them to try and dial them into the best response with the most output, all in that 1.25cuft box. We would purpose build light weight coned woofers so weight could be added to bring them into the performance spec we were looking for. Once there, the final production cones would have the added mass designed into them.

Then the fun part would be trying to get the best performance once that same woofer were placed in the RF standard ported box (something like 2.25cuft or maybe 2.5cuft, I don't remember). Often compromises would have to be made to get the best performance in both sealed and ported enclosures, but pretty much everything about the subs themselves was some sort of compromise. Often cost more so than performance.

[shawn k]

Why do you guys (shawn k and audiophyle_247 specifically) think that when someone disagrees with you they are automatically ignorant?

We don't "automatically" think they're ignorant! Within this specific thread, ttocs admitted right in the begin that he has "never" plotted drivers into programs. Yet he preceeds to debate on the topic. Now I understand that the title of the thread itself doesn't reveal the whole "margin of error" issues that allowed the thread to become heated, but it is certainly related to the topic, as well as the simulation program (WinISD) in which audiophyle gave good solid examples to back up his claims.

Now don't you think it's "ignorant" for ttocs to be debating such a topic when he has absolutely no experience!?

The Internet and forums such as this can be pretty hard to explain ones self on. Especially so in a heated debate, where tensions run high.

I totally agree

Over half the time I argue with you Shawn, I could show you in person the whole point I am trying to make in a few minutes. Trying to explain every last detail becomes an impossibility when you twist everything around to your advantage, or make false claims. And yes, you have been WRONG on at least one occasion before. You don't know everything there is to know about car audio, nor are you flawless at explaining yourself. If you did know everything about car audio, I am pretty sure we would have the privilege of reading about you in car audio magazines, or know of you from technical papers you have published, etc. But, outside of this forum you really don't even exist.

Honestly bro, you need to take that statement and apply it to yourself! Practice what you preach man!

First of all, I will not hesitate for a second to admit when I'm wrong. I've done it several times on this forum. The difference between you and me, is that I admit I'm wrong and allow the thread to continue in hopes that the correct information is provided. I don't drag it out and drage it out just for the sake of arguing!

Not that it matters, and not trying to sound arrogant, but "outside of this forum" I do exist! LOL I'm really not sure what kind of message you're trying to send there. Again, maybe you should practice what you preach!

It is pretty obvious you do know a ton about car audio. I am pretty sure you also know a lot more about car audio than I do.

Yep!

However, it has become apparent over the years, you don't know as much about electronics as I do

Nope!

and when you combine your knowledge of audio with your knowledge of electronics, you make mistakes. So, be a man, admit you are not perfect. Stop beating a dead horse...

STOP BEING IGNORANT!

Never said I was perfect... I do make mistakes! Again.. I admit it when I am wrong! I AM NOT IGNORANT

Now, as for this whole drawn out thread, it is pretty apparent to me the issue here is how you guys are explaining things and interpreting things. Nobody seems ignorant to me. I just think there is some confusion. If someone does not do a great job explaining themselves, and someone else does not interpret it correctly, there still are no grounds for talking down to others.

I don't disagree with you here.

As for the whole topic of sealed vs ported, I stand by my position that each has its own use, and neither is always the way to go.

You guys with your subwoofer modeling can keep having fun running in circles. Modeling works best for home audio or "open field" applications. Often in car audio, modeling will steer you in the wrong direction. Modeling can work when certain conditions are met, one of which is knowing an accurate transfer function of the cabin of the vehicle. This requires an RTA at the very least, and for better results something more advanced would be desirable (like a swept sine analyzer, or a gated response analyzer). With most modeling software, results would vary drastically between putting the system in a compact car, vs a large SUV.

And you can continue to turn a blind-eye to a very useful and powerful tool!

Plotting drivers is to give you a base (starting point). No, it's not magic, but it IS useful. Would you not agree that having solid information as a starting point is a hell of a lot better than starting with nothing (a hunch if you will)?

As audiophyle has also already pointed out, with a litte extra work, you can account for the transfer function of any vehicle and now use this information in conjunction with your plot and have even more useful information. I don't see why anyone would just ignore these pieces of information and just brush them off as worthless.

In addition, WinISD does even more than just projected response curves. You can also predetermine group delay (as mentioned), Port turbulence, power compression, projected spl output, and even target driver xmax limits!

All of that seems pretty useful to me!

[shawn k]

lol. Its not too hard to figure out when someone is too much theory and not enough hands on. Modelling can't be right?! Say it ain't so bro!!!!

If you are referring to me, then you are sadly mistaken bro. If you don't think I'm "hands on" then you truly are "ignorant".

I think you as well need to practice what you preach!

If you would step back for a minute, spend half the time that you spend on trying to up your post count and actually did some "hands on" work yourself, you might actualy learn something!!

[shawn k]

Well, it is probably total car audio blasphemy, but if you want to leave little to chance, just go with the manufacturer recommended enclosures.

Sure you won't get 100% performance this way, but I doubt you would get less than 90% performance.

Now that doesn't make much sense! At least according to your views! The factory's "recommended" ecnlosures are going to suffer from the same effects of transfer function as an enclosure that was plotted in a program.

With the factory's recommended enclosure, you're stuck with what you got.. at least you have options with plotting your own enclosure and can even compensate for transfer function.

[audiophyle_247]

Well, it is probably total car audio blasphemy, but if you want to leave little to chance, just go with the manufacturer recommended enclosures.

Sure you won't get 100% performance this way, but I doubt you would get less than 90% performance.

It does all depend on the way a manufacturer comes up with the box design though.

I never rely on manufacturer recommended specs for subs, not because they are wrong but because they are not designed along the same lines for performance that I'm after.

Manufacturers have a lot on their plate to have a sub sell well, and they need to keep a sub enclosure option as small as possible and provide as much output as possible.
If anything, manufacturer rec'd boxes focus on the smallest box with "acceptable" results (much like collateral damage in warfare), meaning a lot of output up high with just okay low end. Their ported designs usually focus around better spl over sq, because if they publish their sub needs a 5cuft box idiots everywhere would rush to something else if it claimed only needing 2cuft, even though the reality is the 5cuft sub would work just as well in 2cuft as the competition, just their standards for quality sound may have been higher for the published enclosures.

Would you trust a group of marketing experts opinion on what sounds good over what your own opinion is? I sure as hell wouldn't, and I'm sure in most cases the woofer's designer isn't happy with the published specs either. I've talked to many techs at large companies & they were all happy to recommend completely different specs. I like how companies have shifted to offer multiple options with sq or spl orientations, but if you were to model them you will still see they sacrificed some spl & sq to keep enclosure size down.

[shawn k]

^^

Thanks, I was just about to post pretty much the same thing

[ttocs]

how many people are comfortable using these programs to get accurate output graphs, of course ignoring all the transfer functions, environmental differences, and the half dozen other problems we have all agreed make us "take them with a grain of salt"? Seems to me that anyone that has not dedicated years of plugging away to look at plots and then read them as biblical scripture ignoring all the problems when they want has spent some time in the wrong place of audio. I would fully support anyone that did the plot, built the enclosure to spec and then measured the actual output and compaired them but I have to laugh when we trust what the screen tells us will sound good over what our ears might. I am not saying that there is not a use for these plots but it seems that anyone with out the years of experience just plugging in numbers would be considered more ignorant then the dude that build hundreds of boxes, mountes speakers in them and powered them up in a car. You two seem to have a good grasp of this software but at what point did you realize that you knew what you were doing with it, and how long after that did you realize that you were wrong? People tuning cars with volt-meters and projected graphs calling me ignorant over and over just makes me laugh so feel free to keep doing it.

[Eric D]

Well, it is probably total car audio blasphemy, but if you want to leave little to chance, just go with the manufacturer recommended enclosures.

Sure you won't get 100% performance this way, but I doubt you would get less than 90% performance.

It does all depend on the way a manufacturer comes up with the box design though.

I never rely on manufacturer recommended specs for subs, not because they are wrong but because they are not designed along the same lines for performance that I'm after.

Manufacturers have a lot on their plate to have a sub sell well, and they need to keep a sub enclosure option as small as possible and provide as much output as possible.
If anything, manufacturer rec'd boxes focus on the smallest box with "acceptable" results (much like collateral damage in warfare), meaning a lot of output up high with just okay low end. Their ported designs usually focus around better spl over sq, because if they publish their sub needs a 5cuft box idiots everywhere would rush to something else if it claimed only needing 2cuft, even though the reality is the 5cuft sub would work just as well in 2cuft as the competition, just their standards for quality sound may have been higher for the published enclosures.

Would you trust a group of marketing experts opinion on what sounds good over what your own opinion is? I sure as hell wouldn't, and I'm sure in most cases the woofer's designer isn't happy with the published specs either. I've talked to many techs at large companies & they were all happy to recommend completely different specs. I like how companies have shifted to offer multiple options with sq or spl orientations, but if you were to model them you will still see they sacrificed some spl & sq to keep enclosure size down.

Unless I am reading this wrong, you are on the exact same page as I am with this then.

[Eric D]

Shawn, please post one topic in which you admitted to being wrong.

Also, while you are at it, maybe now would be a good time to mention all the "credentials" that you always allude to, but never give any info on. When an argument is not going your way, this is often your primary line of defense.

Well, if you are the car audio genius you claim to be, and have the credentials to back it up, then who am I (or anyone else for that matter) to question you. We could all just start following your teachings as the gospel...

[ttocs]

doesn't sound like too much to ask what the teachers credentials.

[Eric D]

Well, it is probably total car audio blasphemy, but if you want to leave little to chance, just go with the manufacturer recommended enclosures.

Sure you won't get 100% performance this way, but I doubt you would get less than 90% performance.

Now that doesn't make much sense! At least according to your views! The factory's "recommended" ecnlosures are going to suffer from the same effects of transfer function as an enclosure that was plotted in a program.

With the factory's recommended enclosure, you're stuck with what you got.. at least you have options with plotting your own enclosure and can even compensate for transfer function.

Why doesn't this make any sense to you?

And what do you mean by according to my views? I made the point of using a transfer function as a point against the argument to use subwoofer enclosure modeling. I am not advocating people try to find the transfer function of their vehicle. Instead I am making the point that without it, modeling won't work.

I mentioned before I build boxes to fit the space first. Either the space the customer is willing to give up, or a space which works well with the rest of their system (working around the constraints of an amp rack for instance, or using the spare tire well of a vehicle). At this point the enclosure can be made either sealed (if it is small), or ported (if there is significant space). The ported enclosure can then be tuned at this point.

audiophyle_247 made the specific point that he likes to leave little to chance. With this in mind, using the manufacturer recommend enclosure will leave the least to chance. If you try modeling it, you may build something worse than the OEM design, or better. Why should he chance getting it wrong when he can get in the ballpark off the start?

Obviously audiophyle_247 builds enclosures for customers. I highly doubt he goes into the same level of depth on their designs as his own. If he does, then I commend him, he really is going the extra mile. What he does as far as modeling his own vehicle or building countless test designs, all makes sense for a DIY guy with a DIY setup. Building something for a customer where money is of concern often becomes another animal in itself.

[Eric D]

doesn't sound like too much to ask what the teachers credentials.

I think I have held off all this time asking him, simply because I had some sinking feeling he was Richard Clark or the like, in here posting under a different name. But, as time has worn on, his misunderstandings of some of the car audio fundamentals has proven he is not some big name car audio guy in here gracing us with his presence.

It would be even more fun if he is just another IASCA competitor with a trophy or two under his belt. I had the pleasure of working with a guy who had an IASCA winning vehicle, and was also an IASCA judge. I honestly don't think he even knew Ohm's law, so I no longer give automatic respect to anyone in IASCA simply because they are in IASCA. In the case of the guy I knew, throwing money at his instal was his recipe for success. I for one would prefer to throw knowledge at something over money. But, I don't have a ton of money to throw at car audio anyway.

[audiophyle_247]

Eric, Unless I have an idea what the performance is going to look like ahead of time, there is always the chance it will disappoint me. Modeling those boxes shows me that chance is more of a certainty so I don't waste my time trying them.
They are not designed for optimum performance, they are designed for adequate performance in the smallest possible box, not 90% more like 70%. They are designed to make the average uninformed Joe happy enough with his "bangin systum" to tell his friends. Instead I want to maximize my chance of success by eliminating any variable I can control, which is just about every aspect except cabin gain.
That is something you have to live with no matter what box you use.

how many people are comfortable using these programs to get accurate output graphs, of course ignoring all the transfer functions, environmental differences, and the half dozen other problems we have all agreed make us "take them with a grain of salt"? Seems to me that anyone that has not dedicated years of plugging away to look at plots and then read them as biblical scripture ignoring all the problems when they want has spent some time in the wrong place of audio. I would fully support anyone that did the plot, built the enclosure to spec and then measured the actual output and compaired them but I have to laugh when we trust what the screen tells us will sound good over what our ears might. I am not saying that there is not a use for these plots but it seems that anyone with out the years of experience just plugging in numbers would be considered more ignorant then the dude that build hundreds of boxes, mountes speakers in them and powered them up in a car. You two seem to have a good grasp of this software but at what point did you realize that you knew what you were doing with it, and how long after that did you realize that you were wrong? People tuning cars with volt-meters and projected graphs calling me ignorant over and over just makes me laugh so feel free to keep doing it.

Seriously man, download the program and play with it for a couple minutes.
In the time you could make 1 box and test it (in car & in an auditioning room) you could model a thousand variations & see exactly what a slight change would do. The freq response curve is only a small portion of the greater picture, even a noobie can use that program to load up their sub in & see exactly how large their port needs to be, what the air velocity inside the port will be, and at what level it will become too much. (because port length grows with area, which I'm sure you knew already). If you have only so much space it is great to know in advance if your port area is sufficient, vs just building it & finding out it sounds like an old tractor when you crank it up a little. Then again that requires a little foresight, and it sounds to me like you don't design anything. Build to spec, or (gulp) guess on building measurements. Maybe that's why margin of error escapes your grasp...


Until you actually play with the program, you have no fucking idea what you are missing. So give it a go Mr Hands-On, it doesn't cost anything more than a little bit of your time.
I wonder if cavemen stoned the first guy that tried to show them how awesome a wheel was for making life easier. I've built more enclosures than I could even pretend to count, I have gained an insane level of understanding & experience when it comes to box design, and I cannot imagine where I'd be without using this amazing tool perfecting my enclosure designs.

My father swore he'd never use a microwave, and after I bought him one it only took a month before he told me he couldnt live without one. He hasn't been without one since, and that was a LONG time ago.

[audiophyle_247]

I mentioned before I build boxes to fit the space first. Either the space the customer is willing to give up, or a space which works well with the rest of their system (working around the constraints of an amp rack for instance, or using the spare tire well of a vehicle). At this point the enclosure can be made either sealed (if it is small), or ported (if there is significant space). The ported enclosure can then be tuned at this point.

audiophyle_247 made the specific point that he likes to leave little to chance. With this in mind, using the manufacturer recommend enclosure will leave the least to chance. If you try modeling it, you may build something worse than the OEM design, or better. Why should he chance getting it wrong when he can get in the ballpark off the start?

Obviously audiophyle_247 builds enclosures for customers. I highly doubt he goes into the same level of depth on their designs as his own. If he does, then I commend him, he really is going the extra mile. What he does as far as modeling his own vehicle or building countless test designs, all makes sense for a DIY guy with a DIY setup. Building something for a customer where money is of concern often becomes another animal in itself.

Anytime enclosure volume is an issue (spatial restrictions) modeling becomes even more important.
You cannot just port a box & tune for a freq, your port itself reduces internal volume, which makes the needed port even longer (& eats even more volume). I also incorporate ports into the design of the box, not an afterthought, so I need to know 100% in advance what I'm doing on an install.

Manufactured boxes may get you in the ballpark, but last I checked a ballpark is fucking huge.
You think ballpark figures worked for landing Curiosity in a crater 350,000,000 miles away? Doubtful
Ballpark isn't close enough for my expectations, I'm talking strike zone sized targets.

I absolutely put that extra mile into my customers cars, that's what affords me my premium prices on my work. Top notch all the way, my skill, detail, and knowledge is what pays the bills, and when I can get a customer ass-loads of bass with far less equipment & no worries of the system disappointing them, they gladly pay that extra.

[shawn k]

audiophyle's responses are spot on. He deserves credit for the clear and consise information he is providing. This entire time, I've only been trying to reinforce what he's been saying.

audiophyle: I have already suggested that ttocs should download WinISD and aquaint himself with it. Hell, I even made it insanely easy to do as I provided the link for the download. I'll bet the farm that he still hasn't done that. Instead, as I've said before, he would prefer to argue (and up his post) count than actually learn something. Apparently the post counts are more important for him than useful knowledge.

Eric, ttocs: if you truly want to see a list of my credentials, I'll gladly provide them for you via PM. I don't see why it would do any good or even change anything. Especially after Eric has already tried to defame the legendary Vance Dickason. I mean seriously, if Eric will not listen to Vance.. then why the hell would he listen to me right?

Final thought and for the record since Eric asked.... Here's a thread where I was wrong about passive radiators and their effect on group delay. Eric, you should remember this since YOU were the one who corrected me. Now see where I IMEDIATELY admitted where I was wrong and the thread moved on!!! IT'S SO EASY!

[Eric D]

audiophyle's responses are spot on. He deserves credit for the clear and consise information he is providing. This entire time, I've only been trying to reinforce what he's been saying.

audiophyle: I have already suggested that ttocs should download WinISD and aquaint himself with it. Hell, I even made it insanely easy to do as I provided the link for the download. I'll bet the farm that he still hasn't done that. Instead, as I've said before, he would prefer to argue (and up his post) count than actually learn something. Apparently the post counts are more important for him than useful knowledge.

Eric, ttocs: if you truly want to see a list of my credentials, I'll gladly provide them for you via PM. I don't see why it would do any good or even change anything. Especially after Eric has already tried to defame the legendary Vance Dickason. I mean seriously, if Eric will not listen to Vance.. then why the hell would he listen to me right?

Final thought and for the record since Eric asked.... Here's a thread where I was wrong about passive radiators and their effect on group delay. Eric, you should remember this since YOU were the one who corrected me. Now see where I IMEDIATELY admitted where I was wrong and the thread moved on!!! IT'S SO EASY!

Shawn, STOP making things up NOW. I have tons of respect for Vance DIckason, I own some of his books, and I have used his teachings to great success. Changing the subject and making stuff like your false comment up does not make you right. In a past thread you misinterpreted his words, used them against me, and when I then disagreed with you you told me I was disagreeing with Vance. I don't see how that in any way means I am trying to defame him.

Funny you claim I corrected you on group delay, when I have never been in a single group delay discussion on this forum. You have me mistaken for someone else.

I cannot comprehend why you would not post your credentials for all to see. If you are all you claim to be, at least you can put my rantings to rest and I will stop questioning you. Seems like a win-win for you.

[Eric D]

OK then, I have no problem amending my statement to 70% instead of 90% if it gets you and I to agree on something.

Yes you can just build a box and then port it, and tune it. There are two ways to do this. One is to calculate it. If you know the volume of the box, and you know what you want to tune it too, you can setup a formula to converge at the loss of volume from the port, along with the specs of the port getting you the proper tuning.

The other option is the one I choose. I run an impedance curve. I stick a port in the box with the cross sectional area I want (most often driven by the install itself, and how the port will look cosmetically), then use an arbitrary length. I run an impedance curve on the box with the woofer, and with it in the vehicle. This gives me the exact tuning of the enclosure. I then have to either make the port longer to tune lower, or shorter to tune higher. It is not all that difficult, and it is not all that time consuming either. The beauty is I get exact results, and I also get to use my $1,000 analyzer which otherwise does not get used often enough.

It is now obvious to me you are more into car audio than I am, as you seem to have made it your career.

You have made a very important point in this whole thread though, and it is this...

Years of doing shit wrong doesn't make you better than me at anything other than f**king shit up. (which I'll gladly give you rep for)

This is a quote I agree with 110%. You could not be more spot on. Now, I don't know you all that well, but I really hope you don't actually fall into the very point you have made.

I am now pretty sure you are an installer by trade (assuming so from your recent posts), and in my experience over the years, 90%+ of installers fall into the point you made. When you start doing something wrong from the beginning, and do it for years, that does not make it right.

I don't have respect for installers based on technical skill. Unless they have some more formal education, being taught on the job and then doing the same tasks over and over does not make them right at what they do. However, where I do have tons of respect for installers in in the realm of creativity. Some guys can build works of art nearly beyond comprehension. Their attention to detail, and the clean outcomes of their projects are awe inspiring.

I read an interview with Dave "Fishman" Rivera some years ago, where he talked about how little his technical knowledge was. I am pretty sure that anyone who knows who I am talking about agrees he is one of the most creative car audio guys ever. But, being creative does not make him a technical authority.

[shawn k]

Shawn, STOP making things up NOW. I have tons of respect for Vance DIckason, I own some of his books, and I have used his teachings to great success. Changing the subject and making stuff like your false comment up does not make you right. In a past thread you misinterpreted his words, used them against me, and when I then disagreed with you you told me I was disagreeing with Vance. I don't see how that in any way means I am trying to defame him.

Funny you claim I corrected you on group delay, when I have never been in a single group delay discussion on this forum. You have me mistaken for someone else.

I cannot comprehend why you would not post your credentials for all to see. If you are all you claim to be, at least you can put my rantings to rest and I will stop questioning you. Seems like a win-win for you.

I'm not making up anything man. You're really a piece of work.

Here's the thread where you blatently disagreed with Vance: http://phoenixphorum.com/viewtopic.php? ... e&start=50 ... And I never "misinterpreted his words" I mean Jesus.. I even photocopied the the page right out of this book yet you still disagreed with him (Vance Dickason) You don't remember this stuff man???

And here's the other thread that I was refering to in regards to group delay/passive radiators: http://phoenixphorum.com/viewtopic.php? ... ay#p207749 You don't remember this either???

STOP SAYING I'M CHANGING THE SUBJECT!!! Or perhaps you suffer from amnesia... in which case I truly appologize

[shawn k]

The other option is the one I choose. I run an impedance curve. I stick a port in the box with the cross sectional area I want (most often driven by the install itself, and how the port will look cosmetically), then use an arbitrary length. I run an impedance curve on the box with the woofer, and with it in the vehicle. This gives me the exact tuning of the enclosure. I then have to either make the port longer to tune lower, or shorter to tune higher. It is not all that difficult, and it is not all that time consuming either. The beauty is I get exact results, and I also get to use my $1,000 analyzer which otherwise does not get used often enough.

That is the single most rediculous tuning technique I've ever heard of. Good show, jolly good show

So in other words... what you're doing is: guestimating the base volume. "Hoping" that it actually has enough volume to tune within the realm of being ergonimic, and still "hoping" that the sub is tuned low enough to allow dampening

So what happens if the volume of the enclosure is small'ish and you need to tune low. Your vent will be insanely long and quite possibly unusable. On top of that, you still don't know how the sub will perform! You still don't know if the driver is working within it's mechanical limits (excursion limits... usable excursion and or xmax). You still don't know your port velocity. You still don't know your group delay.

Hell, you don't even know if the driver itself is even suitable for a vented enclosure!!!

So all in all, that $1000 analyzer hasn't shown you shit!! LOL.. I can get so much more information via WinISD for FREE!

[ttocs]

not sure why you do not want to tell us/everyone your history, you seem to need no 2nd thought about giving your opinion. But if you insist on pm format then yes please.

[Eric D]

Shawn, STOP making things up NOW. I have tons of respect for Vance DIckason, I own some of his books, and I have used his teachings to great success. Changing the subject and making stuff like your false comment up does not make you right. In a past thread you misinterpreted his words, used them against me, and when I then disagreed with you you told me I was disagreeing with Vance. I don't see how that in any way means I am trying to defame him.

Funny you claim I corrected you on group delay, when I have never been in a single group delay discussion on this forum. You have me mistaken for someone else.

I cannot comprehend why you would not post your credentials for all to see. If you are all you claim to be, at least you can put my rantings to rest and I will stop questioning you. Seems like a win-win for you.

I'm not making up anything man. You're really a piece of work.

Here's the thread where you blatently disagreed with Vance: http://phoenixphorum.com/viewtopic.php? ... e&start=50 ... And I never "misinterpreted his words" I mean Jesus.. I even photocopied the the page right out of this book yet you still disagreed with him (Vance Dickason) You don't remember this stuff man???

And here's the other thread that I was refering to in regards to group delay/passive radiators: http://phoenixphorum.com/viewtopic.php? ... ay#p207749 You don't remember this either???

STOP SAYING I'M CHANGING THE SUBJECT!!! Or perhaps you suffer from amnesia... in which case I truly appologize

OK Shawn, you both win and loose...

Here is my post about Vance....

As for the clip out of the Loudspeaker Cookbook, I guess I am a nutcase then.

I would really want to see the input signal which validates statement number 2 he makes. If one were to play a sine wave at 100Hz (like in your test) recorded at 0db, then the active low pass amp would indeed clip before the amp running the passive setup (assuming 60w, and 175w like he states).

Now, I don't listen to sine waves, nor does anyone else here (so I hope). But, music can be a lot of things. Playing something like country for instance will probably do exactly as he states, increase the dynamic range, and clip later with the active setup.

Now switch to rap, or even worse techno bass music. These types are music are so bass heavy, they don't leave much dynamic range for the high frequencies to ride on without clipping. With music like this, so much of the signal will be sent to the low pass amp, it will end up clipping much closer to the point it would if you just ran a sine wave into it.

So, yes I do agree with Vance, but not in every single case out there. I think he makes more of a "general guideline" statement here, not an absolute.

Please explain to me how that means I don't have respect for Vance?

As for the group delay, you are correct, I did sort of prove you wrong. The reality though is I knew that a post by me would not mean anything to you, so I had to actually find info from Vance D and quote him. This shut you down. So, yes, you are right, I was in an argument with you about group delay. However, considering I did not use any of my own knowledge on the subject and instead had to quote someone else, I can see why I forgot all about it 2 hours ago when I responded to your post. My bad, I do make mistakes.

[Eric D]

The other option is the one I choose. I run an impedance curve. I stick a port in the box with the cross sectional area I want (most often driven by the install itself, and how the port will look cosmetically), then use an arbitrary length. I run an impedance curve on the box with the woofer, and with it in the vehicle. This gives me the exact tuning of the enclosure. I then have to either make the port longer to tune lower, or shorter to tune higher. It is not all that difficult, and it is not all that time consuming either. The beauty is I get exact results, and I also get to use my $1,000 analyzer which otherwise does not get used often enough.

That is the single most rediculous tuning technique I've ever heard of. Good show, jolly good show

So in other words... what you're doing is: guestimating the base volume. "Hoping" that it actually has enough volume to tune within the realm of being ergonimic, and still "hoping" that the sub is tuned low enough to allow dampening

So what happens if the volume of the enclosure is small'ish and you need to tune low. Your vent will be insanely long and quite possibly unusable. On top of that, you still don't know how the sub will perform! You still don't know if the driver is working within it's mechanical limits (excursion limits... usable excursion and or xmax). You still don't know your port velocity. You still don't know your group delay.

Hell, you don't even know if the driver itself is even suitable for a vented enclosure!!!

So all in all, that $1000 analyzer hasn't shown you shit!! LOL.. I can get so much more information via WinISD for FREE!

Can you please re-read my post except this time use an open mind about it, and don't just automatically look for ways to be right and me be wrong.

In the case you mention I would not port the box, I would run it sealed. If it is too small to be ported, then it would not make much sense to try.

Using an impedance curve to validate tuning is a technique AUDIO ENGINEERS use all the time. I don't expect you to understand it, nor do it yourself. But, if you don't understand it, that does not make it wrong.

When I worked for Rockford EVERY box built had to have an impedance curve to confirm its tuning. Every box built required some amount of adjustment, as speaker displacement, exact port dimensions, etc were not known 100%. Just the amount of caulk used would move the tuning enough to require adjustment.

But, what I am talking about was lab grade testing and analysis. Not something most in car audio would really be familiar with, or even concern themselves with.