Hi nas3000,
I think you need to be comfortable simulating in BR first and understand how all the parameters are related. And you need to be able to look at the graphs of your simulation and understand its implications first and not just the recommendations. You would need to modify from that technique because the original technique I believe is for a much bigger driver hence a much lower Fs. For example a good 5 or 6" would probably have fs at about 30 to 40 Hz. In this case 3fe25 has it at 110Hz. So I am not sure you can follow exactly what it says.
Oon
Oon,
Lets forget everything in the last 5-6 post in this thread... and read the first post of this thread:
"Use WinISD bass reflex software (free) and plug in your driver's T/S params and design a vented bass reflex speaker enclosure using the default optimal case. That will give you the volume of the box and the vent cross sectional area and length."
Do I understand correctly, I simply add driver to WinISD, then make default enclosure by pressing "Next" button, then calculate manually from it to be ~30-40inch lenght? If this is correct - I get very very small boxes from default WinISD, ~4 Liters from the drivers I already mentioned. If I compare the box, which is confirmed to work well with the same drivers, like Tabaq - it is 2.5x larger (~10Liters)
So, in some part of this task I am doing smth wrong.
Question is exactly about this, nothing else. I do understand, that you want to help, but read this first...
People will read and do as they wish.
You're not comparing like with like in terms of design methodology. TABAQ was derived from a specific QW simulation, without any reference to conventional T/S (Helmholtz) vented box alignments such as those you can derive in WinISD et al. By contrast, X created his AMLTL approach for people who do not have access to modelling software, and deliberately derived Vb and (nominal) Fb from a stock vented box alignment. The difference between the two approaches is that the former allows you complete freedom in designing and refining the alignment; the latter allows no real control over the alignment in the design stage since it is by intent an approximation.
You're not comparing like with like in terms of design methodology. TABAQ was derived from a specific QW simulation, without any reference to conventional T/S (Helmholtz) vented box alignments such as those you can derive in WinISD et al. By contrast, X created his AMLTL approach for people who do not have access to modelling software, and deliberately derived Vb and (nominal) Fb from a stock vented box alignment. The difference between the two approaches is that the former allows you complete freedom in designing and refining the alignment; the latter allows no real control over the alignment in the design stage since it is by intent an approximation.
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I have no access to MLK sheets, Leonard Audio I use, HornResp is still too much for me.
Can you run WinISD for me?
I'm afraid I don't use WinISD. But even if I did, assuming you have entered all the data correctly, there is no point in my doing so. You have already run it yourself and obtained the Vb and vent dimensions that X's AMLTL methodology provides. You can get everybody else to run the same software, with the same driver data, for the same alignment until the cows come home, and it will spit out exactly the same volume and vent tuning. 2 + 2 = 4, whoever calculates it.
Nas3000,
All of the drivers you mention are generally going to work in a cabinet about the same as a Tabaq. Try it this way, set the volume as what a typical Tabaq is for a 3.5in driver. Then solve for the vent size assuming circa 55Hz tuning. See what that gives you.
If you are getting really small volumes like 2L, something is wrong. The only 3.5in drivers that achieve small volumes like that are ones with fairly low Qts with powerful neodymium magnets. Like 3FE22 or 10F/8424, they will be have nominal volumes in the 2.5L to 3.5L range and tune around 75Hz to 80Hz. They are not ideal for extending well below their Fs due to low Qts.
All of the drivers you mention are generally going to work in a cabinet about the same as a Tabaq. Try it this way, set the volume as what a typical Tabaq is for a 3.5in driver. Then solve for the vent size assuming circa 55Hz tuning. See what that gives you.
If you are getting really small volumes like 2L, something is wrong. The only 3.5in drivers that achieve small volumes like that are ones with fairly low Qts with powerful neodymium magnets. Like 3FE22 or 10F/8424, they will be have nominal volumes in the 2.5L to 3.5L range and tune around 75Hz to 80Hz. They are not ideal for extending well below their Fs due to low Qts.
What I am trying to say is there is no such thing as a single correct perfect answer for cabinet volume. That was for years ago when things were analytical and you had to count everything by hand. Now, It really has to do with what you are trying to simulate for. There are so many possibilities.
Beyond that I think xrk is the best person to answer you. However I think there are some changes. The original had a TL tuning of 60 to 75Hz and assuming a BR tuning that was significantly lower, maybe circa 30 to 40 Hz for most >4inch drivers
Using such a small driver you will probably push the BR frequency quite close to the TL frequency and you probably have to push the TL frequency a bit higher to compensate.
XRK would know best...
Oon
Thanx XRK... Seems you confirmed my WinISD is working wrong, because Leonard Audio and Hornresp show pretty much similar results with bunch of 8-9cm drivers, and all of them are at least 0.5Qts and none neodymium. Will skip manual AMLTL this time
Btw, I am using on my project (prototype) ~12 sq cm, pipe as went, which is different from original TABAQ 5sq cm , how to calculate optimal vent lenght for my already fixed diameter?
Unless you edited the source code and then re-compiled it, it is extremely unlikely that it is working wrong.
Much more likely, you are using it incorrectly. Sorry if you find this insulting. I don't mean it that way.
That would seem favourite.
You appear to have selected the dry humour phrase in the post and ignored what was written in front of it:
You have already run it [WinISD] yourself and obtained the Vb and vent dimensions that X's AMLTL methodology provides. You can get everybody else to run the same software, with the same driver data, for the same alignment until the cows come home, and it will spit out exactly the same volume and vent tuning.
Now: recall that this AMLTL methodology is not the sole way of creating a QW enclosure. It is just a simple means of obtaining a volume &c. for people who do not have access to accurate modelling software, and / or do not have sufficient knowledge of the underlying physics to design an MLQW / MLTL by other means. It can work reasonably, but it does not (and was not meant to create) a detailed or highly refined QW design: just something that should in many cases 'work OK'. Other design approaches will often have very different proportions in terms of length, box volume, tuning, damping driver & vent locations etc., because they are designed in a completely different way, with different alignments or acoustic goals in mind.
You appear to have selected the dry humour phrase in the post and ignored what was written in front of it:
You have already run it [WinISD] yourself and obtained the Vb and vent dimensions that X's AMLTL methodology provides. You can get everybody else to run the same software, with the same driver data, for the same alignment until the cows come home, and it will spit out exactly the same volume and vent tuning.
Now: recall that this AMLTL methodology is not the sole way of creating a QW enclosure. It is just a simple means of obtaining a volume &c. for people who do not have access to accurate modelling software, and / or do not have sufficient knowledge of the underlying physics to design an MLQW / MLTL by other means. It can work reasonably, but it does not (and was not meant to create) a detailed or highly refined QW design: just something that should in many cases 'work OK'. Other design approaches will often have very different proportions in terms of length, box volume, tuning, damping driver & vent locations etc., because they are designed in a completely different way, with different alignments or acoustic goals in mind.
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I am little confused: you are writing so much clever stuff, but almost none about the subject, exept the fact that you are not using the software which I am asking for someone to run with the same speaker driver. Thats it. I have academical degree and some years of paid work experience in software engineering, so it is better for us to skip that part in any future conversations.
No I absolutelly not find it insulting. You are most likelly right - I am doing smth wrong, but I cannot find what. It may be some weird default settings or my mistake somewhere in entering driver data. The problem is I do not have any other computer to reinstall WinISD.
I have enterred 4 drivers mentioned in TABAQ thread and WinISD shows enclosures up to 5 Liters (TABAQ is ~10 L)
If you can run some drivers, including the ones I have mentioned - I would be gratefull. Screenshots are attached somewhere.
NAS3000,
Try an online bass reflex calculator. See what this one gives you. I personally never liked WinISD.
HiFi Loudspeaker Design
Volume Calculator For Closed Loudspeaker
Try an online bass reflex calculator. See what this one gives you. I personally never liked WinISD.
HiFi Loudspeaker Design
Volume Calculator For Closed Loudspeaker
Congratulations on waving your academic qualification about. I'm afraid it doesn't impress me: there are plenty of people on this forum who hold higher degrees including doctorates. There might even be some on this thread. Sadly, it is not a guarantee of expertise in speaker design, especially if the subject does not happen to be acoustical engineering or deal with matters connected with it.
I can't think of any way to be clearer. You seem to be complaining that WinISD provides different box volumes to the TABAQ. Yes. It will. Because the TABAQ has absolutely nothing to do with the AMLTL, or any of the default box [volume] alignments e.g. QB3, BB4 etc. provided by WinISD and equivalent software. Thus its volume and other design characteristics are different, because there is no design connection between them. Simple as that.
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To impress and not to impress - it is not my goal. If you somehow want to continue in that direction think that this is the "testing" phase. It is as important as all the other main phases. So, I am getting lets call it unexpected results. Please do not expand in this direction further.
I wish we stay on the topic and if you know any other tool which you use to verify AMLTL principle, which IMO is pretty cool thing, I am listening with my ears and eyes open.
TABAQ and WIBAQ was mentioned in this thread more than once... So my assumption is not out of topic.
I also started not to like WinISD too. Will try the tools you mentioned. T Y!
Getting pretty similar and nice graphs in Leonard and Hornresp, but the size.volume of the box is not totally clear for me. It is a bit strange, that to find the corect driver position in line was easiest part.
Then why refer to it at all? It is irrelevant.
I'm afraid that you do not get to dictate what people on this forum do. You are the one asking about 'unexpected results'. If you do not wish to learn, I suggest you do not ask questions.
You can use any of the many pieces of software out there to obtain a volume: WinISD is merely one which can provide such default options (along with freedom of adjustability), to which you can add Boxsim, VituixCAD, LspCAD, Winspeakerz, Unibox, Woofer box & Circuit Designer, BassBox in its many variations, Basta, AJhorn, Vented-FDD... the list could continue for quite some time. The aforementioned software does not 'verify AMLTL principle' however; it just provides a quick & convenient way of getting a box volume & vent dimensions to use in the proportions X recommends in this thread. You can always do it longhand if you prefer. For example, Small's maximally-flat vented alignment takes box volume as 20Vas*Qt^3.3 and box tuning frequency as 0.42Fs*Qt^-0.96.
Nobody said your assumtion was out of topic. What I have endevoured to explain is that it is mistaken. TABAQ's volume has nothing to do with a standard Helmholtz vented box alignment such as the default examples provided by WinISD, so by definition they do not match (except by accident on rare occasions).
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