Hello all!
My Fane-bass-reflex speakers are finished. Time for the next project 😵
As the title says, I managed to get 2 W4 2130 Si for a bargain and want to build some PC-speakers.
(https://www.tb-speaker.com/uploads/files/37a412234362bf9297d386299feba31a.pdf)
Currently I have 2 large 42L bass-reflex speakers with W8 1772s in them, but I want to sell them as they take up too much space on the desk.
Concerning desktop/bookshelf speakers, I checked out the "Baby Labs", and fell in love with a smaller, more compact transmission line. However the Baby Lab-models all feature different speakers than the ones I have.
Now I have 2 questions:
Should I just pick the Baby Lab-model that has the closest T/S-parameters and go with that?
(I already compared them and the closest matches I found were the Mark Audio Alpair 6.2 or CHN-70)
https://www.markaudio.com/online_shop/archive/alpair-6-2/#link_additional_information_tab https://www.markaudio.com/online_shop/ch/chn-70-paper-pair/#link_additional_information_tab
Or is there any way a newbie like my can model a MLTL for W4's? I have only worked with WinISD so far.
I have studied the Baby-Lab plans a little and I noticed: there are always three internal walls. And they are always spaced a half length from the previous one. So if the first length is 12cm, the other one is 6 and the last one is 3. Also the vent is always equal to the last walls length, so 3cm.
But that's only what
Ideally speaking maybe someone more knowledgeable than me has the time to do a quick calculation or so, but I hesitate to ask :-D
My Fane-bass-reflex speakers are finished. Time for the next project 😵
As the title says, I managed to get 2 W4 2130 Si for a bargain and want to build some PC-speakers.
(https://www.tb-speaker.com/uploads/files/37a412234362bf9297d386299feba31a.pdf)
Currently I have 2 large 42L bass-reflex speakers with W8 1772s in them, but I want to sell them as they take up too much space on the desk.
Concerning desktop/bookshelf speakers, I checked out the "Baby Labs", and fell in love with a smaller, more compact transmission line. However the Baby Lab-models all feature different speakers than the ones I have.
Now I have 2 questions:
Should I just pick the Baby Lab-model that has the closest T/S-parameters and go with that?
(I already compared them and the closest matches I found were the Mark Audio Alpair 6.2 or CHN-70)
https://www.markaudio.com/online_shop/archive/alpair-6-2/#link_additional_information_tab https://www.markaudio.com/online_shop/ch/chn-70-paper-pair/#link_additional_information_tab
Or is there any way a newbie like my can model a MLTL for W4's? I have only worked with WinISD so far.
I have studied the Baby-Lab plans a little and I noticed: there are always three internal walls. And they are always spaced a half length from the previous one. So if the first length is 12cm, the other one is 6 and the last one is 3. Also the vent is always equal to the last walls length, so 3cm.
But that's only what
Ideally speaking maybe someone more knowledgeable than me has the time to do a quick calculation or so, but I hesitate to ask :-D
Two internal panels. 😉 I designed them as a particular range, so most (most) share similar characteristics in terms of targeted alignment, taper ratio etc. I need to do a couple of others for the current generation Pluvia 7HD & P-HD, so will see if I can work one up for this TB unit while I'm at it.
TABAQ works well with Tangband w4. I build a pair with W4-1320 SIF. They needed a little correction though.
AFAIK there are also plans for a folded version.
AFAIK there are also plans for a folded version.
Only 2 internal in total? But won't the 1/4 line then be way too short? For 70 or 75Hz I calculated the quarter wave length would be between 112 and 125cm.
I'm drawing things up as I I'm writing this, and I even had the idea to add 1 additional panel to the 2 internal ones, so the line ends up long enough.
So you suggest staying with 2? 😀
But if you could work something up, I'd be immensely grateful!
I have to admit: Is TABAQ just an acronym for quarter-wave speakers with a TB-driver in it, or is it a name for a certain "model" like TL, BR or Voigt Pipe?
I stumbled across the bigger TABAQ-speakers, but they don't fit the purpose of a "desktop speaker".
I just found them. They look good, but won't really work for me as the maximum height I have room for is 30-35cm because that's where the PC-monitor is.
I could lay them on their side, though. However I don't know how "bad" they will sound, given that I will listen to them quite off-axis. Hmm.
As I understand TABAQ is an MLTL. It works with a wide variety of driver you can press fit with different amount of stuffing.
Scotts designs should get you the most of a particulary model. When you use a design specificaly made for it.
https://www.diyaudio.com/community/threads/tabaq-tl-for-tang-band.88787/
Scotts designs should get you the most of a particulary model. When you use a design specificaly made for it.
https://www.diyaudio.com/community/threads/tabaq-tl-for-tang-band.88787/
I thought you'd seen the boxes? All that range of enclosures have two internal panels (as in pieces of wood or other construction material). http://wodendesign.com/downloads/Woden-BabyLabs-241018.pdf
Acoustical length depends on a/ the physical length of the line, and b/ the degree of taper (or expansion), in addition to the usual end-correction necessary for all pipes.
I didn't realise they are not long enough; the last time I checked, they were tuned to the intended frequency & alignment, but I defer to you of course -there is always more to learn, so perhaps you can show me what I've done wrong and why they don't work as designed (although to the best of my knowledge, they do, and have, for quite a few years). I don't claim they are 'definitive' or anything like that -they're just a specific configuration and alignment that I created, based on the acoustical labyrinth. There are many potential alternatives of course -strictly speaking an infinite number, so it's quite possible something else will suit you better.
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I have 🙂
I'll just summarize how I calculated the quarter length, because while I trust my (albeit simple) math, I also know that you know some things I don't, and maybe I overlooked some things 😀
1. I found out the wavelength on here: https://www.omnicalculator.com/physics/wavelength
Then /4, of course. At 70Hz it should be 4.9m. 4.9/4 = 1.225m So in my head, a line through from the first chamber to the last one towards the exit should be ~1.225m long, right?
2. I drew something up on my own and calculated the "line length" accordingly (I will use a Lance-model in the PDF as an example):
I will go from right chamber towards the end: Internal height (24.7cm) - the gap (5cm) + half the circumference of a circle with 5cm of radius. Then again: 24.7cm - the 5cm gap at the bottom and -2.5cm gap at the top, + half the circumference of a circle with a radius of 2.5cm until the end.
I quickly did the maths on a piece of paper and typed it into the PC:
25-5+15,7 = 35,7 for the first part.
25-5-2,5+8 = 25,5 for the second part
25-2,5-2,5+2 (not a half, but a quarter circumference) =22 for the last part
So we end up with a line of ~83cm which is a wavelength of 332cm or 3.32m
The FF85wk has a Fs of 115Hz.
oh wait. I see it now. Your calculation was and is correct!
The "error" was that I had a speaker with a Fs of 75Hz and wanted to accomodate a quarter wavelength between 70 and 75Hz. That's where i ran "out of line length", so to speak 😀
That's why I wanted to add a third panel to eek out an additional ~20-25cm to get down to 70Hz.
However I have clarify: I have no knowledge what role the gap-size and width of each section play. I wanted to ask you that anyhow: Why do some of the Lab-models get more narrow towards the end in gap-size and width between the panels?
How does the length of the panels and the width between panels correspond to the line-length?
Basic physics tell me if the panel gaps and the width between panels open up towards the end, we should get a "horn like" behaviour, no? Why do we the opposite in a MLTL? 😀
After some iterations I have a rough sketch with dimensions that would end up with the correct line length. (Please keep in mind, the numbers and the sketch don't correlate in any matter. I just like to visualize things, even if it doesn't represent the proportions)
However I don't know the system behind the width between panels and the gap-size, so I don't know how far apart the panels and how big the gaps need to be.
(I calculated the total internal depth that is available minus the panels, and then divided them so that each panel is located half the length after another. If the first "room" is 12cm deep, the second one will be 6cm, the third 3cm and the last one + the vent will be 1.5cm.)
In other words: The total depth of the speaker cabinet with 3 internal walls is 187.5%. The first section/room where the speaker is located is 100%, the one after that is 50%, then 25% and then 12.5% of the internal depth. That's what I learned from your plans, I think. But what's the rule behind that? And how do the gaps correlate?
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This only works for an untapered pipe with no end correction. As I mentioned above, the acoustical length (aka fundamental resonant frequency) of a pipe is a function of its physical axial length and taper (or expansion), along with any necessary end correction due to the acoustic impedance mismatch at the terminus.
In the former case it's creating a target taper ratio; in the latter it's to establish the required pipe volume to hit the target alignment.
Well, a reverse taper pipe is inherently mass-loaded, although when we talk about MLTLs we're usually talking about an untapered pipe with the mass-loading provided by a duct. They're not horns; impedance matching / maximising efficiency for a given Vb isn't the object, so much as using the eigenmodes to extend the LF. Regular vented enclosures use Helmholtz (cavity) resonance with similar objects in mind.
They're an alignment of my own, and while it's not an especially novel one (several of the experienced QW designers on this forum will either recognise or quickly figure how it's done) I haven't provided a full set of design equations, mainly because there are a large number of little scoundrels out there who like to trawl forums for exactly this sort of information, which they can then exploit for their own gain. It's happened to several people I know, including some here, and me too on a number of occasions. So like some others -unfortunately we need to be a mite careful exactly how much we provide.
Holy moly, is it really you? I stumbled upon your website years ago, your speaker-inventions look impressive. However I already have nice speakers that go down low for listening to music in the living room.
Now my "next" project is to make speakers that help me listening to music while working on the PC or on the desk, which is right next to the PC, that's why I "need" smaller sized speaker enclosures that get the best out of the driver 🙂
Page 5 (or the whole paper) of the attached has supporting info. An earlier paper—MJK derived the maths to support which was over my head of course. http://www.quarter-wave.com/TLs/TL_Alignments.pdf
Ah, didn't know that. Again, the reason why we can't have nice things is ********, I guess. Now I understand why you don't want to give out all the information. Maybe if you could also run a simulation for the TB 4", I'd be really thankful. If I could, I'd offer to buy you a beer or a coffee through the internet 😀
Alright, I think now I get it! So different alignments don't just exist within Bass-reflex enclosures, but just about in any speaker-enclosure, right? And depending on that, MLTL can vary in panel position and gap-size.
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Sadly, yes.
Not a problem, it's in the queue.
Correct; all enclosure types have more or less an infinite range of possible alignments; at the end of the day what you aim for depends on what your design objectives are.
As I mentioned, these are not MLTLs in the usual parlance -99.999% of the time, when the term MLTL is used, it refers to a straight pipe mass-loaded with a conventional duct of some kind. A tapered pipe or line is inherently mass loaded to some degree (extent depending on the degree of taper), but they are not generally described as MLTLs, and I'd probably avoid doing so to avoid confusion. Tapered pipe or line is the most common term. In this case, since the boxes you referred to were partly inspired by Olney and are lagged rather than stuffed, I refer to them as acoustical labyrinths, as in a broad sense they're conceptually a descendent of the old Stromberg-Carlson type.
........to wit, all TL, vented speaker alignments begin as Acoustic High-Pass, Low-Pass, and Band-Stop Filters and specific to BR converted to Voigt Pipe design........ same net Vb, etc., but radically different performance parameters.
Note: will need to use Hornresp (HR) to compare 'critically damped' responses.
Attachments
Attached; for brevity I've borrowed one of Dave's CAD drawings & altered the dimensions so it's not to scale, just for the sake of having something to add the values to. As a 4in with a modest Fs & a Qt at the lower end of middling, it's never going to be a bass monster but depending on damping, you can get relatively flat down to about 10% below Fs, or go with an Augspurger alignment with larger quantities to shift things more toward a classical TL at the expense of reduced LF gain.
Attachments
I really have to come clean now: As a child I've read books upon books upon books, the longer the better. After that, university and my current job require me to read a lot of scientific texts, too, so it kinda took the joy of recreational reading. However if I have to read, I now much prefer informative texts, so all those detailed PDF essays about speaker theory are very attractive to me. However I don't know if I'll read them thoroughly within the near future. But that doesn't matter, I like to save good things on my harddrive, so whenever needed, I'll have a nice "offline library" 😀 Thank you for the link!
(It's also good if you point me into the right direction which PDFs are helpful for me specifically. Because honestly, most websites on speaker theory feature many essays, yet I don't know which one is helpful for me)
Holy moly, did you already run a simulation that resulted in a building plan?! If so, that was quite fast! Thank you so much!
I know the 4" won't go down low much, but a) neither do my current dekstop speakers, and b) I don't even want to when listening to music when working. For that, I have BIBs or the magnificent double mouth horns from the spawn family. I built them with the currently available FE206NV, and they perform beautifully. As I said, if you have a paypal or something like that, please send me a message, I'd like to give a tip 😀 (the forum says I can't send you a message)
A pleasure; hope it'll be of some use for you. 🙂 I quite like these desktop labyrinth alignments -they're usually a reasonable size, and give some tuning flexibility. The existing ones seem to have been liked by their builders anyway, which is what counts!
Apologies, I've got the forum PMs switched off, but you can find me via the contact link on my & Dave's website www.wodendesign.com
Apologies, I've got the forum PMs switched off, but you can find me via the contact link on my & Dave's website www.wodendesign.com
They definitely will be! Started putting them together the day before yesterday. I only had 3 clamps in the right size, so I had to glue 1 or 2 pieces at a time, then wait for a bit, ha. But I just chugged along and had both cabinets themselves ready on the same day.
Yesterday I added the damping, soldered the wires, added the speakers and glued the enclosures shut. Had them sit for the night and tried them today. Damn do they sound good! my office-room is a little smaller and they sound beautifully both when sitting in front of them working on the PC, and also when sitting on the desk doing paperwork.
I guess I'll give the active speakers to someone in the family, then. They are retired as far as I'm concerned, heh 😀