Cheers Dave
Crikey, so the line has to be matched exactly to the Fs - and the length of the closed line, is it measured on the half wave going to the end and returning.. or just one way? 3am, not explaining myself well, apols
Crikey, so the line has to be matched exactly to the Fs - and the length of the closed line, is it measured on the half wave going to the end and returning.. or just one way? 3am, not explaining myself well, apols
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1/2 wave is 1-way. And it changes if the line is tapered. This Natilus prototype can be shorter because of the taper.
dave
dave
If it helps, Bob Brines has a discussion about traditional TLs here: Traditional Transmission Lines and here: Small TL's In the 2nd article linked he notes "Small and TL is a relative thing. A TL enclosure will almost always be the largest option for a given driver".
I'm not sure why you'd want to use a TL but hey, much better people have used them than me. For example Nelson Pass used an open-ended one for the Pioneer B20 (BOFU) driver here: http://www.diyaudio.com/forums/full-range/60632-pioneer-8-fun.html?perpage=25&pagenumber=3
I'm not sure why you'd want to use a TL but hey, much better people have used them than me. For example Nelson Pass used an open-ended one for the Pioneer B20 (BOFU) driver here: http://www.diyaudio.com/forums/full-range/60632-pioneer-8-fun.html?perpage=25&pagenumber=3
Thanks for your replies
I came up with a design a few months ago(see model pics) which wd use two small FR units in a tapered double TL (and a small sub at it's base).
I wanted to use the little spiderless Jordans (which normally use a sealed box as a suspension). I am hoping a closed TL is a good solution and may also add some benefits.
I came up with a design a few months ago(see model pics) which wd use two small FR units in a tapered double TL (and a small sub at it's base).
I wanted to use the little spiderless Jordans (which normally use a sealed box as a suspension). I am hoping a closed TL is a good solution and may also add some benefits.
Attachments
It is, though as already noted it will have to be end loaded 1/2 wave (AKA plane wave tube (PWT)) to keep from having to excessively stuff it to damp its 1/4 WL resonances.
That said and without any detail technical or hands on knowledge of these drivers, IME it will damp them so well if properly designed that they may only be usable over a relatively narrow BW, requiring either a tweeter or CD horn EQ that will significantly reduce its effective efficiency.
As you increase net Vb to allow it to 'breathe', you quickly revert back to being just a near I.B. loading, so of limited use beyond cosmetic.
GM
Hm ok, so in general closed TLs offer some benefits but are effectively narrow bandwidth, hence why the nautilus was 4 way?
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Probably a badly thought out question, but anyhow, do we build the half-wave TL in accordance with the drivers free air fs or, since the driver will effectively be performing in a closed box, do with build to the closed box fs (having found the approximate volume of the closed TL enclosure)? My MJK sheets expired a long time ago 🙁
True, the design wouldnt have looked right otherwise. I'm a bit gutted if I can't use a single closed TL between 175 hz - 20khz .. thought that was the answer to my prayers.
Tapering shape and volume and lenght???
Hi.
(1.25-2)Sd suggested beginning cross sectional area.
Length is 340/2f meters.
While tapering The tube, Is there any restrictions about VOLUME?
Supravox 165lb:
Sd:165cm2
Fs:64hz
Vas:42L.
When I calculated The straight closed end pipe Volume is about 46L.
It is some kind of infinite baffle.
340m/s is The speed of Sound.I think stuffing also affect this Value.
How do tapering effect The lenght?
Is there any equation to calculate The lenght when tapering being used?
(Lets say simple tapered shapes used to calculate easily).
Lets say we use use tapering wrt fibonacci serie.
??
1/2 wave is 1-way. And it changes if the line is tapered. This Natilus prototype can be shorter because of the taper.
dave
Hi.
(1.25-2)Sd suggested beginning cross sectional area.
Length is 340/2f meters.
While tapering The tube, Is there any restrictions about VOLUME?
Supravox 165lb:
Sd:165cm2
Fs:64hz
Vas:42L.
When I calculated The straight closed end pipe Volume is about 46L.
It is some kind of infinite baffle.
340m/s is The speed of Sound.I think stuffing also affect this Value.
How do tapering effect The lenght?
Is there any equation to calculate The lenght when tapering being used?
(Lets say simple tapered shapes used to calculate easily).
Lets say we use use tapering wrt fibonacci serie.
??
You should try to preserve volume
If the line tapers towards a point, the line can be shorter. It is an attempt at an IB but smaller with the intent of the long, well-stuffed line to absorb the entire backwave.
Does not significantly effect the speed of sound.
There are simulators, they are usually used for ¼ wave lines, don’t know how they handle ½ wave lines.
dave
Sorry But I couldn't understand.
If I should preserve Volume while tapering,I should start with bigger starting cross sectional area to obtain same Volume?
I started to think Volume(closed) is only related to ordinary closed box(air suspension or infinite).
And lenght should be FIX is 340/2f meter?
If use symetrical shape Volume, can I use The middle line For calculations?
Lets say we reduce The Volume to acoustic suspension volume and leght is The SAME.
Is it still possible to eliminate the ALL backwaves like the big Volume we started?
Is it still possible to eliminate the ALL backwaves like the big Volume we started?
The thing is, a well damped 1/4 wave open TL actually works very well. The experts can advise on taper. If you like complexity, make a BLH.
I also like The Mr.Tetsuo Nagaoka 'Hasehiro back loaded horns' Design.
But I am still chasing my questions.My brain isn't there 🙂
Yes. The line can be shortened because th etaper bunches up the harmonics.
Bass response will be much the same as the driver in the available volume.
You can, but it really should shorten a bit from that. How much depends on the amount of taper.
dave
So can we assume Volume will be enough to break The air spring and The lenght will be 340/2f meter(tapering shorten this lenght).
It is pretty big enclosure For full range and woofer Drivers.
If I crossover The woofer at 200hz I can use full range Driver in The closed TL with managable size..
Can I ask a question out of this subject?
There are golden ratio enclosures in your site.
How do you classify them?(some kind of ported maybe?)
Thanks!!
It is pretty big enclosure For full range and woofer Drivers.
If I crossover The woofer at 200hz I can use full range Driver in The closed TL with managable size..
Can I ask a question out of this subject?
There are golden ratio enclosures in your site.
How do you classify them?(some kind of ported maybe?)
Thanks!!
Net volume [Vb] determines how much output it will have and its length the tuning, so reduce Vb reduces available [mid] bass output and in general a TL's Vb needs to be anywhere from 4-10x Vas to get good bass output, so if you start at a closed point and need a 100" line, then the driver baffle area at the open end will be whatever is necessary to get the desired Vb.
IOW, if you make a TL's Vb = required for AS, then better overall to just make an AS box.
GM
IOW, if you make a TL's Vb = required for AS, then better overall to just make an AS box.
GM
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