Closed Thread
Page 3 of 5 FirstFirst 1 2 3 4 5 LastLast
Results 31 to 45 of 64

Reload Thread: T line build for Megalomaniac

  1. #31
    rollerdj's Avatar
    rollerdj is offline Low End Master



    Join Date
    Nov 2006
    Location
    Bloomington IN
    Posts
    4,570
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    0 Post(s)

    Re: T line build for Megalomaniac

    how much power is it seeing?



    Car- Nissan Sentra Spec-V
    HU- Kenwood Excelon XXV-01D
    Front stage- Stock for now
    Amps- Sundown Audio SAZ-1500D
    Substage- Single 12" Sundown X12 Prototype
    Box- 1.75ft^3 Sealed


    "Watch the ***** flying twards you, i'm not kidding."
    http://www.youtube.com/watch?v=OWm0C5zxVPw

    nope, he wasn't kidding! lawl




  2. #32
    Join Date
    Dec 2005
    Location
    The Colony, TX
    Age
    25
    Posts
    8,124
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    0 Post(s)

    Re: T line build for Megalomaniac

    not much right now. maybe 40 watts off a plate amp. I have not decided on what amp to buy.

    Im thinking about doing 3 way towers. the eu's will be still Tlined, and use a B&G planar and an Adire Extremis for the mids and highs.



    Quote Originally Posted by Second Skin Rep View Post

    so in closing...
    Don't punch babies..

    ANT
    www.secondskinaudio.com

  3. #33
    rollerdj's Avatar
    rollerdj is offline Low End Master



    Join Date
    Nov 2006
    Location
    Bloomington IN
    Posts
    4,570
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    0 Post(s)

    Re: T line build for Megalomaniac

    yumm. i've been thinking about doing another build for HT using planar tweets. but god are they pricey.



    Car- Nissan Sentra Spec-V
    HU- Kenwood Excelon XXV-01D
    Front stage- Stock for now
    Amps- Sundown Audio SAZ-1500D
    Substage- Single 12" Sundown X12 Prototype
    Box- 1.75ft^3 Sealed


    "Watch the ***** flying twards you, i'm not kidding."
    http://www.youtube.com/watch?v=OWm0C5zxVPw

    nope, he wasn't kidding! lawl

  4. #34
    mobeious's Avatar
    mobeious is offline what does 0hz feel like?



    Join Date
    May 2004
    Location
    Bartow, FL
    Posts
    4,839
    Post Thanks / Like
    Images
    26
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    2 Post(s)

    Re: T line build for Megalomaniac

    thats not a a T-line just a ported box with a really long port... good try looks good



    Alpine CDA-9833
    (2)sets Cresendo ccx65


    Box Engineer for

  5. #35
    IDSkoT's Avatar
    IDSkoT is offline Resonating Reticular



    Join Date
    Jan 2008
    Location
    Miami, Florida
    Posts
    6,274
    Post Thanks / Like
    Images
    2
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    0 Post(s)

    Re: T line build for Megalomaniac

    Quote Originally Posted by mobeious View Post
    thats not a a T-line just a ported box with a really long port... good try looks good
    That's basically what T-lines are. Though, I have to agree it doesn't look very T-liney.



    Now designing / building boxes.
    (Only building sealed and aero port boxes.)
    PM me.

    Feedback Thread

    Refs: MSW Danny, atsaubrey (great seller), ampjunkielikeme, wgsj_fortvalley, tEh koRnDog, bad @SS chevy, Nismos14 (who is the man. )



  6. #36
    mokedaddy's Avatar
    mokedaddy is offline professional idiot



    Join Date
    Apr 2005
    Location
    Siccmade house
    Age
    35
    Posts
    4,902
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    0 Post(s)

    Re: T line build for Megalomaniac

    It depends on who you ask whether it is a t-line or not.

    By definition it isnt since the port appears to be uniform width across the whole port, but it will still, for the most part, act as a t-line does.

    Nice build tho. Craftsmanship looks top notch.



    'a man without enemies, is a man without character'


  7. #37
    Join Date
    Dec 2005
    Location
    The Colony, TX
    Age
    25
    Posts
    8,124
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    0 Post(s)

    Re: T line build for Megalomaniac

    it is a tline

    the qts of the eu is .28, its a bit low for a tline, so you have 2 obvious options either add a compression chamber or tune higher (no more than 5-10hz above fs).This design needed both if I wanted to keep it a straight line. Polyfil will help the response curve substantially, its a matter of trial and error now for me.


    btw its a straight tline not a tapered tline(which is why the port is uniform accross)



    Quote Originally Posted by Second Skin Rep View Post

    so in closing...
    Don't punch babies..

    ANT
    www.secondskinaudio.com

  8. #38
    mokedaddy's Avatar
    mokedaddy is offline professional idiot



    Join Date
    Apr 2005
    Location
    Siccmade house
    Age
    35
    Posts
    4,902
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    0 Post(s)

    Re: T line build for Megalomaniac

    Its a hybrid t-line if you want to get specific.

    1/4 wave does not necessarily equal a t-line.



    'a man without enemies, is a man without character'


  9. #39
    rollerdj's Avatar
    rollerdj is offline Low End Master



    Join Date
    Nov 2006
    Location
    Bloomington IN
    Posts
    4,570
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    0 Post(s)

    Re: T line build for Megalomaniac

    lawl, i don't care what it's called. looks cool to me.



    Car- Nissan Sentra Spec-V
    HU- Kenwood Excelon XXV-01D
    Front stage- Stock for now
    Amps- Sundown Audio SAZ-1500D
    Substage- Single 12" Sundown X12 Prototype
    Box- 1.75ft^3 Sealed


    "Watch the ***** flying twards you, i'm not kidding."
    http://www.youtube.com/watch?v=OWm0C5zxVPw

    nope, he wasn't kidding! lawl

  10. #40
    Join Date
    Dec 2005
    Location
    The Colony, TX
    Age
    25
    Posts
    8,124
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    0 Post(s)

    Re: T line build for Megalomaniac

    Quote Originally Posted by mokedaddy View Post
    Its a hybrid t-line if you want to get specific.

    1/4 wave does not necessarily equal a t-line.
    you can thank eD for having silly specs on the driver



    Quote Originally Posted by Second Skin Rep View Post

    so in closing...
    Don't punch babies..

    ANT
    www.secondskinaudio.com

  11. #41
    mokedaddy's Avatar
    mokedaddy is offline professional idiot



    Join Date
    Apr 2005
    Location
    Siccmade house
    Age
    35
    Posts
    4,902
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    0 Post(s)

    Re: T line build for Megalomaniac

    Quote Originally Posted by Megalomaniac View Post
    you can thank eD for having silly specs on the driver
    Old school t-lines are crazy stupid to design and just about impossible to model. Thus the reason hardly anyone uses them anymore. That is why there are now variations in 1/4 wave designs such as the uniform width ports and compression chambers.

    I would love to hear it though and see how that particular design would compare to a more traditional t-line that I made long ago.



    'a man without enemies, is a man without character'


  12. #42
    RAM_Designs's Avatar
    RAM_Designs is offline SketchUp Master



    Join Date
    Feb 2006
    Location
    Rockwall, TX
    Age
    29
    Posts
    21,044
    Post Thanks / Like
    Images
    1
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    440 Post(s)

    Re: T line build for Megalomaniac

    ^^^I'm curious how it sounds too.



    1,400+ designs since March 2011...
    I have my PM's turned off, please email at [email protected]

  13. #43
    Immacomputer's Avatar
    Immacomputer is offline Cloud disappear



    Join Date
    Sep 2006
    Location
    Ocala/Oviedo, FL
    Age
    30
    Posts
    4,670
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    12 Post(s)

    Re: T line build for Megalomaniac

    Quote Originally Posted by mokedaddy View Post
    Old school t-lines are crazy stupid to design and just about impossible to model. Thus the reason hardly anyone uses them anymore. That is why there are now variations in 1/4 wave designs such as the uniform width ports and compression chambers.

    I would love to hear it though and see how that particular design would compare to a more traditional t-line that I made long ago.
    They're really not too difficult to design and to model. Martin J. King has done excellent work in the area of transmission lines and horns and has uncovered much of their mystery. His matlab simulations are pretty good at modeling transmission line behavior. I was able to get accurate models of not only the transmission line enclosure for my sub, but I was also able to get an accurate model of the sub when in my vehicle. It predicted one peak at 22hz and a dip at 30hz with a passband of 15-70hz and that's very similar to what I measured.

    Transmission lines are not mysterious and they're not uncommon. They have been used for thousands of years. And transmission lines do NOT have to have a taper for them to act like a transmission line. The changing of line area from the open end to the closed end is a way of limiting the upper order harmonics of the 1/4 wave resonance to smooth out peaks and valleys in the frequency response.

    Quote Originally Posted by mobeious View Post
    thats not a a T-line just a ported box with a really long port... good try looks good
    If that is the case, then there has to be reduced cone movement at tuning right? The enclosure on my sub is very similar to this one in that it is a transmission line with a compression chamber. The tuning frequency if you were to calculate it as a ported enclosure would be around 35hz like this one. The problem is that I actually have a maximum of cone movement around 35hz and a minimum around 22hz. The sub also doesn't come anywhere near to unloading below 35hz and on the contrary, has quite a bit of acoustic loading controlling the cone below 35hz. Doesn't sound like a ported enclosure with a long port to me. Something else interesting is that when I model it using Martin J. King's t-line sections mathcad file, it tells me there should a cone movement minimum at 22hz and line velocity max at 22hz as well but it doesn't when trying to model it like a ported enclosure with his ported enclosure mathcad file.

    Quote Originally Posted by mokedaddy View Post
    Its a hybrid t-line if you want to get specific.

    1/4 wave does not necessarily equal a t-line.
    Both of you have a fundamental flaw in your understanding of transmission lines. Every port in every enclosure has transmission line characteristics at certain frequencies. It's effects aren't normally noticed in subwoofer enclosures because they need to be very long to have transmission line characteristics (over 60" to get a 1/4 wave of 60hz... when is the last time you've used a 60" long port?). In this case, there will be some effects of a ported enclosure but the ported tuning frequency is equal to the 1/4 wave frequency which will dampen the oscillation of the port. Also, the air mass ratio of the port to net volume is far too large for the net air mass to effectively drive the port. Instead, the compression chamber will rise in pressure and try to drive the port. As the pressure from the chamber starts to compress the port, the inertia of the port air mass will reject this change and the pressure heading down the line will decrease but the velocity of the air will increase. That's also the exact same thing that happens in a transmission line enclosure.
    Last edited by Immacomputer; 11-19-2008 at 01:30 AM.



    Video 1
    I may make you feel but I can't make you think.
    Your sperm's in the gutter -- your love's in the sink.
    Video 2

  14. #44
    sqhertz's Avatar
    sqhertz is offline CarAudio.com Veteran



    Join Date
    Sep 2006
    Location
    Miami ,Fl
    Posts
    5,638
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    3 Post(s)

    Re: T line build for Megalomaniac

    i poop t-lines.




    btw, it looks good.





    - Ref.s -
    ssbogger , derek9087 , mike dressure , xluben , brocken , QtrHorse , marley1 , byoon001 , IonSQL , Duke , TheBaron929 , SiX , Andar , blackbonnie , SPLV , dbaudio , dillinja666 , 97cavy , dropkick13 , TeamPSI , foreman , integra88 , bangincaraudio , spinelli , gkatmar , MustangGT25YRS , stockgp , FASTIMES , ultimate157 , Reson8 , vitveet , req


  15. #45
    mokedaddy's Avatar
    mokedaddy is offline professional idiot



    Join Date
    Apr 2005
    Location
    Siccmade house
    Age
    35
    Posts
    4,902
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    0 Post(s)

    Re: T line build for Megalomaniac

    Quote Originally Posted by Immacomputer View Post
    They're really not too difficult to design and to model. Martin J. King has done excellent work in the area of transmission lines and horns and has uncovered much of their mystery. His matlab simulations are pretty good at modeling transmission line behavior. I was able to get accurate models of not only the transmission line enclosure for my sub, but I was also able to get an accurate model of the sub when in my vehicle. It predicted one peak at 22hz and a dip at 30hz with a passband of 15-70hz and that's very similar to what I measured.

    Transmission lines are not mysterious and they're not uncommon. They have been used for thousands of years. And transmission lines do NOT have to have a taper for them to act like a transmission line. The changing of line area from the open end to the closed end is a way of limiting the upper order harmonics of the 1/4 wave resonance to smooth out peaks and valleys in the frequency response.



    If that is the case, then there has to be reduced cone movement at tuning right? The enclosure on my sub is very similar to this one in that it is a transmission line with a compression chamber. The tuning frequency if you were to calculate it as a ported enclosure would be around 35hz like this one. The problem is that I actually have a maximum of cone movement around 35hz and a minimum around 22hz. The sub also doesn't come anywhere near to unloading below 35hz and on the contrary, has quite a bit of acoustic loading controlling the cone below 35hz. Doesn't sound like a ported enclosure with a long port to me. Something else interesting is that when I model it using Martin J. King's t-line sections matlab file, it tells me there should a cone movement minimum at 22hz and line velocity max at 22hz as well but it doesn't when trying to model it like a ported enclosure with his ported enclosure matlab file.



    Both of you have a fundamental flaw in your understanding of transmission lines. Every port in every enclosure has transmission line characteristics at certain frequencies. It's effects aren't normally noticed in subwoofer enclosures because they need to be very long to have transmission line characteristics (over 60" to get a 1/4 wave of 60hz... when is the last time you've used a 60" long port?). In this case, there will be some effects of a ported enclosure but the ported tuning frequency is equal to the 1/4 wave frequency which will dampen the oscillation of the port. Also, the air mass ratio of the port to net volume is far too large for the net air mass to effectively drive the port. Instead, the compression chamber will rise in pressure and try to drive the port. As the pressure from the chamber starts to compress the port, the inertia of the port air mass will reject this change and the pressure heading down the line will decrease but the velocity of the air will increase. That's also the exact same thing that happens in a transmission line enclosure.
    He has done great work, I have read a couple of his articles. And no they arent nearly as complicated as designing horns but it does take a great deal of trial and error to get the most of out them.

    So have you ever frequency tested a compression chamber and a traditional tline in a vehicle? I would be willing to bet they arent the same. Most likely close but due to differences in driver vs port placement they will vary. That was my only point. It may 'act' the same but wont be the exact same. Thus the variations of 1/4 wave enclosures.

    To me its like saying ap would be the same thing as id since in theory they produce the same results, but arent necessarily the same thing. Yes its semantics but im bored.



    'a man without enemies, is a man without character'


Closed Thread
Page 3 of 5 FirstFirst 1 2 3 4 5 LastLast

User Tag List

Posting Permissions

  • You may not post new threads
  • You may post replies
  • You may not post attachments
  • You may edit your posts
1e2 Forum