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INDIY 2024 pentapath TL project


This is my design for Ft, Wayne in the spring a 2 1/2 way with SB drivers. The upper woofer operates in a large fiber and foam damped coupling chamber feeding into the two outtermost lines which have a taper ratio of 3 or 4. This will provide excursion control at and also below the tuning frequency. I do not expect much output at all from those 2 exit ports. The lower woofer will provide baffle step cmpensation. It will have no coupling chamber to speak of and will utilize the 3 middle lines. I plan to use only foam behind this woofer to absorb the higher frequency waves. Supression of the overtones in the line will hopefully be attenuated sufficienty by the combined effect of the three paths. Theese three lines will contain no fiber in order to maximize the low frequency reinforcment from the terminus. SB29rdnc neo tweeter and 2ea. SB15nrx2c30-8 woofers.

Silver1omojohnny5jzWolf4thtryjr@macSteve_Leejhollander
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Comments

  • edited December 2023

    Very interesting! Not an egg though....

  • i dont want to be a one trick pony horse soldier

    Steve_Leejhollander
  • Very interesting concept. And it looks really cool! I had to look at your drawing for a while to figure out what you are doing. I would think that this should work to average out the peaks and dips. The challenge will be to get the peaks and dips of the various TL's to align and properly average out once the cabinet is completely assembled. Good luck.

  • Thanks Bill, I am also hoping that Ben will get so frustrated trying to figure gross volume, due to its irregular shape, that he will give up and deem me as being qualified.

    jr@mac4thtrySteve_Leeugly_wooferrjj45
  • Awesome design concept!

    I have a signature.
  • I wish I had more artistic ability. Nothing I've built comes close to those curves.

  • While you were taking silly subjects like physics and calculous, I was taking Art and cooking classes Craig.

    jr@macPWRRYDhifiside4thtrySteve_Leerjj45jholtzTom_SScottS
  • Cut some internal dividers last night for my stupidly complicated project. Although it is not a very efficient way to use materials, I think that not having abrupt folds is a good way to minimize turbulence in the line. I am not sure how beneficial that is but it's better than nothin.

    jr@macjhollandersilverDtajanes4thtryWolfhifisideugly_wooferSilver1omo6thplanetand 3 others.
  • Cool. Saxophone profiles? This will probably sound pretty good when assembled! :+1:

    hifisideSteve_Lee
  • Didn't know Eggman had a CNC.... how'd I miss that?

    Steve_Lee
  • Must be nice.

    Steve_Lee
  • smooth and rounded is very cool - but recently Martin J King was asked a question about "sharp" corners in a folded TL. He has some sort of laminar flow modeling software, and he said that it looked like the turbulence at a sharp corner was responsible for dampening some of the peaks. Brian Steele did some analysis, and suggests that the width of the "turn" is related to the frequency of the effect. Hope I described that accurately!

    Steve_Lee
    But Chahly - Stahkist don't want speakers that look good, Stahkist wants speakers that sound good!
  • @rjj45 said:
    smooth and rounded is very cool - but recently Martin J King was asked a question about "sharp" corners in a folded TL. He has some sort of laminar flow modeling software, and he said that it looked like the turbulence at a sharp corner was responsible for dampening some of the peaks. Brian Steele did some analysis, and suggests that the width of the "turn" is related to the frequency of the effect. Hope I described that accurately!

    That's interesting. I love me some Martin J King.

  • @Wolf said:
    Didn't know Eggman had a CNC.... how'd I miss that?

    Guess you didn't ask

    Steve_Leerjj45
  • Upon further consideration, I do see how the abrupt folds commonly seen in TL's might provide some attenuation of the overtones, but not without also attenuating the fundamental. If the goal is to preserve as much of that fundamental1/4 wavelength pressure wave as possible, I would not choose turbulence as a means of taming the overtones. And I would not use fiber stuffing either. I read somewhere that fiber stuffing in the line introduces a viscosity of sorts, a resistance to flow. This makes sense to me because fiber stuffing works so well as a thermal insulator by resisting the flow of convective air currents. Increasing the taper ratio does several things. It increases effective length, good, while reducing the terminus output somewhat, bad, but its greatest effect is on those overtones. In reduced amplitude, yes, but even more so, the frequencies at which they occur. That first overtone, which is horrendous, In a non tapered line occurs predictably at 3 times the fundamental. In a line with a fairly high taper ratio, say 8 or 9, now is pushed up in frequency an octave or more. The multi-taper line works similarly to multiple subwoofers in a room. It creates more modes or overtones, but with much lesser severity. Damping without damping material. While I was laying on a beach in Florida with my wife I was thinking about speakers, weird I know, I noticed as the waves came in, they would encounter an ever decreasing space in which to travel. Friction from the ocean floor would drag down its movement and cause the upper portion of the wave to break over. I wonder if something like that might be happening inside these spirals that I have been making? I know from an early version, when I missed my target tuning frequency that putting some sonic barrier AB-4 open celled foam on the outer wall lowered my tuning frequency by nearly 20 percent. So I like to imagine the pressure waves inside my egg speakers gently rolling as they travel along without a lot of white caps "turbulence". And after their short and pleasant journey, they release a portion of their constructive energy for the world to enjoy. But due to an acoustic impedance mis-match, there is an inversion, I believe, of the energy reflected back down the line where after another short journey, it meets Its creator and helps to ease the creators burden of producing more pleasantries.

    6thplanetSteve_Lee
  • So the creator is obviously the woofer. The burden is excursion. The pleasantries are low frequency sounds with minimal group delay. And the reason is pain meds

    ugly_wooferSteve_Lee
  • You should smack your thumb with a hammer more often.

    rjj45
  • Speaker Sunday means prefinishing parts before assembly. I wonder what the record is for the worlds longest baffle board

    DrewsBrewshifiside4thtrySteve_Leetajanesjohnny5jzjhollandersilverDugly_wooferSilver1omoand 1 other.
  • Steve says WTF. I think that stands for Wow that's fantastic

  • edited March 4

    Actually it means, "Wow, That (better be) Flexible" to bend around all those French Curves.

    Your optimism and art are entertaining - keep it up.

  • That's french for, I hope so too because I'm kinda just making this shit up

    Steve_Lee6thplanet
  • Looks OK from a distance. But that's about it. Impedance sweeps revealed leaks and buzzing. It's Difficult to solve the mysteries of the universe with a brain that was designed to pick up nuts off of the forest floor.

    jhollanderSteve_LeeSilver1omosilverD6thplanetTurn2jr@mac4thtryhifisideGowaand 1 other.
  • Pretty cool that baffle fits inside. I imagine it takes 5 hands to assemble :)

     John H, btw forum has decided I don't get emails
  • Those look really sharp! Like how you stained them.

  • edited March 5

    Yep I'm still pickin up nuts compared to this guy flying his UFO over my head.

  • Truly outstanding!
    Bravo!!

    J'ai l'applaudissement

  • Still kinda hard to imagine what's actually going on, but it looks neato! How tall is it?

  • Just under 3 feet tall

  • Apparently, "I applaud you" and "I have the clap" are enunciated the same in French while in English they make a distinction that the French obviously take no issue with.

    Language is educational . . .

    6thplanetEggguyEd_Perkins
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