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About bbeljefe

  • Birthday 09/20/1968

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    Shreveport, Louisiana
  • Interests
    Motorcycling, audio, fishing, audio, women, audio, drinking, audio, philosophy, audio, speaker building, audio. Oh and, I also like anything to do with reproducing music...

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  1. Also, I have a t-line page on Facebook where much of what you mentioned is discussed by myself and others. It may be of some use to you as well. https://www.facebook.com/groups/990108914350137/
  2. Tapers don't improve sound quality in as much as I'm aware but frankly, since I haven't done a controlled comparison between tapered, consistent and horn lines I can't say that with any real authority. But I have built a lot of t-lines for drivers ranging from 3" to 18" and for sub bass as well as full range audio and I've never found any appreciable sound quality loss from any particular deviation from convention. That said, tapers do tend to produce higher SPL than consistent dimension lines but as with anything, there is always a compromise. That compromise has been in the increased potential for "vent" noise, which is why I caution to maintain a 2:1 ratio that starts with full Sd or more. Other than that I haven't noticed any problems with tapers and I've done them for both subwoofers and full range loudspeaker systems. As for the presence of wave guides (typically called 45s), I'm not altogether sure the importance of their roles, again owing to a lack of controlled comparison. I have, however, seen and heard a line that had no wave guides and while the system was definitely loud, it wasn't the best sounding setup. But I have to add the caveat that I didn't do any critical listening to it either. Of course, the vehicle that line was in is an older SUV with NO deadener and not much in the way of front stage presence so the poor sound quality could easily be blamed on rattles and poor frequency response because I'm definitely keen on the importance of sound quality. As far as the importance of being precise with wave guides I don't see the utility in spending a lot of time making sure they're perfectly rounded or exactly the right size to make the line "perfect" either. I've built a few lines (not for paying customers) where I was only concerned with speed and saving materials and in those cases the wave guides were all just scraps that came close to being the correct size and I couldn't complain about the sound quality from them so that's the evidence I have for these comments, for whatever it's worth. Measuring a line is no different than measuring a port, in that the center line of the cavity is the actual measurement. So, making your wave guides smaller won't change the length but, the worst thing that could happen by doing so (in my opinion) would be that you may create some turbulence in the line. But again, I think that would be minimal if audible at all. I haven't found the number of bends to affect the SQ of a line but physics kinda tells me that there is a point at which it would negatively affect the sound quality but that's probably a lot longer than we'd ever see in car audio. Not to mention, some early iterations of t-lines in commercial audio are very large and long and they sounded amazing. Using the sealed volume rule of t-line design as well as the recommendations for driver suitability for a line is in my opinion, pedantic, when we're talking about sub bass lines. Such is the same for obsessing over wave guides, as bass is much less localizable than high frequencies and slight variations from "perfect" performance will be inaudible. This is why I always say that a line is the absolute best alignment for a driver, regardless its particular TS specs. And the only exception to that "rule" is in purpose built SPL applications. Lastly, here's a thread with pictures of a lot of the lines I've built. I haven't updated it since January and I don't take many pictures of a lot of the basic enclosures I build so this isn't a complete representation of all the lines I've done but there's a good variety represented. http://www.stevemeadedesigns.com/board/topic/202121-random-t-lines-from-audio-anarchy/?hl=+audio%20+anarchy
  3. I'd maintain an 8:1 ratio, which is the same you should respect in slot ported enclosures to avoid compression. And no, you do not have to tune at Fs but I'm not a fan of tuning above Fs as the boxes I've done that were didn't impress me. But I don't like peaky bass, I like bandwidth so there's that. Also, you can reduce the line area and save some space while also lowering the tuning of the line. I don't know how to calculate the decrease in tuning frequency but I've had a lot of success with reducing line area and having a clean sounding line. Just stay at or above 60% of Sd and you'll be happy. Tapers also lower tuning and they increase the number you'll get on the meter, if that matters to you.
  4. I concur. And while I have Hornresp, I don't use it. Probably because I'm too mathematically stupid to learn it, lol. But mostly because I have only built a couple of lines that didn't perform as I expected so, there isn't a lot of priority in my mind for learning the mathematics associated with them. That said, I'm doing some self education on physics and it's pretty fucking interesting so I would imagine the math will get easier for me. I've never been one who can be forced to learn something. I have to have an interest in the subject matter before I can internalize it. Another thing that's kinda mind boggling to me is the mythology that designing lines is somehow difficult. Granted, you can make it as difficult as you like but at the same time, they are to me the easiest enclosures to calculate and built... and I came from a background of building a lot of 6th orders before I learned about t-lines. You'd have to have either a gun or a lot of money to get me to design and built a 6th order now, lol.
  5. It sounds the best it can sound. Can you tell me a little more about what the op was saying about eq'ing the frequencies? Also he said that if you tune the box the speakers fs that it will sound the best that the sub possibly can. What happens if i go over or under the fs? I disagree with that portion of the OP and only because my experience is different. For a full range loudspeaker I keep with the Fs of the driver but for subs, I normally tune below Fs. Especially high power handling car audio subs, which usually have an Fs above 34. My go to frequency for car audio lines is 30Hz and it works every time. The reason, I think, that people persist with the myth that a driver has to have this or that TS properties, that the line must be stuffed, that low power is necessary, et al, is that the majority of scholarly work on lines has been done using home audio drivers with the goal of an ideally flat response curve. Such is simply not the case for us car audio bassheads, lol.
  6. No you don't. All you have to know is how to calculate line area and tuning, which is infinitely more simple than calculating a conventional vented or bandpass enclosure. I've built lines with reduced area, oversized area, without wave guides, tuned above Fs, tuned below Fs and not one of them was "bad". You may build a line that performs less well than it could but you'd be hard pressed to build one that sucked. ok, so if I built one that just had a simple constant area, would that make it a "one note wonder"? Also, I'm a little confused about the method of tuning to the bass boost freq and how the woofers fs correlates with that, if I did that would that mean that it would have a flatter response at and below the tlines tuned freq? Maybe I'll give it a shot with a constant 15x6 port for starters and see how it goes. I just don't wanna risk the time/money but sometimes ya gotta, right? Thanks I've never heard a line with that narrow a bandwidth. And I have no idea what you mean by tuning to bass boost frequency so I can't speak to that. As for tuning to Fs, that's the starting point, not the only point. If you're building a line for the purpose of pure sound quality or if you're building a full range loudspeaker, tuning at Fs is important. But if you're building a subwoofer line, with a typical high Fs car audio sub that performs well at lower frequencies, tuning below Fs is a good idea. And the loss of upper end frequency response will be negligible.
  7. No you don't. All you have to know is how to calculate line area and tuning, which is infinitely more simple than calculating a conventional vented or bandpass enclosure. I've built lines with reduced area, oversized area, without wave guides, tuned above Fs, tuned below Fs and not one of them was "bad". You may build a line that performs less well than it could but you'd be hard pressed to build one that sucked.
  8. Okay, got the box built and tested. I'm loving these little crickets more and more every time I do something with them....
  9. Well I got the box built but we only had four of them in stock and Big E sold two of them on Saturday, lol. I have some more on the way though and the box is done so I should have video up on it by Wednesday. Here's the box for four...
  10. I don't know that I'd want to put subs in a door, unless it was an older vehicle with nothing much in there to get in the way because it'd take some work to stabilize that enclosure for sub bass, lol. But it would be pretty cool.
  11. The TW switch is tweeter level. 0db is flat or, full power to the tweeter. -3 & -6db are attenuated settings, in case the tweeter sounds too bright. Mid is the same for the midbass driver. It attenuates the midrange if your midbass doesn't sound right... which is pretty common in doors that aren't properly deadened and sealed. The unlabeled switch is the crossover slope. It changes how much attenuation there is outside the crossover frequency. Set at 12db means that the frequencies outside the crossover frequency will be attenuated 12db per octave. Likewise for 18. There is no "right" or "wrong" setting with the crossovers, there is only what sounds best and what keeps the speakers from breaking up or being over driven. Oh and, those are nice sounding components. You'll enjoy them.
  12. It doesn't have them yet but yes, it will have two squirrel cage fans when we install the second 4500. And thanks!
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