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Forevrbumpn

Quarter Wave / T-Line tutorial-UPDATED

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:^ VERY INFORMATIVE AND PRECISE. I LIKE- ILIKE!!

I'M IN ORLANDO WITH A CREW CRAB F-150 WITHOUT THE REAR SEATS. I HAD A WALL WITH 4 15 AUTO-TEK DUAL 4 OHM 15'S RUNNING OFF 1 AUTOTEK MEAN MACHINE 3000.1. I GOT TIRED OF THAT SET-UP AND SOLD IT. NOW I HAVE 2 RF T2000.1'S TO RUN 2 18'S(NOT SURE WHICH SUBS) THINK I HAVE ENOUGH SPACE TO GET A T-LINE ENCLOSURE FOR TWO 18'S??? KEEP N MIND I HAVE A 4 DOOR CREW CAB F-150 WITHOUT THE REAR SEATS, IF SO I'LL BE WILLING TO PAY FOR IT.

Positive you can do 1 in there, but 2? doubt it. Unless you tune it high, with a high eq boost, maybe in the 50hz range. Ofcourse a cut thru is a different story. Look at the cut thrus Ray did, those were really nice, and took up the bed, can you imagine the pressure in that cab?


sundown.jpg
I have a ritual called "terminator". I crouch in the shower in the "naked terminator" pose. With eyes closed I crouch for a minute and visualize either Arnie or the guy from the 2nd movie. I then start to hum the T2 theme. Slowly I rise to a standing position and open my eyes. It helps me get through my day. The only problem is if the shower curtain sticks to my terminator leg. It sorta ruins the fantasy.

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Sent you a PM about this, but figured you may want to address it here also. 

I run no bass boost at all, and my new subs have an Fs of 27hz, which makes the t-line way too long for what I'm trying to do.  Can I design it around 35-40hz anyway, since according to your tutorial, it hits a full octave under the tuning, and I really don't need anything that hits much under 25-30hz anyways.

Well, to sit there and say the sub hits an octave lower than what the tline is tuned to, is really hard to say. Most of the time, I would say yes. The more subs you ad to a tline, the steeper the slope from the tline tunning it is.(so no in that situation) Also, it really helps to run a LOWWW Qts sub, a low QTS sub basically has a flatter free air Fs, a high QTS sub has a peakier Fs if seen on a graph. So, knowing that, it will play easier past the tunning point of the tline..... And as far as doing a tline with a higher tunning point than the subs Fs, with No boost, well, it will work, but will sound like ass based on the songs bass line. A songs bass line acts as a boost as well. So then the box will really pound when the sub/box see's that freq, but anything else, not really.... Some sort of boost needs to be there wether it is a Higher Fs driver, or a Mild bass boost from a eq/ amp boost, ect. And you only need about a 3db gain at tline tunning point to see some great numbers, than with out a boost at all. Its just that extra 3db gain, allows the woofer to achive a easier xmax At tunning, to bring the sub/box to life.  Fs is only the subwoofers ability to achieve highest natural xmax, wich in turn changes the Resitance of the subwoofer, becuase of the coil and magnet reacting to eachother more because of the xmax


sundown.jpg
I have a ritual called "terminator". I crouch in the shower in the "naked terminator" pose. With eyes closed I crouch for a minute and visualize either Arnie or the guy from the 2nd movie. I then start to hum the T2 theme. Slowly I rise to a standing position and open my eyes. It helps me get through my day. The only problem is if the shower curtain sticks to my terminator leg. It sorta ruins the fantasy.

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So, in essence, I can tune higher, but would have to set my PEQ 3db up at the tuning point in order for it to sound good?  Or else find a woofer with a higher Qts and Fs.  The Qts is .217 and the Fs is actually 25.7hz on the woofers I would like to run.

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yes pretty much. You can still tune at like 35hz, with a 30hz boost. If the boost is close as possible to tunning, or a few hz lower, its fine. Over the tunning, like say a 45hz boost, on a 35hz tline, it will still sound like a 45hz tline, and a waste of that extra 10hz difference. But best way to do it, is to try it, practice it. I started almost 4yrs ago with 4" Vifa home drivers, and pvc pipes, and I was like "wow, that 4" has the bass response of a 8" woofer"  And the vocals did NOT get muddy at all, even with that huge bass gain by playing with pvc... just worked up from there, got very familiar with the formula, and just learned so much... practiced with a few 4"s, then 5"s, stuck with 6.5"s and 8s for awhile, then 10"s seemed to be awesome.  I would really like to try a 18" woofer, with a very low Fs, and do a tline based on its Fs, just to feel it.... BTW, in a house


sundown.jpg
I have a ritual called "terminator". I crouch in the shower in the "naked terminator" pose. With eyes closed I crouch for a minute and visualize either Arnie or the guy from the 2nd movie. I then start to hum the T2 theme. Slowly I rise to a standing position and open my eyes. It helps me get through my day. The only problem is if the shower curtain sticks to my terminator leg. It sorta ruins the fantasy.

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Well, I've got it all planned out based on the woofer's Fs now, so that's probably what I'm going to try out first.  Big box for a pair of 8's.  Ends up being 35x22x11 based on the Fs.  I'm looking for good output, but very accurate, so this seems like the way to go for me.

With the Qts of .217 and the Fs of 25.7, box tuned at that 25.7, for a pair of 8's, I figured 62" of port, 123" long.  The actual on wood doesn't work out perfect, it ends up being 129" of port, which shouldn't affect me too much, I think.  Sound like a good plan?

I'm going to try to draw them out tonight, and if you wouldn't mind taking a look at them for me, since this is my first one, I'd appreciate it.  I appreciate you taking the time to explain all this in the first place, you've made me a happy man.

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so far that box sounds good to me. Thats gonna be great if you have a video system. Explosions and action movies. Thats a great home theater sub design right there. That extra few inches shouldnt effect anything. But I do advise, subs that small, playing down that low, not to use any gain, and just allow the sub to play the fs. And if you do it that way, that will be one damn fine musical box, and great for movies. Also a subsonic filter would be nice to, but then that will kill the Fs, and throw off the tunning of the tline all together. But try it... Just curious, are those 8s, the MCM High xmax 8"s?

if so, Ive been wanting to get some of them also


sundown.jpg
I have a ritual called "terminator". I crouch in the shower in the "naked terminator" pose. With eyes closed I crouch for a minute and visualize either Arnie or the guy from the 2nd movie. I then start to hum the T2 theme. Slowly I rise to a standing position and open my eyes. It helps me get through my day. The only problem is if the shower curtain sticks to my terminator leg. It sorta ruins the fantasy.

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the Soundsplinters are really high Q speakers right? like .7-.8 Qts? Well, I thought they were, but I see you said they were  .21.... thats awesome then


sundown.jpg
I have a ritual called "terminator". I crouch in the shower in the "naked terminator" pose. With eyes closed I crouch for a minute and visualize either Arnie or the guy from the 2nd movie. I then start to hum the T2 theme. Slowly I rise to a standing position and open my eyes. It helps me get through my day. The only problem is if the shower curtain sticks to my terminator leg. It sorta ruins the fantasy.

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These are the specs on them.  When you said low Qts woofer, them and the DD 1008's came to mind.

Qts: 0.217

Qes: 0.235

Qms: 2.798

Fs: 25.7 Hz

Re: 3.78 

Ls: 2.022 mH

Lp: 3.859 mH

Rp: 3.786 

Dia:

(% shift) 160 m

44.7 %

Vas: 23.44 L

Mms: 92.47 g

Cms: 412.8 u

Bl: 15.51 T*m

n0: 163.8 m

SPL: 84.14 dB

Sd: 0.020 m^2

RMS: 300 watts

Xmax: 18.3 mm

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Positive you can do 1 in there, but 2? doubt it. Unless you tune it high, with a high eq boost, maybe in the 50hz range. Ofcourse a cut thru is a different story. Look at the cut thrus Ray did, those were really nice, and took up the bed, can you imagine the pressure in that cab?

:-* :-* I WOULDN'T MIND DOING A CUT THRU, I GUESS MY NEXT STEP IS TO TALK TO RAY AND DEVISE AN EVIL BASS SET-UP :R, BESIDES, I LIKE TO BE DIFFERENT. THANKS FOR REPLYING BRO. AFTER I SEE WHAT RAY THINKS, I'LL BE BACK TO SEE YOU, I DEFINITELY WANT A DUAL T-LINE SET-UP, EVEN IF IT MEANS USING 15'S INSTEAD OF 18'S. KEEP ON SUBWOOFIN....

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