TL length question

[Bose(o)]

I believe that statement however, is regarding it's performance due to the 'special' tweeter it used. One of those "works with the room" speakers like 901s and the such.

[theChris]

update:
pipe was made and tuned before placing the top on firmly. sadly when i placed the lid on i forgot a layer of glue on the top of the devider, so there is about a 1mm gap... the results aren't as good as expected and i may rebuild the box to see if i can get better results -- the box sounded better before i glued the lid on. there was air leaking out of the sides...

i think since the top of the box is 32x14 (81cm x 36cm) and not braced, it is causeing a rattleing sound. i agree, this was a terrible oversight.

the bassline is definately not right. one song seems to bottom out the woofers without trouble, yet another song with louder and deeper bass works fine and at louder volumes. the line seems to have issues with hard drum hits.

i was also wondering about half wavelength sealed end pipes. i never see any designs.

in anycase, i have peerless CSC-X 4ohm car woofers from madisound.com . i was hoping to get results close to 130dB in car at some point on a bass-heavy track. i know this is too high for a daily listening level, where i'd probably go for a more respectable 90-110dB level - depending on the drive length. i had wanted a decent response level to 30hz, while not losing control on complex basslines.

[Bose(o)]

Rebuild...Tl's are leak sensitive, the effect of the resonance within the enclosure diminishes rapidly with leaks. I haven't seen any 1/2 wave enclosures either, though this thread got me thinking of one. I'm assuming that one would have to 'kill off' the soundwaves before they can travel back towards the driver.

We wouldn't just want a sealed enclosure either.

[planet10]

Originally posted by Bose(o)
I haven't seen any 1/2 wave enclosures either

dave

[theChris]

yeah, that was the only half wave that i've seen.

in anycase i'm having issues with the woofers bottoming out easily and with seemingly little SPL in the cabin. i can get maby 90dB in car before the cones hit something...

so i guess i'll have to rebuild. the construction was going great until i had to put the lid on. first the wire got on to of the diveder preventing it from sitting flat then i forgot to seal the top...

[Bose(o)]

Just like the Wendy's commercial; Thanks Dave!

I was thinking of something exactly like that....I'm also pretty sure I mentioned that sort of use of TL principle back in the day when I was still (and I am still today) learning about TL enclosures. Soemthing that tapers is a must, I believe, and I wonder what the sound characteristics, tuning problems, etc. that went on for such a machine.

[christophorus]

Hi Planet10,

The effective length of the TL should be no longer than a 1/4 wavelength of the Fs of the driver. if it is longer you will typically get less bass.

is it correct, if I make TL length longer than 1/4 wavelength, it will make TL freq. resonance(Fr) below Fs?
if it's correct, then Fr<Fs will get weak bass response?

Chris.

[planet10]

Originally posted by christophorus
if it's correct, then Fr<Fs will get weak bass response?

This is basically true... Martin above has stated that tuning just a bit below Fs can get bass extension. Tuning above Fs can gain quantity.

Each specific driver/line should be modeled thou to find what works best.

dave

[christophorus]

Hi Planet10,
how low can we go and still get good result?
Can we see the "weak bass" in MJK mathcad #6 graph? (rolling down below Fs, I guess?)
I use MJK mathcad and tune the TL 20% below Fs(38Hz) and still got flat Freq. response down to TL Fr(30Hz), is it good design or something will happen in real listening (weak bass start below 38Hz instead of 30Hz)?

Thankyou,

Chris.