Transmission Line box

[MTA 0]

what happens when u tune a TL box lower than the drivers Fs ? for exampl the driver in question has an Fs of 26Hz and I would like to tune @ 20Hz

besides the obvious wavelength being longer....

does the driver/box not perform quite as efficiently as one with an Fs of 20Hz?

btw: how do I test the Fs of a sub ? I have a DVM and tone gen available...is that enough ?

thanx guys

Edited January 21, 2009 by MTA

[MTA 0]

wow I'm amazed... no replies for help on transmission line box ?

[NB50 206]

There is no rule that you tune to the drivers FS.

[aznboi3644 2]

for a 1/4 wave resonator you can tune to whatever wavelength you want...there is no set rule

[carlopogi 0]

is the bass really delayed in t-line boxes?

and if it is delayed, by how much? will it ruin songs that have fast bass?

thanks

[aznboi3644 2]

delayed? Not at all...My t-line was a lot more transient than my sealed enclosure.

[Punkeyboozter 19]

even so ...often times a phase shift or TA will fix that problem

[carlopogi 0]

for a t-line box, should i tune it around 37-38?

cuz i read somewhere that t-line boxes doesn't need to be tuned so low anymore since

it can really reach the lowends good already

[aznboi3644 2]

It really depends on the install.

I had a 33Hz 1/4 wave line and the lowest it played was 27Hz...VERY audibly. But after that it fell on its face and had no output below that. Depends on the design and the install.

40Hz line is fine for most ppl...it should still easily play down to 30Hz audibly and the line will be shorter for easier folding. I would taper it also as there are peaks and dips involved with 1:1 ratio lines.

[MTA 0]

thanx for the replies guys... when I first read up on t-line about 6 years ago I read that the quarterwave should be equal to the drivers Fs... right now and for the past 5 years I have been using an 8" RE RE which is listed to have an Fs of 22.8Hz so that is what I tuned..it sounds amazing..but I want more output...lol so Im working on doing something with a 10" or a 12" which will still fit in my Jetta's trunk. the 8" did some amazing feats such as hitting an incredible 137.8dB in an Equinox with only an amp rated at 2x60 RMS

now the reason I asked my question was I cant find a sub at a reasonable cost that will have the same Fs with more xmax..Im really working on hitting into 20Hz as hard as I possibly can for a competition...but I just simply love the sound of my 8" TL

so any other suggestions would be great.... Ive even considered rebuilding a sub myself to have a low Fs that is why I asked how to measure the Fs of the sub.

thanx again... sorry to ramble on :0

[aznboi3644 2]

I would think that you can find the FS with test tones and a ammeter. If the impedance of a driver is highest at FS than I would play tones and see where the current is lowest.

[carlopogi 0]

if what MTA said is correct, since the Fi BL 10's Fs is 40.3hz, then i should tune my t-line to 40hz ? isn't that too high ?

[aznboi3644 2]

nope

[efxtruck 0]

20Hz wow talk about a ground pounder lol

[MTA 0]

ground pound... yeah... but really as one other memeber mentioned...the transient response is amazing...but then dont try to play a tl tuned for 23hz at 60hz at high power levels...it does not seem to perform well at more than 2x the frequency...but I tell ya the lows are amazing and at lower output levels it just sounds sooooo sweet.

it really doesnt need alot of power to hit awsome lows. but make sure whatever sub is used has lots of linear xmax( the Fi q's should be awsome ) and get a really good front stage with powerful midbass... otherwise it will not sound good at all.

carlapogi: no... 40hz is OK just make sure you use a subsonic filter several Hz below your TL tuning frequency to prevent powerwaste and keep your sub from unloading

btw my 8" shocks ppl when they see it..they swear that when they listened to it they listened to a 12" or a 15"

[MTA 0]

I would think that you can find the FS with test tones and a ammeter. If the impedance of a driver is highest at FS than I would play tones and see where the current is lowest.

thanx...that sounds familiar. I will have to buy some soft parts and test...see i I can build a nice sub with an FS of 20Hz