Need input on my TL. FR has a nasty dip in it.

[GuyPanico]

I've been testing my newly constructed TL today with the help of Pink Floyd and test tones. What i'm noticing is a dip in output from 61-85hz. At it's center, around 75hz, there is very little sound at all. Otherwise, as compared to a sealed cabinet I have for this sub (.95qtc), 40-60hz is definantly stronger, and below that is approximately the same or slightly better on the TL (at least to my ears). It's hard to make determinations between small differences when it takes so long to transplant the driver from one cabinet to another.

Stuffing helped with the overall sound. I ended up using way more then I was expecting to. But didn't have much effect on the void. I'm about to test if line length effects it. At the moment i'm using a passive 80hz xover. Which I think is a bit high. Soon as I get my amp back, I'm thinking 65-70hz will be a better xover.

Here's my setup...

Sub is placed about 5ft behind listening spot. Speakers are about 9ft in front.

25.5hz
133.1l vas
4.16ohm
.28qms
4.57qes
13.2Bl
510cm sd

The TL is 101" long right now. The finished line will probably be 115". Inner diameter is 12.5".

Any input or ideas would be greatly appreciated. I just hope I hadn't chosen a bad project for my first one. From my readings here, and with MJK's spreadsheets, it seemed easy enough.

 

[GuyPanico]

Ok...I shortened the line to 48", and that null dissappeared. Now bass is strong from 45hz+. But lower then that and it falls off into oblivion. So it must be related to line length and phase right? Guess I didn't know what to look for in MJK's spreadsheets.

 

[planet10]

How big is the driver? from the Sd i'd have to guess a 15". A 12.5" diameter tube is really more suited to an 8" driver.

Did you run your TL/driver up with at least Martin's tables?

dave

 

[GuyPanico]

The driver is an HSU ASW1201 (12"). The cross sectional area of the tube is 1.57sd. Not terribly large I know. I used Martins sections sheet to sim my line. Unfortunantly I dont know how to interpret many of the graphs.