Originally Posted by omegaslast
Since the TD18H are pretty cheap would it really be that bad to use them as sealed 18" home theater woofers (covering ~20hz-100hz)? Whats out there that beats it for $312?
I don't think they are the best solution for sealed. I'd go with dual RSS390HF for about the same money if you want sealed.
The TD18H would be a great setup ported or PR'd. You could clone the JBL S1S-EX with a 6.5cu ft box tuned to 25hz with a B6 peaking highpass filter at 20hz. This boosts the lowend and controls excursion. Two of these would easily top reference from 20hz and up in even the biggest HT rooms. Extremely clean too. A single EP4000 with an 8 ohm TD18 on each channel would be perfect. For $900 + wood this would be an awesome setup. IMO, it is not a bad idea to forego the below 20hz stuff if your budget/space dictate.
If you have the space you could go with a larger box and less or no boost.
Originally Posted by tgse3
How come there is almost no attention to the TD15X? When I model this sealed it looks like it digs the deepest in a smaller box than the S. Seems like all the love is for the 15M. Am I missing something?
Like others have said, the TD15M works better in the midrange (300hz-1200hz) which is why it is more commonly spec'd for 2-way horns. You lose out on extension. IMO, extension is not needed if you are using bass management with a HT receiver or pre/pro.
The X, H and S drivers are fine drivers but you give up efficiency and there are some response quibbles higher up because of the different surround.
Originally Posted by chrapladm
What exactly is the difference between the X and the H TD15?
If I wanted to use the TD for a ported box and in a 3 way does it matter which one I would use?
I dont think I will be able to be apart of the group buy yet but wondered on using either a H or an X. And if John can four of these TD15ms hit 120hz at 10hz then I figured what more would you want. Did that sub have to have a Hpas or no?
Lastly on all these TD15 speakers if porting for say 15hz would the speaker still behave well up to 250hz or so? In comparison if the cabinet was tuned higher is what I am wondering.
I did some simple sims and the AV15 did dig deeper but just wondering what others thought due toi my limited knowledge of these speakers.
The X, H and S like different box sizes and tunes. It just depends on your design which would work best. What range do you want to cover and what box size? Modeling in Winisd is extremely easy. If you can post on the internet you can model subwoofers.
Four of the TD15's won't hit 120db at 10hz. He did this with the SBP15 which is similar, but I'd guess has a much lower Fs. It would take way too much boost for any of the TD15's to hit 120db at 10hz unless you were using them as headphones. I believe the study he is referring to is rather small as well. I'd guess he'd need at least 16-20db of boundary gain to reach 120db at 10hz with that much displacement.
There is a reason he sells the AV15 line. They are better suited to subwoofer duty, IMO.
I don't know why you are trying to achieve 15hz from the same woofer that will cover all the way up to 250hz. It is just not wise. The only reason I could see doing that is if you are a 2-channel "purist" and you won't run a separate subwoofer for some unknown reason.