Best value LLT

[cynical2]

We have a dedicated HT in my basement (untreated...no current plans to treat). Room is 15x18x8 (~2200 cu ft)....100% movies, NO music.

Currently, I have a Paradigm PS-1200 sub in the HT. I blew up my sub in our Family Room, so my plan is to move the Paradigm up to the FamRm. This leaves me the opportunity to undertake my 1st sub build. It'll take a while, as I don't have all that much free time. But, at least part of the battle is behind me, in that I've decided to go for it.

Based on the reading I've done thus far, my plan is to make an LLT. Our movie screen is on one of the short sides of the room, and I figure it'll be laying down, centered under the screen.

Base plan is to drive it with an EP2500.

So...first, I need to decide what driver(s) to use. I'm looking for decent quality and want to feel the effect of the high impact scenes., but this by no means needs to be some super-duper audiophile sub. It's for my wife and me, and our kids and their friends to enjoy.

All this being said, I don't mind spending a little more $$ for the extra performance...but I'm really after the best bang for the buck. IOW, what is going to put a smile on my face for the least amount of money? (I know that's a question only I can answer, as we all smile at different levels of performance...but hopefully you get the idea).

For the drivers, where should I look for the best value? I see that the Tempest 15" subs are $350/pair. Is 2 of those overkill? Are their better ways to spend my $$ and get similar/better performance?

Thanks in advance for any/all advice. I've been spending a lot of time reading the DIY sub forums lately, and we have some BRILLIANT folks at the Shack! I'm hopeful I can tap into that knowledge.

[Mike P.]

Best bang for the buck LLT would be a IXL-18 in 12.5 cubic feet tuned to 15hz. The price is 250 shipped to your door. For more money the Tempest-X pair is a good choice, however the 350 price does not include shipping. Determine exactly how much money you want to spend on subs and take it from there.

[mdrake]

Best bang for the buck LLT would be a IXL-18 in 12.5 cubic feet tuned to 15hz.

Here is a link for a thread that shows box plans for the IXL-18.

Another Link

[cynical2]

Thanks for the info, gentlemen.

Any other opinions (besides the IXL-18) on drivers that I should look at?

[mdrake]

There is this new bad boy.
Or the Ficar subs.

Matt

[Jodean]

diycable is still doing free shipping on the tempest x, but im pretty sure id do that bad boy option instead of two tempests....thats cool!

If time is the order, the quickest(and cheapest) thing to build is a sonosub. but they may not work laying down.....ill know shortly as my binding posts just showed up and ill be able to glue it all together as soon as i put them in.

[SteveCallas]

Maelstrom X 18", Tempest X 15", FiCar Q18, FiCar IB18, Dayton HiFi 15", Mach5 IXL 18", SS RL-p18, etc., many options to choose from.

I would tend to agree that the IXL 18 at $250 shipped is the best bang for the buck now that the $300 Maelstrom X 18 pre-order price is gone.

[cynical2]

Thanks for the further recos, Matt and Steve. Jodean, I'm curious how a sonotube does laying down...it would definitely be a simpler build for me (I would assume it would, at least). I've been operating under the assumption that they needed to stand up and downfire.

Jay, can you say a little more about the inductance of the IXL-18? What is "normal"? And, what are the implications of a high inductance in a sub driver?

[cynical2]

DS-21 wrote:

I think DIYCable.com website has Dan Wiggins' old white-paper on inductance somewhere. But in a nutshell, inductance affects the frequency response, and even on bandwidth-limited systems seems to "slow" the bass down subjectively.

"Normal' is hard to say. I've found anecdotally that few drivers with more than, say, 0.75mH of Le per ohm of Re, sound very good in the upper deep bass.

Thanks, Jay. You're not the first person I've seen that voiced a concern over the inductance level of the IXL-18. It is definitely high when compared to most of the other drivers I've looked at.

I couldn't find anything on diycable's site, so I looked for the paper using Google. I believe this is the one you're talking about.

In this paper, the results are reported of a test setup where they took a 6.5" woofer and ran the following test scenarios:

1. the driver in it's native form
2. the driver with twice the moving mass
3. the driver with 78% more inductance

They ran both impulse tests and frequency response measurements on all 3 scenarios, looking for the affect of added mass and added inductance on the driver's behavior.

The idea was to show that inductance is indeed the most important factor when it comes to transient response of a driver...NOT the moving mass. However, my conclusion after reading the paper is that inductance definitely is important at mid-high frequencies (>1 kHz). But, at the frequencies that a subwoofer operates, it seems to make no discernible difference in the response.

If you look at Page 6 of the paper (the frequency response of the 3 scenarios), you'll see that from ~70Hz-1kHz the response between the native driver is almost identical to the driver with added inductance. Below 70Hz, the match is "OK", but there is some deviation between the two...but this is a small woofer and I'm not sure any conclusions can be drawn from the response at frequencies that low. As you move well above 1kHz, the driver with the added inductance suffers badly...but it doesn't seem (to my interpretation, at least) like the conclusions drawn by the offer are applicable to low frequencies, where things happen (relatively) slowly.

So...is inductance not an issue in selecting a subwoofer driver, or am I thinking about this wrong?

[Mike P.]

The Le issue for sub drivers is overrated. Crossed over at 80hz my two IXL-18's sound great.

[audio newbie]

If you dont mind using a lot of speakers, you can get 10" NHT woofers for $20. I used 8 of them, which should have roughly the same output as 2 18" woofers. There X-max is "only" 12.5mm, so you probably wont get tremendous SPL at super low frequencies. I think around 121db @ 20hz (with 8) in a LLT is probably reasonable.

Here is a link to my build, which has a link to the woofer sale site.

http://www.hometheatershack.com/foru...sub-build.html


I dont know anything about interpreting speaker specs, so I cant tell you how these speakers compare to others. I can say that I'm extremely happy with how they sound... of course there are probably quite a few people with bose systems who would say the same thing

[mdrake]

I could not find the link to the sale. Do you have a URL?

Matt

[Mike P.]

Scroll down to the NHT NPT-11-075-2.

http://home.comcast.net/~jhidley/index.html

[avaserfi]

cynical2 wrote:

So...is inductance not an issue in selecting a subwoofer driver, or am I thinking about this wrong?

Inductance is a rule of thumb, no more no less. To me, that means don't bother worrying about it and look at real world performance. There are many superb drivers out there that have high inductance as well as many that are just the opposite.

What exactly are your goals with this design? How large is too large, how low do you want to go (at what SPL) etc...?

My suggestion while not typical will provide high fidelity, at low cost, along with massive SPL, in room, down to at least 15Hz.

Two Infinity Kappa VQ 12" in MidQ. The price combined would slightly break $300 and the Kappa perfect (almost the same exact driver) measures superbly in Ilkka's subwoofer test.

Two of these in a 15 cubic foot box tuned to 15 Hz with a slot port 18"x4"x50.25" would result in 100+dB from 15Hz up to its crossover point with minimal distortion and virtually no port compression even at high spl.

I have included a WinISD Pro file in the attachments. Just change the extension from txt to wpr. Please note, this was a quick simulation - it is possible a more ideal circumstance is found as I did not model the drivers other motor possibilities.

Another reason this driver is recommended is sheer versatility. If one day you want to move to another enclosure type it is very possible, from sealed to various types of ported due to its adjustable BL/Q functions.

[avaserfi]

DS-21 wrote:

Such as? I would certainly not put the TC 3HP/4HP or Jello W7 in that category.

Not only the JL W7, but also many of SoudSplinter's offerings which were manufactured/designed by TC Sounds. These subwoofers are some of the best on the market today* 'despite' their higher inductance.

Do you have any actual evidence** that higher inductance is directly related to quality sound in a subwoofer? I am aware of none except for this simple, and near pointless, rule of thumb.

*This statement is based on credible 3rd party measurements correlated with an understanding of human perception of sound - not anecdotal data.

**Please note your or others anecdotal "evidence" is anything but proof in this discussion and will be regarded as biased and thus not applicable or generalizable.

DS-21 wrote:

I don't know that woofer. My only question is why, if one's going to use such a massive enclosure, would one want to limit herself/himself to such a small piston? The Infinity may be a great driver, but it's always better, all else equal, to have as little cone movement as possible. That suggests to me the biggest possible driver. Assuming that line is exceptionally well-designed, is there no 15" driver in it? If not, that same 15 cubic foot enclosure could also hold two Tempest-X's, which would be about $350 right now shipped, I believe. That's huge output from a big piston with low Le and tons of throw.

This is exactly why I asked for more detail on the desired goals. The design I offered would produce high SPL with minimal to no port compression along with low (inaudible) distortion at these SPLs. I see no reason to seek out a larger piston unless one wants increased headroom at the possible cost of future flexibility due to this drivers massive functionality as previously mentioned.

As far as the tempest X driver goes, I am unaware of any credible 3rd party measurements of the unit, such as Ilkka's, and am thus its actual performance. Due to this I am unable to make such a recommendation.

[cynical2]

OK...I'm feeling like I stepped in the middle of something here.

I really am interested in hearing a (civilized) debate on the topic, so you guys (and others) can feel free to use this thread to discuss the importance of inductance. I read the white paper that I linked to, and my (admittedly non-expert) opinion after reading it was that Le appears to be quite important at mid->high frequencies (> 1 kHz), but below that I didn't see any difference in response. But, as I said, I'm not an expert...a mechanical engineer by trade, understanding the ins-and-outs of inductance just isn't my thing.

To Andrew's question...goals for the design (again, putting in perspective that I'm not an "audiphile" and that this room is 100% for movies/satellite content)...I view these as "ideals" and I'm sure I'll be blown away with whatever I end up with:

• Reasonably priced...and I want the most performance for my $$$. I'd like to keep the driver(s) at $350 or below...but if something comes along for $400 that's going to change my life, then I'm in.
• Ability to go loud...how loud? I don't really know, and don't have anything to measure with (at least, not yet). I like the volume level to be set louder than most theaters I've been to...but not so loud that I'm breaking windows.
• Ability to go low...how low? Well, I guess as low as DVDs pass information that's intended for the audience (within reason). If it becomes too expensive to go that low...then I'll take what I can get.
• Clean/accurate...I hate "muddy" bass at frequencies where that's not the intent...simply put, I want it to sound the way it was intended. For lower frequencies, I'm all for feeling the seats vibrate...brings you into the movie.
• Size...Smaller is always better as long as the goals are being met...but I assume that I need to go fairly big to reach my performance goals. 15cuft is no problem. 25cuft is probably around the upper limit.
• Orientation...I want this centered under the screen, so it needs to lay horizontally. If a sonotube laying on it's side is a viable option, I'm open to that too. It would probably simplify the build (and, as a reminder, this will be my first...so, simpler=better, as long as performance doesn't take a significant hit).

Please let me know if I missed anything.

For some perspective...as I mentioned in the first post, I have a Paradigm PS-1200 now. It's a strange sub with the driver on the inside...at least I hadn't seen a design like that before. For the most part, sound level is OK at the frequencies that it will reproduce. But, I have to put the gain pretty high to achieve those sounds levels, and it starts to get muddy at those higher volumes...doesn't feel like there's any headroom at all. It's a bit difficult for me (as a non-bass expert) to describe...overall, it just seems "weaker" than I would prefer. If my sub were a horse, I'd want to feel like the guy struggling with all my might to hold the powerful beast behind the gate at the start of the race, all the while feeling like it's a futile exercise to contain it's strength. With my current sub, I feel like the jockey who's whipping the horse time after time in an attempt to squeeze out every ounce of performance...and the horse just doesn't have any more to give.

[cynical2]

One other question...what should I be looking for as far as impedence (if I drive the sub with an EP2500)? # coils? Ohms/coil? I assume the answer depends on whether I use 1 or 2 drivers?

BTW, Mike I just looked at your build thread. Holy cow! I'm at a loss for words...that makes my little paradigm look like a child's play toy!

[Jodean]

so far the sonosub works pretty good laying on its side. wish i had a test meter. I also need to check placement as ive only had it in the one position so far. I do have the driver and port within 10" of a wall on each end that might act as a base plate.

Joe

[cynical2]

Jodean, please let me know your impressions as you get more time with it!

Andrew, thanks for making the wpr file for me. The response looks great!

[avaserfi]

cynical2 wrote:

To Andrew's question...goals for the design (again, putting in perspective that I'm not an "audiphile" and that this room is 100% for movies/satellite content)...I view these as "ideals" and I'm sure I'll be blown away with whatever I end up with:

• Reasonably priced...and I want the most performance for my $$$. I'd like to keep the driver(s) at $350 or below...but if something comes along for $400 that's going to change my life, then I'm in.
• Ability to go loud...how loud? I don't really know, and don't have anything to measure with (at least, not yet). I like the volume level to be set louder than most theaters I've been to...but not so loud that I'm breaking windows.
• Ability to go low...how low? Well, I guess as low as DVDs pass information that's intended for the audience (within reason). If it becomes too expensive to go that low...then I'll take what I can get.
• Clean/accurate...I hate "muddy" bass at frequencies where that's not the intent...simply put, I want it to sound the way it was intended. For lower frequencies, I'm all for feeling the seats vibrate...brings you into the movie.
• Size...Smaller is always better as long as the goals are being met...but I assume that I need to go fairly big to reach my performance goals. 15cuft is no problem. 25cuft is probably around the upper limit.
• Orientation...I want this centered under the screen, so it needs to lay horizontally. If a sonotube laying on it's side is a viable option, I'm open to that too. It would probably simplify the build (and, as a reminder, this will be my first...so, simpler=better, as long as performance doesn't take a significant hit).

If you want low and loud I strongly recommend taking the unconventional route and using a slot port. Port compression become quite severe at high spl with typical tube port use. If you use a properly designed slot not only will you have a cleaner sound you will also get more output. If you run the subs at 85-90dB average then you would likely want output up to 120-130dB in room for some extreme dynamics, just in case.

Since your room is and will be completely untreated I would recommend sacrificing low end output (ex tune to 20Hz rather than 15Hz) for two subwoofers, tuned higher, but separate from each other so they can be placed such that you achieve an ideal response (less 'muddy'/'boomieness' bass). This is a personal choice and does go against some of the placement you had planned, but is just a suggestion. If you go true LLT you should be able to deal with most of these issues through equalization, but there is no guarantee. This would also likely result in a higher average SPL above tuning frequency with appropriate driver choice.

If you do choose the higher tune option I could recommend a pair of subwoofers which would be substantially smaller (4-6 cubic feet) and capable of at least 120dB at 20Hz with the pair.

As far as Sonotubes go I simply cannot recommend them for two reasons. The first is the previously mentioned port situation. Sonotubes completely lend themselves to typical port styles which will, with a high excursion driver, result in significant port compression and thus loss of output. The other is they are cardboard! I just don't like th