LLT Explained - Discussion Thread

**Sonnie** · **09-20-06, 12:00 AM**

This is the discussion thread for the LLT Explained Sticky Thread.

**brucek** · **09-20-06, 04:08 PM**

Very interesting read Steve. Well done. I quite enjoyed it.

I do have to take a small exception to your three graphs in the original post, although I suppose you copied them from elsewhere and had no control.

The vertical scaling is quite inconsistent between the three graphs, and makes it difficult to draw meaningful conclusions......

brucek

**kramskoi** · **09-20-06, 05:24 PM**

Quote:

brucek wrote:

Very interesting read Steve. Well done. I quite enjoyed it.

I do have to take a small exception to your three graphs in the above post, although I suppose you copied them from elsewhere and had no control.

The vertical scaling is quite inconsistent between the three graphs, and makes it difficult to draw meaningful conclusions......
brucek

it would "seem" that the only one that is coupling to the room properly is the first example given in the 18" Avalanche...i wonder what the dimensions are for each room...

**JorgenMan** · **09-20-06, 07:07 PM**

The guidelines/specific advice section is very helpful. Thanks for doing this writeup. I'm sure it took a good amount of time and effort to get everything worded the way you want and organized into a presentable fashion, but it's nice to have something comprehensive. Thanks again for the effort.

Hopefully this will save you from answering so many questions.

**chasw98** · **09-20-06, 08:31 PM**

Wow! Are you prepping for a presentation at AES this fall? Are you sure you should not have been a writer instead of what you are doing in life now? Excellent explanation. Very factual, scientific, and based upon repeatable results if the "formula" is followed. You should make up a general spreadsheet with different drivers, sonotube sizes, port lengths, and the various tuning frquencies that go along with the other factors as kind of like a general reference card of where to start when one wants to build one. How many times has the brotherhood put its arm around someone and gone through the WinISD ritual to come up with the same values we have come up with before. A little cheat sheet you could put out as a starting point for people thinking about build ing one of these might give them an idea of what they are getting into. Good work.

Chuck

**SteveCallas** · **09-20-06, 09:04 PM**

Quote:

I do have to take a small exception to your three graphs in the above post, although I suppose you copied them from elsewhere and had no control.

The vertical scaling is quite inconsistent between the three graphs, and makes it difficult to draw meaningful conclusions......

Yeah, three different owners running their measurements in three different months. Not ideal, but just a very generic representation of what can be achieved at various tuning points with different drivers.

Quote:

it would "seem" that the only one that is coupling to the room properly is the first example given in the 18" Avalanche

Well the coupling area with an LLT will begin around 25-30hz and extend down to just below the tune - below that, the 4th order rolloff comes into play and there will be a dropoff. Flat output definitely won't go on for ever. Considering the third sub's tuning is coming in around the high 16hz area I believe, the extension to ~13hz is pretty impressive. If you were to take a ported sub that measured very flat to 18hz anechoically, like an Axiom EP1500, you would not get such results without heavy EQ in room.

Quote:

Hopefully this will save you from answering so many questions

HOPEFULLY

Quote:

Excellent explanation. Very factual, scientific, and based upon repeatable results if the "formula" is followed

Thanks. A logical and factual explanation of the real benefits was one of my top goals, as there are people with no clue as to how such a design really works saying things about it that are completely wrong and backwards - it's not a knock, but they just don't fully grasp the design intent. For people who have enough interest to want to understand why this design works and why it came about, hopefully this will shed some light.

Quote:

A little cheat sheet you could put out as a starting point for people thinking about building one of these might give them an idea of what they are getting into

Yeah, I might just list my main designs for popular drivers so it could be a one stop source.

**WillyD** · **09-20-06, 10:45 PM**

Excellent write-up Steve!

**Exocer** · **09-21-06, 04:05 PM**

Good thing this was made a sticky

It would be a shame to lose all of this easily read information.

My next but very distant project will be a ported Avalanche 15" sub. Whether or not it'll fit the LLT description by design is still up in the air. Haven't figured out where an LLT would fit in my room

**steve nn** · **10-27-06, 06:32 PM**

Quote:

My next but very distant project will be a ported Avalanche 15" sub. Whether or not it'll fit the LLT description by design is still up in the air. Haven't figured out where an LLT would fit in my room

I don't know Ex? I'll be real surprised if you don't do another sealed.

Nice writeup Steve, who could ever explain it better than you..and to think that's been there since 9/20! I've definitely been out of the loop lately.

**Exocer** · **11-01-06, 03:35 PM**

Yeah, another sealed is definitely my only option.My mom didn't like the idea of housing a water heater in the living room

She just doesn't understand the sacrafices we need to make to join the brotherhood! My dad thought the sono was a cool idea though..

Once the Tumult gets fixed and I build another enclosure, unibox shows something in the neighborhood of 110db at 20hz and 100db at 10hz with just 450 watts of power to the Ava15 and 450 to the Tumult. That should hold me over for a while...afterwards is a well needed amp upgrade. With 450 watts each of these babies are just coasting along

**SteveCallas** · **11-01-06, 05:42 PM**

Quote:

My mom didn't like the idea of housing a water heater in the living room She just doesn't understand the sacrafices we need to make to join the brotherhood!

Reminds me of the Fresh Prince song, Parents Just Don't Understand

So how many more years of school do you have before you can move out and go nuts?

**JorgenMan** · **11-01-06, 07:23 PM**

Quote:

SteveCallas wrote:

Reminds me of the Fresh Prince song, Parents Just Don't Understand

So how many more years of school do you have before you can move out and go nuts?

Yeah, you gotta fight. For your right. To paaaaaaaaaaaaaaaaaar-tay.

**Exocer** · **11-01-06, 07:32 PM**

Quote:

SteveCallas wrote:

Reminds me of the Fresh Prince song, Parents Just Don't Understand

So how many more years of school do you have before you can move out and go nuts?

Yeah, I remember that song haha, great song.

Well, the mrs. graduates before me and wants me to move in but she graduates in may 07'...i'll have to worry about WAF in that situation

and another sad things is I won't graduate for another few years because I switched from one major to another at a different school and lost LOTS of credits

I could easily be on my way to graduation by now...but at my first school i didn't like the idea of sitting on my arse and maintaining a gpa of 3.7..wanted something a little more challenging

boy did i get it.

**SteveCallas** · **11-02-06, 12:41 AM**

Wait a second, so if I understand this right, you haven't finished college, but you're married?

You're married but you live at your parents house?

Oh man.....oh man

Before you got the chance to be independent, you went and got married, so now you will transition from one form of control (parents) directly into another (wife), one that's supposed to last for the rest of your life, with no buffer inbetween. But hey man, different strokes for different folks, more power to you.

**Exocer** · **11-02-06, 01:05 AM**

Quote:

SteveCallas wrote:

Wait a second, so if I understand this right, you haven't finished college, but you're married?

You're married but you live at your parents house?

Oh man.....oh man

Before you got the chance to be independent, you went and got married, so now you will transition from one form of control (parents) directly into another (wife), one that's supposed to last for the rest of your life, with no buffer inbetween. But hey man, different strokes for different folks, more power to you.

hahaha, i guess i'll never enjoy that single life eh

Thats the only thing I honestly feel like im missing out on...I've been there, done that. At this point I guess you're right, couldn't see myself without her though...its that nice spending time w/ her. Hope it stays this way

But man, LLT is going to be awesome, especially when I get a dedicated room that "I" and only "I" have control over

Whenever that may be.

**terry j** · **11-09-06, 10:05 PM**

hi all

new here. Thanks for the write up, will have to read it another ten times yet tho!

Earlier read the saga that Exocer had with his subs, and got very confused every time Steve jumped in with hints about using an LLT!! For the life of me couldn't work it out, now I know.

Will continue browsing but this idea does appeal to me so in all likelihood - I'll be back (said in my best Arnie/terminator accent).

One quick question tho, in order 'to get around' the huge volume requirements, can some of the enclosure be the under floor space? ie some sort of opening into the cavity a la an IB type arrangement and using the space under the floor as a psuedo enclosure. I'd guess no, as in all likelihood it needs to be totally airtight, but thought I'd ask anyway, if only to straight away establish my credentials as 'the one who asks stupid questions' !

lots of love

terry

**SteveCallas** · **11-09-06, 11:33 PM**

Well volume is volume, so I don't see why it wouldn't work. The enclosure does have to be air tight though, aside from the port, otherwise the leaks will act like several ports, and that will throw off your design. Feel free to ask any questions along the way if you go forward

**terry j** · **11-10-06, 04:30 AM**

thanks Steve

to be honest I think my suggestion/thought was a tad daft, there is no way even in my situation that it would be airtight. Forget it. Thanks for the response tho!!

Am busily printing off your writeup (much prefer to read it in my hands so to speak), to fit it on my page had to print it sideways??!!

May as well get this out of the way first up. I've got four peerless XLS drivers, unfortunately they are the 10 inch versions- seems the 12's are useful but moo baby moo can I do with these??

I hoped that your LLT's might prove useful in getting these things to work, but my little bit of mucking around with winisd (admittedly with little real understanding of the process) still seems to yield useless results.

I know there are two versions of the xls 10, mine is the 830452. I will stop now if you or someone else lets me know they are useless in this application, otherwise I will study your writeup and try and suss it out, maybe asking for a bit of advice along the way.(I don't want to just 'pick someones brains', I'd like to contribute a bit. You know, god helps those who helps themselves type of thing.) Needless to say I'm new to speaker design.

If it is not a straight 'forget it', then I'll start a new thread and see where we end up. Thanks a lot.

If it is a straight forget it in this application, maybe a bandpass? I only really want to do from 20 to 50 or 60 hz.

It'd nearly printed off!

lots of love

terry

**WillyD** · **11-10-06, 04:53 PM**

Terry,

You're in a luck. Someone built an EBS using four Peerless 10" XLS drivers.

http://www.avsforum.com/avs-vb/showthread.php?t=718062

It seems as if all of his pictures are down, but he was very impressed with the performance.

**SteveCallas** · **11-10-06, 08:00 PM**

I haven't looked at the parameters for those specific drivers as of yet, but assuming they aren't really geared for deep low end sensitivity (I'd imagine that's a pretty safe assumption), I don't think LLT would be the best application. I'd consider a more traditional ported design - smaller, tuned higher, using a highpass. Can you post the paremeters here?

**terry j** · **11-10-06, 08:46 PM**

firstly, thanks Willy for the thread, had a look and sounds like he's happy, but like you I could get no pictures. Posted a reply asking if he could try reposting his design, let's hope he puts it up again. Interesting that at one point he or someone else mentions that regardless of some of the design programs these drivers make a good sealed sub. Maybe I should just bloody well build one and see what happens??!!?? But, I do think it would be more logical to get some advice first and so here I am.

Steve, thanks for having a look. These are published figures, I haven't measured them

Qts 0.17; Vas 89.7 l; Fs 18.9; Re 3.4; Le 4.3; Xmax 12.5 mm; Z 8; Qms 2.63; Qes 0.18; spl 88.4; Sd .035m2

I may as well learn a bit as we go, from what I can gather the problem parameter here is the Qts?? If that's true can you explain why it is so??

thanks a lot, even if it ends up I can't do anything with these drivers, at least I will have a better understanding of things. I might be in the states early next year, maybe I should just buy an Adire Tumult while I'm over there !!!Probably couldn't bring it back as luggage tho because of the weight??

lots of love

terry

**SteveCallas** · **11-10-06, 10:41 PM**

The low Qts means that the driver is naturaly pretty well damped and will have a less steep rolloff - adding port output to this creates a hump rather than a smooth union. So what you end up doing to get a smooth-ish union is tuning really low, and the low Vas and limited air displacement capabilities of this driver don't suit a low tune that well. A single 15" TC 2000 is better suited to such a task. If you stick with these and go ported, you'll want to tune higher with a smaller enclosure in my opinion, something like 4 drivers, 200 liters, high pass ~18hz, 1400 watts, and a 6-6.5" diameter port.

**terry j** · **11-10-06, 11:06 PM**

thanks Steve
just finished reading the thread on LLT on the AVS forum, I'm exhausted...

OK moving on, these drivers aren't suited. Bugger. Hopefully the OP Willy mentioned will get back to me. From that other post, I gather your sonosub is actually an LLT?

Thanks for your help guys, for now will hope that I can use these drivers, but will revisit this later when have a better driver. Is the tumult a better or worse driver than the one you mentioned Steve? Bear in mind I'm in Australia, not sure how supplies go in this area yet, but by the time shipping etc is factored in things get VERY expensive over here. The tumult 15 will cost me $1150 Aus for eg, don't know what they are worth there.

For reference sake, have you posted 'preferred parameters' for this alignment? For example, I could have seen my drivers weren't suitable if I'd had access to such a list. Would also enable me to search locally available drivers for suitability.

Due to house constraints an IB is not an option, so this alignment does appeal to me. Size is not a problem, I have 17 feet ceilings so from a scale perspective the larger the better!! I can end up with the LLT, like yours, and another three or four lookalikes that are actually bass traps! They would all blend in nicely then.

Please, a quick rundown on preferred drivers??

lots of love

terry

**SteveCallas** · **11-10-06, 11:55 PM**

Tumult is a nice driver, but for it's price, you can get multiples of other really good drivers, at least here in the States.

How much did you pay for those 4 Peerless drivers and how much might you be able to sell them for? I ask because it seems it may not be worth the hassle to sell and buy new drivers. If you do though, I'd see how much a 15" TC 2000 svc would cost, as based on what's currently available, that is the best bang for the buck driver suited to LLT in my opinion.

Preferred parameters, generally speaking, would be a low Fs, high Vas, low Bl, high Xmax (preferably using a low distortion motor technology), low Le, and what I guess you would call a medium Qts. If we wanna try to assign values to those low, medium, and high descriptions, ideally speaking, let's say Qts between 0.3-0.45, Fs < 20hz, Bl <20 N/A, Xmax > 20mm, Le < 3. And obviously, the larger the surface area of the cone, the better.

Yes, my sub is indeed a LLT, a very moo baby moo LLT

**Exocer** · **11-13-06, 12:17 AM**

I've decided to use the Avalanche 15 in the LLT instead of the Tumult. They model pretty similar with 240 effective liters and a 16hz tune.

The only way to make this possible would be with any size sonotube 22" in diameter or smaller since the driver/port would be way too close together with 24" tube.

I'd like to keep it at or under 4' if possible.

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