My Ultimate HT Subwoofer build help wanted

[spy8181]

My room is approx 6500cuft with a large short hallway leading to another huge room which I'm guessing is around 6500cuft as well.

My current setup is Polk Rti12's as mains and a Hsu Research VTF HO currently running w/o the turbocharger and a Hsu MBM 12 MK2

I just don't think the Hsu's are enough to properly pressurize that large of an airspace. They are impressive for one or two 12's but I'm thinking I need more displacement to achieve the kind of experience I'm looking for.

My options, A. sell my current HO and purchase one or two Hsu VTF 15H or similar subs prob costing in the $1000-2000 range. Option B. figure out what I can do in the DIY field for the same or less money.

My thoughts for the DIY setup would be to go with between two and four individual sealed 15"s powered by a pro amp or two(i.e. Behringer ep4000).
Starting with two and adding up to two more as needed. "Smaller" sealed subs that I can move around and play with different placements and stack if I want to.

Driver selection is where I'm starting. Looking for a driver that looks good, with decent numbers and models well in a smaller sealed enclosure. I am a novice when it come to DIY so any help or recommendations are welcomed.

I peeked around at some subs and this JBL caught my eye.

http://www.jbl.com/EN-US/Products/Pages/ProductDetails.aspx?PID=W15GTI%20MKII

Are there any box programs that i can use and are free to cheap to use to model? I have a couple of WinISD's I've played with which I've had difficulties with.

[evilskillit]

That JBL looks quite nice but you might be able to do even better for $600.

Here are some units people have used in the past:

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=293-642

http://www.soundsplinter.com/rlp15_subwoofer_information.html

https://ssl.perfora.net/www.ficaraudio.com/sess/utn154e63ab56c4e88/shopdata/0050_Speakers/0030_Q/product_overview.shopscript

As for modeling software WinISD is actually pretty easy to use if you read the help file and ask people questions as you go. However there is also UniBox, Bass Box Pro and probably a few others I'm forgetting.

[spy8181]

I prob should have said the JBL's can be had for around $330 a piece. I will take a closer look at those you posted.

Maybe I need to find an updated WinISD, I have one that's a beta and one that gets angry when I try to enter driver specs with no help section.

[spy8181]

I grabbed bassbox6pro and I'm not sure I'm modeling these correctly but what I came up with was

JBL F3: 49Hz
Fi F3: 71Hz
Spinter F3: 56Hz

They all came out with small enclosures in the 40 liter range and increasing the box size to 130ish liters just rolled the low end off a bit slower.

The TC Sounds is too expensive unless I can find a great price somewhere.

It looks to me like the JBL would play the lowest. I just don't know about keeping that cone dust free... 8O

[Face]

A F3 of 49Hz would not be suitable for HT.

[looneybomber]

A F3 of 49Hz would not be suitable for HT.

With a sealed box, just eq to taste. The bad thing about the GTi is the ~21mm xmax IIRC. Right now is a bad time for DIY subs due to a lack of choices.

Multiples of the Dayton RS 15" subwoofers can work.

[evilskillit]

Well WinISD will autocaculate unknowns but it'll tell you if the numbers don't add up. Here are the instructions from WinISD. If you enter the values in the order it tells you to and let it auto calculate the rest they'll come out pretty close to what the manufacturer claims and it wont complain at you.

1: Enter Mms and Cms which results in Fs being calculated. If Mmm and Cms are not known enter Fs. If Fs and Mmm or Cms are known enter Fs and the other known value.
2: Enter Sd, Bl and Re. This will result in more auto calculations being made, but Qms and Qts will be blank. If Re is not available, go ahead and enter Sd and Bl.
3: Enter either Qms or Rms, whichever is available, generally Qms is available.
4: If Mms and/or Cms were not provided for input, now input Qes. This will cause some other fields to auto calculate.
5: Enter Hc, Hg and Pe if available. These are not required, however Pe (RMS Power Rating) will give a good idea of how much power signal input to model with.
6: Enter the number of voice coils. NOTE: Drivers using dual voice coils may cause the Bl and Re parameters to change when changing the connection wiring from parallel to series. Be sure to monitor these when changing the connection option, but WinISD should automatically change these values properly.
7: Correct Znom (nominal impedance) if needed. Many times this will change to 6 and should be 2 or 4... or the ultimate resistance (in ohms) you intend to run based on the voice coil configuration and your connection setting (parallel or series).
8: Enter Xmax and any other missing parameters if known and continue. DO NOT change any of the blue auto calculations. If they are only slightly different, this is okay. If they are off significantly, contact the manufacturer or vendor of the driver.

As to the F3 of the sealed sub... I'm not sure of any small sealed sub is going to have a really low f3 without EQ. So you're going to have to add a lot of EQ to the bottom end, at that point power handling and max excursion are going to be more important than the natrual frequency of the thing.

[spy8181]

I've run 8 different drivers through bassbox without one being a large improvement in F3 so I'm starting to look for bass management solutions. The SMS-1 is the only one I remember people mentioning in the past. Any other suggestions to look at? I'll have to do some reading on how these work. I am guessing add some eq on the bottom end and take out any peaks and adjust gains to correct volume. I think this approach would be beneficial anyways as my room is not ideal.

I didn't have windows help program loaded on my computer apparently so maybe now the help will work on winisd but I'm liking bassbox so far

[looneybomber]

The Behringer feedback destoyer pro is an option for eq. I have the DEQ-2496, which is overkill, but it does have dynamic eq which could be used to help keep excusion in check at the highest output levels if that ended up being a problem. I don't even use that function though.
There's also miniDSP.

[dsrviola]

With a sealed box, just eq to taste. The bad thing about the GTi is the ~21mm xmax IIRC. Right now is a bad time for DIY subs due to a lack of choices.

Multiples of the Dayton RS 15" subwoofers can work.

+1 From the requirements you've listed, for the money, for the loud and for the deep this is a no brainer.

[boostinsteve]

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=295-475

2 of these would be beastly. Each with a dayton 240 watt amp.

[evilskillit]

A good option for bass management is the MiniDSP for around $125.

It has not only 6 bands of parametric eq but a big graphic eq and other functions that can make it fun to play with, like digital crossover functionality, etc. It can be used with REW like the BFD can.

[mackintire]

http://www.avsforum.com/avs-vb/showthread.php?t=1093893

(2) Easy Button Max boxes with TC Sounds LMS-R 15" in them.

Should easily get you below 15hz and pressurize the room, just fine.

[evilskillit]

http://www.avsforum.com/avs-vb/showthread.php?t=1093893

(2) Easy Button Max boxes with TC Sounds LMS-R 15" in them.

Should easily get you below 15hz and pressurize the room, just fine.

Yeah that'll probably shake your fillings out while watching movies.

[Paul W]

What are your true expectations? 6500/13000 cu ft and "Ultimate HT Subwoofer"...seems like too tall an order for just a couple of 15", even the very best drivers. Have you explored the Cult of the Infinitely Baffled?

[mackintire]

I have to agree, if you have the room to do Infinite Baffle....just do it. Otherwise The Easy Button is one of the better vented "lower compromise" designs out there. Basically its a modified LLT or Extended bass shelf design that is a few more db efficient without the typical sagging issues. Interesting points are the angles in the port attenuate the harmonics that are typically heard with similar designs and the internal wall of the slot port makes the box measure with a lower tuning than what you would model in something like base box pro or win ISD. Typical tuning results with the knee at 12-13hz.

[spy8181]

What are your true expectations? 6500/13000 cu ft and "Ultimate HT Subwoofer"...seems like too tall an order for just a couple of 15", even the very best drivers. Have you explored the Cult of the Infinitely Baffled?

What I was expecting was to go from two 12"s, One that handles up to 40Hz and the other that handles 40-80Hz duty and go to a properly EQed 4x 15" sealed setup that would ease the load on the drivers and yet be in small enough enclosures that I could have some options as far as placement. i.e. "My Ultimate HT Sub"

Putting a couple of dishwasher sized subs in there would do the job but it would probably limit placement to one spot and anger the wife.

I've contemplated checking into putting up a glass wall and door to seal off the theater room to try to cut down the cubic footage. IB prob would not be a choice because of the WAF, single story, and anything exposed to outside the insulated house may experiece temps in the 150-160 degree range.

Yesterday I read up on the Behringer BFD, REW and the Velodyne SMS-1 and I definitely think I can benefit from proper calibration so I will be ordering some equipment once I figure out what I want.

What I am trying to learn about is the relationship of where the subs would roll off, room gain, and EQing, and if that combo would get me to where I'm satisfied or not.

Originally Posted by looneybomber With a sealed box, just eq to taste. The bad thing about the GTi is the ~21mm xmax IIRC.

Why would the 20.32mm xmax be a bad thing?

[looneybomber]

Why would the 20.32mm xmax be a bad thing?

To maintain the same output, dropping an octave requires 4x more excursion. Eq'ing to taste could mean running out of excursion.

[JeremyG]

Don't discount an IB based on heat. Many of us in the deep south have/had IB's in attics. I think my attic was hot enough to split (fuse?) atoms. If you haven't read through them, you owe yourself at least a look through the Cult FAQ's:

http://ibsubwoofers.proboards.com/index.cgi?

Sign in for free and take a gander.

ThomasW, one of our esteemed mods here, is THE man in charge of the Cult. I've heard/sold/built just about every kind of subwoofer out there, and I'd throw rocks at them all compared to a proper IB.

My wife didn't like me cutting a hole in the ceiling, but she liked the thought of a big sub in the room, er, "Infinitely" less.

Jeremy

[evilskillit]

Why would the 20.32mm xmax be a bad thing?

20.3 is pretty respectable but several of the subs people have pointed out have more like 30mm. So every 2 of those equals 3 of the JBL as far as displacement is concerned.

As far as the subs being exposed to 150-160. Any sub thats rated for car audio use (all of the afformentioned units) should be ok with that seeing as how they'll have to be built to be used in the trunks of black cars in your area...

[mackintire]

20.3 is pretty respectable but several of the subs people have pointed out have more like 30mm. So every 2 of those equals 3 of the JBL as far as displacement is concerned.

As far as the subs being exposed to 150-160. Any sub thats rated for car audio use (all of the afformentioned units) should be ok with that seeing as how they'll have to be built to be used in the trunks of black cars in your area...

TC Sounds LMS-R is 35mm. Its an expensive driver, but if sf matters......

Dishwasher sized "yes", they are fairly large, but then again it isn't a DTS-10 8O

[looneybomber]

Just a heads up. Dayton DVC on sale 129.00

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=295-190&AID=10603269&PID=4169658&SID=c6kax405qehp

[penngray]

I've contemplated checking into putting up a glass wall and door to seal off the theater room to try to cut down the cubic footage. IB prob would not be a choice because of the WAF, single story, and anything exposed to outside the insulated house may experiece temps in the 150-160 degree range.

I live in Florida and my attic hits 140+ in the summers. I have had an IB array in my family room ceiling for 6+ years now. Never had an issue with it.

IB designs have the HIGHEST WAF period, if you have adjancent space that is 8 to 10X VAS of the drivers you are using then its a perfect $$$/performance solution.

Why would the 20.32mm xmax be a bad thing?

It simply means the driver has pretty low displacement. Displacement = Surface Area * Xmax.

Displacement dictates how low a subwoofer will extend and in the world of HT at least 15Hz @ 110dB performance is truely needed (IMO).

[spy8181]

PE lists the TC Sounds LMS-R xmax at 29.4mm, it was mentioned in this thread it was 35mm. Their site list like 4 measurements which I don't completely understand. What is the correct number and how do I get a driver displacement volume?

[looneybomber]

The LMS-R is 29.4. You take 29.4mm x 2 (that's the xmax out and in, so its total stroke) and multiply that by the cone area. It's listed as Sd somewhere. The conversion is the hard part getting everything in mm or cm or keeping track of your units and knowing what to divide by later. You should get something around 3-4 which is liters of displacement.

One liter is 1000 mL, and one mL is 1cm cubed. 1 liter = 10x10x10cm.

[spy8181]

I probably called it the wrong name, they don't list the box volume displaced by the driver. I have the Sd.

I found a few builds using the tc sounds and i'm considering it as my choice.

Also I took some measurements of my room again and I was way wrong on the cuft its 20"w X 23"d with 10ft ceilings so that puts it at about 4500cuft.

[spy8181]

Alright guys it's time to bring this back from the dead. I'm finally done collecting parts to make this happen. The one thing I need help with is enclosure size. I have messed around with bass box pro and still don"t think I quite know what I'm doing. I know some of you guys can do this in your sleep so I'm asking for your help one last time before I start a build thread.

Sealed enclosures EQed by a SMS-1 or possibly with TACT in the future.
Powered by a Behringer EP4000 at 4Ohms per channel
Drivers: Fi Q18 Dual 2 Ohm with the high QTS option. They said it bumps the QTS to ~.57

Q18

DUAL 1 | DUAL 2

Fs: 32.4 Hz | 32.1 Hz
Re: 0.7 Ohms/coil | 1.4 Ohms/coil
Qms: 9.31 | 9.37
Qes: .48 | .48
Qts: .46 | .46
Mms: 341g | 347g
Cms: 0.73mm/N | 0.73mm/N
Sd: 1210cm^2 | 1210cm^2
Vas: 149.7 l | 149.7 l
Spl: 92.0dB 1W/1m | 91.9dB 1W/1m
Bl: 13.9 N/A | 19.65 N/A
Xmax: 28mm
Rms: 1500W
Sealed box: 4-8 cuft
Ported box: 6-10 cuft @ 28Hz
Sub OD: 18.500”
Cut ID: 16.750”
Mounting depth: 10.000”
Displacement: 0.24cuft

I'd like to keep the box as small as possible without suffocating the driver. I was thinking a 24" cube externally OR SMALLER. My net volume calcs for a 24" cube come out to about 5.36cuft after subtracting driver and bracing. I'm worried this may start to kill bottom end.

[craigk]

if money is not to much of an issues, and you are wanting s small as possible cab's, you might look in to the velodyne DD series. i know this is not DIY. i run a couple of DD10's and they can make your chest feel funny if you really want to crank them up. also about as small of cab as you are goint to find. plus the base is truely amazing.