# sub bass room gain, anybody have any info?



## tcguy85 (Oct 29, 2007)

i wanna build a sub for my ht. i am thinking of just grabbing one of the o-audio 500 watts plate amps. seems like a great value. was thinking of pairing it with a 12" sub that i had laying around that came out of a jbl pre-made sub for the time being. but replacing it later on with something better once i can afford to.

my main question is how bad will the low end suffer if i go with a sealed box? the room is 14'wide x 22'long, and 8'tall. it is a sealed room, it doesn't branch off into a kitchen or dining room or anything. 

i was playing around with the dayton hf 12 on winisd. 2.0 cubes gets it to a .707 alignment. on the graph it's down like 11db at 20hz. if i stick the box in one of the front corners of the room what is a typical room gain going to get me? i know i can eq a little bit in if i have to but i don't want to quickly run out of excursion.


----------



## Oliver (Jun 25, 2007)

I would just build it and play with it 

Otherwise you will have to do research [ yuck }


----------



## tcguy85 (Oct 29, 2007)

a$$hole said:


> I would just build it and play with it
> 
> Otherwise you will have to do research [ yuck }


i did some research. used google. 

it looks like if i corner load it i might be ok. i think i'm going to try a sealed box. it will be used for 80 - 90% music anyway.


----------



## ItalynStylion (May 3, 2008)

That O-Audio amp rocks out. I've got one on two peerless 12's and they sound great. It also has a parametric EQ if you are worried about your low end suffering; just do a little EQing....


----------



## my89_928gt (Aug 22, 2006)

I would not worry to much about being down 11db at 20hz. The human ear is not very sensative to low bass magnitude. So, it should still be usable to near 20. Corner loading may help. Though may need to tame freq ***** on or near upper range.
Even most movies down not have extreamly low bass anyway. 
My sub can go subsonic(down to about 16hz) but if I do I losse on the upper end were most of the information is at. So, I keep curve and subsonic filter set at 25hz.


----------



## BlackLac (Aug 8, 2005)

I have a eD 13kv.3 running sealed, powered off a Dayton SA240 plate amp. I think it's about 2.25 cubes and about 1.25lbs stuffing. It sounds very nice, has enough low bass for my apartment. Too much actually. It is in the corner downfiring into the carpet, I really should put a piece of wood under it though, for my neighbors not to effect the bass output. I fully intended on having it ported, but I was so anxious just to test it out, I just ran it sealed and was really happy with the results. Also, 2.25 cubes is on the small side for a ported box, I should have went closer to 2.75-3 probably. I love it sealed though! For around $200, it's one hell of a setup. I keep recommending it on HT forums, but people prefer to waste money on prefab junk.


----------



## tcguy85 (Oct 29, 2007)

OK, well i did some testing and had some fun.

i brought my dayton ho ten out of my car and up to my room.

here is how the ho plots on winisd in the box i have it in..









note how its down 14 at 20hz.

this is how it rta'd at the main listening position









in this graph it's crossed at 40hz. once i cross it at 60 or 80 that 50hz spike gets CRAAAAZZZY!!!

so it looks like a sealed 12 thats down about 10 at 20 will work just fine. i'll just need to EQ out the huge spike thats at 50hz.


----------



## tcguy85 (Oct 29, 2007)

did some modeling... 

shiva-x(blue) VS. Dayton hf(yellow) VS. Mach5 ixl 12.2(green)








all were models up at a .688 qtc, and all were set at 500 watts input power.

the shiva-x from diycable looks like a great choice.


----------



## tcguy85 (Oct 29, 2007)

while browsing through the aplication notes on the shiva-x i found this interesting info. his "standard room" dimensions are the same as mine. and he's saying 12-15db boost at 20hz. so hell yea!!

Things of note: I’ve changed the room simulation to my standard room dimensions (8 ½’
Ceiling height, 14’ Room Width, 21’ Room depth) and standard subwoofer position of 1 meter from each wall, in one of the front corners of the room. The listening position is assumed to be 2/3 back from the front wall, slightly off center and 39” listening height. Take the room simulation with a grain of salt since it changes significantly with small changes in measurement position. You can count on about 12-15dB of gain by 20Hz for my standard room size calculation, more in some rooms, less in others depending on construction, size & how it is sealed off from the rest of the house. That basic room-gain at 20Hz does change but not as dramatically as does the room modes, higher in frequency. Those are highly unpredictable and change with small changes in measurement position. For general design guidelines though plan on about 12dB @ 20Hz.


----------



## pwnt by pat (Mar 13, 2006)

Iirc, its 12db/octave gain below the standing wave frequency.... I have a PDF on my home PC with the equation. Something like 1143/(2* longest wall (ft)) or something like that/


----------



## tcguy85 (Oct 29, 2007)

my o-audio amp should arrive tomorrow. but for the time being, i got the sub in the box and have it hooked up to an old rockford amp i had laying around just to test things out. 

took a quick scan, i'll need to eq 50hz out quite a bit, like 5-7db. but overall it extends pretty low. this is a 12" jbl sub in roughly 2.0 cubes net sealed firing right into the front right corner of the room. sounds pretty damn good with no EQ but the peak at 50hz is quite noticeable. once i get the o-audio amp i should have plenty of EQ to kill the spike.










looks pretty good right?


----------



## tcguy85 (Oct 29, 2007)

got the o-audio amp, and got 50hz under control 

sound great on music and totally sick on movies. i just skimmed through war of the worlds quickly at a really moderate level and it sounds great and gets looowwwww. i haven't cranked it yet cause i don't want to piss one particular person here at the house off. i'll have to wait till she's gone to give it a good go and see what she's got.

here is what she looks like on my music setting..









pretty darn flat and extends low.


----------



## 60ndown (Feb 8, 2007)

looks like your doing great

you know anything about 'nodes' ?

http://www.kettering.edu/~drussell/Demos/RoomModes/driving.html


----------



## 60ndown (Feb 8, 2007)

afaik,

put your sub on a long speaker wire, sit in your tv chair (normal listening position) and try the sub in many different locations in the room. you should notice some locations sound much better then others.you might have lucked out and found the ideal place by accident? but its worth trying a few different locations one day when you have an hour to kill.


----------



## tcguy85 (Oct 29, 2007)

60ndown said:


> looks like your doing great
> 
> you know anything about 'nodes' ?
> 
> http://www.kettering.edu/~drussell/Demos/RoomModes/driving.html


i have had a sub in this room before and it seemed like this was the best location to keep the bass up front w/o giving its location away. it gives a nasty peak at 50hz, i guess thats a room node that i have, but once i tamed it, it sounds very good and kinda disappears. thank god for the rta though or i never would have known or realized how to fix it.

here are a couple pics of my setup. i didn't take any pics of the rears though.




































the system also consists of a Yamaha RX-V2500 receiver, Infinity alpha 50 mains, the matching Infinity Alpha center channel, and a pair of HK bookshelves for the rears/surrounds. the tv is a Toshiba 30" wide screen HDTV.

the sub box doesn't look pretty but it's just a temp test enclosure that happens to work very well. i am very proud of how it sounds overall. 

next step is to swap out the sub with the Shiva-x, then i'll probably build a new slightly bigger box in the spring time. probably a 3.2 cu ft net sealed enclosure. 3.2 will give the Shiva a .707 qtc.


----------



## 60ndown (Feb 8, 2007)

your mains play down to 35hz,


http://www.crutchfield.com/S-dcFEDh8IKoM/App/Product/Item/Main.aspx?i=700A50B


so wheres your sub xed at?

32hz?

more than 1 driver playing the same freq is asking for issues.

if i were you, id try something like this

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=266-274

let your mains play down to about 80hz and let the moofa take over from there.


----------



## tcguy85 (Oct 29, 2007)

60ndown said:


> your mains play down to 35hz,
> 
> 
> http://www.crutchfield.com/S-dcFEDh8IKoM/App/Product/Item/Main.aspx?i=700A50B
> ...


i'm using 60hz as my crossover point(on the sub and all 5 channels), both for movies and music. the receiver is a pretty good unit and has it's own crossovers along with EQ, T/A, and all kinds of goodies.


----------



## 60ndown (Feb 8, 2007)

tcguy85 said:


> i'm using 60hz as my crossover point(on the sub and all 5 channels), both for movies and music. the receiver is a pretty good unit and has it's own crossovers along with EQ, T/A, and all kinds of goodies.


sounds good.

id try 55,50,45,and 40

with a lil gap between the mains and the sub if possible

just for fun.

link to the amp?


----------



## tcguy85 (Oct 29, 2007)

60ndown said:


> sounds good.
> 
> id try 55,50,45,and 40
> 
> ...


well on the receiver i can choose OFF, 40, 60, 80 and upwards from there.

i tried the mains at 60 and making a small gap using the crossover on the o-audio subwoofer plate amp and it didn't work out so well. keeping them both at 60hz seems great.

here is a link to the receiver: http://www.yamaha.com/yec/products/...00004&CTID=5000300&ATRID=1000&DETYP=ATTRIBUTE


----------



## 60ndown (Feb 8, 2007)

i got my ht amp from a thrift store for $30:blush:


----------



## tcguy85 (Oct 29, 2007)

well i guess i should update this. i decided to make a box for the shiva-x that i ordered. 

the shiva will arrive tuesday so for today and tomorrow i have the jbl sub in the box.

the following i'll copy and paste from my thread on avsforum:

well not so much a build log as it is the finished results.  i forgot to take pictures along the way. i was to busy and having to much fun to remember to take pics.

well anyway its a 31" tall by 17.5" deep by 15" wide sealed box with a double baffle front. no internal bracing, figured the double baffle would suffice. it's 3.32 net sealed with 52 oz of poly-fil.

i am using the o-audio 500 watt bash plate amp on the 16hz sub-sonic/EQ setting. the shiva-x will be here Tuesday (i can't wait) but for now i am using a jbl driver that came out of one of these. http://jbl.com/home/products/produc...age=ENG&Country=US&Region=USA&cat=SUB&ser=PER

she sounds great right now until you push it hard on the low notes. the little jbl just doesn't have enough linear excursion(xmax). 

here is the in room response at the main listening position.









she's DAMN flat for a sealed box. +/- 4db from 12hz up to 100hz where i sit!

this is how the shiva-x models up in 3.32 net sealed.









i'm not sure how the current jbl driver models up in winisd because i don't have any specs on it. i'm hoping for very similar results, just with the ability to play the low notes without sounding like a mess.

snapped a quick pic of the box as it sits right now.









not sure how or when i'll cover it. looks aren't as important to me as the sound. 

i will update once again on tuesday night after i get the shiva-x in the box.

so all in all i guess you can have quite a bit of room gain.


----------



## tcguy85 (Oct 29, 2007)

ooops double post. damn server.


----------



## 14642 (May 19, 2008)

Go here and click on "Calculators" in the box on the left. If you want more info, click on white papers.

http://www.harman.com/about_harman/technology_leadership.aspx


----------



## Benihana (Nov 30, 2008)

the shiva will rock in that size box. I have the older tempest in a 240L box, destroys my room!


----------



## tcguy85 (Oct 29, 2007)

Benihana said:


> the shiva will rock in that size box. I have the older tempest in a 240L box, destroys my room!


yea, she does good for music and gaming. seems to do ok for most movies. it hates war of the worlds though, just to much low end in that movie for a single sealed 12 in a 2400 ft room.


----------



## 60ndown (Feb 8, 2007)

tcguy85 said:


> yea, she does good for music and gaming. seems to do ok for most movies. it hates war of the worlds though, just to much low end in that movie for a single sealed 12 in a 2400 ft room.


man thats a big room.

build the 12 inch version of this with your shiva and you will be very happy

http://www.decware.com/newsite/hwk15.htm

This enclosure will properly load rooms between 144 sq. ft. and 3200 sq. ft. with extremely serious bass.


----------



## tcguy85 (Oct 29, 2007)

60ndown said:


> man thats a big room.
> 
> build the 12 inch version of this with your shiva and you will be very happy
> 
> ...


well its 2,352 cubic ft. 14'x21'x8' are the room dimensions. so it's not really huge. just a good sized sealed room.

this single sealed 12 is plenty for music and gaming. it's enough for most of the movies i've played so far. it hates War of the Worlds. it did awesome on Transformers though, i played that as loud as i wanted to and it kept right up.

and yea, that sub looks like it'd be a monster. maybe someday.


----------

