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Discussion Starter · #1 ·
Re: post count before attatchments aloud?

This thread was an inspiration and I thank you very much Rodny.

http://www.hometheatershack.com/forums/diy-subwoofers-general-discussion/7048-ib-makeover.html

I used REW for the first time 2 days ago, I am still getting the hang of it, but here is what I have so far. I haven't run Audyssey yet, I don't know how to, so this is no EQing yet, no room treatments (I have a 60"x90" entryway leak, bedroom door leak, and a false roof that has almost 3" of flex) and no HP filter. Dual 128 cubic foot cabinets, each loaded with a pair of FiCarAudio IB3 18's, each powered by an EP4000 ( four IB3 18s and two EP4000s total) each with a 12" diameter port 5" long with two free ends for a 13.5Hz tune. My electrical is very lacking, that will come another day as well.

Sweeps at 5dB increments starting at -40dB master ending at -10dB master to see compression. Distortion tests yet to come once I figure out how to do them. LP was set to 80Hz, I will sweep some more with it at 250Hz.





SLLT is not a myth.
 

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Discussion Starter · #3 ·
I ran some this morning, I still dont have this mastered by any means, these were taken with the Audyssey mic at LP... 7' from the subs. A 5Hz sine wave is of course overcome by the 1st harmonic, 10Hz is much higher in SPL and its distortion is terrible, but its almost 2 octaves below tuning :)



Here are two done at 10Hz, I forgot to increase the image size on the 1st so i did a second test.





Here is a snapshot isolating 2Hz-10Hz to see the effect of the HT room sealed up vs opened up, though I don't know how much the Audyssey mic can be trusted this low, especially when the drivers are completely unloading.



I ran several sweeps until I could hear the suspension complaining with the room both sealed up and opened up, anything more than -12dB on the master gets nasty. So here are sweeps in 5Hz increments starting at -42dB master and ending at -12dB to show compression and room effects, such as walls and ceiling that flex massively no longer being able to increase in how much they flex. Sealed up, Audyssey mic.



A good single shot of the FR at a moderate level.

 

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Discussion Starter · #4 ·
Mike, here are my very first shots taken back on the 23rd when I was even more novice with this than I am now. These were with the RS meter, I believe I had the correction file added at this point, I don't remember for sure. I apologize for most of these being very hard to see and most of them not having any text typed to go with them. I was still learning how to take snapshots :)













10Hz -3.6dB FS
THD: 7.70% THD+N: 7.75%
2nd: 5.74% 3rd: 5.11%
4th: .339% 5th:.363
6th: .228 7th: .129
8th: .032 9th: .0258

124.4dB






REW sig gen only goes to 10Hz so I used NCH and did 5Hz but got weird results. No black spike had my level view too high, and the top says 15Hz -36.6dB FS since it was "louder" than the 5Hz tone, the circled window said 94.5dB. THD was just below 10%.









 

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Discussion Starter · #5 ·
Was planning to go from 1 IB3 18" per tower to a 21" IA DP modded for HT, the silver line, but Nick is a busy guy and by the time he emailed back I had already purchased four more IB3 18's. Here Brandy is installing 2"x4" bracing. She is inside the 2nd tower, each are 128 cubic feet with a 12" port 5" long for a 13.4Hz tuning.







Shot of tower 2's port aimed at the 8'x8' platform. Overhead lights on.



Underbody lights on.

 

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Discussion Starter · #8 ·
Apparently you folk are "at war" with The Cult? I know nothing about it but ThomasW gave me a little sneak attack today and mentioned Steve Callus and his LLT, Rodney's IB conversion and "SLLT", and HTS having it's own IB area...god forbid you don't skip over IBs because it's the cult's territory... cult not capitalized because I mean it as an adjective not a pronoun :) ( I am neither good at grammar nor spelling, I may be way off here )




I could EQ flat to 10Hz at 115dB with up to 15dB headroom at 23Hz





Or I could EQ flat to 7Hz at 110dB with up to 20dB headroom at 23Hz









just cuz i love/hate it:

 

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Discussion Starter · #9 ·
If I could do it all over again, I would build 2 manifolds with 4 subs in each, one in each corner of the spare room. The spare room is 990 cubic feet. My door is 23"x88"x4". With my door open, I am tuned to 11.5Hz. Door closed it is IB. 8 Fi IB3 18's.

 

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Discussion Starter · #11 ·
alright, I may skip the option of plugging for IB and build a hallway walk through port/manifold off the outter edge of the door frame and remove the door. The outter dimensions of the frame are 41" wide and 95" tall... perfect. I can either go 1 sheet of 4'x8' long and put ends going outward at a 90 degree to further prevent cancellation of the rear wave, or 2 sheets long doubling port length and reducing cancellation of the rear wave while tuning lower.

I haven't slept yet, I had to retype all that and edit my pics. At first I thought I was leaving the door in so i could plug the port and keep a door on the spare room... then i realized if I shut the door, um, hmm... I am sealing the subs off altogether...and with it open it would obstruct the 2 subs on that side unless I move them down past the door, defeating the purpose of the long hallway in the first place to prevent rear wave cancellation :(

I need to go to bed.

this is using 2 wide for longer port length, lower tuning



this is only 1 wide and blocks at the ends to reduce port length but kill more rear wave cancellation



this is 2 wide, long port, door in (DOH) would have been able to open and close the door inside the halway/manifold/port



this is 1 wide short port door in (DOH)



2 wide long port door gone



1 wide short port end caps for rear wave door gone



sleepy time
 

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Discussion Starter · #12 ·
or I can slide woofers 29.5" back so I can leave door in, leaving 19.5" for the subs to mount at the end of board 1. 4x8 is actually 49 wide. I still couldn't use it with the door shut, but I'd still have a door.

What would all this accomplish by tearing the towers down? You guys would think getting space back. I suppose yes, but thats not the driving force... exactly. One, I need easier access to the spare room. Right now we have to walk up the bleechers, step up the side shelf, open the door standing on the shelf, climb down to the floor, back up, reverse process. It's a pain going in and out of the spare room several times a day. Two. Most of you know I am a post you-know-what. I crave attention, even if it has to be bad it's better than none. The towers have died, there's nothing left but to listen...well, it needs more bracing, then left alone. Three... The towers are dead! Now what do I do? The fun of it is building, posting, testing, modding...its finito! Morte! Four.. I love thinking, plotting, planning, building, realizing, modifying... the process itself. Its just what i do. I need to keep on doing it. Five: I need more low end FR! MORE! The "low" bass, "mid" bass, "high" bass all overpowers my ULF. ULF is very hard to create and easy to get burried under lesser SPLs of higher frequencies. I LOVE the ULF, like the rest, but I get way more of the rest. SIX: cuz I am (edit) :p





I still want desperately to try IB, so you all know full well i will design another door for the other end so I can seal it up with the BR door open and go tru IB ;)
 

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Discussion Starter · #13 ·
I am pretty sure this is what I am going to do. My MDF is actually 97 x 49..sheesh.

I'll have to butt up part of a 2nd sheet to the end of each side and top (bottom too?) for a total length of 70". I want to mount the subs side by side, at the top, and run 2x4s between them... 4 in each "corner" of the subs so 4 of the mounting screws will go through the subs and into 2x4 studs like in the towers. So I will need 21" wide off each sheet, leaving 28" pieces.

I'll take those 28" pieces and make the end caps for the rear waves, that leaves over 10" clearance from the closest wall to prevent the air getting trapped/loaded into a corner.







830 cubic feet 41" x 95" x 70" port 10Hz tuning

 

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Discussion Starter · #15 ·
Yes, I'm making a manifold/port 41" wide...the outside of the door frame... 95" tall... top of the door frame...and 70" long, 30" to clear the door, 40" to mount 2 IB3s side by side, on each side, 4 IB3s total. Then adding ends 28" wide on each side to isolate the rear wave somewhat. The room is 990 cubic feet before manifold/port displacement, 880 after, resulting in apx 10Hz tuning.
 

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Discussion Starter · #16 ·
got to thinking the front wave will go backwards through the manifold as much as forward without a back on it, IDK how this works in a tapped horn or 6th order, more thinking. Maybe manifold on top of the port.



 

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Discussion Starter · #17 ·
before I go completely screwing things up I'm going to get more 2x4s to do side to side bracing and get 2 more 12" pipes, 48" for 6.5Hz. doesnt look near as bad until 10Hz HP is added for electronics roll off.

fr



lotta watts



spl

 

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Discussion Starter · #18 ·
Go to Home Depot buy a cheap solid core door, do something like this .......



I know I brain storm fast and take quick turns out of nowhere, now I am really liking Thomas-W's idea. I just went out to my garage and pulled an old door down, it's too short and wide... was hoping to spare the door I have now... but after all the other things I have done to it, what the .

The current door, the top rectangle dims are 21" wide 49" tall... if thats not perfect... I can cut 49"x21" panels for the manifold back layers and 49x21" panels for the sides... 2 or more layers thick. So 21"x21"x49" manifold like pictured above.

The bottom is 21" x 18", I can either cut it ou as a square and make a slot port thats easily pluggable with a panel cover, or I can hack it to a 21" diameter circle and use the 20" sonotube up to 48" length so it clears the wall when opened...but not so easily pluggable.
 
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