[Mike Edwards]

Ok, here's my dilemma. I used to own two THT's... they had more output than I could ever hope for, but they didn't like being corner loaded with the horn facing the corner... produced some rather boomy bass that I could never get over, and of course they showed their limitations when you faced the throats into the room. so I changed over to two SI 18's in 12 cu ft ported boxes (martysubs) and cleaned up the bass dramatatically. only problem is that I miss the insane OUTPUT that the THT's afforded me and I'm craving more.

My ISSUE is that I have a 12 foot wide by 22 foot long room (12 food wide section is where the screen is at and my room is open to an addition to the left (no door with a 7x6 foot opening that I KNOW is sucking out output like a sponge( and opens up into the kitchen and a hallway in the back (not as bad, small openings)

here is a picture (excuse the cruddy picture, I was lazy and just used paint

now the decisions I have is three fold. I'm thinking of adding two more marty's to add to the two I have... one in the front left (can't fit two more up front, my equipment rack and center would have no place to go) and one just to the left/behind of the seating arena where the X is.


the second option is to take out my SI 18 d2's, use them on the amp I have for nearfield subs and add 4 more sealed to go up front with a total of 6 SI 18's in the room vs 3 or 4 ported si 18's....

the LAST option is to turn my si 18's into sealed like I mentioned, use them as nearfield and add two Gjallarhorn's up front (using UXL 18's instead of the LMR Ultras) and lie them on their sides with the throats facing into the room (I figure their insane amounts of output will overcome not being corner loaded


any thoughts on the three options?

 

[Tonto]

Do you have room in the attic for the horns? You could fire them down into the room & positoning would be less problematic...if you have attic space.

 

[Mike Edwards]

Do you have room in the attic for the horns? You could fire them down into the room & positoning would be less problematic...if you have attic space.

I have a flat roof. Meaning I have six inches of space between ceiling drywall and the roofing panels underneath the roofing material

 

[chrapladm]

Of coarse two Ghorns and all sealed SI's. BUT its not my money. What are you missing now?

I had a pair of THT's also and really like them a lot. I got into a lot of UULF movies and then moved onto larger drivers. Always hard to make suggestions without knowing exactly what the OP is wanting /needing.

Do you have any REW sample of your current setup?

 

[Mike Edwards]

Of coarse two Ghorns and all sealed SI's. BUT its not my money. What are you missing now?

I had a pair of THT's also and really like them a lot. I got into a lot of UULF movies and then moved onto larger drivers. Always hard to make suggestions without knowing exactly what the OP is wanting /needing.

Do you have any REW sample of your current setup?

I'm missing output... I'm limiting out my amp and wanting to push them harder... I want that feeling to be able to run them 6-7 db's hot and get that pressurization. I can get decently close with the 18's but nothing like the output I had wit the THT's... only thing was they sounded boomy in my room (tile floor combined with corner loading) and with that alcove off to the left it's sucking out spl pretty decently as I can go into that room and just FEEL the LFE pulsing more violently than out there. I can't "pressurize" it like I want. I can get it in a small enclosed room, but an open floor plan makes 2 subs drastically under par for that type of situation.

 

[chrapladm]

BRUTE force I think will be the answer. Having near field will help out your experience. (feeling the bass)

And having a pair of Ghorns will always be difficult in placing because of room logistics and large cabinets. BUT you will have a LOT more output than your old pair of THT's. A LOT MORE.

Sealed SI's would help take off where the Ghorn needs to be crossed. So if you have the room then 2 Ghorns and four sealed near field would be about as loud as your going to get.

 

[Mike Edwards]

BRUTE force I think will be the answer. Having near field will help out your experience. (feeling the bass)

And having a pair of Ghorns will always be difficult in placing because of room logistics and large cabinets. BUT you will have a LOT more output than your old pair of THT's. A LOT MORE.

Sealed SI's would help take off where the Ghorn needs to be crossed. So if you have the room then 2 Ghorns and four sealed near field would be about as loud as your going to get.

yeah, I'm thinking near field is what I need to do more than anything... well that and close off that alcove room to the left... that "squiggle" to the left labeled "alcove" is a 6x7 foot opening that goes into an 8x22 long room and I can FEEL the bass so much better in there. the opening is at the halfway point of the room so I know it's causing a big suckout... one of my next projects is have a double door set installed there to really close off that room and keep the LFE contained in my seating area (ironically the seating area is about level with that opening too).

as for nearfield, that should give me more SPL as well, since I'm limiting out the two I have now pretty decently (although that may not be as big a deal once I close off that opening). now I just have to figure out if I want to just add a nearfield to the left by that opening and one more in the front left (I can't do anything on the right hand side since it's a walkway to the back and has doors and pantry's off to that side), or whether I should just buy 4 more drivers and go sealed. I've never done sealed, only horns and ported, but I hear that the sealed have more of that mid chest slam to them.

 

[chrapladm]

MDF is cheap. :T So have a try and see if you like it.

 

[Mike Edwards]

MDF is cheap. :T So have a try and see if you like it.

lol, that it is.... I did the graphs and if I get a few db boost with 4 ported marty's over the 17-25 hz range, but I get a good 3-4 db's in the 30hz and up range with the 6 sealed (my two D2's I have in the marty's off of a peavey IPR 3000 + the 4 I'm considering running off of a single Inuke 6000)....too many decisions lol....

with the 6 sealed I can do 4 up front, one near field just to the FRONT of my seating position on the right, and one near field just to the left and behind the seating position. (at the X on the picture)...

whereas with adding 2 more ported I'd do one sonosub where the X is to save on space (just to the left and rear of the seating position) and the 4th one would be front and left, directly across the room from where my two ported are now...


as much as I'd like the insanity of the Gjallahorns, the need to EQ for that 60-70 hz ringing and the missing upper bass frequencies.....that and add in the fact that they are a PAIN to build, make them a bit less desirable.

 

[Mike Edwards]

since my laptop died this year I can't run REW, but I did notice something I hadn't tested before.... right in the middle of the room it sounds pretty good, but I went to the back of the room to grab something during a heavy bass scene and noticed I got HUGE amounts of pressurization and those two marty's were just devestating, but when I shift back to the center of the room (where the seating area is) that "impact" and pressure went down quite a bit, so I'm guessing I have a pretty nasty null right there. the LFE in the back of the room was more powerful and impactful than when I was sitting right there next to the subs up at the very FRONT of the room.

wish I had a longer speakon cable to give one of the subs a try in the back left corner of the room to see if it would cancel out that null.


EDIT:... double checked. I forgot I had played around with my subs a little. Put one in each front corner of the room. when I did that I created a weird null right at my seating arrangement. Bass sounds less directional, and smoother in some ways, but that "pound in the chest" LFE wasn't there...rather noticeable...

I changed them back to the way I had in the diagram, both of them in the front right corner of the room next to each other and it came back with a vengeance. Just as powerful in the middle as in the back. (but still would like some more output of course).... guess I can't put another sub in that front left corner when I make some more since it sounds like it will cause that null again... well that stinks. Guess I'll have to experiment with some near field subs by the seating area, see if that will help

 

[NBPk402]

I like your last option. :T

 

[GPM]

so I'm guessing I have a pretty nasty null right there. the LFE in the back of the room was more powerful and impactful than when I was sitting right there next to the subs up at the very FRONT of the room.

Correct, rooms are ½ WL open pipe resonators, so have both even and odd harmonics, which means the 1st pressure mode is at the ends of the room and a deep null at its center: http://dev.physicslab.org/Document.aspx?doctype=3&filename=WavesSound_ResonancePipes.xml

From this we see that speaker, listening position ideally need to be at the room’s length, width odd harmonics and no amount of EQ is going to offset its even order harmonic nulls.

For dealing with height modes, speakers ideally need to be up in space to average out the room using the same calculations, so something to consider when using ‘fill’ subs an mains bass height off the floor Vs floor bounce to find and acceptable trade-off.

GM

 

[Mike Edwards]

Yup. Which is why I think near fields just behind or to the side of the searing position will help knock out that null

 

[GPM]

Yup. Which is why I think near fields just behind or to the side of the searing position will help knock out that null

Well, it will reduce its impact due to the subs being close, but the LP or at least the subs needs to be either forward or backward to be in the room's 3rd, 5th, or 7th harmonic for max impact/efficiency either with the subs in the corners.

GM

 

[Mike Edwards]

Well, it will reduce its impact due to the subs being close, but the LP or at least the subs needs to be either forward or backward to be in the room's 3rd, 5th, or 7th harmonic for max impact/efficiency either with the subs in the corners.

GM

Yeah. I should have clarified. I can't really move the seating position much since any closer and that 120 inch screen strains the eyes by being too close and moving back to the next harmonic rang is about 16 feet from the screen ....which is too far for proper immersion. As for the other two sub's I'm building. They can be placed along the left wall behind the seating position directly in the 3rd and 5th harmonic location.

As I had said in my edit. With both sub's that I gave now in the front right it severely compensates for that null that happens if they are separated in the two front corners. I just loose some smoothing as I can slightly tell its coming from the right

 

[Mike Edwards]

Basically... with the 2 subs at the front right like this picture I get some powerful bass (I'm sitting about 12 feet back from the screen in a 22 foot long room, but the subs drivers are about 4 feet from the wall since they are 4 feet long marty subs)....but put them on opposite ends of that front room each corner loaded and there's a HUGE suckout at the listening position. so both subs are back to the right corner again like the picture states

Now with the added subs I'm thinking of stacking them at about the 14 foot back mark where the X is. or putting one there and one behind it even further under the TV that's in the back left of the room as you can see labeled in my fantastic paint drawing...which SHOULD get it in either the 3rd or 5th harmonic.. I'll probably have to shift them around a foot or so either direction to find out

 

[dougc]

Mike, can you get your hands on 2 or 4 more subs to place around the room to see how they will react with each other before you buy and build? REW RoomSim was pretty close to getting my subs where they needed to be, but the way they reacted to the odd shapes in my room and seated position was different enough that I ended up moving them a bit. A tall, wide, smartly disguised ported sub nearfield to the back of the couch would give you enough "slam" and plenty of tactile feel as long as it plays nice with the other subs.

The G-horns are special as far as output, but if not properly placed, you will have to keep cranking them up and you will hear the things in your house shaking more than the subs at the frequency of your nulls. I sure do love my G-horns...

 

[Mike Edwards]

Mike, can you get your hands on 2 or 4 more subs to place around the room to see how they will react with each other before you buy and build? REW RoomSim was pretty close to getting my subs where they needed to be, but the way they reacted to the odd shapes in my room and seated position was different enough that I ended up moving them a bit. A tall, wide, smartly disguised ported sub nearfield to the back of the couch would give you enough "slam" and plenty of tactile feel as long as it plays nice with the other subs.

The G-horns are special as far as output, but if not properly placed, you will have to keep cranking them up and you will hear the things in your house shaking more than the subs at the frequency of your nulls. I sure do love my G-horns...

Yeah. I think I'll pass on the ghorns. I'm gonna go add two johnny sub's along the back left seating position . I love my twin Marty's up front but I need some more overhead and room smoothing

Unfortunately I don't know anyone else besides me who has a ported sub to test out (my other buddy us using twin thts)

I MIGHT be able to borrow my buddies ED A5 - 300 but its a long shot