Open baffle suggestions

AJ

Member
2003-08-01 7:06 am
Oregon
Hey guys

I'm looking for some input from some of you that have messed around with way too many bass drivers in a single OB. :)

I've got sixteen 12 inch Madison Warriors to play with and I'm going to go with 8 per side on an OB with two Audax PR170s for mids and a B&C DE250 in an ENG90 WG for the highs. The baffle is limited to 48 inches wide and I'll go 77 inches high if needed. I can squeak another 4-6 inches of width out of it if it looks like keeping all 8 woofers low to the floor will have a significant advantage. Crossover will be LR4 500/1500hz, active, triamp. These will be in corners on the long wall and angled in toward the center of the room at about 30 degrees.

There's obviously an infinite number of ways to organize the contraption, so I drew up some options to think about. I'm looking for maximum bass extension without adding any boost, but I'm aware that to get a decent 40hz will probably require it.

[IMGDEAD]http://www.lakefly.com/images/choices6.gif[/IMGDEAD]

Where would you start with something like this, given the stated limitations? Any ideas beyond the six shown here?

Thanks.
 

ttan98

Member
2006-04-04 11:24 am
Melb
AJ

Hi,

I once asked this question to J.K., he mentioned that Soundeasy s/w has a feature that it can simulate the type of configuration you want.

I have the s/w but not good at using it, possibly you may want to post this query to him.

PS still thinking of buying the Audax midrange, has not pulled the trigger yet. I heard many good reports on it.

cheers.
 

AJ

Member
2003-08-01 7:06 am
Oregon
"Just curious - how will adding drivers extend the low end? Other than you'll need a bigger baffle."

I wouldn't think additional drivers would lower it either. I'm just relating to Magnetar's experience with his five 10's per side where he was getting lower output than expected. Why this would be the case, I don't know either. At what levels the lower frequencies end up is another unknown. I suspect room gain will help here.

Also, Mike's woofers have a higher Qts than mine, so I may not get the same results. These drivers have a lower Fs, but that may not make up for their lower Qts. I'm just hopeful, but nothing's gonna be known till they're built. :)
 
With that many drivers facing the same direction, you'll be shaking that baffle to within an inch of its life. :smash: You might want to think about separating / isolating it from your mids and waveguide. I have 8 cheap 12" drivers (4 per side) that I plan on putting in a Linkwitz W baffle. In that configuration, I can keep the dimensions down around 30"H x 18"W x 20" D. You have to deal with the cavity resonance, but the opposing forces cancelling each other makes it worth it.
 

AJ

Member
2003-08-01 7:06 am
Oregon
"With that many drivers facing the same direction, you'll be shaking that baffle to within an inch of its life."

heh heh...yeah that thought ocurred to me too. I was even wondering why I couldn't turn every other driver around, although I haven't really thought that one thru yet. :)
 

AJ

Member
2003-08-01 7:06 am
Oregon
"isn't the point of multiple drivers to decrease excursion for a given spl and then you can apply more eq to the bottom end given the limiting factor in ob bass is always xmax and not power"

Yeah, that would be right. In the end, and if I like them, I'll be rolling these off to sub. I need some higher sensitivity than my current single 18 inch and the multiple drivers seemed like a good way to go. Before that happens though, I want to mess around with them and see what it takes to get a good solid 40hz. (probably need some boost).

Got any suggestions for driver placement? I just know I'm gonna have to build a dozen baffles before I find the one that works best. :)
 

AJ

Member
2003-08-01 7:06 am
Oregon
Hey Brett

I was hoping you'd weigh in. I like #6 too, but I'm really tempted to build #4 first. It's probably a sonic disaster, but I think it's very high in the cool looking factor. :)

BTW, I'm gonna build a tapped horn pair for the subs. I think I can fit them in behind the OBs.
 

Brett

Member
2002-01-07 6:02 pm
AJ said:
Hey Brett

I was hoping you'd weigh in. I like #6 too, but I'm really tempted to build #4 first. It's probably a sonic disaster, but I think it's very high in the cool looking factor. :)
It does look funky.

Just thinking, if you go OB, are you going to Treanorize your room?

AJ said:
BTW, I'm gonna build a tapped horn pair for the subs. I think I can fit them in behind the OBs.
I keep looking at Erik's (Volvotreter, post 666) TH and thinking of one with a 3015LF in it. But like I really need them with a pair of KHorns in the room (14x15x10')
 

AJ

Member
2003-08-01 7:06 am
Oregon
"Just thinking, if you go OB, are you going to Treanorize your room?"

I already have four 3-foot traps behind the bass boxes and a coupla mid-range absorbers. Anymore than that and I'll be running train sets around them. I've seen what too much audiophilia can do to a man, and it's not pretty. :)

"But like I really need them with a pair of KHorns in the room (14x15x10')"

geeze Brett, you got all kinds of room. I'm in 11-1/2 X 15 X 8' and there's never enough bass in here.

Don't know which driver I'll be looking at. I'm watching the discussions on which T/S parameters give what best results. I want as wide a bandwidth as possible - maybe 20-100hz if that's doable.
 

Brett

Member
2002-01-07 6:02 pm
AJ said:
I've seen what too much audiophilia can do to a man, and it's not pretty. :)
Every time I see the pics, I get a little scared.

AJ said:
geeze Brett, you got all kinds of room. I'm in 11-1/2 X 15 X 8' and there's never enough bass in here.
I agree with the never too much bass sentiment, but this is my bedroom and with thKHorns in the corners I'm damned if I know where I can fit the 3015LF versions. If I raised the bed up on a brick, I could probably put them under the bed.
AJ said:
Don't know which driver I'll be looking at. I'm watching the discussions on which T/S parameters give what best results. I want as wide a bandwidth as possible - maybe 20-100hz if that's doable.
From what I remember in the long TH thread, I'm not sure if you'll get that sort of BW. 2 octaves seems like about it.
 
Hello, two above and two below the MMT, hinge the sides and mount the other four as vertical pairs on each of the hinged wings low to the ground next to the bottom two WWMMTWW woofers, you can curve the center down to angle top of the wings. This will narrow the whole system and will get you good bass
 

AJinFLA

Banned
2005-02-09 4:35 am
Tampa
Hi Paul,

That makes sense if you need subwoofer frequencies well below dipole resonance. Unfortunately, AJ has chosen a midrange unit, Sd 139cm2 (x 2), 0.5mm xmax, that even with a barn door sized baffle as proposed (and the associated independent music it would play), would be SPL limited below 200hz. I would not use it below 300hz. This becomes problematic for W type baffles like the so called ripole.

cheers,

AJ