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matt ristrom
Posts: 11
Joined: Wed Jul 10, 2019 6:21 pm


#1 Post by matt ristrom » Thu Jul 11, 2019 9:59 am

Hey fellow engineers and DIY folks,

I own a studio in DeSoto (recordingincolor.com), Kansas and a small IT company (rfcpro.com). My passion is playing guitar and creating music but I also design and build line arrays for ROX Audio in Kansas City. My "Flame-Thrower" design is on the Partsexpress builders list.

I usually over-do it which is what led me here. My Flame-Thrower system will put out almost 140db at one meter with six elements (1x8", 2x1" compression horns per element). And like an idiot I use it for general PA use in a 20 x 30 room. I am hoping some of Bill's designs will help me get lower than a typical pro sub and provide enough spl to keep up with my other gear.

Glad to finally get on the forum here after looking in from the outside for a few years. Bill always pops up if you like horn designs or serious bass.
Last edited by matt ristrom on Thu Jul 11, 2019 12:25 pm, edited 2 times in total.

matt ristrom
Posts: 11
Joined: Wed Jul 10, 2019 6:21 pm


#2 Post by matt ristrom » Thu Jul 11, 2019 11:16 am

I tried emailing Bill a few questions to help me decide which plans I need. I just got an email back saying I needed to ask questions here. Now that I am in the forum and can search I am still not finding the info I need. Here are the questions I was trying to solve:

1 – Are there any tested designs using 18” or 21" drivers?
2 – Would the Tuba designs allow for coverage up to 120hz? I want to pair them with a line array that doesn't like to go below 120hz.
3 – Do your designs perform well outdoors in pro audio applications? I want to make around 140db outside at one meter/50hz and be able to reach below 30hz.

I have a pile of 18's and marine grade plywood. I have not seen anyone using 18's though in any of the designs. I realize that the horn allows for more bass with a smaller driver. I want to take that to the extreme and also use a large driver. I just want to make sure there is a design that has been tested with some of the larger high powered modern drivers. I don't want to turn this plywood into toothpicks.

I will try to figure out how to post this separately if I can't find any other info.


Bruce Weldy
Posts: 7567
Joined: Fri Nov 27, 2009 11:37 am
Location: New Braunfels, TX


#3 Post by Bruce Weldy » Thu Jul 11, 2019 11:52 am

Welcome to the forum....

There are no plans that use any driver larger than a 15" in a folded horn cab.

The Tubas and Titans can both go up to 120hz with no problem...

The pro designs are different from the Home Theater designs. Sounds like you are looking for Tuba 60s based on your wanting to go below 30hz.

What you need to understand is that these designs require drivers with certain T/S parameters, so most likely you'll have to get new drivers. Also, I imagine the plywood you have is 3/4". All of these designs use 1/2" ply. Because of the bracing, there is no need for 3/4 - it's just added weight and you'd have to re-design the plans to keep internal volumes the same.

As for the 140db at 1 meter.....you'll have to look at the charts.

6 - T39 4-25" 2-22" 3012LF
4 - OT12 2512 Melded/NSD2005
1 - T24
2 - XF210

"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."

matt ristrom
Posts: 11
Joined: Wed Jul 10, 2019 6:21 pm


#4 Post by matt ristrom » Thu Jul 11, 2019 12:24 pm

Yep - I'm new. And I have used horn loaded cabs like the Community Leviathans and always thought bigger was better for subs.

I have now read through ALL of the posts for newbies explaining why I can't use my collection of 18's or the 3/4" plywood that has fallen into my lap (shit!).

Well...................better to learn that waste time building stuff that doesn't work. Now what to do with all these 18's...................

Posts: 47
Joined: Sat Jan 26, 2019 2:57 pm


#5 Post by rfauske » Thu Jul 11, 2019 12:52 pm

Build a wall of simplex cases..

Posts: 1571
Joined: Thu Sep 10, 2009 8:06 pm
Location: Sacramento, California, USA


#6 Post by Seth » Fri Jul 12, 2019 2:09 am

matt ristrom wrote:
Thu Jul 11, 2019 12:24 pm
Now what to do with all these 18's.
Ebay LOL :cowboy:

Welcome to the forum Matt
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

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