Hi guys, I'm trying to design a subwoofer horn to use in a stack of 12 at our events. I keep doing simulations but I can't seem to fall on something right. I need them to go from 30~80hz and a kicker will take the higher bass. The size doesn't matter that much since we have a lot of helping hands to transport the equipment. I would like to use the LF21n551 from RCF (2000w rms!!!) to have the maximum efficiency by sq cm of mouth area. I love my techno loud as F*** lol I was thinking of making them active and a bit as the terrahorn. Which means to not fold the pattern and make a perfect (almost) curving expension.
So the goals for that design:
- High sensitivity
- Flat response from 30~80hz
- Hifi quality bass
So I have a few questions:
1- If somebody can verify I have the right parameters for the LF21n551, it would be greatly appreciated:
Sd=1720
Cms=4,74E-05
Mmd=434
Re=5,2
Bl=39
Rms=6,2
Le=3,2
2- What is the best horn type (Hyp, Exp, Con, ...) for subwoofers?
3- Should I use combinations of horn (Exp+Con)?
4- What would be the compression ratio you would recommend?
4- Any tips?
So the goals for that design:
- High sensitivity
- Flat response from 30~80hz
- Hifi quality bass
So I have a few questions:
1- If somebody can verify I have the right parameters for the LF21n551, it would be greatly appreciated:
Sd=1720
Cms=4,74E-05
Mmd=434
Re=5,2
Bl=39
Rms=6,2
Le=3,2
2- What is the best horn type (Hyp, Exp, Con, ...) for subwoofers?
3- Should I use combinations of horn (Exp+Con)?
4- What would be the compression ratio you would recommend?
4- Any tips?
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Hey mister deep pockets, how commercial are you? Just wondering if we are designing a stack for a hobbyist or a big business.
Also, before I begin, looks like Walmart carries this driver. How weird is that?
RCF LF21N551 Professional Low Frequency Transducer - Walmart.com
When size doesn't matter and you want a stack of 12 for 30 hz, front loaded horn is the only reasonable option. Here's a 27 hz full size ideal front loaded horn for 12 of these drivers with 1000 watts per driver (12000 per stack) into the 2.8 ohm load of the stack, shown without power compression or any filters.
The results look good and this big horn sim could be chopped into 12 modular units (Labhorn size, 45 x 45 x 22.5 inches) that have this response when stacked properly. But it should be noted that you can get pretty close to this with much less expensive 18 inch drivers.
Pic 1 - inputs
Pic 2 - schematic
Pic 3 - impedance, showing the minimum 2.8 ohm load of the stack through it's bandwidth
Pic 4 - spl
Pic 5 - displacement - without a high pass filter 1000 watts per cab is about as high as you can go - but with a hpf you could get a LOT louder in the upper bandwidth - also it could be tweaked in subtle ways to allow for quite a bit more power within xmax limits but I'm not getting into that right now
I'm not going to explain how to turn a sim like this into plans right now. But I should explain that individually these cabs won't have a response anything like this, so they need to all be used as a whole and stacked properly if you expect to see this kind of response.
Also, before I begin, looks like Walmart carries this driver. How weird is that?
RCF LF21N551 Professional Low Frequency Transducer - Walmart.com
When size doesn't matter and you want a stack of 12 for 30 hz, front loaded horn is the only reasonable option. Here's a 27 hz full size ideal front loaded horn for 12 of these drivers with 1000 watts per driver (12000 per stack) into the 2.8 ohm load of the stack, shown without power compression or any filters.
The results look good and this big horn sim could be chopped into 12 modular units (Labhorn size, 45 x 45 x 22.5 inches) that have this response when stacked properly. But it should be noted that you can get pretty close to this with much less expensive 18 inch drivers.
Pic 1 - inputs
Pic 2 - schematic
Pic 3 - impedance, showing the minimum 2.8 ohm load of the stack through it's bandwidth
Pic 4 - spl
Pic 5 - displacement - without a high pass filter 1000 watts per cab is about as high as you can go - but with a hpf you could get a LOT louder in the upper bandwidth - also it could be tweaked in subtle ways to allow for quite a bit more power within xmax limits but I'm not getting into that right now
I'm not going to explain how to turn a sim like this into plans right now. But I should explain that individually these cabs won't have a response anything like this, so they need to all be used as a whole and stacked properly if you expect to see this kind of response.
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Basicly, were a group that organize outdoor free raves, not a big business! Why you think a front loaded horn is the only reasonable option?
Whenever I go through these 'exercises' I get slightly better efficiency numbers using 18's. That is, higher Zin for given SPL. Which means less heat and less AC current draw. They also seem to be less 'lumpy', but still rising smoothly, when the stack is undersized.
You want a driver with low QES, high BL and long xmax. The cone should be stiff, the specification should state that the driver is intended for horn use. 18 sound, Precision Devices and B&C speakers have lots to choose from.
If this is your first project, use an existing design. Read about the designs on the internet. Speakerplans was popular a few years ago. I preffer front loaded horns, but they get bigger than back loaded ones. A very nice backloaded horn is the hog scoop.
If this is your first project, use an existing design. Read about the designs on the internet. Speakerplans was popular a few years ago. I preffer front loaded horns, but they get bigger than back loaded ones. A very nice backloaded horn is the hog scoop.
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I made a front loaded design for 15" JBL 2226. It can be used with Faital Pro driver. You can stack them. Very easy to build.
build othorns with the b&C or 18 sound drivers. apply $20k in amplifiers, and $5-10k in generators.
Let the good times commence.
Let the good times commence.
As mentioned, with a small tweak (reduced rear chamber size) and it can take almost 2000 watts per cab within xmax without a high pass filter (shown at 2000 watts per cab, 1 mm past xmax).
But add a high pass filter and it can take almost 6000 watts per cab within xmax (shown with 6000 watts per cab, 1 mm past xmax). You won't be able to run at this level without a boatload of compression, but this shows what it takes to get to xmax in this design.
An externally hosted image should be here but it was not working when we last tested it.
But add a high pass filter and it can take almost 6000 watts per cab within xmax (shown with 6000 watts per cab, 1 mm past xmax). You won't be able to run at this level without a boatload of compression, but this shows what it takes to get to xmax in this design.
An externally hosted image should be here but it was not working when we last tested it.
For comparison to my design here's a 12 pack of Othorns with 2000 watts per cab.
Graph 1 - spl
Graph 2 - excursion
Graph 3 - real low knee
We know that tapped horns don't couple as well as front loaded, so graph 3 with the 35 hz low knee is probably closer to the real low knee a stack of Othorns will have, instead of the extended low knee shown in the multiple speakers sim (Graph 1). Compare this to my flh at 2000 watts in my last post. The Othorn isn't big enough to keep up.
When size is no object, use the size and make a full size ideal front loaded horn. It's hard to beat them.
An externally hosted image should be here but it was not working when we last tested it.
But assuming OP doesn't want to learn to fold, a 12 pack of Othorns is probably his best bet. Forgot to mention that.
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