I've been given some components that I want to use to build my home theatre sub.
I have various tools such as a jig saw, circular saw, drills etc and enough handyman skills to build things.
I want to build a sub box to place under my entertainment unit (400mm clearance). Possibly down-firing as I have kids with curious fingers.
I don't know where to start!
- Vifa M25W0-49
- Whatmough 150W plate amp.
- Sliding port
- Sheet of 18mm thick ply, 900mm x 2050mm
I have various tools such as a jig saw, circular saw, drills etc and enough handyman skills to build things.
I want to build a sub box to place under my entertainment unit (400mm clearance). Possibly down-firing as I have kids with curious fingers.
I don't know where to start!
Attachments
First thing is to get the paperwork on the drivers and plug the figures into a program that will give what you need to get started. Hopefully you will be able to make use of that port.
Well posting here was not a bad beginning!
- Here are specs for your woofers http://www.sea.vg/vifa/M25WO-49-08.pdf
- 10" is a decent beginning size for a subwoofer. The parameters are more for a woofer, the resonance is about like the Q, so a sealed box would die off below 70 Hz. You will have to use a vented box, likely "undertuned" to 30-36 Hz, which will give a slow rolloff with somewhat more bass than a sealed box wood. Hopefully room gain will help fill that in, or maybe EQ needed, or a specialized crossover.
- What are you going to use for a highpass crossover to your main speakers? What are your mains? What amplifier and so on?
- To help with the enclosure a picture and dimensions of your entertainment unit would help
- I don't like down firing setups due to this thing called "Gravity" which always wins in the end. It could be slot loaded though to keep away from little fingers, although my philosophy in that regard was to train my kid to keep the hell away.
Please tell us what kind of main speakers you use. The VIFA is a nice, high quality driver, but not really made for a sub. So is you got small mains and don't play loud anyway, it might be OK. Dont expect it to shake the walls with home cinema.
For the cabinet, you should have at least a volume of 70 liters, vented. Anything else will not be able to give any noticeable low output.
Even if you later decide the output is not enough, you can use a well build and braced cabinet with a "real" subwoofer.
70 liters internal volume will lead to a cube of 45cm on the outside. You may modify the size, so a 35x35x70cm will be just as good.
You got to decide what size you can fit in your room. To protect the cone, any kind of mash will do.
For the cabinet, you should have at least a volume of 70 liters, vented. Anything else will not be able to give any noticeable low output.
Even if you later decide the output is not enough, you can use a well build and braced cabinet with a "real" subwoofer.
70 liters internal volume will lead to a cube of 45cm on the outside. You may modify the size, so a 35x35x70cm will be just as good.
You got to decide what size you can fit in your room. To protect the cone, any kind of mash will do.
I also happen to be messing around with a down firing scenario at the moment, so this caught my attention. After playing with the equations a bit, I'm inclined to ask if the Adire approach is unnecessarily complex if a sag estimate is all one is interested in. The Google AI Overlord suggested the following, which gives essentially the same result (unless I screwed something up in my spreadsheet):
Sag Percentage = 24,849 / (Xmax * Fs^2)
Xmax: Maximum linear excursion of the voice coil (mm)
Fs: Free-air resonant frequency of the woofer (Hz)
With these sort of question, I have to ask if you know how you plan wire this?
You have options with the plate amp. You have high and line level inputs. If you use the high levels, you don’t need to xo your mains as that is done for you by the plate amp.
If your mains are robust, you won’t need to xo at all and if they are small speakers sometimes a simple capacitor will suffice.
If you are using the high levels, you want to acquire a new nut to replace the missing one.
You have options with the plate amp. You have high and line level inputs. If you use the high levels, you don’t need to xo your mains as that is done for you by the plate amp.
If your mains are robust, you won’t need to xo at all and if they are small speakers sometimes a simple capacitor will suffice.
If you are using the high levels, you want to acquire a new nut to replace the missing one.
