DIY subwoofer

rubberduck · 7 Apr 2020 at 13:35

Anyone done this or looked in to it? I know the downsides in terms of being left with something with little residual value and not saving much money over buying something off the shelf. Still keen to explore it though as would really enjoy the planning and crafting aspect associated with it, with the end result being less important. I have seen a few guides which are USA centric, really looking for components that can be obtained easily in the UK to spec something out.

Kei · 9 Apr 2020 at 13:29

Done it twice now. First one I built for GCSE technology 17 years ago. Still working and in use today. The exterior is a bit battered now as it spent a few years in the boot of the car.

I upgraded the drive unit a few years ago from the cheap car audio sub I had, which provided a good improvement. It uses an old MCM custom audio class AB 250W plate amp and a SEAS L26ROY driver. It looks a bit odd as the photo is showing the base with the feet as this is a downward firing design with a front facing port. The aluminium feet raise the sub up so it has room to breath.

Version 2 I built specifically for the car, which ironically, looks substantially nicer. This has no built in amplifier as it's run from a car amp (old alpine MRV-1000 bridged giving around 450W) and uses a Dayton RSS265HO-4.

Both of the above were designed using winISD modelling software as they are both ported and this requires careful driver, cabinet and port tuning. I don't tend to bother trying to tune for sub 20Hz as I don't care for movie LF. A -3dB point of around 20-25Hz does me just fine. Sure a bought one might model better, but I prefer the fun of building them.

hornetstinger · 9 Apr 2020 at 13:33

In theory a sealed sub is much easier to build, no?

Kei · 9 Apr 2020 at 22:35

hornetstinger said:
In theory a sealed sub is much easier to build, no?

In theory, yes it is simpler to design an infinite baffle sub vs a vented one. It does still require choosing an appropriate driver with thiele small parameters that suit sealed enclosures and the enclosure still needs to be of an appropriate volume too.

rubberduck · 10 Apr 2020 at 00:04

Kei said:
In theory, yes it is simpler to design an infinite baffle sub vs a vented one. It does still require choosing an appropriate driver with thiele small parameters that suit sealed enclosures and the enclosure still needs to be of an appropriate volume too.

I'm confused.... A sealed sub is very different from an infinite baffle sub is it not??? My understanding is that a sealed sub is a contained box while an infinite baffle sub you essentially use the cavities within your building act as the subwoofer enclosure???

Kei · 10 Apr 2020 at 09:14

Technically, they are one and the same. You are right insofar as people now seem to commonly refer to infinite baffle in the way you describe. I didn’t come across this back when I learned a lot of the theory during my GCSEs. Infinite baffle was used to describe sealed back then. This describes it better than I could.
https://www.diyaudio.com/forums/full-range/139738-infinite-baffle-vs-sealed-enclosure.html

rubberduck · 11 Apr 2020 at 13:20

If going down the budget, home theatre route with an external amplifier what brands/models should I keep an eye out for second hand?

goonerfromlag · 22 Apr 2020 at 15:24

Behringer amps give the best bang for buck, used crowns xls models though less, have silent cooling so don't require fan mods. Your choices/options will be determined by the drivers you intend to use.

goonerfromlag · 22 Apr 2020 at 15:31

Still using my diy build from 2016; got a pair of used audiobahn Aw150t drivers for ~£70, got two 21 inch mdf boxes built for £120ish and a used crown xls1000 for £150. Have only got the one sub in use due to lack of space so far but I'm chuffed with it.