Has anybody made DIY active bass traps using cheap subwoofers?

[Scoox]

In 2-3 weeks' time I might give it a try with a 15" sealed speaker and with DSP (with no servo unfortunately)

Nice! If you give it a go let us know. I think the servo part probably just makes the system more responsive? TBH I don't know what difference it makes, since the whole system is a feedback loop going through the microphone anyway. Perhaps the servo feedback loop tightens things a little more, but that's ok, the first step is to validate the theory.

The Yamaha NS-SW100 is a ported 10" sub that features active servo technology and it only costs $200. My Genelec subs also use 10" drivers so they are equivalent in size. A couple of these at the back of my room with a cheap microphone and preamp might do the trick.

 

[Scoox]

Hmm, interesting. I'm sure there's got to be some filtering to linearize the response of this thing, but maybe your original idea would work better than I thought at first. If the frequency response of the mic and the sub aren't matched properly, you could still get feedback even if you invert the signal.

I think there's a big clue on the AVAA product page, which is that you need to place it "where the modes are". In that case I guess if you place it exactly at a peak, the job is simply to reduce the bass SPL by 50% at that location. (I think??) As long as your frequency responses line up, I guess it could be that simple.

In my mind, you would be placing the sub at an arbitrary location, more like how Dirac ART works. In that case, I think you would need to make significant adjustments to the response of the cancellation sub to make it do what you want.

Anyway, I am mostly talking out of my ear here - I think it's an interesting idea and I'd love to follow the thread if you actually try it.

My guess is that you can put it anywhere you like, but you want to put it where it's most effective. If you put it on a spot where max air pressure is half the max air pressure in the room, then you are only going to get 50% efficiency.

 

[ppataki]

Nice! If you give it a go let us know. I think the servo part probably just makes the system more responsive? TBH I don't know what difference it makes, since the whole system is a feedback loop going through the microphone anyway. Perhaps the servo feedback loop tightens things a little more, but that's ok, the first step is to validate the theory.

The Yamaha NS-SW100 is a ported 10" sub that features active servo technology and it only costs $200. My Genelec subs also use 10" drivers so they are equivalent in size. A couple of these at the back of my room with a cheap microphone and preamp might do the trick.

I will definitely try it sometime next month (I need to wait for my new amp to arrive first)
I will use one of these speakers (all my designs have sealed cabinets) for this test, will put it in the corner of my home office where I have this system
I will post here the measurements too

 

[Scoox]

I will definitely try it sometime next month (I need to wait for my new amp to arrive first)
I will use one of these speakers (all my designs have sealed cabinets) for this test, will put it in the corner of my home office where I have this system
I will post here the measurements too

Thanks. BTW that system looks classy AF.